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8078675aae
ORCA-C/DAG.pas
Stephen Heumann 8078675aae Do not eliminate expressions with side effects in "exp | -1" or "exp & 0". 
This was previously happening in intermediate code peephole optimization.

The following example program demonstrates the problem:

#pragma optimize 1
int main(void) {
        int i = 0;
        long j = 0;
        ++i | -1;
        ++i & 0;
        ++j | -1;
        ++j & 0;
        return i+j; /* should be 4 */
}
2021-02-11 14:50:36 -06:00

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{$optimize 7}
{---------------------------------------------------------------}
{ }
{ DAG Creation }
{ }
{ Places intermediate codes into DAGs and trees. }
{ }
{---------------------------------------------------------------}
unit DAG;
interface
{$segment 'CG'}
{$LibPrefix '0/obj/'}
uses CCommon, CGI, CGC, Gen;
{---------------------------------------------------------------}
procedure DAG (code: icptr);
{ place an op code in a DAG or tree }
{ }
{ parameters: }
{ code - opcode }
function TypeOf (op: icptr): baseTypeEnum;
{---------------------------------------------------------------}
implementation
var
c_ind: iclist; {vars that can be changed by indirect stores}
maxLoc: integer; {max local label number used by compiler}
memberOp: icptr; {operation found by Member}
optimizations: array[pcodes] of integer; {starting indexes into peeptable}
peepTablesInitialized: boolean; {have the peephole tables been initialized?}
rescan: boolean; {redo the optimization pass?}
{-- External unsigned math routines; imported from Expression.pas --}
function udiv (x,y: longint): longint; extern;
function umod (x,y: longint): longint; extern;
function umul (x,y: longint): longint; extern;
{---------------------------------------------------------------}
function CodesMatch (op1, op2: icptr; exact: boolean): boolean;
{ Check to see if the trees op1 and op2 are equivalent }
{ }
{ parameters: }
{ op1, op2 - trees to check }
{ exact - is an exact match of operands required? }
{ }
{ Returns: True if trees are equivalent, else false. }
function LongStrCmp (s1, s2: longStringPtr): boolean;
{ Are the strings s1 and s2 equal? }
{ }
{ parameters: }
{ s1, s2 - strings to compare }
{ }
{ Returns: True if the strings are equal, else false }
label 1;
var
i: integer; {loop/index variable}
begin {LongStrCmp}
LongStrCmp := false;
if s1^.length = s2^.length then begin
for i := 1 to s1^.length do
if s1^.str[i] <> s2^.str[i] then
goto 1;
LongStrCmp := true;
end; {if}
1:
end; {LongStrCmp}
function OpsEqual (op1, op2: icptr): boolean;
{ See if the operands are equal }
{ }
{ parameters: }
{ op1, op2 - operations to check }
{ }
{ Returns: True if the operands are equivalent, else }
{ false. }
var
result: boolean; {temp result}
begin {OpsEqual}
result := false;
case op1^.opcode of
pc_cup, pc_cui, pc_tl1, pc_bno:
{this rule prevents optimizations from removing sensitive operations}
;
pc_adi, pc_adl, pc_adr, pc_and, pc_lnd, pc_bnd, pc_bal, pc_bor,
pc_blr, pc_bxr, pc_blx, pc_equ, pc_neq, pc_ior, pc_lor, pc_mpi,
pc_umi, pc_mpl, pc_uml, pc_mpr: begin
if op1^.left = op2^.left then
if op1^.right = op2^.right then
result := true;
if not result then
if op1^.left = op2^.right then
if op1^.right = op2^.left then
result := true;
if not result then
if not exact then
if CodesMatch(op1^.left, op2^.left, false) then
if CodesMatch(op1^.right, op2^.right, false) then
result := true;
if not result then
if not exact then
if CodesMatch(op1^.left, op2^.right, false) then
if CodesMatch(op1^.right, op2^.left, false) then
result := true;
end;
otherwise: begin
if op1^.left = op2^.left then
if op1^.right = op2^.right then
result := true;
if not result then
if not exact then
if CodesMatch(op1^.left, op2^.left, false) then
if CodesMatch(op1^.right, op2^.right, false) then
result := true;
end;
end; {case}
OpsEqual := result;
end; {OpsEqual}
begin {CodesMatch}
CodesMatch := false;
if op1 = op2 then
CodesMatch := true
else if (op1 <> nil) and (op2 <> nil) then
if op1^.opcode = op2^.opcode then
if op1^.q = op2^.q then
if op1^.r = op2^.r then
if op1^.s = op2^.s then
if (op1^.lab = op2^.lab) or (op1^.lab^ = op2^.lab^) then
if OpsEqual(op1, op2) then
if op1^.optype = op2^.optype then
case op1^.optype of
cgByte, cgUByte, cgWord, cgUWord:
if op1^.opnd = op2^.opnd then
if op1^.llab = op2^.llab then
if op1^.slab = op2^.slab then
CodesMatch := true;
cgLong, cgULong:
if op1^.lval = op2^.lval then
CodesMatch := true;
cgReal, cgDouble, cgComp, cgExtended:
if op1^.rval = op2^.rval then
CodesMatch := true;
cgString:
CodesMatch := LongStrCmp(op1^.str, op2^.str);
cgVoid, ccPointer:
if op1^.pval = op2^.pval then
CodesMatch := LongStrCmp(op1^.str, op2^.str);
end; {case}
end; {CodesMatch}
{- Peephole Optimization ---------------------------------------}
function Base (val: longint): integer;
{ Assuming val is a power of 2, find ln(val) base 2 }
{ }
{ parameters: }
{ val - value for which to find the base }
{ }
{ Returns: ln(val), base 2 }
var
i: integer; {base counter}
begin {Base}
i := 0;
while not odd(val) do begin
val := val >> 1;
i := i+1;
end; {while}
Base := i;
end; {Base}
procedure BinOps (var op1, op2: icptr);
{ Make sure the operands are of the same type }
{ }
{ parameters: }
{ op1, op2: two pc_ldc operands }
var
opt1, opt2: baseTypeEnum; {temp operand types}
begin {BinOps}
opt1 := op1^.optype;
opt2 := op2^.optype;
if opt1 = cgByte then begin
op1^.optype := cgWord;
opt1 := cgWord;
end {if}
else if opt1 = cgUByte then begin
op1^.optype := cgUWord;
opt1 := cgUWord;
end {else if}
else if opt1 in [cgReal, cgDouble, cgComp] then begin
op1^.optype := cgExtended;
opt1 := cgExtended;
end; {else if}
if opt2 = cgByte then begin
op2^.optype := cgWord;
opt2 := cgWord;
end {if}
else if opt2 = cgUByte then begin
op2^.optype := cgUWord;
opt2 := cgUWord;
end {else if}
else if opt2 in [cgReal, cgDouble, cgComp] then begin
op2^.optype := cgExtended;
opt2 := cgExtended;
end; {else if}
if opt1 <> opt2 then begin
case opt1 of
cgWord:
case opt2 of
cgUWord:
op1^.optype := cgUWord;
cgLong, cgULong: begin
op1^.lval := op1^.q;
op1^.optype := opt2;
end;
cgExtended: begin
op1^.rval := op1^.q;
op1^.optype := cgExtended;
end;
otherwise: ;
end; {case}
cgUWord:
case opt2 of
cgWord:
op2^.optype := cgUWord;
cgLong, cgULong: begin
op1^.lval := ord4(op1^.q) & $0000FFFF;
op1^.optype := opt2;
end;
cgExtended: begin
op1^.rval := ord4(op1^.q) & $0000FFFF;
op1^.optype := cgExtended;
end;
otherwise: ;
end; {case}
cgLong:
case opt2 of
cgWord: begin
op2^.lval := op2^.q;
op2^.optype := cgLong;
end;
cgUWord: begin
op2^.lval := ord4(op2^.q) & $0000FFFF;
op2^.optype := cgLong;
end;
cgULong:
op1^.optype := cgULong;
cgExtended: begin
op1^.rval := op1^.lval;
op1^.optype := cgExtended;
end;
otherwise: ;
end; {case}
cgULong:
case opt2 of
cgWord: begin
op2^.lval := op2^.q;
op2^.optype := cgLong;
end;
cgUWord: begin
op2^.lval := ord4(op2^.q) & $0000FFFF;
op2^.optype := cgLong;
end;
cgLong:
op2^.optype := cgULong;
cgExtended: begin
op1^.rval := op1^.lval;
if op1^.rval < 0.0 then
op1^.rval := 4294967296.0 + op1^.rval;
op1^.optype := cgExtended;
end;
otherwise: ;
end; {case}
cgExtended: begin
case opt2 of
cgWord:
op2^.rval := op2^.q;
cgUWord:
op2^.rval := ord4(op2^.q) & $0000FFFF;
cgLong:
op2^.rval := op2^.lval;
cgULong: begin
op2^.rval := op2^.lval;
if op2^.rval < 0.0 then
op2^.rval := 4294967296.0 + op2^.rval;
end;
otherwise: ;
end; {case}
op2^.optype := cgExtended;
end;
otherwise: ;
end; {case}
end; {if}
end; {BinOps}
procedure CheckLabels;
{ remove unused dc_lab labels }
var
lop: icptr; {predecessor of op}
op: icptr; {used to trace the opcode list}
function Used (lab: integer): boolean;
{ see if a label is used }
{ }
{ parameters: }
{ lab - label number to check }
{ }
{ Returns: True if the label is used, else false. }
var
found: boolean; {was the label found?}
op: icptr; {used to trace the opcode list}
begin {Used}
found := false;
op := DAGhead;
while (not found) and (op <> nil) do begin
if op^.opcode in [pc_add, pc_fjp, pc_tjp, pc_ujp] then
found := op^.q = lab
else if op^.opcode = pc_nat then
found := true;
op := op^.next;
end; {while}
Used := found;
end; {Used}
begin {CheckLabels}
op := DAGhead;
while op^.next <> nil do begin
lop := op;
op := op^.next;
if op^.opcode = dc_lab then
if not Used(op^.q) then begin
lop^.next := op^.next;
op := lop;
rescan := true;
end; {if}
end; {while}
end; {CheckLabels}
procedure RemoveDeadCode (op: icptr);
{ remove dead code following an unconditional branch }
{ }
{ parameters: }
{ op - unconditional branch opcode }
begin {RemoveDeadCode}
while not (op^.next^.opcode in [dc_lab, dc_enp, dc_cns, dc_glb,
dc_dst, dc_str, dc_pin, pc_ent, dc_loc, dc_prm, dc_sym]) do begin
op^.next := op^.next^.next;
rescan := true;
end; {while}
end; {RemoveDeadCode}
function NoFunctions (op: icptr): boolean;
{ are there any function calls? }
{ }
{ parameters: }
{ op - operation tree to search }
{ }
{ returns: True if there are no pc_cup or pc_cui operations }
{ in the tree, else false. }
begin {NoFunctions}
if op = nil then
NoFunctions := true
else if op^.opcode in [pc_cup,pc_cui,pc_tl1] then
NoFunctions := false
else
NoFunctions := NoFunctions(op^.left) or NoFunctions(op^.right);
end; {NoFunctions}
function OneBit (val: longint): boolean;
{ See if there is exactly one bit set in val }
{ }
{ parameters: }
{ val - value to check }
{ }
{ Returns: True if exactly one bit is set, else false }
begin {OneBit}
if val = 0 then
OneBit := false
else begin
while not odd(val) do
val := val >> 1;
OneBit := val = 1;
end; {else}
end; {OneBit}
procedure PeepHoleOptimization (var opv: icptr);
{ do peephole optimization on a list of opcodes }
{ }
{ parameters: }
{ opv - pointer to the first opcode }
{ }
{ Notes: }
{ 1. Many optimizations assume the children have already }
{ been optimized. In particular, many optimizations }
{ depend on pc_ldc operands being on a specific side of }
{ a child's expression tree. (e.g. pc_fjp and pc_equ) }
var
done: boolean; {optimization done test}
doit: boolean; {should we do the optimization?}
lq, lval: longint; {temps for long calculations}
op2,op3: icptr; {temp opcodes}
op: icptr; {copy of op (for efficiency)}
opcode: pcodes; {temp opcode}
optype: baseTypeEnum; {temp optype}
q: integer; {temp for integer calculations}
rval: double; {temp for real calculations}
fromtype, totype, firstType: record {for converting numbers to optypes}
case boolean of
true: (i: integer);
false: (optype: baseTypeEnum);
end;
function SideEffects (op: icptr): boolean;
{ Check a tree for operations that have side effects }
{ }
{ parameters: }
{ op - tree to check }
var
result: boolean; {temp result}
begin {SideEffects}
if op = nil then begin
if volatile then
SideEffects := true
else
SideEffects := false
end {if}
else if op^.opcode in
[pc_mov,pc_cbf,pc_cop,pc_cpi,pc_cpo,pc_gil,pc_gli,pc_gdl,
pc_gld,pc_iil,pc_ili,pc_idl,pc_ild,pc_lil,pc_lli,pc_ldl,
pc_lld,pc_sbf,pc_sro,pc_sto,pc_str,pc_cui,pc_cup,pc_tl1] then
SideEffects := true
else if op^.opcode = pc_ldc then
SideEffects := false
else
SideEffects := SideEffects(op^.left) or SideEffects(op^.right);
end; {SideEffects}
procedure JumpOptimizations (op: icptr; newOpcode: pcodes);
{ handle common code for jump optimizations }
{ }
{ parameters: }
{ op - jump opcode }
{ newOpcode - opcode to use if the jump sense is reversed }
var
done: boolean; {optimization done test}
topcode: pcodes; {temp opcode}
begin {JumpOptimizations}
topcode := op^.left^.opcode;
if topcode = pc_not then begin
op^.left := op^.left^.left;
op^.opcode := newOpcode;
PeepHoleOptimization(opv);
end {else if}
else if topcode in [pc_neq,pc_equ] then begin
with op^.left^.right^ do
if opcode = pc_ldc then
if optype in [cgByte,cgUByte,cgWord,cgUWord] then
if q = 0 then begin
op^.left := op^.left^.left;
if topcode = pc_equ then
op^.opcode := newOpcode;
end; {if}
end; {else if}
if op^.next^.opcode = dc_lab then
if op^.next^.q = op^.q then
if not SideEffects(op^.left) then begin
rescan := true;
opv := op^.next;
end; {else if}
end; {JumpOptimizations}
procedure RealStoreOptimizations (op, opl: icptr);
{ do strength reductions associated with stores of reals }
{ }
{ parameters: }
{ op - real store to optimize }
{ opl - load operand for the store operation }
var
disp: 0..9; {disp to the word to change}
same: boolean; {are the operands the same?}
op2: icptr; {new opcode}
opt: icptr; {temp opcode}
cnvrl: record {for stuffing a real in a long space}
case boolean of
true: (lval: longint);
false: (rval: real);
end;
begin {RealStoreOptimizations}
if opl^.opcode = pc_ngr then begin
same := false;
with opl^.left^ do
if op^.opcode = pc_sro then begin
if opcode = pc_ldo then
if q = op^.q then
if optype = op^.optype then
if lab^ = op^.lab^ then
same := true;
end {if}
else {if op^.opcode = pc_str then}
if opcode = pc_lod then
if q = op^.q then
if r = op^.r then
if optype = op^.optype then
same := true;
if same then begin
case op^.optype of
cgReal: disp := 3;
cgDouble: disp := 7;
cgExtended: disp := 9;
cgComp: disp := 11;
end; {case}
opl^.left^.optype := cgWord;
opl^.left^.q := opl^.left^.q + disp;
op^.optype := cgWord;
op^.q := op^.q + disp;
op2 := pointer(Calloc(sizeof(intermediate_code)));
op2^.opcode := pc_ldc;
op2^.optype := cgWord;
op2^.q := $0080;
opl^.right := op2;
opl^.opcode := pc_bxr;
end {if}
else if op^.optype = cgReal then begin
opt := opl^.left;
if opt^.opcode in [pc_ind,pc_ldo,pc_lod] then
if opt^.optype = cgReal then begin
opt^.optype := cgLong;
op^.optype := cgLong;
op2 := pointer(Calloc(sizeof(intermediate_code)));
op2^.opcode := pc_ldc;
op2^.optype := cgLong;
op2^.lval := $80000000;
opl^.right := op2;
opl^.opcode := pc_blx;
end; {if}
end; {else if}
end {if}
else if op^.optype = cgReal then begin
if opl^.opcode = pc_ldc then begin
cnvrl.rval := opl^.rval;
opl^.lval := cnvrl.lval;
opl^.optype := cgLong;
op^.optype := cgLong;
end {if}
else if opl^.opcode in [pc_ind,pc_ldo,pc_lod] then
if opl^.optype = cgReal then begin
opl^.optype := cgLong;
op^.optype := cgLong;
end; {if}
end; {if}
end; {RealStoreOptimizations}
procedure ReplaceLoads (ldop, stop, tree: icptr);
{ Replace any pc_lod operations in tree that load from the }
{ location stored to by the pc_str operation stop by ldop }
{ }
{ parameters: }
{ ldop - operation to replace the pc_lods with }
{ stop - pc_str operation }
{ tree - tree to check for pc_lod operations }
{ }
{ Notes: ldop must be an instruction, not a tree }
begin {ReplaceLoads}
if tree^.left <> nil then
ReplaceLoads(ldop, stop, tree^.left);
if tree^.right <> nil then
ReplaceLoads(ldop, stop, tree^.right);
if tree^.opcode = pc_lod then
if tree^.optype = stop^.optype then
if tree^.q = stop^.q then
if tree^.r = stop^.r then
tree^ := ldop^;
end; {ReplaceLoads}
procedure ReverseChildren (op: icptr);
{ reverse the children of a node }
{ }
{ parameters: }
{ op - node for which to reverse the children }
var
opt: icptr; {temp opcode pointer}
begin {ReverseChildren}
opt := op^.right;
op^.right := op^.left;
op^.left := opt;
end; {ReverseChildren}
procedure ZeroIntermediateCode (op: icptr);
{ Set all fields in the record to 0, nil, etc. }
{ }
{ Parameters: }
{ op - intermediate code record to clear }
begin {ZeroIntermediateCode}
op^.q := 0;
op^.r := 0;
op^.s := 0;
op^.lab := nil;
op^.next := nil;
op^.left := nil;
op^.right := nil;
op^.optype := cgWord;
op^.opnd := 0;
op^.llab := 0;
op^.slab := 0;
end; {ZeroIntermediateCode}
begin {PeepHoleOptimization}
{if printSymbols then begin write('Optimize: '); WriteCode(opv); end; {debug}
op := opv; {copy for efficiency}
if op^.left <> nil then {optimize the children}
PeepHoleOptimization(op^.left);
if op^.right <> nil then
PeepHoleOptimization(op^.right);
case op^.opcode of {check for optimizations of this node}
pc_add: begin {pc_add}
if op^.next^.opcode <> pc_add then
RemoveDeadCode(op);
end; {case pc_add}
pc_adi: begin {pc_adi}
if (op^.right^.opcode = pc_ldc) and (op^.left^.opcode = pc_ldc) then begin
op^.left^.q := op^.left^.q + op^.right^.q;
opv := op^.left;
end {if}
else begin
if op^.left^.opcode = pc_ldc then
ReverseChildren(op);
if op^.right^.opcode = pc_ldc then begin
q := op^.right^.q;
if q = 0 then
opv := op^.left
else if q > 0 then begin
op^.opcode := pc_inc;
op^.q := q;
op^.right := nil;
end {else if}
else {if q < 0 then} begin
op^.opcode := pc_dec;
op^.q := -q;
op^.right := nil;
end; {else if}
end {if}
else if CodesMatch(op^.left, op^.right, false) then begin
if not SideEffects(op^.left) then begin
ZeroIntermediateCode(op^.right);
with op^.right^ do begin
opcode := pc_ldc;
q := 1;
optype := cgWord;
end; {with}
op^.opcode := pc_shl;
PeepHoleOptimization(opv);
end; {if}
end {else if}
else if op^.left^.opcode in [pc_inc,pc_dec] then begin
if op^.right^.opcode in [pc_inc,pc_dec] then begin
op2 := op^.left;
if op2^.opcode = pc_inc then
q := op2^.q
else
q := -op2^.q;
if op^.right^.opcode = pc_inc then
q := q + op^.right^.q
else
q := q - op^.right^.q;
if q >= 0 then begin
op2^.opcode := pc_inc;
op2^.q := q;
end {if}
else begin
op2^.opcode := pc_dec;
op2^.q := -q;
end; {else}
op^.left := op^.left^.left;
op^.right := op^.right^.left;
op2^.left := op;
opv := op2;
PeepHoleOptimization(opv);
end; {if}
end; {else if}
end; {else}
end; {case pc_adi}
pc_adl: begin {pc_adl}
if (op^.right^.opcode = pc_ldc) and (op^.left^.opcode = pc_ldc) then begin
op^.left^.lval := op^.left^.lval + op^.right^.lval;
opv := op^.left;
end {if}
else begin
done := false;
if op^.left^.opcode = pc_ldc then
ReverseChildren(op);
if op^.right^.opcode = pc_ldc then begin
lval := op^.right^.lval;
if lval = 0 then begin
opv := op^.left;
done := true;
end {if}
else if (lval >= 0) and (lval <= maxint) then begin
op^.opcode := pc_inc;
op^.optype := cgLong;
op^.q := ord(lval);
op^.right := nil;
done := true;
end {else if}
else if (lval > -maxint) and (lval < 0) then begin
op^.opcode := pc_dec;
op^.optype := cgLong;
op^.q := -ord(lval);
op^.right := nil;
done := true;
end; {else if}
end {if}
else if CodesMatch(op^.left, op^.right, false) then
if not SideEffects(op^.left) then begin
ZeroIntermediateCode(op^.right);
with op^.right^ do begin
opcode := pc_ldc;
lval := 1;
optype := cgLong;
end; {with}
op^.opcode := pc_sll;
done := true;
end; {if}
if not done and (op^.right^.opcode in [pc_lao,pc_lda,pc_ixa]) then
ReverseChildren(op);
if not done and (op^.left^.opcode in [pc_lao,pc_lda,pc_ixa]) then
if op^.right^.opcode = pc_sll then begin
if op^.right^.right^.opcode = pc_ldc then
if (op^.right^.right^.lval & $FFFF8000) = 0 then
if op^.right^.left^.opcode = pc_cnv then begin
fromtype.i := (op^.right^.left^.q & $00F0) >> 4;
if fromType.optype in [cgByte,cgUByte,cgWord,cgUWord] then
if op^.left^.opcode = pc_lda then
begin
if fromType.optype = cgByte then
op^.right^.left^.q := $02
else if fromType.optype = cgUByte then
op^.right^.left^.q := $13
else
op^.right^.left := op^.right^.left^.left;
with op^.right^.right^ do begin
lq := lval;
lval := 0;
q := long(lq).lsw;
optype := cgUWord;
end; {with}
op^.right^.opcode := pc_shl;
op^.opcode := pc_ixa;
if fromType.optype in [cgByte,cgWord] then
op^.optype := cgWord
else
op^.optype := cgUWord;
PeepHoleOptimization(opv);
end; {if}
end; {if}
end {if}
else if op^.right^.opcode = pc_cnv then begin
fromtype.i := (op^.right^.q & $00F0) >> 4;
if fromtype.optype in [cgByte,cgUByte,cgWord,cgUWord] then begin
if fromType.optype = cgByte then
op^.right^.q := $02
else if fromType.optype = cgUByte then
op^.right^.q := $13
else
op^.right := op^.right^.left;
op^.opcode := pc_ixa;
if fromType.optype in [cgByte,cgWord] then
op^.optype := cgWord
else
op^.optype := cgUWord;
PeepHoleOptimization(opv);
end; {if}
end; {else if}
end; {else}
end; {case pc_adl}
pc_adr: begin {pc_adr}
if (op^.right^.opcode = pc_ldc) and (op^.left^.opcode = pc_ldc) then begin
op^.left^.rval := op^.left^.rval + op^.right^.rval;
opv := op^.left;
end {if}
else begin
if op^.left^.opcode = pc_ldc then
ReverseChildren(op);
if op^.right^.opcode = pc_ldc then begin
if op^.right^.rval = 0.0 then
opv := op^.left;
end; {if}
end; {else}
end; {case pc_adr}
pc_and: begin {pc_and}
if op^.right^.opcode = pc_ldc then begin
if op^.left^.opcode = pc_ldc then begin
op^.left^.q := ord((op^.left^.q <> 0) and (op^.right^.q <> 0));
opv := op^.left;
end {if}
else begin
if op^.right^.q = 0 then
if not SideEffects(op^.left) then
opv := op^.right;
end {else}
end {if}
else if op^.left^.opcode = pc_ldc then
if op^.left^.q = 0 then
opv := op^.left;
end; {case pc_and}
pc_bal: begin {pc_bal}
if op^.left^.opcode = pc_ldc then
ReverseChildren(op);
if op^.left^.opcode = pc_ldc then begin
op^.left^.lval := op^.left^.lval & op^.right^.lval;
opv := op^.left;
end {if}
else if op^.right^.opcode = pc_ldc then begin
if op^.right^.lval = 0 then begin
if not SideEffects(op^.left) then
opv := op^.right;
end {if}
else if op^.right^.lval = -1 then
opv := op^.left;
end; {else if}
end; {case pc_bal}
pc_blr: begin {pc_blr}
if op^.left^.opcode = pc_ldc then
ReverseChildren(op);
if op^.left^.opcode = pc_ldc then begin
op^.left^.lval := op^.left^.lval | op^.right^.lval;
opv := op^.left;
end {if}
else if op^.right^.opcode = pc_ldc then begin
if op^.right^.lval = -1 then begin
if not SideEffects(op^.left) then
opv := op^.right;
end {if}
else if op^.right^.lval = 0 then
opv := op^.left;
end; {else if}
end; {case pc_blr}
pc_blx: begin {pc_blx}
if op^.left^.opcode = pc_ldc then
ReverseChildren(op);
if op^.left^.opcode = pc_ldc then begin
op^.left^.lval := op^.left^.lval ! op^.right^.lval;
opv := op^.left;
end {if}
else if op^.right^.opcode = pc_ldc then begin
if op^.right^.lval = 0 then
opv := op^.left
else if op^.right^.lval = -1 then begin
op^.opcode := pc_bnl;
op^.right := nil;
end; {else if}
end; {else if}
end; {case pc_blx}
pc_bnd: begin {pc_bnd}
if op^.left^.opcode = pc_ldc then
ReverseChildren(op);
if op^.left^.opcode = pc_ldc then begin
op^.left^.q := op^.left^.q & op^.right^.q;
opv := op^.left;
end {if}
else if op^.right^.opcode = pc_ldc then begin
if op^.right^.q = 0 then begin
if not SideEffects(op^.left) then
opv := op^.right;
end {if}
else if op^.right^.q = -1 then
opv := op^.left;
end; {else if}
end; {case pc_bnd}
pc_bnl: begin {pc_bnl}
if op^.left^.opcode = pc_ldc then begin
op^.left^.lval := op^.left^.lval ! $FFFFFFFF;
opv := op^.left;
end; {if}
end; {case pc_bnl}
pc_bno: begin {pc_bno}
{Invalid optimization disabled}
{if op^.left^.opcode = pc_str then
if op^.left^.left^.opcode in [pc_lda,pc_lao] then begin
ReplaceLoads(op^.left^.left, op^.left, op^.right);
opv := op^.right;
end;} {if}
end; {case pc_bno}
pc_bnt: begin {pc_bnt}
if op^.left^.opcode = pc_ldc then begin
op^.left^.q := op^.left^.q ! $FFFF;
opv := op^.left;
end; {if}
end; {case pc_bnt}
pc_bor: begin {pc_bor}
if op^.left^.opcode = pc_ldc then
ReverseChildren(op);
if op^.left^.opcode = pc_ldc then begin
op^.left^.q := op^.left^.q | op^.right^.q;
opv := op^.left;
end {if}
else if op^.right^.opcode = pc_ldc then begin
if op^.right^.q = -1 then begin
if not SideEffects(op^.left) then
opv := op^.right;
end {if}
else if op^.right^.q = 0 then
opv := op^.left;
end; {else if}
end; {case pc_bor}
pc_bxr: begin {pc_bxr}
if op^.left^.opcode = pc_ldc then
ReverseChildren(op);
if op^.left^.opcode = pc_ldc then begin
op^.left^.q := op^.left^.q ! op^.right^.q;
opv := op^.left;
end {if}
else if op^.right^.opcode = pc_ldc then begin
if op^.right^.q = 0 then
opv := op^.left
else if op^.right^.q = -1 then begin
op^.opcode := pc_bnt;
op^.right := nil;
end; {else if}
end; {else if}
end; {case pc_bxr}
pc_cnv: begin {pc_cnv}
fromtype.i := (op^.q & $00F0) >> 4;
totype.i := op^.q & $000F;
if (fromtype.optype = cgWord) and (TypeOf(op^.left) = cgUByte) then begin
fromType.optype := cgUWord;
op^.q := (op^.q & $FF0F) | (fromtype.i << 4);
end; {if}
if op^.left^.opcode = pc_ldc then begin
case fromtype.optype of
cgByte,cgWord:
case totype.optype of
cgByte,cgUByte,cgWord,cgUWord: ;
cgLong,cgULong: begin
lval := op^.left^.q;
op^.left^.q := 0;
op^.left^.lval := lval;
end;
cgReal,cgDouble,cgComp,cgExtended: begin
rval := op^.left^.q;
op^.left^.q := 0;
op^.left^.rval := rval;
end;
otherwise: ;
end; {case}
cgUByte,cgUWord:
case totype.optype of
cgByte,cgUByte,cgWord,cgUWord: ;
cgLong,cgULong: begin
lval := ord4(op^.left^.q) & $0000FFFF;
op^.left^.q := 0;
op^.left^.lval := lval;
end;
cgReal,cgDouble,cgComp,cgExtended: begin
rval := ord4(op^.left^.q) & $0000FFFF;
op^.left^.q := 0;
op^.left^.rval := rval;
end;
otherwise: ;
end; {case}
cgLong:
case totype.optype of
cgByte,cgUByte,cgWord,cgUWord: begin
q := long(op^.left^.lval).lsw;
op^.left^.lval := 0;
op^.left^.q := q;
end;
cgLong, cgULong: ;
cgReal,cgDouble,cgComp,cgExtended: begin
rval := op^.left^.lval;
op^.left^.lval := 0;
op^.left^.rval := rval;
end;
otherwise: ;
end; {case}
cgULong:
case totype.optype of
cgByte,cgUByte,cgWord,cgUWord: begin
q := long(op^.left^.lval).lsw;
op^.left^.lval := 0;
op^.left^.q := q;
end;
cgLong, cgULong: ;
cgReal,cgDouble,cgComp,cgExtended: begin
lval := op^.left^.lval;
op^.left^.lval := 0;
if lval >= 0 then
rval := lval
else
rval := (lval & $7FFFFFFF) + 2147483648.0;
op^.left^.rval := rval;
end;
otherwise: ;
end; {case}
cgReal,cgDouble,cgComp,cgExtended: begin
rval := op^.left^.rval;
case totype.optype of
cgByte: begin
if rval < -128.0 then
q := -128
else if rval > 127.0 then
q := 127
else
q := trunc(rval);
op^.left^.rval := 0.0;
op^.left^.q := q;
end;
cgUByte: begin
if rval < 0.0 then
q := 0
else if rval > 255.0 then
q := 255
else
q := trunc(rval);
op^.left^.rval := 0.0;
op^.left^.q := q;
end;
cgWord: begin
if rval < -32768.0 then
lval := -32768
else if rval > 32767.0 then
lval := 32767
else
lval := trunc(rval);
op^.left^.rval := 0.0;
op^.left^.q := long(lval).lsw;
end;
cgUWord: begin
if rval < 0.0 then
lval := 0
else if rval > 65535.0 then
lval := 65535
else
lval := trunc4(rval);
op^.left^.rval := 0.0;
op^.left^.q := long(lval).lsw;
end;
cgLong: begin
if rval < -2147483648.0 then
lval := $80000000
else if rval > 2147483647.0 then
lval := 2147483647
else
lval := trunc4(rval);
op^.left^.rval := 0.0;
op^.left^.lval := lval;
end;
cgULong: begin
if rval < 0.0 then
lval := 0
else if rval >= 4294967295.0 then
lval := $FFFFFFFF
else if rval > 2147483647.0 then begin
rval := rval - 2147483647.0;
lval := 2147483647 + trunc4(rval);
end {else if}
else
lval := trunc4(rval);
op^.left^.rval := 0.0;
op^.left^.lval := lval;
end;
cgReal,cgDouble,cgComp,cgExtended: ;
otherwise: ;
end;
end; {case}
otherwise: ;
end; {case}
if fromtype.optype in
[cgByte,cgUByte,cgWord,cgUWord,cgLong,cgULong,cgReal,cgDouble,
cgComp,cgExtended] then
if totype.optype in
[cgByte,cgUByte,cgWord,cgUWord,cgLong,cgULong,cgReal,cgDouble,
cgComp,cgExtended] then begin
op^.left^.optype := totype.optype;
opv := op^.left;
end; {if}
end {if}
else if op^.left^.opcode = pc_cnv then begin
doit := false;
firsttype.i := (op^.left^.q & $00F0) >> 4;
if fromType.optype in [cgReal,cgDouble,cgComp,cgExtended] then begin
if toType.optype in [cgReal,cgDouble,cgComp,cgExtended] then
doit := true;
end {if}
else begin
if firstType.optype in [cgByte,cgWord,cgLong] then
if fromType.optype in [cgByte,cgWord,cgLong] then
if toType.optype in [cgByte,cgWord,cgLong] then
doit := true;
if firstType.optype in [cgUByte,cgUWord,cgULong] then
if fromType.optype in [cgUByte,cgUWord,cgULong] then
if toType.optype in [cgUByte,cgUWord,cgLong] then
doit := true;
if TypeSize(firstType.optype) = TypeSize(fromType.optype) then
if TypeSize(firstType.optype) = TypeSize(toType.optype) then
doit := true;
if TypeSize(fromType.optype) < TypeSize(firstType.optype) then
if TypeSize(fromType.optype) < TypeSize(toType.optype) then
doit := false; {disable optimization in invalid cases}
end; {else}
if doit then begin
op^.q := (op^.left^.q & $00F0) | (op^.q & $000F);
op^.left := op^.left^.left;
PeepHoleOptimization(opv);
end; {if}
end {else if}
else if op^.left^.opcode in [pc_lod,pc_ldo,pc_ind] then begin
