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Optimize 16-bit multiplication by various constants.

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This optimizes most multiplications by a power of 2 or the sum of two powers of 2, converting them to equivalent operations using shifts which should be faster than the general-purpose multiplication routine.
This commit is contained in:
Stephen Heumann 2022-07-06 22:24:54 -05:00
parent 497e5c036b
commit 393b7304a0
3 changed files with 110 additions and 21 deletions
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1
CGI.pas
View File

@ -147,6 +147,7 @@ const
m_ply = 122;
m_plp = 40;
m_rep = 194;
m_ror_a = $6A;
m_rtl = 107;
m_rts = 96;
m_sbc_abs = 237;

128
Gen.pas
View File

@ -6441,29 +6441,117 @@ procedure GenTree {op: icptr};
var
nd: icptr;
val: integer;
begin {GenMpi}
if not Complex(op^.left) then
if ((op^.left^.opcode = pc_ldc) or (op^.right^.opcode = pc_ldc))
and ((op^.opcode = pc_umi) or (not rangeCheck)) then begin
if op^.left^.opcode = pc_ldc then begin
val := op^.left^.q;
nd := op^.right;
end {if}
else begin
val := op^.right^.q;
nd := op^.left;
end; {else}
if nd^.opcode = pc_ldc then
GenNative(m_lda_imm, immediate, long(ord4(val) * nd^.q).lsw, nil, 0)
else begin
GenTree(nd);
case val of
0: GenNative(m_lda_imm, immediate, 0, nil, 0);
1,2,4,8,16,32,64,128:
while not odd(val) do begin
GenImplied(m_asl_a);
val := val >> 1;
end; {while}
256,512,1024,2048,4096,8192,16384: begin
GenNative(m_and_imm, immediate, $00FF, nil, 0);
GenImplied(m_xba);
val := val >> 8;
while not odd(val) do begin
GenImplied(m_asl_a);
val := val >> 1;
end; {while}
end;
3,5,6,9,10,12,17,18,20,24,33,34,36,40,48,65,66,68,72,80,96: begin
if odd(val) then {prevent lda+pha -> pei optimization}
GenLab(GenLabel);
while not odd(val) do begin
GenImplied(m_asl_a);
val := val >> 1;
end; {while}
GenImplied(m_pha);
val := val - 1;
while not odd(val) do begin
GenImplied(m_asl_a);
val := val >> 1;
end; {while}
GenImplied(m_clc);
GenNative(m_adc_s, direct, 1, nil, 0);
GenImplied(m_plx);
end;
-1,-2,-4,-8,-16,-32,-64,-128: begin
GenNative(m_eor_imm, immediate, -1, nil, 0);
GenImplied(m_ina);
val := -val;
while not odd(val) do begin
GenImplied(m_asl_a);
val := val >> 1;
end; {while}
end;
-256: begin
GenNative(m_eor_imm, immediate, -1, nil, 0);
GenImplied(m_ina);
GenNative(m_and_imm, immediate, $00FF, nil, 0);
GenImplied(m_xba);
end;
otherwise: begin
if val = $8000 then begin
GenImplied(m_lsr_a);
GenNative(m_lda_imm, immediate, 0, nil, 0);
GenImplied(m_ror_a);
end {if}
else begin
GenNative(m_ldx_imm, immediate, val, nil, 0);
if op^.opcode = pc_mpi then
GenCall(28)
else {pc_umi}
GenCall(94);
end; {else}
end;
end; {case}
end; {else}
end {if}
else begin
if not Complex(op^.left) then
if Complex(op^.right) then begin
nd := op^.left;
op^.left := op^.right;
op^.right := nd;
end; {if}
GenTree(op^.left);
if Complex(op^.right) then begin
nd := op^.left;
op^.left := op^.right;
op^.right := nd;
end; {if}
GenTree(op^.left);
if Complex(op^.right) then begin
GenImplied(m_pha);
GenTree(op^.right);
GenImplied(m_plx);
end {if}
else
LoadX(op^.right);
if op^.opcode = pc_mpi then begin
GenCall(28);
if rangeCheck then
GenCall(25);
end {if}
else {pc_umi}
GenCall(94);
GenImplied(m_pha);
GenTree(op^.right);
GenImplied(m_plx);
end {if}
else
LoadX(op^.right);
if op^.opcode = pc_mpi then begin
GenCall(28);
if rangeCheck then
GenCall(25);
end {if}
else {pc_umi}
GenCall(94);
end; {else}
end; {GenMpi}

2
Native.pas
View File

@ -775,7 +775,7 @@ case p_opcode of
m_ora_dir,m_ora_dirX,m_ora_imm,m_ora_long,m_ora_longX,m_ora_s,m_pla,
m_sbc_abs,m_sbc_dir,m_sbc_imm,m_sbc_s,m_tdc,m_tsc,m_adc_indl,m_adc_indly,
m_and_indl,m_and_indly,m_ora_indl,m_ora_indly,m_sbc_indl,m_sbc_indly,
m_eor_indl,m_eor_indly:
m_eor_indl,m_eor_indly,m_ror_a:
aRegister.condition := regUnknown;
m_ldy_absX,m_ldy_dirX,m_ply: