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Allow FindNextRead over conditionals #410

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merged 2 commits into from
Nov 23, 2023
Merged

Allow FindNextRead over conditionals #410

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42fb92a
Allow FindNextRead over conditionals
Wuerfel21 Aug 3, 2023
723afbb
Gate behind IsMemoryOrderSafe and add getbyte/getword support
Wuerfel21 Aug 3, 2023
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26 changes: 21 additions & 5 deletions backends/asm/optimize_ir.c
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Original file line number Diff line number Diff line change
Expand Up @@ -4443,7 +4443,7 @@ static bool IsMemoryOrderSafe(Operand *op) {
// returns NULL if we spot anything that changes src, dest,
// memory, or a branch
//
static IR* FindNextRead(IR *irorig, Operand *dest, Operand *src)
static IR* FindNextRead(IR *irorig, Operand *dest, Operand *src, bool branch_ok)
{
IR *ir;
int32_t offset = 0;
Expand All @@ -4455,18 +4455,26 @@ static IR* FindNextRead(IR *irorig, Operand *dest, Operand *src)
if (IsBranch(ir)) {
if (ir->opc == OPC_CALL && isMulDivFunc(ir->dst) && !IsCallThatUsesReg(ir, src) && !IsCallThatUsesReg(ir, dest)) {
// Do nothing
} else if (branch_ok && IsJump(ir) && ir->cond != COND_TRUE) {
// Also do nothing
} else {
return NULL;
}
}
#if 0
if (ir->cond != irorig->cond) {
return NULL;
}
#endif
if (ir->src == src && offset == 0 && (ir->opc == OPC_RDLONG||ir->opc == OPC_RDWORD||ir->opc == OPC_RDBYTE)) {
return ir;
}
if ((ir->opc == OPC_ADD || ir->opc == OPC_SUB) && ir->dst == src && ir->src && ir->src->kind == IMM_INT) {
offset += AddSubVal(ir);
if (ir->cond == irorig->cond) {
offset += AddSubVal(ir);
} else {
return NULL;
}
} else if (InstrModifies(ir, dest) || InstrModifies(ir, src)) {
return NULL;
}
Expand Down Expand Up @@ -4568,14 +4576,22 @@ OptimizeReadWrite(IRList *irl)
bool write = IsWrite(ir);
// don't mess with it if src==dst
if (!write && ir->src == ir->dst) goto get_next;
nextread = FindNextRead(ir, dst1, base);
nextread = FindNextRead(ir, dst1, base, (curfunc->optimize_flags & OPT_EXPERIMENTAL) && IsMemoryOrderSafe(ir->src));
int nextsize = MemoryOpSize(nextread);
if (nextread && CondIsSubset(ir->cond,nextread->cond)) {
// wrlong a, b ... rdlong c, b -> mov c, a
// rdlong a, b ... rdlong c, b -> mov c, a
if(size == nextsize && (!write || size==4) && (gl_p2 || !InstrSetsFlags(nextread,FLAG_WC)) ) {
if(size == nextsize && (!write || size==4 || gl_p2) && (gl_p2 || !InstrSetsFlags(nextread,FLAG_WC)) ) {
nextread->src = dst1;
ReplaceOpcode(nextread, OPC_MOV);
if (!write || size == 4) {
ReplaceOpcode(nextread, OPC_MOV);
} else if (size == 2) {
ReplaceOpcode(nextread,OPC_GETWORD);
nextread->src2 = NewImmediate(0);
} else if (size == 1) {
ReplaceOpcode(nextread,OPC_GETBYTE);
nextread->src2 = NewImmediate(0);
}
change = 1;
goto get_next;
}
Expand Down
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