if fromtype.optype in [cgWord,cgUWord] then
if totype.optype in [cgByte,cgUByte,cgWord,cgUWord] then begin
op^.left^.optype := totype.optype;
opv := op^.left;
end; {if}
if fromtype.optype in [cgLong,cgULong] then
if totype.optype in [cgByte,cgUByte,cgWord,cgUWord,cgLong,cgULong]
then begin
op^.left^.optype := totype.optype;
opv := op^.left;
end; {if}
end {else if}
else if op^.q in [$40,$41,$50,$51] then begin
{any long type to byte type}
with op^.left^ do
if opcode = pc_bal then
if right^.opcode = pc_ldc then
if right^.lval = 255 then begin
op^.left := op^.left^.left;
PeepHoleOptimization(opv);
end; {if}
with op^.left^ do
if opcode in [pc_slr,pc_vsr] then
if right^.opcode = pc_ldc then
if left^.opcode in [pc_lod,pc_ldo,pc_ind] then begin
lq := right^.lval;
if long(lq).msw = 0 then
if long(lq).lsw in [8,16,24] then begin
lq := lq div 8;
left^.q := left^.q + long(lq).lsw;
op^.left := left;
PeepHoleOptimization(opv);
end; {if}
end; {if}
end; {else if}
end; {case pc_cnv}
pc_dec: begin {pc_dec}
if op^.q = 0 then
opv := op^.left
else begin
opcode := op^.left^.opcode;
if opcode = pc_dec then begin
if ord4(op^.left^.q) + ord4(op^.q) < ord4(maxint) then begin
op^.q := op^.q + op^.left^.q;
op^.left := op^.left^.left;
end; {if}
end {if}
else if opcode = pc_inc then begin
q := op^.q - op^.left^.q;
if q < 0 then begin
q := -q;
op^.opcode := pc_inc;
end; {if}
op^.q := q;
op^.left := op^.left^.left;
PeepHoleOptimization(opv);
end {else if}
else if opcode = pc_ldc then begin
if op^.optype in [cgLong, cgULong] then begin
op^.left^.lval := op^.left^.lval - op^.q;
opv := op^.left;
end {if}
else if op^.optype in [cgUByte, cgByte, cgUWord, cgWord] then begin
op^.left^.q := op^.left^.q - op^.q;
opv := op^.left;
end; {else if}
end; {else if}
end; {else}
end; {case pc_dec}
pc_dvi: begin {pc_dvi}
if op^.right^.opcode = pc_ldc then begin
if op^.left^.opcode = pc_ldc then begin
if op^.right^.q <> 0 then begin
op^.left^.q := op^.left^.q div op^.right^.q;
opv := op^.left;
end; {if}
end {if}
else if op^.right^.q = 1 then
opv := op^.left;
end; {if}
end; {case pc_dvi}
pc_dvl: begin {pc_dvl}
if op^.right^.opcode = pc_ldc then begin
if op^.left^.opcode = pc_ldc then begin
if op^.right^.lval <> 0 then begin
op^.left^.lval := op^.left^.lval div op^.right^.lval;
opv := op^.left;
end; {if}
end {if}
else if op^.right^.lval = 1 then
opv := op^.left;
end; {if}
end; {case pc_dvl}
pc_dvr: begin {pc_dvr}
if op^.right^.opcode = pc_ldc then begin
if op^.left^.opcode = pc_ldc then begin
if op^.right^.rval <> 0.0 then begin
op^.left^.rval := op^.left^.rval/op^.right^.rval;
opv := op^.left;
end; {if}
end {if}
else if op^.right^.rval = 1.0 then
opv := op^.left;
end; {if}
end; {case pc_dvr}
pc_equ: begin {pc_equ}
if op^.left^.opcode = pc_ldc then
ReverseChildren(op);
if op^.right^.opcode = pc_ldc then begin
if op^.left^.opcode = pc_ldc then begin
BinOps(op^.left, op^.right);
case op^.left^.optype of
cgByte,cgUByte,cgWord,cgUWord: begin
op^.opcode := pc_ldc;
op^.q := ord(op^.left^.q = op^.right^.q);
op^.left := nil;
op^.right := nil;
end;
cgLong,cgULong: begin
op^.opcode := pc_ldc;
op^.q := ord(op^.left^.lval = op^.right^.lval);
op^.left := nil;
op^.right := nil;
end;
cgReal,cgDouble,cgComp,cgExtended: begin
op^.opcode := pc_ldc;
op^.q := ord(op^.left^.rval = op^.right^.rval);
op^.left := nil;
op^.right := nil;
end;
cgVoid,ccPointer: begin
op^.opcode := pc_ldc;
op^.q := ord(op^.left^.pval = op^.right^.pval);
op^.left := nil;
op^.right := nil;
end;
end; {case}
op^.optype := cgWord;
end {if}
else if op^.right^.optype in [cgByte, cgUByte, cgWord, cgUWord] then begin
if op^.right^.q = 1 then
if op^.left^.opcode in
[pc_and,pc_ior,pc_neq,pc_equ,pc_geq,pc_leq,pc_les,pc_grt]
then begin
opv := op^.left;
opv^.next := op^.next;
end; {if}
end {else if}
else if op^.right^.optype in [cgLong, cgULong] then begin
if op^.right^.lval = 1 then
if op^.left^.opcode in
[pc_and,pc_ior,pc_neq,pc_equ,pc_geq,pc_leq,pc_les,pc_grt]
then begin
opv := op^.left;
opv^.next := op^.next;
end; {if}
end; {else if}
end; {if}
end; {case pc_equ}
pc_fjp: begin {pc_fjp}
opcode := op^.left^.opcode;
if opcode = pc_ldc then begin
if op^.left^.optype in [cgByte, cgUByte, cgWord, cgUWord] then begin
if op^.left^.q <> 0 then begin
opv := op^.next;
rescan := true;
end {if}
else begin
op^.opcode := pc_ujp;
op^.left := nil;
PeepHoleOptimization(opv);
end; {else}
end {if}
end {if}
else if opcode = pc_and then begin
op2 := op^.left;
op2^.next := op^.next;
op^.next := op2;
op^.left := op2^.left;
op2^.left := op2^.right;
op2^.right := nil;
op2^.opcode := pc_fjp;
op2^.q := op^.q;
PeepHoleOptimization(opv);
end {else if}
else if opcode = pc_ior then begin
op2 := op^.left;
op2^.next := op^.next;
op^.next := op2;
op^.left := op2^.left;
op2^.left := op2^.right;
op2^.right := nil;
op2^.opcode := pc_fjp;
op2^.q := op^.q;
op^.opcode := pc_tjp;
op3 := pointer(Calloc(sizeof(intermediate_code)));
op3^.opcode := dc_lab;
op3^.optype := cgWord;
op3^.q := GenLabel;
op3^.next := op2^.next;
op2^.next := op3;
op^.q := op3^.q;
PeepHoleOptimization(opv);
end {else if}
else
JumpOptimizations(op, pc_tjp);
end; {case pc_fjp}
pc_inc: begin {pc_inc}
if op^.q = 0 then
opv := op^.left
else begin
opcode := op^.left^.opcode;
if opcode = pc_inc then begin
if ord4(op^.left^.q) + ord4(op^.q) < ord4(maxint) then begin
op^.q := op^.q + op^.left^.q;
op^.left := op^.left^.left;
end; {if}
end {if}
else if opcode = pc_dec then begin
q := op^.q - op^.left^.q;
if q < 0 then begin
q := -q;
op^.opcode := pc_dec;
end; {if}
op^.q := q;
op^.left := op^.left^.left;
PeepHoleOptimization(opv);
end {else if}
else if opcode = pc_ldc then begin
if op^.optype in [cgLong, cgULong] then begin
op^.left^.lval := op^.left^.lval + op^.q;
opv := op^.left;
end {if}
else if op^.optype in [cgUByte, cgByte, cgUWord, cgWord] then begin
op^.left^.q := op^.left^.q + op^.q;
opv := op^.left;
end; {else if}
end {else if}
else if opcode in [pc_lao,pc_lda] then begin
op^.left^.q := op^.left^.q + op^.q;
opv := op^.left;
end; {else if}
end; {else}
end; {case pc_inc}
pc_ind: begin {pc_ind}
opcode := op^.left^.opcode;
if opcode = pc_lda then begin
op^.left^.opcode := pc_lod;
op^.left^.optype := op^.optype;
op^.left^.q := op^.left^.q + op^.q;
opv := op^.left;
end {if}
else if opcode = pc_lao then begin
op^.left^.opcode := pc_ldo;
op^.left^.optype := op^.optype;
op^.left^.q := op^.left^.q + op^.q;
opv := op^.left;
end {else if}
else if opcode = pc_inc then begin
if op^.left^.optype = cgULong then begin
if ord4(op^.left^.q) + ord4(op^.q) < ord4(maxint - 1) then begin
op^.q := op^.q + op^.left^.q;
op^.left := op^.left^.left;
PeepHoleOptimization(opv);
end; {if}
end; {if}
end; {else if}
end; {case pc_ind}
pc_ior: begin {pc_ior}
if op^.right^.opcode = pc_ldc then begin
if op^.left^.opcode = pc_ldc then begin
op^.left^.q := ord((op^.left^.q <> 0) or (op^.right^.q <> 0));
opv := op^.left;
end {if}
else begin
if op^.right^.q <> 0 then begin
if not SideEffects(op^.left) then begin
op^.right^.q := 1;
opv := op^.right;
end; {if}
end {if}
else
op^.opcode := pc_neq;
end {if}
end {if}
else if op^.left^.opcode = pc_ldc then
if op^.left^.q <> 0 then begin
op^.left^.q := 1;
opv := op^.left;
end; {if}
end; {case pc_ior}
pc_ixa: begin {pc_ixa}
if op^.right^.opcode = pc_ldc then begin
optype := op^.optype;
if optype in [cgUByte, cgByte, cgUWord, cgWord] then begin
lval := op^.right^.q;
if optype = cgUByte then
lval := lval & $000000FF
else if optype = cgUWord then
lval := lval & $0000FFFF;
done := false;
if op^.left^.opcode in [pc_lao, pc_lda] then begin
lq := op^.left^.q + lval;
if (lq >= 0) and (lq < maxint) then begin
done := true;
op^.left^.q := ord(lq);
opv := op^.left;
end; {if}
end; {if}
if not done then begin
op^.right^.lval := lval;
op^.right^.optype := cgLong;
op^.opcode := pc_adl;
PeepHoleOptimization(opv);
end; {if}
end; {if}
end {if}
else if op^.left^.opcode = pc_lao then begin
if op^.right^.opcode = pc_inc then begin
lq := ord4(op^.right^.q) + ord4(op^.left^.q);
if lq < maxint then begin
op^.left^.q := ord(lq);
op^.right := op^.right^.left;
end; {if}
PeepHoleOptimization(opv);
end; {if}
end {else if}
else if op^.left^.opcode = pc_ixa then begin
if smallMemoryModel then
if op^.left^.left^.opcode in [pc_lao,pc_lda] then
if op^.left^.left^.q = 0 then begin
op2 := op^.left;
op^.left := op^.left^.left;
op2^.left := op^.right;
op2^.opcode := pc_adi;
op^.right := op2;
op^.optype := cgUWord;
end; {if}
end; {else if}
end; {case pc_ixa}
pc_leq, pc_les, pc_geq, pc_grt: begin {pc_leq, pc_les, pc_geq, pc_grt}
if (op^.opcode = pc_leq) and (op^.optype in [cgWord,cgUWord]) then
if op^.right^.opcode = pc_ldc then
if op^.right^.q < maxint then begin
op^.right^.q := op^.right^.q + 1;
op^.opcode := pc_les;
end; {if}
if (op^.optype = cgWord) then
if (TypeOf(op^.right) = cgUByte)
or ((op^.right^.opcode = pc_ldc) and (op^.right^.q >= 0)
and (op^.right^.optype in [cgByte,cgUByte,cgWord])) then
if (TypeOf(op^.left) = cgUByte)
or ((op^.left^.opcode = pc_ldc) and (op^.left^.q >= 0)
and (op^.left^.optype in [cgByte,cgUByte,cgWord])) then
op^.optype := cgUWord;
end; {case pc_leq, pc_les, pc_geq, pc_grt}
pc_lnd: begin {pc_lnd}
if op^.right^.opcode = pc_ldc then begin
if op^.left^.opcode = pc_ldc then begin
op^.left^.q := ord((op^.left^.lval <> 0) and (op^.right^.lval <> 0));
op^.left^.optype := cgWord;
opv := op^.left;
end {if}
else begin
if op^.right^.lval = 0 then begin
if not SideEffects(op^.left) then begin
with op^.right^ do begin
lval := 0;
optype := cgWord;
q := 0;
end; {with}
opv := op^.right;
end; {if}
end; {if}
end; {if}
end {if}
else if op^.left^.opcode = pc_ldc then
if op^.left^.lval = 0 then begin
with op^.left^ do begin
lval := 0;
optype := cgWord;
q := 0;
end; {with}
opv := op^.left;
end; {if}
end; {case pc_lnd}
pc_lnm: begin {pc_lnm}
if op^.next^.opcode = pc_lnm then begin
opv := op^.next;
rescan := true;
end; {if}
end; {case pc_lnm}
pc_lor: begin {pc_lor}
if op^.right^.opcode = pc_ldc then begin
if op^.left^.opcode = pc_ldc then begin
op^.left^.q := ord((op^.left^.lval <> 0) or (op^.right^.lval <> 0));
optype := cgWord;
opv := op^.left;
end {if}
else begin
if op^.right^.lval <> 0 then begin
if not SideEffects(op^.left) then begin
op^.right^.lval := 0;
op^.right^.q := 1;
op^.right^.optype := cgWord;
opv := op^.right;
end; {if}
end {if}
else begin
op^.opcode := pc_neq;
op^.optype := cgLong;
end; {else}
end; {if}
end {if}
else if op^.left^.opcode = pc_ldc then
if op^.left^.lval <> 0 then begin
op^.left^.lval := 0;
op^.left^.q := 1;
op^.left^.optype := cgWord;
opv := op^.left;
end; {if}
end; {case pc_lor}
pc_mdl: begin {pc_mdl}
if op^.right^.opcode = pc_ldc then
if op^.left^.opcode = pc_ldc then
if (op^.left^.lval >= 0) and (op^.right^.lval > 0) then begin
op^.left^.lval := op^.left^.lval mod op^.right^.lval;
opv := op^.left;
end; {if}
end; {case pc_mdl}
pc_mod: begin {pc_mod}
if op^.right^.opcode = pc_ldc then
if op^.left^.opcode = pc_ldc then
if (op^.left^.q >= 0) and (op^.right^.q > 0) then begin
op^.left^.q := op^.left^.q mod op^.right^.q;
opv := op^.left;
end; {if}
end; {case pc_mod}
pc_mpi, pc_umi: begin {pc_mpi, pc_umi}
if (op^.right^.opcode = pc_ldc) and (op^.left^.opcode = pc_ldc) then begin
if op^.opcode = pc_mpi then
op^.left^.q := op^.left^.q*op^.right^.q
else {if op^.opcode = pc_umi then} begin
lval := umul(op^.left^.q & $0000FFFF, op^.right^.q & $0000FFFF);
op^.left^.q := long(lval).lsw;
end; {else}
opv := op^.left;
end {if}
else begin
if op^.left^.opcode = pc_ldc then
ReverseChildren(op);
if op^.right^.opcode = pc_ldc then begin
q := op^.right^.q;
if q = 1 then
opv := op^.left
else if q = 0 then begin
if not SideEffects(op^.left) then
opv := op^.right;
end {else if}
else if (q = -1) and (op^.opcode = pc_mpi) then begin
op^.opcode := pc_ngi;
op^.right := nil;
end {else if}
else if OneBit(q) then begin
op^.right^.q := Base(q);
op^.opcode := pc_shl;
PeepHoleOptimization(opv);
end; {else if}
end; {if}
end; {else}
end; {case pc_mpi, pc_umi}
pc_mpl, pc_uml: begin {pc_mpl, pc_uml}
if (op^.right^.opcode = pc_ldc) and (op^.left^.opcode = pc_ldc) then begin
if op^.opcode = pc_mpl then
op^.left^.lval := op^.left^.lval*op^.right^.lval
else {if op^.opcode = pc_uml then}
op^.left^.lval := umul(op^.left^.lval, op^.right^.lval);
opv := op^.left;
end {if}
else begin
if op^.left^.opcode = pc_ldc then
ReverseChildren(op);
if op^.right^.opcode = pc_ldc then begin
lval := op^.right^.lval;
if lval = 1 then
opv := op^.left
else if lval = 0 then begin
if not SideEffects(op^.left) then
opv := op^.right;
end {else if}
else if (lval = -1) and (op^.opcode = pc_mpl) then begin
op^.opcode := pc_ngl;
op^.right := nil;
end {else if}
else if OneBit(lval) then begin
op^.right^.lval := Base(lval);
op^.opcode := pc_sll;
end; {else if}
end; {if}
end; {else}
end; {case pc_mpl, pc_uml}
pc_mpr: begin {pc_mpr}
if (op^.right^.opcode = pc_ldc) and (op^.left^.opcode = pc_ldc) then begin
op^.left^.rval := op^.left^.rval*op^.right^.rval;
opv := op^.left;
end {if}
else begin
if op^.left^.opcode = pc_ldc then
ReverseChildren(op);
if op^.right^.opcode = pc_ldc then begin
rval := op^.right^.rval;
if rval = 1.0 then
opv := op^.left
else if rval = 0.0 then
if not SideEffects(op^.left) then
opv := op^.right;
end; {if}
end; {else}
end; {case pc_mpr}
pc_neq: begin {pc_neq}
if op^.left^.opcode = pc_ldc then
ReverseChildren(op);
if op^.right^.opcode = pc_ldc then begin
if op^.left^.opcode = pc_ldc then begin
BinOps(op^.left, op^.right);
case op^.left^.optype of
cgByte,cgUByte,cgWord,cgUWord: begin
op^.opcode := pc_ldc;
op^.q := ord(op^.left^.q <> op^.right^.q);
op^.left := nil;
op^.right := nil;
end;
cgLong,cgULong: begin
op^.opcode := pc_ldc;
op^.q := ord(op^.left^.lval <> op^.right^.lval);
op^.left := nil;
op^.right := nil;
end;
cgReal,cgDouble,cgComp,cgExtended: begin
op^.opcode := pc_ldc;
op^.q := ord(op^.left^.rval <> op^.right^.rval);
op^.left := nil;
op^.right := nil;
end;
cgVoid,ccPointer: begin
op^.opcode := pc_ldc;
