6502/PLASMA
1
0
Fork 0
mirror of https://github.com/dschmenk/PLASMA.git synced 2024-10-18 22:24:28 +00:00
Code Issues Projects Releases Wiki Activity

Allow optimiser to introduce DUP opcodes

Browse Source
This commit is contained in:
Steven Flintham 2017-07-28 23:06:02 +01:00
parent e9c4e062c3
commit b6efb90995
2 changed files with 83 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

85
src/toolsrc/codegen.c
View File

@ -908,10 +908,67 @@ void release_seq(t_opseq *seq)
freeop_lst = op;
}
}
/*
* Indicate if an address is (or might be) memory-mapped hardware; used to avoid
* optimising away accesses to such addresses.
*/
int is_hardware_address(int addr)
{
// TODO: I think this is reasonable for Apple hardware but I'm not sure.
// It's a bit too strong for Acorn hardware but code is unlikely to try to
// read from high addresses anyway, so there's no real harm in not
// optimising such accesses anyway.
return addr >= 0xC000;
}
/*
* Replace all but the first of a series of identical load opcodes by DUP. This
* doesn't reduce the number of opcodes but does reduce their size in bytes.
* This is only called on the second optimisation pass because the DUP opcodes
* may inhibit other peephole optimisations which are more valuable.
*/
int try_dupify(t_opseq *op)
{
int crunched = 0;
t_opseq *opn = op->nextop;
for (; opn; opn = opn->nextop)
{
if (op->code != opn->code)
return crunched;
switch (op->code)
{
case CONST_CODE:
if (op->val != opn->val)
return crunched;
break;
case LADDR_CODE:
case LLB_CODE:
case LLW_CODE:
if (op->offsz != opn->offsz)
return crunched;
break;
case GADDR_CODE:
case LAB_CODE:
case LAW_CODE:
if ((op->tag != opn->tag) || (op->offsz != opn->offsz) ||
(op->type != opn->type))
return crunched;
break;
default:
return crunched;
}
opn->code = DUP_CODE;
crunched = 1;
}
return crunched;
}
/*
* Crunch sequence (peephole optimize)
*/
int crunch_seq(t_opseq **seq)
int crunch_seq(t_opseq **seq, int pass)
{
t_opseq *opnext, *opnextnext, *opprev = 0;
t_opseq *op = *seq;
@ -1006,7 +1063,8 @@ int crunch_seq(t_opseq **seq)
freeops = 1;
}
break;
case CONST_CODE: // Collapse constant operation
case CONST_CODE:
// Collapse constant operation
if ((opnextnext = opnext->nextop))
switch (opnextnext->code)
{
@ -1083,6 +1141,9 @@ int crunch_seq(t_opseq **seq)
freeops = 2;
break;
}
// End of collapse constant operation
if ((pass > 0) && (freeops == 0) && (op->val != 0))
crunched = try_dupify(op);
break; // CONST_CODE
case BINARY_CODE(MUL_TOKEN):
for (shiftcnt = 0; shiftcnt < 16; shiftcnt++)
@ -1143,6 +1204,8 @@ int crunch_seq(t_opseq **seq)
freeops = 1;
break;
}
if ((pass > 0) && (freeops == 0))
crunched = try_dupify(op);
break; // LADDR_CODE
case GADDR_CODE:
switch (opnext->code)
@ -1183,7 +1246,13 @@ int crunch_seq(t_opseq **seq)
freeops = 1;
break;
}
if ((pass > 0) && (freeops == 0))
crunched = try_dupify(op);
break; // GADDR_CODE
case LLB_CODE:
if (pass > 0)
crunched = try_dupify(op);
break; // LLB_CODE
case LLW_CODE:
// LLW [n]:CB 8:SHR -> LLB [n+1]
if ((opnext->code == CONST_CODE) && (opnext->val == 8))
@ -1199,7 +1268,13 @@ int crunch_seq(t_opseq **seq)
}
}
}
if ((pass > 0) && (freeops == 0))
crunched = try_dupify(op);
break; // LLW_CODE
case LAB_CODE:
if ((pass > 0) && (op->type || !is_hardware_address(op->offsz)))
crunched = try_dupify(op);
break; // LAB_CODE
case LAW_CODE:
// LAW x:CB 8:SHR -> LAB x+1
if ((opnext->code == CONST_CODE) && (opnext->val == 8))
@ -1215,6 +1290,9 @@ int crunch_seq(t_opseq **seq)
}
}
}
if ((pass > 0) && (freeops == 0) &&
(op->type || !is_hardware_address(op->offsz)))
crunched = try_dupify(op);
break; // LAW_CODE
case LOGIC_NOT_CODE:
switch (opnext->code)
@ -1351,7 +1429,8 @@ int emit_seq(t_opseq *seq)
int emitted = 0;
if (outflags & OPTIMIZE)
while (crunch_seq(&seq));
for (int pass = 0; pass < 2; pass++)
while (crunch_seq(&seq, pass));
while (seq)
{
op = seq;

2
src/toolsrc/codegen.h
View File

@ -142,7 +142,7 @@ void emit_start(void);
void emit_rld(void);
void emit_esd(void);
void release_seq(t_opseq *seq);
int crunch_seq(t_opseq **seq);
int crunch_seq(t_opseq **seq, int pass);
t_opseq *gen_seq(t_opseq *seq, int opcode, long cval, int tag, int offsz, int type);
t_opseq *cat_seq(t_opseq *seq1, t_opseq *seq2);
int emit_seq(t_opseq *seq);