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[instcombine] Adjust style of MemIntrinsic code to be more idiomatic [nfc] #138715

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Merged
merged 1 commit into from
May 6, 2025
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[instcombine] Adjust style of MemIntrinsic code to be more idiomatic [nfc] #138715

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47 changes: 21 additions & 26 deletions llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1671,38 +1671,15 @@ Instruction *InstCombinerImpl::visitCallInst(CallInst &CI) {
// Intrinsics cannot occur in an invoke or a callbr, so handle them here
// instead of in visitCallBase.
if (auto *MI = dyn_cast<AnyMemIntrinsic>(II)) {
bool Changed = false;

// memmove/cpy/set of zero bytes is a noop.
if (Constant *NumBytes = dyn_cast<Constant>(MI->getLength())) {
if (NumBytes->isNullValue())
return eraseInstFromFunction(CI);
}

// No other transformations apply to volatile transfers.
if (auto *M = dyn_cast<MemIntrinsic>(MI))
if (M->isVolatile())
return nullptr;

// If we have a memmove and the source operation is a constant global,
// then the source and dest pointers can't alias, so we can change this
// into a call to memcpy.
if (auto *MMI = dyn_cast<AnyMemMoveInst>(MI)) {
if (GlobalVariable *GVSrc = dyn_cast<GlobalVariable>(MMI->getSource()))
if (GVSrc->isConstant()) {
Module *M = CI.getModule();
Intrinsic::ID MemCpyID =
isa<AtomicMemMoveInst>(MMI)
? Intrinsic::memcpy_element_unordered_atomic
: Intrinsic::memcpy;
Type *Tys[3] = { CI.getArgOperand(0)->getType(),
CI.getArgOperand(1)->getType(),
CI.getArgOperand(2)->getType() };
CI.setCalledFunction(
Intrinsic::getOrInsertDeclaration(M, MemCpyID, Tys));
Changed = true;
}
}
if (MI->isVolatile())
return nullptr;

if (AnyMemTransferInst *MTI = dyn_cast<AnyMemTransferInst>(MI)) {
// memmove(x,x,size) -> noop.
Expand Down Expand Up @@ -1734,7 +1711,25 @@ Instruction *InstCombinerImpl::visitCallInst(CallInst &CI) {
return eraseInstFromFunction(CI);
}

if (Changed) return II;
// If we have a memmove and the source operation is a constant global,
// then the source and dest pointers can't alias, so we can change this
// into a call to memcpy.
if (auto *MMI = dyn_cast<AnyMemMoveInst>(MI)) {
if (GlobalVariable *GVSrc = dyn_cast<GlobalVariable>(MMI->getSource()))
if (GVSrc->isConstant()) {
Module *M = CI.getModule();
Intrinsic::ID MemCpyID =
isa<AtomicMemMoveInst>(MMI)
? Intrinsic::memcpy_element_unordered_atomic
: Intrinsic::memcpy;
Type *Tys[3] = { CI.getArgOperand(0)->getType(),
CI.getArgOperand(1)->getType(),
CI.getArgOperand(2)->getType() };
CI.setCalledFunction(
Intrinsic::getOrInsertDeclaration(M, MemCpyID, Tys));
return II;
}
}
}

// For fixed width vector result intrinsics, use the generic demanded vector
Expand Down
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