op^.q := ord(op^.left^.pval <> op^.right^.pval);
op^.left := nil;
op^.right := nil;
end;
end; {case}
op^.optype := cgWord;
end {if}
else if op^.right^.optype in [cgByte, cgUByte, cgWord, cgUWord] then begin
if op^.right^.q = 0 then
if op^.left^.opcode in
[pc_and,pc_ior,pc_neq,pc_equ,pc_geq,pc_leq,pc_les,pc_grt]
then begin
opv := op^.left;
opv^.next := op^.next;
end; {if}
end {else if}
else if op^.right^.optype in [cgLong, cgULong] then begin
if op^.right^.lval = 0 then
if op^.left^.opcode in
[pc_and,pc_ior,pc_neq,pc_equ,pc_geq,pc_leq,pc_les,pc_grt]
then begin
opv := op^.left;
opv^.next := op^.next;
end; {if}
end; {else if}
end; {if}
end; {case pc_neq}
pc_ngi: begin {pc_ngi}
if op^.left^.opcode = pc_ldc then begin
op^.left^.q := -op^.left^.q;
opv := op^.left;
end; {if}
end; {case pc_ngi}
pc_ngl: begin {pc_ngl}
if op^.left^.opcode = pc_ldc then begin
op^.left^.lval := -op^.left^.lval;
opv := op^.left;
end; {if}
end; {case pc_ngl}
pc_ngr: begin {pc_ngr}
if op^.left^.opcode = pc_ldc then begin
op^.left^.rval := -op^.left^.rval;
opv := op^.left;
end; {if}
end; {case pc_ngr}
pc_not: begin {pc_not}
opcode := op^.left^.opcode;
if opcode = pc_ldc then begin
if op^.left^.optype in [cgByte,cgUByte,cgWord,cgUWord] then begin
op^.left^.q := ord(op^.left^.q = 0);
opv := op^.left;
end {if}
else if op^.left^.optype in [cgLong,cgULong] then begin
q := ord(op^.left^.lval = 0);
lval := 0;
op^.left^.q := q;
op^.left^.optype := cgWord;
opv := op^.left;
end; {else if}
end {if}
else if opcode = pc_equ then begin
op^.left^.opcode := pc_neq;
opv := op^.left;
end {else if}
else if opcode = pc_neq then begin
op^.left^.opcode := pc_equ;
opv := op^.left;
end {else if}
else if opcode = pc_geq then begin
op^.left^.opcode := pc_les;
opv := op^.left;
end {else if}
else if opcode = pc_grt then begin
op^.left^.opcode := pc_leq;
opv := op^.left;
end {else if}
else if opcode = pc_les then begin
op^.left^.opcode := pc_geq;
opv := op^.left;
end {else if}
else if opcode = pc_leq then begin
op^.left^.opcode := pc_grt;
opv := op^.left;
end; {else if}
end; {case pc_not}
pc_pop: begin {pc_pop}
if op^.left^.opcode = pc_cnv then begin
fromtype.i := (op^.left^.q & $00F0) >> 4;
op^.optype := fromtype.optype;
op^.left := op^.left^.left;
end; {if}
opcode := op^.left^.opcode;
if opcode = pc_cop then begin
op^.left^.opcode := pc_str;
opv := op^.left;
opv^.next := op^.next;
PeepHoleOptimization(opv);
end {if}
else if opcode = pc_cpi then begin
op^.left^.opcode := pc_sto;
opv := op^.left;
opv^.next := op^.next;
PeepHoleOptimization(opv);
end {else if}
else if opcode = pc_cbf then begin
op^.left^.opcode := pc_sbf;
opv := op^.left;
opv^.next := op^.next;
end {else if}
else if opcode = pc_cpo then begin
op^.left^.opcode := pc_sro;
opv := op^.left;
opv^.next := op^.next;
PeepHoleOptimization(opv);
end {else if}
else if opcode in [pc_inc,pc_dec] then
op^.left := op^.left^.left;
end; {case pc_pop}
pc_ret: begin {pc_ret}
RemoveDeadCode(op);
end; {case pc_ret}
pc_sbi: begin {pc_sbi}
if op^.left^.opcode = pc_ldc then begin
if op^.right^.opcode = pc_ldc then begin
op^.left^.q := op^.left^.q - op^.right^.q;
opv := op^.left;
end {if}
else if op^.left^.q = 0 then begin
op^.opcode := pc_ngi;
op^.left := op^.right;
op^.right := nil;
end; {else if}
end {if}
else if op^.right^.opcode = pc_ldc then begin
q := op^.right^.q;
if q = 0 then
opv := op^.left
else if (q > 0) then begin
op^.opcode := pc_dec;
op^.q := q;
op^.right := nil;
end {else if}
else {if q < 0) then} begin
op^.opcode := pc_inc;
op^.q := -q;
op^.right := nil;
end; {else if}
end {if}
else if op^.left^.opcode in [pc_inc,pc_dec] then
if op^.right^.opcode in [pc_inc,pc_dec] then begin
op2 := op^.left;
if op^.left^.opcode = pc_inc then
q := op^.left^.q
else
q := -op^.left^.q;
if op^.right^.opcode = pc_inc then
q := q - op^.right^.q
else
q := q + op^.right^.q;
if q >= 0 then begin
op2^.opcode := pc_inc;
op2^.q := q;
end {if}
else begin
op2^.opcode := pc_dec;
op2^.q := -q;
end; {else}
op^.left := op^.left^.left;
op^.right := op^.right^.left;
op2^.left := op;
opv := op2;
PeepHoleOptimization(opv);
end; {if}
end; {case pc_sbi}
pc_sbl: begin {pc_sbl}
if op^.left^.opcode = pc_ldc then begin
if op^.right^.opcode = pc_ldc then begin
op^.left^.lval := op^.left^.lval - op^.right^.lval;
opv := op^.left;
end {if}
else if op^.left^.lval = 0 then begin
op^.opcode := pc_ngl;
op^.left := op^.right;
op^.right := nil;
end; {else if}
end {if}
else if op^.right^.opcode = pc_ldc then begin
lval := op^.right^.lval;
if lval = 0 then
opv := op^.left
else if (lval > 0) and (lval <= maxint) then begin
op^.opcode := pc_dec;
op^.q := ord(lval);
op^.right := nil;
op^.optype := cgLong;
end {else if}
else if (lval > -maxint) and (lval < 0) then begin
op^.opcode := pc_inc;
op^.q := -ord(lval);
op^.right := nil;
op^.optype := cgLong;
end; {else if}
end; {if}
end; {case pc_sbl}
pc_sbr: begin {pc_sbr}
if op^.left^.opcode = pc_ldc then begin
if op^.right^.opcode = pc_ldc then begin
op^.left^.rval := op^.left^.rval - op^.right^.rval;
opv := op^.left;
end {if}
else if op^.left^.rval = 0.0 then begin
op^.opcode := pc_ngr;
op^.left := op^.right;
op^.right := nil;
end; {else if}
end {if}
else if op^.right^.opcode = pc_ldc then begin
if op^.right^.rval = 0.0 then
opv := op^.left;
end; {if}
end; {case pc_sbr}
pc_shl: begin {pc_shl}
if op^.right^.opcode = pc_ldc then begin
opcode := op^.left^.opcode;
if opcode = pc_shl then begin
if op^.left^.right^.opcode = pc_ldc then begin
op^.right^.q := op^.right^.q + op^.left^.right^.q;
op^.left := op^.left^.left;
end; {if}
end {if}
else if opcode = pc_inc then begin
op2 := op^.left;
op^.left := op2^.left;
op2^.q := op2^.q << op^.right^.q;
op2^.left := op;
opv := op2;
PeepHoleOptimization(op2^.left);
end; {else if}
end; {if}
end; {case pc_shl}
pc_sro, pc_str: begin {pc_sro, pc_str}
if op^.optype in [cgReal,cgDouble,cgExtended] then
RealStoreOptimizations(op, op^.left);
end; {case pc_sro, pc_str}
pc_sto: begin {pc_sto}
if op^.optype in [cgReal,cgDouble,cgExtended] then
RealStoreOptimizations(op, op^.right);
if op^.left^.opcode = pc_lao then begin
op^.q := op^.left^.q;
op^.lab := op^.left^.lab;
op^.opcode := pc_sro;
op^.left := op^.right;
op^.right := nil;
end {if}
else if op^.left^.opcode = pc_lda then begin
op^.q := op^.left^.q;
op^.r := op^.left^.r;
op^.opcode := pc_str;
op^.left := op^.right;
op^.right := nil;
end; {if}
end; {case pc_sto}
pc_tjp: begin {pc_tjp}
opcode := op^.left^.opcode;
if opcode = pc_ldc then begin
if op^.left^.optype in [cgByte, cgUByte, cgWord, cgUWord] then
if op^.left^.q = 0 then begin
opv := op^.next;
rescan := true;
end {if}
else begin
op^.opcode := pc_ujp;
op^.left := nil;
PeepHoleOptimization(opv);
end; {else}
end {if}
else if opcode = pc_ior then begin
op2 := op^.left;
op2^.next := op^.next;
op^.next := op2;
op^.left := op2^.left;
op2^.left := op2^.right;
op2^.right := nil;
op2^.opcode := pc_tjp;
op2^.q := op^.q;
PeepHoleOptimization(opv);
end {else if}
else if opcode = pc_and then begin
op2 := op^.left;
op2^.next := op^.next;
op^.next := op2;
op^.left := op2^.left;
op2^.left := op2^.right;
op2^.right := nil;
op2^.opcode := pc_tjp;
op2^.q := op^.q;
op^.opcode := pc_fjp;
op3 := pointer(Calloc(sizeof(intermediate_code)));
op3^.opcode := dc_lab;
op3^.optype := cgWord;
op3^.q := GenLabel;
op3^.next := op2^.next;
op2^.next := op3;
op^.q := op3^.q;
PeepHoleOptimization(opv);
end {else if}
else
JumpOptimizations(op, pc_fjp);
end; {case pc_tjp}
pc_tri: begin {pc_tri}
opcode := op^.left^.opcode;
if opcode = pc_not then begin
ReverseChildren(op^.right);
op^.left := op^.left^.left;
PeepHoleOptimization(opv);
end {if}
else if opcode in [pc_equ, pc_neq] then begin
with op^.left^.right^ do
if opcode = pc_ldc then
if optype in [cgByte,cgUByte,cgWord,cgUWord] then
if q = 0 then begin
if op^.left^.opcode = pc_equ then
ReverseChildren(op^.right);
op^.left := op^.left^.left;
end; {if}
end; {else if}
end; {case pc_tri}
pc_udi: begin {pc_udi}
if op^.right^.opcode = pc_ldc then begin
q := op^.right^.q;
if op^.left^.opcode = pc_ldc then begin
if q <> 0 then begin
op^.left^.q := ord(udiv(op^.left^.q & $0000FFFF, q & $0000FFFF));
opv := op^.left;
end; {if}
end {if}
else if q = 1 then
opv := op^.left
else if OneBit(q) then begin
op^.right^.q := Base(q);
op^.opcode := pc_usr;
end; {else if}
end; {if}
end; {case pc_udi}
pc_udl: begin {pc_udl}
if op^.right^.opcode = pc_ldc then begin
lq := op^.right^.lval;
if op^.left^.opcode = pc_ldc then begin
if lq <> 0 then begin
op^.left^.lval := udiv(op^.left^.lval, lq);
opv := op^.left;
end; {if}
end {if}
else if lq = 1 then
opv := op^.left
else if OneBit(lq) then begin
op^.right^.lval := Base(lq);
op^.opcode := pc_vsr;
end; {else if}
end; {if}
end; {case pc_udl}
pc_uim: begin {pc_uim}
if op^.right^.opcode = pc_ldc then
if op^.left^.opcode = pc_ldc then
if op^.right^.q <> 0 then begin
op^.left^.q :=
ord(umod(op^.left^.q & $0000FFFF, op^.right^.q & $0000FFFF));
opv := op^.left;
end; {if}
end; {case pc_uim}
pc_ujp: begin {pc_ujp}
RemoveDeadCode(op);
if op^.next^.opcode = dc_lab then begin
if op^.q = op^.next^.q then begin
opv := op^.next;
rescan := true;
end {if}
else if op^.next^.next^.opcode = dc_lab then
if op^.next^.next^.q = op^.q then begin
opv := op^.next;
rescan := true;
end; {if}
end; {if}
end; {case pc_ujp}
pc_ulm: begin {pc_ulm}
if op^.right^.opcode = pc_ldc then
if op^.left^.opcode = pc_ldc then
if op^.right^.lval <> 0 then begin
op^.left^.lval := umod(op^.left^.lval, op^.right^.lval);
opv := op^.left;
end; {if}
end; {case pc_ulm}
otherwise: ;
end; {case}
end; {PeepHoleOptimization}
{- Common Subexpression Elimination ----------------------------}
function MatchLoc (op1, op2: icptr): boolean;
{ See if two loads, stores or copies refer to the same }
{ location }
{ }
{ parameters: }
{ op1, op2 - operations to check }
{ }
{ Returns: True if they do, false if they don't. }
begin {MatchLoc}
MatchLoc := false;
if (op1^.opcode in [pc_str,pc_cop,pc_lod,pc_lli,pc_lil,pc_lld,pc_ldl,pc_lda])
and (op2^.opcode in [pc_str,pc_cop,pc_lod,pc_lli,pc_lil,pc_lld,pc_ldl,pc_lda]) then begin
if op1^.r = op2^.r then
MatchLoc := true;
end {if}
else if (op1^.opcode in [pc_sro,pc_cpo,pc_ldo,pc_gli,pc_gil,pc_gld,pc_gdl,pc_lao])
and (op2^.opcode in [pc_sro,pc_cpo,pc_ldo,pc_gli,pc_gil,pc_gld,pc_gdl,pc_lao]) then
if op1^.lab^ = op2^.lab^ then
MatchLoc := true;
end; {MatchLoc}
function Member (op: icptr; list: iclist): boolean;
{ See if the operand of a load is referenced in a list }
{ }
{ parameters: }
{ op - load to check }
{ list - list to check }
{ }
{ Returns: True if op is in list, else false. }
{ }
{ Notes: As a side effect, this subroutine sets memberOp to }
{ point to any matching member; memberOp is undefined if }
{ there is no matching member. }
begin {Member}
Member := false;
while list <> nil do begin
if MatchLoc(op, list^.op) then begin
Member := true;
memberOp := list^.op;
list := nil;
end {if}
else
list := list^.next;
end; {while}
end; {Member}
function TypeOf {(op: icptr): baseTypeEnum};
{ find the type for the expression tree }
{ }
{ parameters: }
{ op - tree for which to find the type }
{ }
{ Returns: base type }
begin {TypeOf}
case op^.opcode of
pc_gil, pc_gli, pc_gdl, pc_gld, pc_iil, pc_ili, pc_idl, pc_ild,
pc_ldc, pc_ldo, pc_lil, pc_lli, pc_ldl, pc_lld, pc_lod, pc_dec,
pc_inc, pc_ind, pc_lbf, pc_lbu, pc_cop, pc_cbf, pc_cpi, pc_cpo,
pc_tri, pc_cup, pc_cui:
TypeOf := op^.optype;
pc_lad, pc_lao, pc_lca, pc_lda, pc_psh, pc_ixa:
TypeOf := cgULong;
pc_nop, pc_bnt, pc_ngi, pc_not, pc_adi, pc_and, pc_lnd, pc_bnd,
pc_bor, pc_bxr, pc_dvi, pc_equ, pc_geq, pc_grt, pc_leq, pc_les,
pc_neq, pc_ior, pc_lor, pc_mod, pc_mpi, pc_sbi, pc_shl, pc_shr:
TypeOf := cgWord;
pc_udi, pc_uim, pc_umi, pc_usr:
TypeOf := cgUWord;
pc_bnl, pc_ngl, pc_adl, pc_bal, pc_blr, pc_blx, pc_dvl, pc_mdl,
pc_mpl, pc_sbl, pc_sll, pc_slr:
TypeOf := cgLong;
pc_udl, pc_ulm, pc_uml, pc_vsr:
TypeOf := cgULong;
pc_ngr, pc_adr, pc_dvr, pc_mpr, pc_sbr:
TypeOf := cgExtended;
pc_cnn, pc_cnv:
TypeOf := baseTypeEnum(op^.q & $000F);
pc_stk:
TypeOf := TypeOf(op^.left);
pc_bno:
TypeOf := TypeOf(op^.right);
pc_tl1: {pc_tl1 doesn't have type info.}
TypeOf := cgVoid; {Just return cgVoid for now.}
otherwise: Error(cge1);
end; {case}
end; {TypeOf}
procedure CommonSubexpressionElimination;
{ Remove common subexpressions }
type
localPtr = ^localRecord; {list of local temp variables}
localRecord = record
next: localPtr; {next label in list}
inUse: boolean; {is this temp already in use?}
size: integer; {size of the temp area}
lab: integer; {label number}
end;
var
bb: blockPtr; {used to trace basic block lists}
done: boolean; {for loop termination tests}
op: icptr; {used to trace operation lists, trees}
lop: icptr; {predecessor of op}
temps: localPtr; {list of temp variables}
procedure DisposeTemps;
{ dispose of the list of temp variables }
var
tp: localPtr; {temp pointer}
begin {DisposeTemps}
while temps <> nil do begin
tp := temps;
temps := tp^.next;
dispose(tp);
end; {while}
end; {DisposeTemps}
function GetTemp (bb: blockPtr; size: integer): integer;
{ Allocate a temp storage location }
{ }
{ parameters: }
{ bb - block in which the temp is allocated }
{ size - size of the temp }
{ }
{ Returns: local label number for the temp }
var
lab: integer; {label number}
loc: icptr; {for dc_loc instruction}
tp: localPtr; {used to trace lists, allocate new items}
begin {GetTemp}
lab := 0; {no label found, yet}
tp := temps; {try for a temp of the exact size}
while tp <> nil do begin
if not tp^.inUse then
if tp^.size = size then begin
lab := tp^.lab;
tp^.inUse := true;
tp := nil;
end; {if}
if tp <> nil then
tp := tp^.next;
end; {while}
if lab = 0 then begin {try for a larger temp}
tp := temps;
while tp <> nil do begin
if not tp^.inUse then
if tp^.size > size then begin
lab := tp^.lab;
tp^.inUse := true;
tp := nil;
end; {if}
if tp <> nil then
tp := tp^.next;
end; {while}
end; {if}
if lab = 0 then begin {allocate a new temp}
loc := pointer(Calloc(sizeof(intermediate_code)));
