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RFC: [TTI] Assume casts between aliasing addrspaces are valid. NFCI. #137969

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RFC: [TTI] Assume casts between aliasing addrspaces are valid. NFCI. #137969

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2 changes: 1 addition & 1 deletion llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
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Original file line number Diff line number Diff line change
Expand Up @@ -136,7 +136,7 @@ class TargetTransformInfoImplBase {
virtual bool isAlwaysUniform(const Value *V) const { return false; }

virtual bool isValidAddrSpaceCast(unsigned FromAS, unsigned ToAS) const {
return false;
return addrspacesMayAlias(FromAS, ToAS);
}

virtual bool addrspacesMayAlias(unsigned AS0, unsigned AS1) const {
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4 changes: 0 additions & 4 deletions llvm/include/llvm/CodeGen/BasicTTIImpl.h
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Expand Up @@ -387,10 +387,6 @@ class BasicTTIImplBase : public TargetTransformInfoImplCRTPBase<T> {

bool isAlwaysUniform(const Value *V) const override { return false; }

bool isValidAddrSpaceCast(unsigned FromAS, unsigned ToAS) const override {
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@jayfoad jayfoad Apr 30, 2025 •
edited
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TBH I don't understand the relationship between BasicTTIImpl and TargetTransformInfoImplBase. I just removed this to stop it from overriding my default implementation in TTIIB.

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@s-barannikov s-barannikov Apr 30, 2025 •
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TTIImplBase has two derived classes, BasicTTIImpl and NoTTIImpl. The latter is used when the target doesn't provide its own implementation of TTIImplBase (which is usually, if not always, done by inheriting from BasicTTIImpl).

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Probably anything that doesn't make use of TM/TLI (like this and surrounding methods) should only be in TTIImplBase rather than BasicTTIImpl?

return false;
}

bool addrspacesMayAlias(unsigned AS0, unsigned AS1) const override {
return true;
}
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21 changes: 0 additions & 21 deletions llvm/lib/Target/AMDGPU/AMDGPUTargetTransformInfo.h
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Expand Up @@ -177,27 +177,6 @@ class GCNTTIImpl final : public BasicTTIImplBase<GCNTTIImpl> {
bool isSourceOfDivergence(const Value *V) const override;
bool isAlwaysUniform(const Value *V) const override;

bool isValidAddrSpaceCast(unsigned FromAS, unsigned ToAS) const override {
// Address space casts must cast between different address spaces.
if (FromAS == ToAS)
return false;

if (FromAS == AMDGPUAS::FLAT_ADDRESS)
return AMDGPU::isExtendedGlobalAddrSpace(ToAS) ||
ToAS == AMDGPUAS::LOCAL_ADDRESS ||
ToAS == AMDGPUAS::PRIVATE_ADDRESS;

if (AMDGPU::isExtendedGlobalAddrSpace(FromAS))
return AMDGPU::isFlatGlobalAddrSpace(ToAS) ||
ToAS == AMDGPUAS::CONSTANT_ADDRESS_32BIT;

if (FromAS == AMDGPUAS::LOCAL_ADDRESS ||
FromAS == AMDGPUAS::PRIVATE_ADDRESS)
return ToAS == AMDGPUAS::FLAT_ADDRESS;

return false;
}

bool addrspacesMayAlias(unsigned AS0, unsigned AS1) const override {
return AMDGPU::addrspacesMayAlias(AS0, AS1);
}
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