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Improved sub rewrite, fixed potential load aliasing issues

This commit is contained in:
Brian Fiete 2024-12-02 06:27:19 -05:00
parent 289d5026c2
commit ba436231cb
2 changed files with 52 additions and 28 deletions

View file

@ -5387,6 +5387,20 @@ X64CPURegister BeMCContext::GetFullRegister(X64CPURegister reg)
return ResizeRegister(reg, 8);
}
bool BeMCContext::HasLoad(const BeMCOperand& operand)
{
if (operand.mKind == BeMCOperandKind_VRegLoad)
return true;
if (operand.mKind != BeMCOperandKind_VReg)
return false;
auto vregInfo = mVRegInfo[operand.mVRegIdx];
if (HasLoad(vregInfo->mRelTo))
return true;
if (HasLoad(vregInfo->mRelOffset))
return true;
return false;
}
bool BeMCContext::IsAddress(BeMCOperand& operand)
{
if (operand.mKind == BeMCOperandKind_VRegAddr)
@ -8932,6 +8946,21 @@ bool BeMCContext::DoLegalization()
continue;
}
if ((inst->mKind == BeMCInstKind_Sub) && (OperandsEqual(inst->mResult, inst->mArg1)))
{
// From: b = Sub a, b
// To: Neg b
// Add b, a
AllocInst(BeMCInstKind_Add, inst->mResult, inst->mArg0, instIdx + 1);
inst->mKind = BeMCInstKind_Neg;
inst->mArg0 = inst->mResult;
inst->mArg1 = BeMCOperand();
inst->mResult = BeMCOperand();
isFinalRun = false;
instIdx++;
continue;
}
// Check operands
if ((!inst->IsPsuedo()) && (arg0Type != NULL) && (!arg0Type->IsNonVectorComposite()))
{
@ -9031,7 +9060,18 @@ bool BeMCContext::DoLegalization()
BeMCOperand savedOperand = BeMCOperand::FromVReg(remappedOperand.mVRegIdx);
BeMCOperand newOperand;
if (origOperand.mKind == BeMCOperandKind_VRegLoad)
bool replaceLoad = origOperand.mKind == BeMCOperandKind_VRegLoad;
// If we have a load on both the target and a load on a failed arg then do *not* keep the load-ness of the replaced arg
if ((replaceLoad) &&
((inst->mArg0 == origOperand) || (inst->mArg1 == origOperand)) &&
(HasLoad(inst->mResult)) && (HasLoad((origOperand))))
{
// This can not only fix further 'bad operand' passes, it can fix aliasing problems
replaceLoad = false;
}
if (replaceLoad)
{
// Loads keep their load-ness
savedOperand = BeMCOperand::FromVReg(remappedOperand.mVRegIdx);
@ -9310,26 +9350,9 @@ bool BeMCContext::DoLegalization()
bool handled = false;
if (OperandsEqual(inst->mResult, inst->mArg1))
{
if (inst->mKind == BeMCInstKind_Sub)
{
// From: b = Sub a, b
// To: Neg b
// Add b, a
AllocInst(BeMCInstKind_Add, inst->mResult, inst->mArg0, instIdx + 1);
inst->mKind = BeMCInstKind_Neg;
inst->mArg0 = inst->mResult;
inst->mArg1 = BeMCOperand();
inst->mResult = BeMCOperand();
handled = true;
instIdx--; // Rerun on the Neg
}
else
{
// We need a scratch reg for this
ReplaceWithNewVReg(inst->mArg1, instIdx, true);
IntroduceVRegs(inst->mArg1, mcBlock, instIdx, instIdx + 2);
}
// We need a scratch reg for this
ReplaceWithNewVReg(inst->mArg1, instIdx, true);
IntroduceVRegs(inst->mArg1, mcBlock, instIdx, instIdx + 2);
}
if (!handled)
@ -16237,7 +16260,7 @@ void BeMCContext::Generate(BeFunction* function)
mDbgPreferredRegs[32] = X64Reg_R8;*/
//mDbgPreferredRegs[8] = X64Reg_RAX;
mDebugging = (function->mName == "?Main@TestProgram@BeefTest@bf@@SAXPEAV?$Array1@PEAVString@System@bf@@@System@3@@Z");
mDebugging = (function->mName == "?MyFunction@MyStruct@BeefTest5@bf@@QEAAXAEAI@Z");
// || (function->mName == "?MethodA@TestProgram@BeefTest@bf@@CAXXZ");
// || (function->mName == "?Hey@Blurg@bf@@SAXXZ")
// ;

View file

@ -1433,6 +1433,7 @@ public:
X64CPURegister ResizeRegister(X64CPURegister reg, int numBits);
X64CPURegister ResizeRegister(X64CPURegister reg, BeType* type);
X64CPURegister GetFullRegister(X64CPURegister reg);
bool HasLoad(const BeMCOperand& operand);
bool IsAddress(BeMCOperand& operand);
bool IsAddressable(BeMCOperand& operand);
bool IsVRegExpr(BeMCOperand& operand);