loc^.opcode := dc_loc;
loc^.optype := cgWord;
maxLoc := maxLoc + 1;
loc^.r := maxLoc;
lab := maxLoc;
loc^.q := size;
if bb^.code = nil then begin
loc^.next := nil;
bb^.code := loc;
end {if}
else begin
loc^.next := bb^.code^.next;
bb^.code^.next := loc;
end; {else}
new(tp);
tp^.next := temps;
temps := tp;
tp^.inUse := true;
tp^.size := loc^.q;
tp^.lab := lab;
end; {if}
GetTemp := lab; {return the temp label number}
end; {GetTemp}
procedure ResetTemps;
{ Mark all temps as available }
var
tp: localPtr; {temp pointer}
begin {ResetTemps}
tp := temps;
while tp <> nil do begin
tp^.inUse := false;
tp := tp^.next;
end; {while}
end; {ResetTemps}
procedure CheckForBlocks (op: icptr);
{ Scan a tree for blocked instructions }
{ }
{ parameters: }
{ op - tree to check }
{ }
{ Notes: Some code takes less time to execute than saving }
{ and storing the intermediate value. This subroutine }
{ identifies such patterns. }
function Block (op: icptr): boolean;
{ See if the pattern should be blocked }
{ }
{ parameters: }
{ op - pattern to check }
{ }
{ Returns: True if the pattern should be blocked, else }
{ false. }
var
opcode: pcodes; {temp opcode}
begin {Block}
Block := false;
opcode := op^.opcode;
if opcode = pc_ixa then begin
if op^.left^.opcode in [pc_lao,pc_lca,pc_lda] then
Block := true;
end {else if}
else if opcode = pc_shl then begin
if op^.right^.opcode = pc_ldc then
if op^.right^.q = 1 then
if op^.parents <= 3 then
Block := true;
end {else if}
else if opcode = pc_stk then
Block := true
else if opcode = pc_psh then
Block := true
else if opcode = pc_cnv then
if op^.q & $000F = ord(cgVoid) then
Block := true;
end; {Block}
function Max (a, b: integer): integer;
{ Return the larger of two integers }
{ }
{ parameters: }
{ a, b - integers to check }
{ }
{ Returns: a if a > b, else b }
begin {Max}
if a > b then
Max := a
else
Max := b;
end; {Max}
begin {CheckForBlocks}
if Block(op) then begin
if op^.left <> nil then {handle a blocked instruction}
op^.left^.parents := op^.left^.parents + Max(op^.parents - 1, 0);
if op^.right <> nil then
op^.right^.parents := op^.right^.parents + Max(op^.parents - 1, 0);
op^.parents := 1;
end; {if}
if op^.left <> nil then {check the children}
CheckForBlocks(op^.left);
if op^.right <> nil then
CheckForBlocks(op^.right);
end; {CheckForBlocks}
procedure CheckTree (var op: icptr; bb: blockPtr);
{ check the trees used by op for common subexpressions }
{ }
{ parameters: }
{ op - operation to check }
{ bb - start of the current BASIC block }
var
op2: icptr; {result from Match calls}
op3: icptr; {used to trace the codes in a block}
function Match (var op: icptr; tree: icptr): icptr;
{ Check for matches to op in tree }
{ }
{ parameters: }
{ op - operation to check }
{ tree - tree to examine for matches }
{ }
{ Returns: pointer to matching node or nil if none found }
var
op2: icptr; {result from recursive Match calls}
kill, start, stop: boolean; {used by Scan}
skip: boolean; {used to see if children should be scanned}
procedure Combine (var op1, op2: icptr);
{ Op2 is a save or copy of the same value as op1; use a copy }
{ for op2. }
{ }
{ parameters: }
{ op1 - first copy or save }
{ op2 - copy or save to optimize }
var
op3: icptr; {work pointer}
begin {Combine}
done := false; {force another labeling pass}
op3 := op2; {remove op2 from the list}
if op3^.opcode in [pc_str,pc_sro] then begin
if op3^.opcode = pc_str then
op3^.opcode := pc_cop
else
op3^.opcode := pc_cpo;
op2 := op3^.next;
op3^.next := nil;
end {if}
else
op2 := op3^.left;
if op2 = nil then begin
op2 := pointer(Calloc(sizeof(intermediate_code)));
op2^.opcode := pc_nop;
op2^.optype := cgWord;
end; {if}
op1^.left := op3; {place in the new location}
end; {Combine}
function SameTree (list, op1, op2: icptr): boolean;
{ Are op1 and op2 in the same expression tree? }
{ }
{ parameters: }
{ list - list of expression trees }
{ op1, op2 - operations to check }
function InTree (tree, op: icptr): boolean;
{ See if op is in the tree }
{ }
{ parameters: }
{ tree - expression tree to check }
{ op - operatio to look for }
begin {InTree}
if tree = nil then
InTree := false
else if tree = op then
InTree := true
else
InTree := InTree(tree^.left, op) or InTree(tree^.right, op);
end; {InTree}
begin {SameTree}
SameTree := false;
while list <> nil do
if InTree(list, op1) then begin
SameTree := InTree(list, op2);
list := nil;
end {if}
else
list := list^.next;
end; {SameTree}
procedure Scan (list, op1, op2: icptr);
{ Check to see if any operation between op1 and op2 kills the }
{ optimization }
{ }
{ parameters: }
{ list - instruction stream }
{ op1 - starting operation }
{ op2 - ending operation }
{ }
{ globals: }
{ kill - set to true if the optimization must be blocked, }
{ or false if it can be performed }
{ start - has op1 been found? (initialize to false) }
{ stop - has kill been set? (initialize to false) }
label 1;
begin {Scan}
1: if not start then {see if it is time to start}
if list = op1 then
start := true;
if list^.left <> nil then {scan the children}
Scan(list^.left, op1, op2);
if not stop then
if list^.right <> nil then
Scan(list^.right, op1, op2);
if start then {check for a kill or termination}
if not stop then
if list = op2 then begin
kill := false;
stop := true;
end {if}
{kill indirect accesses on stores}
{to indirectly-accessible locations}
else if op1^.opcode in [pc_sto,pc_cpi,pc_iil,pc_ili,pc_idl,pc_ild,
pc_cup,pc_cui,pc_tl1,pc_ind,pc_sbf,pc_cbf] then begin
if list^.opcode in [pc_sto,pc_cpi,pc_iil,pc_ili,pc_idl,pc_ild,
pc_cup,pc_cui,pc_tl1,pc_sbf,pc_cbf] then begin
kill := true;
stop := true;
end {if}
else if list^.opcode in [pc_str,pc_sro,pc_cop,pc_cpo,pc_lli,
pc_lil,pc_lld,pc_ldl,pc_gli,pc_gil,pc_gld,pc_gdl] then
if Member(list, c_ind) then begin
kill := true;
stop := true;
end {if}
end {else if}
else if list^.opcode in [pc_str,pc_sro,pc_cop,pc_cpo,pc_lli,pc_lil,
pc_lld,pc_ldl,pc_gli,pc_gil,pc_gld,pc_gdl] then begin
if MatchLoc(list, op2) then begin
kill := true;
stop := true;
end {if}
end {else if}
else if list^.opcode in [pc_sto,pc_cpi,pc_iil,pc_ili,pc_idl,pc_ild,
pc_cup,pc_cui,pc_tl1,pc_sbf,pc_cbf] then
if Member(op1, c_ind) or (op1^.opcode in [pc_lbf,pc_lbu]) then
begin
kill := true;
stop := true;
end; {if}
if not stop then {scan forward in the stream}
if list^.next <> nil then begin
list := list^.next;
goto 1;
end; {if}
end; {Scan}
begin {Match}
op2 := nil; {check for an exact match}
skip := false;
if not (op^.opcode in [pc_str,pc_sro]) and CodesMatch(op, tree, true)
then begin
if op = tree then
op2 := tree
else begin
start := false;
stop := false;
Scan(bb^.code, tree, op);
if not kill then
op2 := tree;
end; {else}
end {if}
{check for stores of a common value}
else if op^.opcode in [pc_str,pc_sro,pc_cop,pc_cpo] then
if tree^.opcode in [pc_str,pc_sro,pc_cop,pc_cpo] then
if op^.left = tree^.left then begin
start := false;
stop := false;
Scan(bb^.code, tree, op);
if not kill then
if not SameTree(bb^.code, op, tree) then
if (op^.left^.opcode <> pc_ldc)
or ((op^.left^.optype in [cgByte,cgUByte,cgWord,cgUWord])
and (op^.left^.q <> 0))
or ((op^.left^.optype in [cgLong,cgULong])
and (op^.left^.lval <> 0))
or (not (op^.left^.optype in [cgByte,cgUByte,cgWord,cgUWord,cgLong,cgULong]))
then begin
Combine(tree, op);
skip := true;
end; {if}
end; {if}
if not skip then begin {check for matches in the children}
if op2 = nil then
if tree^.left <> nil then
op2 := Match(op, tree^.left);
if op2 = nil then
if tree^.right <> nil then
op2 := Match(op, tree^.right);
end; {if}
Match := op2;
end; {Match}
begin {CheckTree}
op^.parents := 0; {zero the parent counter}
if op^.left <> nil then {check the children}
CheckTree(op^.left, bb);
if op^.right <> nil then
CheckTree(op^.right, bb);
if op^.next = nil then {look for a match to the current code}
if not (op^.opcode in [pc_cup,pc_cui,pc_tl1,pc_bno,pc_pop,pc_sto,pc_sbf])
then begin
op2 := nil;
op3 := bb^.code;
while (op2 = nil) and (op3 <> nil) do begin
op2 := Match(op, op3);
if op2 <> nil then
if op2^.next = nil then begin
op := op2;
bb := nil;
op3 := nil;
end ;{if}
if op3 <> nil then
op3 := op3^.next;
end; {while}
end; {if}
end; {CheckTree}
procedure CountParents (op: icptr);
{ increment the parent counter for all children of this node }
{ }
{ parameters: }
{ op - node for which to check the children }
begin {CountParents}
if op^.parents = 0 then begin
if op^.left <> nil then begin
CountParents(op^.left);
op^.left^.parents := op^.left^.parents + 1;
end; {if}
if op^.right <> nil then begin
CountParents(op^.right);
op^.right^.parents := op^.right^.parents + 1;
end; {if}
end; {if}
end; {CountParents}
procedure CreateTemps (var op: icptr; bb: blockPtr; var lop: icptr);
{ create temps for nodes with multiple parents }
{ }
{ parameters: }
{ op - node for which to create temps }
{ bb - current basic block }
{ lop - predecessor to op }
var
children: boolean; {does this node have children?}
llab: integer; {local label number; for temp}
op2, str: icptr; {new opcodes}
optype: baseTypeEnum; {type of the temp variable}
begin {CreateTemps}
children := false; {create temps for the children}
if op^.left <> nil then begin
children := true;
CreateTemps(op^.left, bb, lop);
end; {if}
if op^.right <> nil then begin
children := true;
CreateTemps(op^.right, bb, lop);
end; {if}
if children then
if op^.parents > 1 then begin
optype := TypeOf(op); {create a temp label}
llab := GetTemp(bb, TypeSize(optype));
{make a copy of the duplicated tree}
op2 := pointer(Calloc(sizeof(intermediate_code)));
op2^ := op^;
op^.opcode := pc_lod; {substitute a load of the temp}
op^.optype := optype;
op^.parents := 1;
op^.r := llab;
op^.q := 0;
op^.left := nil;
op^.right := nil;
{store the temp result}
str := pointer(Calloc(sizeof(intermediate_code)));
str^.opcode := pc_str;
str^.optype := optype;
str^.r := llab;
str^.q := 0;
str^.left := op2;
if lop = nil then begin {insert the store in the basic block}
str^.next := bb^.code;
bb^.code := str;
end {if}
else begin
str^.next := lop^.next;
lop^.next := str;
end; {else}
lop := str;
end; {if}
end; {CreateTemps}
begin {CommonSubexpressionElimination}
temps := nil; {no temps allocated, yet}
repeat {identify common parts}
done := true;
bb := DAGblocks;
while bb <> nil do begin
Spin;
op := bb^.code;
if op <> nil then begin
CheckTree(bb^.code, bb);
while op^.next <> nil do begin
CheckTree(op^.next, bb);
if op^.next <> nil then
op := op^.next;
end; {while}
end; {if}
bb := bb^.next;
end; {while}
until done;
bb := DAGblocks; {count the number of parents}
while bb <> nil do begin
op := bb^.code;
Spin;
while op <> nil do begin
CountParents(op);
op := op^.next;
end; {while}
bb := bb^.next;
end; {while}
bb := DAGblocks; {check for blocked instructions}
while bb <> nil do begin
op := bb^.code;
Spin;
while op <> nil do begin
CheckForBlocks(op);
op := op^.next;
end; {while}
bb := bb^.next;
end; {while}
bb := DAGblocks; {create temps for common subexpressions}
while bb <> nil do begin
op := bb^.code;
lop := nil;
ResetTemps;
Spin;
while op <> nil do begin
CreateTemps(op, bb, lop);
lop := op;
op := op^.next;
end; {while}
bb := bb^.next;
end; {while}
DisposeTemps; {get rid of the temp variable list}
end; {CommonSubexpressionElimination}
{- Loop Optimizations ------------------------------------------}
procedure AddOperation (op: icptr; var lp: iclist);
{ Add an operation to an operation list }
{ }
{ parameters: }
{ op - operation to add }
{ lp - list to add the operation to }
var
inList: boolean; {is op already in the list?}
llp: iclist; {work pointer}
begin {AddOperation}
llp := lp;
inList := false;
while llp <> nil do
if MatchLoc(llp^.op, op) then begin
inList := true;
llp := nil;
end {if}
else
llp := llp^.next;
if not inList then begin
new(llp);
llp^.next := lp;
lp := llp;
llp^.op := op;
end; {if}
end; {AddOperation}
procedure DisposeBlkList (var blk: blockListPtr);
{ dispose of all entries in the block list }
{ }
{ parameters: }
{ blk - list of blocks to dispose of }
var
bk1, bk2: blockListPtr; {work pointers}
begin {DisposeBlkList}
bk1 := blk;
blk := nil;
while bk1 <> nil do begin
bk2 := bk1;
bk1 := bk2^.next;
dispose(bk2);
end; {while}
end; {DisposeBlkList}
procedure DisposeOpList (var oplist: iclist);
{ dispose of all entries in the list }
{ }
{ parameters: }
{ oplist - operation list to dispose of }
var
op1, op2: iclist; {work pointers}
begin {DisposeOpList}
op1 := oplist;
oplist := nil;
while op1 <> nil do begin
op2 := op1;
op1 := op2^.next;
dispose(op2);
end; {while}
end; {DisposeOpList}
procedure DumpLoopLists;
{ dispose of lists created by ReachingDefinitions and Dominators}
var
bb: blockPtr; {used to trace basic block list}
dom: blockListPtr; {used to dispose of a dominator}
begin {DumpLoopLists}
bb := DAGBlocks;
while bb <> nil do begin
DisposeOpList(bb^.c_in); {dump the reaching definition lists}
DisposeOpList(bb^.c_out);
DisposeOpList(bb^.c_gen);
DisposeBlkList(bb^.dom);
while bb^.dom <> nil do begin {dump the dominator lists}
dom := bb^.dom;
bb^.dom := dom^.next;
dispose(dom);
end; {while}
bb := bb^.next;
end; {while}
end; {DumpLoopLists}
procedure AddLoads (jp: icptr; var lp: iclist);
{ Add any load addresses from the children of this }
{ operation }
{ }
{ parameters: }
{ jp - operation to check }
{ lp - list to add the loads to }
begin {AddLoads}
if jp^.opcode in [pc_lda,pc_lao,pc_lod,pc_lod] then
AddOperation(jp, lp)
else begin
if jp^.left <> nil then
AddLoads(jp^.left, lp);
if jp^.right <> nil then
AddLoads(jp^.right, lp);
end {else}
end; {AddLoads}
procedure FlagIndirectUses;
{ Find all variables that could be changed by an indirect }
{ access. }
var
bb: blockPtr; {used to trace block list}
procedure Check (op: icptr; doingInd: boolean);
{ Check op and its children & followers for dangerous }
{ references }
{ }
{ parameters: }
{ op - operation to check }
{ doingInd - are we doing a pc_ind? If so, pc_lda's }
{ are safe }
var
lDoingInd: boolean; {local doingInd}
begin {Check}
while op <> nil do begin
if op^.opcode = pc_ind then
lDoingInd := true
else
lDoingInd := doingInd;
if op^.left <> nil then
Check(op^.left, lDoingInd);
if op^.right <> nil then
Check(op^.right, lDoingInd);
if op^.opcode in [pc_lao,pc_cpo,pc_ldo,pc_sro,pc_gil,pc_gli,
pc_gdl,pc_gld] then
AddOperation(op, c_ind)
else if op^.opcode = pc_ind then begin
if op^.left^.opcode = pc_ind then
AddLoads(op^.left^.left, c_ind);
end {else if}
else if op^.opcode = pc_lda then
if not doingInd then
AddOperation(op, c_ind);
op := op^.next;
end; {while}
end; {Check}
begin {FlagIndirectUses}
c_ind := nil;
bb := DAGBlocks;
while bb <> nil do begin
Check(bb^.code, false);
bb := bb^.next;
end; {while}
end; {FlagIndirectUses}
procedure DoLoopOptimization;
{ Perform optimizations related to loops and data flow }
type
dftptr = ^dftrecord; {depth first tree edges}
dftrecord = record
next: dftptr;
from, dest: blockPtr;
end;
var
backEdge: dftptr; {list of back edges}
dft: dftptr; {depth first tree}
dft2: dftptr; {work pointer}
function DFN (i: integer): blockPtr;
{ find the basic block with dfn index of i }
{ }
{ parameters: }
{ i - index to look for }
{ }
{ Returns: block pointer, or nil if there is none }
var
bb: blockPtr; {used to trace block list}
begin {DFN}
bb := DAGBlocks;
DFN := nil;
while bb <> nil do begin
if bb^.dfn = i then begin
DFN := bb;
bb := nil;
end
else
bb := bb^.next;
end; {while}
end; {DFN}
function MemberDFNList (dfn: integer; bl: blockListPtr): boolean;
{ See if dfn is a member of the list bl }
{ }
{ parameters: }
{ dfn - block number to check }
{ bl - list of block numbers to check }
{ }
{ Returns: True if dfn is in bl, else false. }
begin {MemberDFNList}
MemberDFNList := false;
while bl <> nil do
if bl^.dfn = dfn then begin
MemberDFNList := true;
bl := nil;
end {if}
else
bl := bl^.next;
end; {MemberDFNList}
function FindDAG (q: integer): blockPtr;
{ Find the DAG containing label q }
{ }
{ parameters: }
{ q - label to find }
{ }
{ Returns: pointer to the proper basic block }
var
bb: blockPtr; {used to trace basic block list}
begin {FindDAG}
bb := DAGBlocks;
FindDAG := nil;
while bb <> nil do begin
if bb^.code^.opcode = dc_lab then
if bb^.code^.q = q then begin
FindDAG := bb;
bb := nil;
end; {if}
if bb <> nil then
bb := bb^.next;
end; {while}
end; {FindDAG}
procedure DepthFirstOrder;
{ Number the DAG for depth first order }
var
bb: blockPtr; {used to trace basic block lists}
i: integer; {dfn index}
procedure Search (bb: blockPtr);
{ Search this block }
{ }
{ parameters: }
{ bb - basic block to search }
var
blk: blockPtr; {work block}
ndft: dftptr; {for new tree entries}
op: icptr; {used to trace operation list}
function NotUnconditional: boolean;
{ See if the block ends with something other than an }
{ unconditional jump }
{ }
{ Returns: True if the block ends with something other }
{ than pc_ujp or pc_add, else false }
var
op: icptr; {used to trace the list}
begin {NotUnconditional}
NotUnconditional := true;
op := bb^.code;
if op <> nil then begin
while op^.next <> nil do
op := op^.next;
if op^.opcode in [pc_add,pc_ujp] then
NotUnconditional := false;
end; {if}
end; {NotUnconditional}
begin {Search}
Spin;
if bb <> nil then
if not bb^.visited then begin
bb^.visited := true;
if NotUnconditional then
if bb^.next <> nil then begin
new(ndft);
ndft^.next := dft;
dft := ndft;
ndft^.from := bb;
ndft^.dest := bb^.next;
Search(bb^.next);
end; {if}
op := bb^.code;
while op <> nil do begin
if op^.opcode in [pc_ujp, pc_fjp, pc_tjp, pc_add] then begin
blk := FindDAG(op^.q);
new(ndft);
if blk^.visited then begin
ndft^.next := backEdge;
backEdge := ndft;
end {if}
else begin
ndft^.next := dft;
dft := ndft;
Search(blk);
end; {else}
ndft^.from := bb;
ndft^.dest := blk;
end; {if}
op := op^.next;
end; {while}
bb^.dfn := i;
i := i-1;
end; {if}
end; {Search}
begin {DepthFirstOrder}
dft := nil;
backEdge := nil;
i := 0;
bb := DAGblocks;
while bb <> nil do begin
bb^.visited := false;
i := i+1;
bb := bb^.next;
end; {while}
Search(DAGBlocks);
if i <> 0 then begin {ensure DFNs start from 1}
bb := DAGblocks;
while bb <> nil do begin
if bb ^.dfn <> 0 then
bb^.dfn := bb^.dfn - i;
bb := bb^.next;
end; {while}
end; {if}
end; {DepthFirstOrder}
procedure AddDominator (var dom: blockListPtr; dfn: integer);
{ Add dfn to the list of dominators }
{ }
{ parameters: }
{ dom - dominator list }
{ dfn - new dominator number }
var
dp: blockListPtr; {new node}
begin {AddDominator}
new(dp);
dp^.last := nil;
dp^.next := dom;
if dom <> nil then
dom^.last := dp;
dom := dp;
dp^.dfn := dfn;
end; {AddDominator}
procedure Dominators;
{ Find a list of dominators for each node }
var
bb: blockPtr; {used to trace the block list}
change: boolean; {for loop termination test}
i, j: integer; {loop variables}
maxdfn, mindfn: integer; {max and min dfn values used}
procedure CheckPredecessors (bb: blockPtr; bl: dftptr);
{ Eliminate nodes that don't dominate a predecessor }
{ }
{ parameters: }
{ bb - block being checked }
{ bl - list of edges to check for predecessors }
var
dp: blockListPtr; {list of dominator numbers}
tdp: blockListPtr; {used to remove a dominator entry}
begin {CheckPredecessors}
while bl <> nil do begin
if bl^.dest = bb then begin
dp := bb^.dom;
while dp <> nil do
if dp^.dfn <> bb^.dfn then
if not MemberDFNList(dp^.dfn, bl^.from^.dom) then begin
change := true;
tdp := dp;
if tdp^.last = nil then
bb^.dom := tdp^.next
else
tdp^.last^.next := tdp^.next;
if tdp^.next <> nil then
tdp^.next^.last := tdp^.last;
dp := tdp^.next;
dispose(tdp);
end {if}
else
dp := dp^.next
else
dp := dp^.next;
end; {if}
bl := bl^.next;
end; {while}
end; {CheckPredecessors}
begin {Dominators}
Spin;
maxdfn := 0; {find the largest dfn}
bb := DAGBlocks;
while bb <> nil do begin
if bb^.dfn > maxdfn then
maxdfn := bb^.dfn;
bb := bb^.next;
end; {while}
AddDominator(DAGBlocks^.dom, DAGBlocks^.dfn); {the first node is it's own dominator}
mindfn := DAGBlocks^.dfn; {assume all other nodes are dominated by every other node}
for i := mindfn+1 to maxdfn do begin
bb := DFN(i);
if bb <> nil then
for j := mindfn to maxdfn do
AddDominator(bb^.dom, j);
end; {for}
repeat {iterate to the true set of dominators}
change := false;
for i := mindfn+1 to maxdfn do begin
bb := DFN(i);
CheckPredecessors(bb, dft);
CheckPredecessors(bb, backEdge);
end; {for}
until not change;
end; {Dominators}
procedure ReachingDefinitions;
{ find the list of reaching definitions for each basic block }
var
bb: blockPtr; {block being scanned}
change: boolean; {loop termination test}
i: integer; {node index number}
newIn: iclist; {list of inputs}
function Gen (op: icptr): iclist;
{ find a list of generated values }
{ }
{ parameters: }
{ op - list of intermediate codes to scan }
{ }
{ Returns: list of generated definitions }
var
gp: iclist; {list of generated definitions}
indFound: boolean; {has an indirect store been found?}
procedure Check (ip: icptr);
{ Add any result from ip to gp }
{ }
{ parameters: }
{ ip - instruction to check }
var
lc_ind: iclist; {used to trace the c_ind list}
begin {Check}
if ip^.left <> nil then
Check(ip^.left);
if ip^.right <> nil then
Check(ip^.right);
if ip^.opcode in
[pc_str,pc_sro,pc_cop,pc_cpo,pc_lli,pc_lil,pc_lld,pc_ldl,
pc_gli,pc_gil,pc_gld,pc_gdl] then
AddOperation(ip, gp)
else if ip^.opcode in [pc_mov,pc_sto,pc_cpi,pc_iil,pc_ili,pc_idl,pc_ild] then
AddLoads(ip, gp);
if not indFound then
if ip^.opcode in
[pc_sto,pc_cpi,pc_iil,pc_ili,pc_idl,pc_ild,pc_cup,pc_cui,pc_tl1]
then begin
lc_ind := c_ind;
while lc_ind <> nil do begin
AddOperation(lc_ind^.op, gp);
lc_ind := lc_ind^.next;
end; {while}
indFound := true;
end; {if}
end; {Check}
begin {Gen}
indFound := false;
gp := nil;
while op <> nil do begin
Check(op);
op := op^.next;
end; {while}
Gen := gp;
end; {Gen}
function EqualSets (l1, l2: iclist): boolean;
{ See if two sets of stores and copies are equivalent }
{ }
{ parameters: }
{ l1, l2 - lists of copies and stores }
{ }
{ Returns: True if the lists are equivalent, else false }
{ }
{ Notes: The members of each list are assumed to be }
{ unique within that list. }
var
c1, c2: integer; {number of elements in the sets}
l3: iclist; {used to trace the lists}
matchFound: boolean; {was a match found?}
begin {EqualSets}
EqualSets := false; {assume they are not equal}
c1 := 0; {count the elements of l1}
l3 := l1;
while l3 <> nil do begin
c1 := c1+1;
l3 := l3^.next;
end; {while}
c2 := 0; {count the elements of l2}
l3 := l2;
while l3 <> nil do begin
c2 := c2+1;
l3 := l3^.next;
end; {while}
if c1 = c2 then begin {make sure each member of l1 is in l2}
EqualSets := true;
while l1 <> nil do begin
matchFound := false;
l3 := l2;
while l3 <> nil do begin
if MatchLoc(l1^.op, l3^.op) then begin
l3 := nil;
matchFound := true;
end {if}
else
l3 := l3^.next;
end; {while}
if not matchFound then begin
EqualSets := false;
l1 := nil;
end {if}
else
l1 := l1^.next;
end; {while}
end; {if}
end; {EqualSets}
function Union (l1, l2: iclist): iclist;
{ Returns a list that is the union of two input lists }
{ }
{ parameters: }
{ l1, l2 - lists }
{ }
{ Returns: New, dynamically allocated list that includes }
{ all of the members in l1 and l2. }
{ }
{ Notes: }
{ 1. If there are duplicates, the member from l1 is }
{ returned. }
{ 2. It is assumed that all members of l1 and l2 are }
{ unique within their own list. }
{ 3. The original lists are not disturbed. }
{ 4. The caller is responsible for disposing of the }
{ memory used by the list. }
var
lp: iclist; {new list pointer}
np: iclist; {new list member pointer}
tp: iclist; {temp list pointer}
begin {Union}
lp := nil;
tp := l1;
while tp <> nil do begin
new(np);
np^.next := lp;
lp := np;
np^.op := tp^.op;
tp := tp^.next;
end; {while}
while l2 <> nil do begin
if not Member(l2^.op, l1) then begin
new(np);
np^.next := lp;
lp := np;
np^.op := l2^.op;
end; {if}
l2 := l2^.next;
end; {while}
Union := lp;
end; {Union}
function UnionOfPredecessors (bptr: blockPtr): iclist;
{ create a union of the outputs of predecessors to bptr }
{ }
{ parameters: }
{ bptr - block for which to look for predecessors }
{ }
{ Returns: Resulting set }
var
bp: dftptr; {used to trace edge lists}
plist: iclist; {result list}
tlist: iclist; {temp result list}
begin {UnionOfPredecessors}
plist := nil;
bp := dft;
while bp <> nil do begin
if bp^.dest = bptr then begin
tlist := Union(plist, bp^.from^.c_out);
DisposeOpList(plist);
plist := tlist;
end; {if}
bp := bp^.next;
end; {while}
bp := backEdge;
while bp <> nil do begin
if bp^.dest = bptr then begin
tlist := Union(plist, bp^.from^.c_out);
DisposeOpList(plist);
plist := tlist;
end; {if}
bp := bp^.next;
end; {while}
UnionOfPredecessors := plist;
end; {UnionOfPredecessors}
begin {ReachingDefinitions}
i := 1; {initialize the lists}
repeat
bb := DFN(i);
if bb <> nil then begin
bb^.c_in := nil;
bb^.c_gen := Gen(bb^.code);
bb^.c_out := Union(nil, bb^.c_gen);
end; {if}
i := i+1;
until bb = nil;
repeat {iterate to a solution}
change := false;
i := 1;
repeat
Spin;
bb := DFN(i);
if bb <> nil then begin
newIn := UnionOfPredecessors(bb);
if not EqualSets(bb^.c_in, newIn) then begin
{IN[n] := newIn}
DisposeOpList(bb^.c_in);
bb^.c_in := newIn;
newIn := nil;
{OUT[n] := IN[n] - KILL[n] U GEN[n]}
DisposeOpList(bb^.c_out);
bb^.c_out := Union(bb^.c_in, nil);
change := true;
end; {if}
DisposeOpList(newIn);
end; {if}
i := i+1;
until bb = nil;
until not change;
end; {ReachingDefinitions}
procedure LoopInvariantRemoval;
{ Remove all loop invariant computations }
type
loopPtr = ^loopRecord; {blocks in a list}
loopRecord = record
next: loopPtr; {next entry}
block: blockPtr; {code block}
exit: boolean; {is this a loop exit?}
end;
loopListPtr = ^loopListRecord; {list of loop lists}
loopListRecord = record
next: loopListPtr;
loop: loopPtr;
end;
var
icount: integer; {order invariant found}
loops: loopListPtr; {list of loops}
lp: loopPtr; {used to trace loop lists}
llp: loopListPtr; {used to trace the list of loops}
fakeDFN: integer; {to uniquely number newly-created blocks}
function InLoop (blk: blockPtr; lp: loopPtr): boolean;
{ See if the block is in the loop }
{ }
{ parameters: }
{ blk - block to check for }
{ lp - loop list }
{ }
{ Returns: True if blk is in the list, else false }
begin {InLoop}
InLoop := false;
while lp <> nil do begin
if lp^.block = blk then begin
lp := nil;
InLoop := true;
end {if}
else
lp := lp^.next;
end; {while}
end; {InLoop}
procedure FindLoops;
{ Create a list of the natural loops }
var
blk: blockPtr; {target block for a jump}
bp: dftptr; {used to trace the back edges}
lp, lp2: loopPtr; {used to reverse the list}
llp: loopListPtr; {loop list header entry}
llp2: loopListPtr; {used to reverse the list}
op: icptr; {used to trace the opcode list}
procedure Add (block: blockPtr);
{ Add a block to the current loop list }
{ }
{ parameters: }
{ block - block to add }
var
lp: loopPtr; {new loop entry}
begin {Add}
new(lp);
lp^.next := llp^.loop;
llp^.loop := lp;
lp^.block := block;
lp^.exit := false;
end; {Add}
procedure Insert (block: blockPtr);
{ Insert a block into the loop list }
{ }
{ parameters: }
{ block - block to add }
procedure AddPredecessors (block: blockPtr; bl: dftptr);
{ add any predecessors to the loop }
{ }
{ parameters: }
{ block - block for which to check for }
{ predecessors }
{ bl - list of edges to check }
begin {AddPredecessors}
while bl <> nil do begin
if bl^.dest = block then
Insert(bl^.from);
bl := bl^.next;
end; {while}
end; {AddPredecessors}
begin {Insert}
if not InLoop(block, llp^.loop) then begin
Add(block);
AddPredecessors(block, dft);
AddPredecessors(block, backEdge);
end; {if}
end; {Insert}
begin {FindLoops}
loops := nil;
bp := backEdge; {scan the back edges}
while bp <> nil do begin
if MemberDFNList(bp^.dest^.dfn, bp^.from^.dom) then begin
new(llp); {create a new loop list entry}
llp^.next := loops;
loops := llp;
llp^.loop := nil;
Add(bp^.dest);
Insert(bp^.from);
lp := llp^.loop; {reverse the list}
llp^.loop := nil;
while lp <> nil do begin
lp2 := lp;
lp := lp2^.next;
lp2^.next := llp^.loop;
llp^.loop := lp2;
end; {while}
lp := llp^.loop; {mark the exits}
while lp <> nil do begin
op := lp^.block^.code;
while op <> nil do begin
if op^.opcode in [pc_ujp, pc_fjp, pc_tjp, pc_add] then begin
blk := FindDAG(op^.q);
if not InLoop(blk, llp^.loop) then
lp^.exit := true;
if op^.opcode in [pc_fjp,pc_tjp] then
if not InLoop(lp^.block^.next, llp^.loop) then
lp^.exit := true;
end; {if}
op := op^.next;
end; {while}
lp := lp^.next;
end; {while}
end; {if}
bp := bp^.next;
end; {while}
llp := loops; {reverse the loop list}
loops := nil;
while llp <> nil do begin
llp2 := llp;
llp := llp2^.next;
llp2^.next := loops;
loops := llp2;
end; {while}
end; {FindLoops}
function MarkInvariants (lp: loopPtr): boolean;
{ Make a pass over the opcodes, marking those that are }
{ invariant. }
{ }
{ parameters: }
{ lp - loop to scan }
{ }
{ Returns: True if any new nodes were marked, else false. }
var
count: integer; {number of generating blocks}
indirectStores: boolean; {does the loop contain indirect stores or function calls?}
inhibit: boolean; {inhibit stores?}
lp2: loopPtr; {used to trace the loop}
op: icptr; {used to trace the instruction list}
opcode: pcodes; {op^.opcode; for efficiency}
procedure Check (op: icptr; olp: loopPtr);
{ See if this node or its children is invariant }
{ }
{ parameters: }
{ op - node to check }
{ olp - loop entry for the block containing the store }
var
invariant: boolean; {are the operands invariant?}
function IndirectInhibit (op: icptr): boolean;
{ See if a store should be inhibited due to indirect }
{ accesses }
{ }
{ parameters: }
{ op - instruction to check }
{ }
{ Returns: True if the instruction should be inhibited, }
{ else false. }
begin {IndirectInhibit}
IndirectInhibit := false;
if indirectStores then
if Member(op, c_ind) then
IndirectInhibit := true;
end; {IndirectInhibit}
function NoOtherStoresOrUses (lp, olp: loopPtr; op: icptr): boolean;
{ Check for invalid stores }
{ }
{ parameters: }
{ lp - loop to check }
{ olp - loop entry for the block containing the store }
{ op - store to check }
{ }
{ Returns: True if the store is valid, false if not. }
{ }
{ Notes: Specifically, these two rules are enforced: }
{ 1. No other stores to the same location appear in the }
{ loop. }
{ 2. All uses of the value in the loop can be reached }
{ only by the assign. }
var
lp2: loopPtr; {used to trace the loop list}
op2: icptr; {used to trace code list}
function SafeLoad (sop, lop: icptr; sbk, lbk: blockPtr): boolean;
{ See if a load is in a safe position }
{ }
{ parameters: }
{ sop - save opcode that may need to be left in loop }
{ lop - load operation that may inhibit the save }
{ sbk - block containing the save }
{ lbk - block containing the load }
function First (op1, op2, stream: icptr): icptr;
{ See which operation comes first }
{ }
{ parmeters: }
{ op1, op2 - instructions to check }
{ stream - start of block containing the instructions }
{ }
{ Returns: First operation found, or nil if missing }
var
op: icptr; {temp opcode}
begin {First}
if stream = op1 then
First := op1
else if stream = op2 then
First := op2
else begin
op := nil;
if stream^.left <> nil then
op := First(op1, op2, stream^.left);
if op = nil then
if stream^.right <> nil then
op := First(op1, op2, stream^.right);
if op = nil then
if stream^.next <> nil then
op := First(op1, op2, stream^.next);
First := op;
end; {else}
end; {First}
begin {SafeLoad}
if sbk = lbk then
SafeLoad := First(sop, lop, sbk^.code) = sop
else
SafeLoad := MemberDFNList(sbk^.dfn, lbk^.dom);
end; {SafeLoad}
function MatchStores (op, tree: icptr; opbk, treebk: blockPtr):
boolean;
{ Check the tree for stores to the same location as op }
{ }
{ parameters: }
{ op - store to check for }
{ tree - operation tree to check }
{ opbk - block containing op }
{ treebk - block containing tree }
{ }
{ Returns: True if there are matching stores, else false }
var
result: boolean; {function result}
begin {MatchStores}
result := false;
if tree^.opcode in [pc_lli,pc_lil,pc_lld,pc_ldl,pc_str,pc_cop,
pc_sro,pc_cpo,pc_gli,pc_gil,pc_gld,pc_gdl] then begin
if tree <> op then
result := MatchLoc(op, tree);
end {if}
else if tree^.opcode in [pc_ldo,pc_lod] then
if MatchLoc(op, tree) then
result := not SafeLoad(op, tree, opbk, treebk);
if not result then
if tree^.left <> nil then
result := MatchStores(op, tree^.left, opbk, treebk);
if not result then
if tree^.right <> nil then
result := MatchStores(op, tree^.right, opbk, treebk);
MatchStores := result;
end; {MatchStores}
begin {NoOtherStoresOrUses}
NoOtherStoresOrUses := true;
lp2 := lp;
while lp2 <> nil do begin
op2 := lp2^.block^.code;
while op2 <> nil do
if MatchStores(op, op2, olp^.block, lp2^.block) then begin
op2 := nil;
lp2 := nil;
NoOtherStoresOrUses := false;
end {if}
else
op2 := op2^.next;
if lp2 <> nil then
lp2 := lp2^.next;
end; {while}
end; {NoOtherStoresOrUses}
function NumberOfGens (op: icptr; lp: loopPtr): integer;
{ Count the number of nodes that generate op }
{ }
{ parameters: }
{ op - instruction to check }
{ lp - loop to check }
var
count: integer; {number of generators}
begin {NumberOfGens}
count := 0;
while lp <> nil do begin
if Member(op, lp^.block^.c_gen) then
count := count+1;
lp := lp^.next;
end; {while}
NumberOfGens := count;
end; {NumberOfGens}
function PreviousStore (op, list: icptr): boolean;
{ See if the last save was invariant }
{ }
{ parameters: }
{ op - load operation }
{ list - block containing the load }
{ }
{ Returns: True if the previous store was invariant, else }
{ false. }
var
indop: icptr; {any indirect operation after strop}
strop: icptr; {last matching store before op}
procedure Check (lop: icptr);
{ Stop if this is lop; save if it is a matching store }
{ }
{ parameters: }
{ lop - check this operation and it's children }
begin {Check}
if lop^.left <> nil then
Check(lop^.left);
if list <> nil then
if lop^.right <> nil then
Check(lop^.right);
if list <> nil then
if lop = op then
list := nil
else if (lop^.opcode in [pc_str,pc_cop,pc_str,pc_cop])
and MatchLoc(op, lop) then begin
strop := lop;
indop := nil;
end {else if}
else if op^.opcode in
[pc_sto,pc_cpi,pc_iil,pc_ili,pc_idl,pc_ild,pc_cup,pc_cui,pc_tl1]
then
indop := op;
end; {Check}
function Inhibit (indop, op: icptr): boolean;
{ See if op should be inhibited due to indirect stores }
{ }
{ parameters: }
{ indop - inhibiting indirect store or nil }
{ op - instruction to check }
begin {Inhibit}
Inhibit := false;
if indop <> nil then
if Member(op, c_ind) then
Inhibit := true;
end; {Inhibit}
begin {PreviousStore}
indop := nil;
strop := nil;
while list <> nil do begin
Check(list);
if list <> nil then
list := list^.next;
end; {while}
PreviousStore := false;
if strop <> nil then
if strop^.parents <> 0 then
if not Inhibit(indop, op) then
PreviousStore := true;
end; {PreviousStore}
begin {Check}
if op^.parents = 0 then begin
invariant := true;
if op^.left <> nil then begin
Check(op^.left, olp);
if op^.left^.parents = 0 then
invariant := false;
end; {if}
if op^.right <> nil then begin
Check(op^.right, olp);
if op^.right^.parents = 0 then
invariant := false;
end; {if}
if invariant then begin
opcode := op^.opcode;
if opcode in
[pc_adi,pc_adl,pc_adr,pc_and,pc_lnd,pc_bnd,pc_bal,
pc_bnt,pc_bnl,pc_bor,pc_blr,pc_bxr,pc_blx,pc_bno,
pc_dec,pc_dvi,pc_udi,pc_dvl,pc_udl,pc_dvr,pc_equ,pc_neq,
pc_grt,pc_les,pc_geq,pc_leq,pc_inc,pc_ior,pc_lor,
pc_ixa,pc_lad,pc_lao,pc_lca,pc_lda,pc_ldc,pc_mod,pc_uim,
pc_mdl,pc_ulm,pc_mpi,pc_umi,pc_mpl,pc_uml,pc_mpr,pc_ngi,
pc_ngl,pc_ngr,pc_not,pc_pop,pc_sbi,pc_sbl,pc_sbr,
pc_shl,pc_sll,pc_shr,pc_usr,pc_slr,pc_vsr,pc_tri]
then begin
op^.parents := icount;
icount := icount+1;
end {if}
else if opcode = pc_ind then begin
{conservatively assume any indirect stores may alias with op}
if not indirectStores then begin
op^.parents := icount;
icount := icount+1;
end; {if}
end {else if}
else if opcode = pc_cnv then begin
if op^.q & $000F <> ord(cgVoid) then begin
op^.parents := icount;
icount := icount+1;
end; {if}
end {else if}
else if opcode
in [pc_sro,pc_sto,pc_str,pc_cop,pc_cpo,pc_cpi]
then begin
if not inhibit then
if not IndirectInhibit(op) then
if NoOtherStoresOrUses(lp, olp, op) then begin
op^.parents := icount;
icount := icount+1;
end; {if}
end {else if}
else if opcode in [pc_ldo,pc_lod] then begin
{invariant if there is an immediately preceding invariant store}
if PreviousStore(op, lp2^.block^.code) then begin
op^.parents := icount;
icount := icount+1;
end {if}
else if not Member(op, lp2^.block^.c_gen) then begin
{invariant if there are no generators in the loop}
count := NumberOfGens(op, lp);
if count = 0 then begin
op^.parents := icount;
icount := icount+1;
end {if}
else if count = 1 then begin
{invariant if there is one generator AND the generator}
{is not in the current block AND no reaching }
{definitions for the loop AND generating statement is }
{invariant }
if memberOp^.parents <> 0 then
if not Member(op, lp^.block^.c_in) then begin
op^.parents := icount;
icount := icount+1;
end; {if}
end; {else if}
end; {else}
end {else if}
end; {if}
if op^.parents <> 0 then
MarkInvariants := true;
end; {if}
end; {Check}
function CheckForIndirectStores (lp: loopPtr): boolean;
{ See if there are any indirect stores or function calls in }
{ the loop }
{ }
{ parameters: }
{ lp - loop to check }
{ }
{ Returns: True if there are indirect stores or function }
{ calls, else false. }
function CheckOps (op: icptr): boolean;
{ Check this operation list }
{ }
{ parameters: }
{ op - operation list to check }
{ }
{ Returns: True if an indirect store or function call is }
{ found, else false. }
var
result: boolean; {value to return}
begin {CheckOps}
result := false;
while op <> nil do begin
if op^.opcode in
[pc_sto,pc_cpi,pc_iil,pc_ili,pc_idl,pc_ild,pc_cup,pc_cui,
pc_tl1,pc_mov]
then begin
result := true;
op := nil;
end {if}
else begin
if op^.left <> nil then
result := CheckOps(op^.left);
if not result then
if op^.right <> nil then
result := CheckOps(op^.right);
if result then
op := nil;
end; {if}
if op <> nil then
op := op^.next;
end; {while}
CheckOps := result;
end; {CheckOps}
begin {CheckForIndirectStores}
CheckForIndirectStores := false;
while lp <> nil do
if CheckOps(lp^.block^.code) then begin
CheckForIndirectStores := true;
lp := nil;
end {if}
else
lp := lp^.next;
end; {CheckForIndirectStores}
function DominatesExits (dfn: integer; lp: loopPtr): boolean;
{ See if this block dominates all loop exits }
{ }
{ parameters: }
{ dfn - block that must dominate exits }
{ lp - loop list }
{ }
{ Returns: True if the block dominates all exits, else false. }
var
dom: blockListPtr; {used to trace dominator list}
begin {DominatesExits}
DominatesExits := true;
while lp <> nil do begin
if lp^.exit then begin
dom := lp^.block^.dom;
while dom <> nil do
if dom^.dfn = dfn then
dom := nil
else begin
dom := dom^.next;
if dom = nil then begin
lp := nil;
DominatesExits := false;
end; {if}
end; {else}
end; {if}
if lp <> nil then
lp := lp^.next;
end; {while}
end; {DominatesExits}
begin {MarkInvariants}
MarkInvariants := false;
lp2 := lp;
while lp2 <> nil do begin
inhibit := not DominatesExits(lp2^.block^.dfn, lp);
indirectStores := CheckForIndirectStores(lp);
op := lp2^.block^.code;
while op <> nil do begin
Check(op, lp2);
op := op^.next;
end; {while}
lp2 := lp2^.next;
end; {while}
end; {MarkInvariants}
procedure RemoveInvariants (llp: loopListPtr);
{ Remove loop invariant calculations }
{ }
{ parameters: }
{ llp - pointer to the loop entry to process }
var
icount, oldIcount: integer; {invariant order counters}
nhp: blockPtr; {new loop header pointer}
ohp: blockPtr; {old loop header pointer}
op1, op2, op3: icptr; {used to reverse the code list}
procedure CreateHeader;
{ Create the new loop header }
{ }
{ Notes: As a side effect, CreateHeader sets nhp to point to }
{ the new loop header, and ohp to point to the old header. }
var
lp: loopPtr; {new loop list entry}
begin {CreateHeader}
nhp := pointer(Calloc(sizeof(block))); {create the new block}
ohp := llp^.loop^.block; {insert it in the block list}
nhp^.last := ohp^.last;
if nhp^.last <> nil then
nhp^.last^.next := nhp;
nhp^.next := ohp;
ohp^.last := nhp;
nhp^.dfn := fakeDFN; {just a unique number, not a real DFN}
fakeDFN := fakeDFN - 1;
new(lp); {add it to the loop list}
lp^.next := llp^.loop;
llp^.loop := lp;
lp^.block := nhp;
lp^.exit := false;
end; {CreateHeader}
function FindInvariant (ic: integer): integer;
{ Find the next invariant calculation }
{ }
{ parameters: }
{ ic - base count; the new count must exceed this }
{ }
{ Returns: count for the invariant record to remove }
var
lp: loopPtr; {used to trace loop list}
op: icptr; {used to trace code list}
nic: integer; {lowest count > ic}
procedure Check (op: icptr);
{ See if op or its children represent a newer invariant }
{ calculation than the one numbered nic }
{ }
{ parameters: }
{ op - instruction to check }
{ }
{ Notes: Rejecting pc_bno here is rather odd, but it allows }
{ expressions _containing_ pc_bno to be removed without }
{ messing up pc_tri operations by allowing pc_bno to be }
{ removed as the top level of an expression. }
begin {Check}
if op^.parents = 0 then begin
if op^.left <> nil then
Check(op^.left);
if op^.right <> nil then
Check(op^.right);
end {if}
else begin
if op^.parents < nic then
if op^.parents > ic then
if op^.opcode <> pc_bno then
nic := op^.parents;
end; {else}
end; {Check}
begin {FindInvariant}
nic := maxint;
lp := llp^.loop;
while (lp <> nil) and (nic <> ic+1) do begin
op := lp^.block^.code;
while op <> nil do begin
Check(op);
op := op^.next;
end; {while}
lp := lp^.next;
end; {while}
FindInvariant := nic;
end; {FindInvariant}
procedure RemoveInvariant (ic: integer);
{ Move the invariant calculation to the header }
{ }
{ parameters: }
{ ic - index number for instruction to remove }
var
done: boolean; {loop termination test}
lp: loopPtr; {used to trace loop list}
op: icptr; {used to trace code list}
procedure Check (op: icptr);
{ See if a child of op is the target instruction to move }
{ (If so, move it.) }
{ }
{ parameters: }
{ op - instruction to check }
procedure Remove (var op: icptr);
{ Move a calculation to the loop header }
{ }
{ parameters: }
{ op - invariant calculation to move }
var
loc, op2, str: icptr; {new opcodes}
optype: baseTypeEnum; {type of the temp variable}
begin {Remove}
if op^.opcode in [pc_pop,pc_str,pc_sro,pc_sto,pc_sbf] then
{do nothing for now - would need special code to move these}
else if (op^.left <> nil) or (op^.right <> nil) then begin
optype := TypeOf(op); {create a temp label}
loc := pointer(Calloc(sizeof(intermediate_code)));
loc^.opcode := dc_loc;
loc^.optype := cgWord;
maxLoc := maxLoc + 1;
loc^.r := maxLoc;
loc^.q := TypeSize(optype);
loc^.next := nhp^.code;
nhp^.code := loc;
{make a copy of the tree}
op2 := pointer(Malloc(sizeof(intermediate_code)));
op2^ := op^;
op^.opcode := pc_lod; {substitute a load of the temp}
op^.optype := optype;
op^.r := loc^.r;
op^.q := 0;
op^.left := nil;
op^.right := nil;
{store the temp result}
str := pointer(Calloc(sizeof(intermediate_code)));
str^.opcode := pc_str;
str^.optype := optype;
str^.r := loc^.r;
str^.q := 0;
str^.left := op2;
str^.next := loc^.next; {insert the store in the basic block}
loc^.next := str;
end; {else if}
done := true;
end; {Remove}
begin {Check}
if op^.left <> nil then begin
if op^.left^.parents = ic then
Remove(op^.left);
if not done then
Check(op^.left);
end; {if}
if not done then
if op^.right <> nil then begin
if op^.right^.parents = ic then
Remove(op^.right);
if not done then
Check(op^.right);
end; {if}
end; {Check}
procedure RemoveTop (var op: icptr);
{ Move a top-level instruction to the header }
{ }
{ parameters: }
{ op - top level instruction to remove }
var
op2: icptr; {temp operation}
begin {RemoveTop}
op2 := op;
op := op^.next;
op2^.next := nhp^.code;
nhp^.code := op2;
end; {RemoveTop}
begin {RemoveInvariant}
lp := llp^.loop;
done := false;
while not done do begin
op := lp^.block^.code;
if op <> nil then
if op^.parents = ic then begin
RemoveTop(lp^.block^.code);
done := true;
end {if}
else begin
Check(op);
while (op^.next <> nil) and (not done) do begin
if op^.next^.parents = ic then begin
RemoveTop(op^.next);
done := true;
end {if}
else
Check(op^.next);
if op^.next <> nil then
op := op^.next;
end; {while}
end; {else}
lp := lp^.next;
if lp = nil then
done := true;
end; {while}
end; {RemoveInvariant}
procedure AdjustControlFlow;
{ Adjust control flow to account for loop invariant removal. }
{ The current loop's back edges should go to the old header }
{ block, bypassing removed invariant computations. Any other }
{ jumps to the start of the loop should go to the new header }
{ block so that those computations are performed. }
var
lp: loopPtr; {used to trace loop list}
op, op1: icptr; {used to trace code list}
begin {AdjustControlFlow}
{move old header label to new header}
{(for any jumps to it from outside loop)}
if (ohp^.code = nil) or (ohp^.code^.opcode <> dc_lab) then
TermError(3); {shouldn't happen, but let's be sure}
op1 := pointer(Calloc(sizeof(intermediate_code)));
op1^.opcode := dc_lab;
op1^.q := ohp^.code^.q;
op1^.next := nhp^.code;
nhp^.code := op1;
ohp^.code^.q := GenLabel; {make new label for old header &}
lp := llp^.loop; {adjust loop back edges to go to it}
while (lp <> nil) do begin
op := lp^.block^.code;
while op <> nil do begin
if op^.opcode in [pc_ujp,pc_fjp,pc_tjp,pc_add] then
if op^.q = op1^.q then begin
op^.q := ohp^.code^.q;
end;
op := op^.next;
end; {while}
lp := lp^.next;
end; {while}
end; {AdjustControlFlow}
procedure UpdateLoopLists;
{ Update not-yet-processed loops to include the new header }
{ block if appropriate. Also update any additional loops with }
{ the same original header to now include all the nodes of the }
{ loop just processed, since their back edges will now go to }
{ the new header, which dominates the original header. }
var
lp, lp2, lp3: loopPtr; {used to trace loop list}
begin {UpdateLoopLists}
loops := llp^.next;
while loops <> nil do begin
if loops^.loop^.block = ohp then begin
{Another loop with the same header.}
{Nodes of llp^.loop must be added to it.}
{They go after the original header.}
lp3 := loops^.loop;
lp := llp^.loop;
while lp <> nil do begin
if lp^.block <> nhp then
if not InLoop(lp^.block, loops^.loop) then begin
new(lp2);
lp2^.next := lp3^.next;
lp2^.block := lp^.block;
lp2^.exit := lp^.exit;
lp3^.next := lp2;
lp3 := lp2;
end; {if}
lp := lp^.next;
end; {while}
end; {if}
lp := loops^.loop; {Add nhp to other loops containing ohp}
while lp <> nil do begin
if lp^.block = ohp then begin
new(lp2);
lp2^.next := lp^.next;
lp2^.block := lp^.block;
lp2^.exit := lp^.exit;
lp^.next := lp2;
lp^.block := nhp;
lp^.exit := false;
lp := nil;
end {if}
else
lp := lp^.next;
end; {while}
loops := loops^.next;
end; {while}
end; {UpdateLoopLists}
procedure UpdateDominators;
{ Set dominators of the new header block, and update }
{ dominators of other blocks to include it where appropriate. }
var
bb: blockPtr; {used to trace list of basic blocks}
dom: blockListPtr; {used to trace dominator list}
begin {UpdateDominators}
dom := ohp^.dom; {Set dominators of new header block}
while dom <> nil do begin
if dom^.dfn <> ohp^.dfn then
AddDominator(nhp^.dom, dom^.dfn);
dom := dom^.next;
end; {while}
AddDominator(nhp^.dom, nhp^.dfn);
bb := DAGBlocks; {Add nhp to other loops' dominators}
while bb <> nil do begin
if MemberDFNList(ohp^.dfn, bb^.dom) then
AddDominator(bb^.dom, nhp^.dfn);
bb := bb^.next;
end; {while}
end; {UpdateDominators}
begin {RemoveInvariants}
CreateHeader; {create a loop header block}
icount := 0; {find & remove all invariants}
repeat
oldIcount := icount;
icount := FindInvariant (icount);
if icount <> maxint then
RemoveInvariant(icount);
until icount = maxint;
op1 := nhp^.code; {reverse the new code list}
op2 := nil;
while op1 <> nil do begin
op3 := op1;
op1 := op1^.next;
op3^.next := op2;
op2 := op3;
end; {while}
nhp^.code := op2;
{adjust things to account for changes}
if nhp^.code <> nil then begin
Spin;
AdjustControlFlow;
UpdateLoopLists;
UpdateDominators;
end; {if}
end; {RemoveInvariants}
procedure ZeroParents (lp: loopPtr);
{ Zero the parents field in all nodes }
{ }
{ parameters: }
{ lp - loop for which to zero the parents }
var
op: icptr; {used to trace the opcode list}
procedure Zero (op: icptr);
{ Zero the parents field for this node and its }
{ children. }
{ }
{ parameters: }
{ op - node to zero }
begin {Zero}
op^.parents := 0;
if op^.left <> nil then
Zero(op^.left);
if op^.right <> nil then
Zero(op^.right);
end; {Zero}
begin {ZeroParents}
while lp <> nil do begin
op := lp^.block^.code;
while op <> nil do begin
Zero(op);
op := op^.next;
end; {while}
lp := lp^.next;
end; {while}
end; {ZeroParents}
begin {LoopInvariantRemoval}
Spin;
FindLoops; {find a list of natural loops}
fakeDFN := -1;
llp := loops; {scan the loops...}
icount := 1;
while llp <> nil do begin
Spin;
ZeroParents(llp^.loop); {set the parents field to zero}
while MarkInvariants(llp^.loop) do {mark the loop invariant computations}
;
if icount <> 1 then
RemoveInvariants(llp); {remove loop invariant calculations}
llp := llp^.next;
end; {while}
while loops <> nil do begin {dispose of the loop lists}
while loops^.loop <> nil do begin
lp := loops^.loop;
loops^.loop := lp^.next;
dispose(lp);
end; {while}
llp := loops;
loops := llp^.next;
dispose(llp);
end; {while}
end; {LoopInvariantRemoval}
begin {DoLoopOptimization}
DepthFirstOrder; {create the depth first tree}
ReachingDefinitions; {find reaching definitions}
Dominators; {find the lists of dominators}
LoopInvariantRemoval; {remove loop invariant computations}
while dft <> nil do begin {dispose of the depth first tree}
dft2 := dft;
dft := dft2^.next;
dispose(dft2);
end; {while}
while backEdge <> nil do begin {dispose of the back edge list}
dft2 := backEdge;
backEdge := dft2^.next;
dispose(dft2);
end; {while}
end; {DoLoopOptimization}
{---------------------------------------------------------------}
procedure DAG {code: icptr};
{ place an op code in a DAG or tree }
{ }
{ parameters: }
{ code - opcode }
var
temp: icptr; {temp node}
procedure Generate;
{ generate the code for the current procedure }
var
op: icptr; {temp opcode pointers}
procedure BasicBlocks;
{ Break the code up into basic blocks }
var
blast: blockPtr; {last block pointer}
bp: blockPtr; {current block pointer}
cb: icptr; {last code in block pointer}
cp: icptr; {current code pointer}
begin {BasicBlocks}
cp := DAGhead;
DAGblocks := nil;
if cp <> nil then begin
bp := pointer(Calloc(sizeof(block)));
DAGblocks := bp;
blast := bp;
bp^.code := cp;
cb := cp;
cp := cp^.next;
cb^.next := nil;
while cp <> nil do
{labels start a new block}
if cp^.opcode = dc_lab then begin
Spin;
bp := pointer(Calloc(sizeof(block)));
bp^.last := blast;
blast^.next := bp;
blast := bp;
bp^.code := cp;
cb := cp;
cp := cp^.next;
cb^.next := nil;
end {if}
{conditionals are followed by a new block}
else if cp^.opcode in [pc_fjp, pc_tjp, pc_ujp, pc_ret, pc_xjp] then
begin
Spin;
while cp^.next^.opcode = pc_add do begin
cb^.next := cp;
cb := cp;
cp := cp^.next;
cb^.next := nil;
end; {while}
cb^.next := cp;
cb := cp;
cp := cp^.next;
cb^.next := nil;
bp := pointer(Calloc(sizeof(block)));
bp^.last := blast;
blast^.next := bp;
blast := bp;
bp^.code := cp;
cb := cp;
cp := cp^.next;
cb^.next := nil;
end {else if}
else begin {all other statements get added to a block}
cb^.next := cp;
cb := cp;
cp := cp^.next;
cb^.next := nil;
end; {else}
end; {if}
end; {BasicBlocks}
begin {Generate}
if peepHole then {peephole optimization}
repeat
rescan := false;
PeepHoleOptimization(DAGhead);
op := DAGHead;
while op^.next <> nil do begin
Spin;
PeepHoleOptimization(op^.next);
op := op^.next;
end; {while}
CheckLabels;
until not rescan;
BasicBlocks; {build the basic blocks}
if commonSubexpression or loopOptimizations then
if not volatile then
FlagIndirectUses; {create a list of all indirect uses}
if commonSubexpression then {common sub-expression removal}
if not volatile then
CommonSubexpressionElimination;
if loopOptimizations then {loop optimizations}
if not volatile then
DoLoopOptimization;
{ if printSymbols then {debug}
{ PrintBlocks(@'DAG: ', DAGblocks); {debug}
if commonSubexpression or loopOptimizations then
if not volatile then
DisposeOpList(c_ind); {dispose of indirect use list}
Gen(DAGblocks); {generate native code}
if loopOptimizations then {dump and dynamic space}
if not volatile then
DumpLoopLists;
DAGhead := nil; {reset the DAG pointers}
end; {Generate}
procedure CheckReturn;
{ Check if a noreturn function looks like it might return, }
{ or if a non-void function might return with no value. }
{ }
{ This uses a heuristic of basically looking for code at the }
{ end of the function that would lead to it returning if }
{ executed. Control flow operations are optimistically }
{ assumed not to lead to a return. This may produce both }
{ false positives and false negative, but any false }
{ positives should reflect extraneous code that is not }
{ actually reachable (which is dubious in its own right). }
var
code: icptr;
begin {CheckReturn}
code := DAGhead;
while code^.opcode in [pc_lnm,dc_lab,dc_loc,pc_add] do
code := code^.next;
while code^.opcode = pc_pop do
code := code^.left;
while code^.opcode = pc_bno do
code := code^.right;
if not (code^.opcode in [pc_fjp,pc_tjp,pc_ujp,pc_xjp,pc_cui,pc_cup,pc_tl1])
then begin
if fIsNoreturn then
Error(154)
else
Error(155);
end;
end; {CheckReturn}
procedure Push (code: icptr);
{ place a node on the operation stack }
{ }
{ parameters: }
{ code - node }
begin {Push}
code^.next := DAGhead;
DAGhead := code;
end; {Push}
function Pop: icptr;
{ pop a node from the operation stack }
{ }
{ returns: node pointer or nil }
var
node: icptr; {node poped}
tn: icptr; {temp node}
begin {Pop}
node := DAGhead;
if node = nil then
Error(cge1)
else begin
DAGhead := node^.next;
node^.next := nil;
end; {else}
if node^.opcode = dc_loc then begin
tn := node;
node := Pop;
Push(tn);
end; {if}
Pop := node;
end; {Pop}
procedure Reverse;
{ Reverse the operation stack }
var
list, temp: icptr; {work pointers}
begin {Reverse}
list := nil;
while DAGhead <> nil do begin
temp := DAGhead;
DAGhead := temp^.next;
temp^.next := list;
list := temp;
end; {while}
DAGhead := list;
end; {Reverse}
begin {DAG}
case code^.opcode of
pc_bnt, pc_bnl, pc_cnv, pc_dec, pc_inc, pc_ind, pc_lbf, pc_lbu,
pc_ngi, pc_ngl, pc_ngr, pc_not, pc_stk, pc_cop, pc_cpo, pc_tl1,
pc_sro, pc_str, pc_fjp, pc_tjp, pc_xjp, pc_cup, pc_pop, pc_iil,
pc_ili, pc_idl, pc_ild:
begin
code^.left := Pop;
Push(code);
end;
pc_adi, pc_adl, pc_adr, pc_and, pc_lnd, pc_bnd, pc_bal, pc_bno,
pc_bor, pc_blr, pc_bxr, pc_blx, pc_cbf, pc_cpi, pc_dvi, pc_mov,
pc_udi, pc_dvl, pc_udl, pc_dvr, pc_equ, pc_geq, pc_grt, pc_leq,
pc_les, pc_neq, pc_ior, pc_lor, pc_ixa, pc_mod, pc_uim, pc_mdl,
pc_ulm, pc_mpi, pc_umi, pc_mpl, pc_uml, pc_mpr, pc_psh, pc_sbi,
pc_sbl, pc_sbr, pc_shl, pc_sll, pc_shr, pc_usr, pc_slr, pc_vsr,
pc_tri, pc_sbf, pc_sto, pc_cui:
begin
code^.right := Pop;
code^.left := Pop;
Push(code);
end;
pc_gil, pc_gli, pc_gdl, pc_gld, pc_lil, pc_lli, pc_ldl, pc_lld,
pc_lad, pc_lao, pc_lca, pc_lda, pc_ldc, pc_ldo, pc_lod, pc_nop,
dc_cns, dc_glb, dc_dst, pc_lnm, pc_nam, pc_nat, dc_lab, pc_add,
pc_ujp, dc_pin, pc_ent, dc_sym:
Push(code);
pc_ret:
begin
if (lint & lintReturn) <> 0 then
if fIsNoreturn or ((code^.optype <> cgVoid) and not doingMain) then
CheckReturn;
Push(code);
end;
pc_cnn:
begin
code^.opcode := pc_cnv;
temp := Pop;
code^.left := Pop;
Push(code);
Push(temp);
end;
dc_loc: begin
Push(code);
if code^.r > maxLoc then
maxLoc := code^.r;
end;
dc_prm: begin
Push(code);
if code^.s > maxLoc then
maxLoc := code^.s;
end;
dc_str: begin
Push(code);
maxLoc := 0;
end;
dc_enp: begin
Push(code);
Reverse;
Generate;
end;
otherwise: Error(cge1); {invalid opcode}
end; {case}
end; {DAG}
end.
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