[AMDGPU] Infer amdgpu-no-flat-scratch-init attribute in AMDGPUAttributor #94647
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@@ -439,6 +439,26 @@ struct AAAMDAttributesFunction : public AAAMDAttributes { | |
| indicatePessimisticFixpoint(); | ||
| return; | ||
| } | ||
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| SmallPtrSet<const Constant *, 8> VisitedConsts; | ||
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| for (Instruction &I : instructions(F)) { | ||
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| if (isa<AddrSpaceCastInst>(I) && | ||
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| cast<AddrSpaceCastInst>(I).getSrcAddressSpace() == | ||
| AMDGPUAS::PRIVATE_ADDRESS) { | ||
| removeAssumedBits(FLAT_SCRATCH_INIT); | ||
| return; | ||
| } | ||
| // check for addrSpaceCast in constant expressions | ||
| for (const Use &U : I.operands()) { | ||
| if (const auto *C = dyn_cast<Constant>(U)) { | ||
| if (constHasASCast(C, VisitedConsts)) { | ||
| removeAssumedBits(FLAT_SCRATCH_INIT); | ||
| return; | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } | ||
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| ChangeStatus updateImpl(Attributor &A) override { | ||
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@@ -525,6 +545,9 @@ struct AAAMDAttributesFunction : public AAAMDAttributes { | |
| if (isAssumed(COMPLETION_ACTION) && funcRetrievesCompletionAction(A, COV)) | ||
| removeAssumedBits(COMPLETION_ACTION); | ||
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| if (isAssumed(FLAT_SCRATCH_INIT) && needFlatScratchInit(A)) | ||
| removeAssumedBits(FLAT_SCRATCH_INIT); | ||
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| return getAssumed() != OrigAssumed ? ChangeStatus::CHANGED | ||
| : ChangeStatus::UNCHANGED; | ||
| } | ||
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@@ -683,6 +706,59 @@ struct AAAMDAttributesFunction : public AAAMDAttributes { | |
| return !A.checkForAllCallLikeInstructions(DoesNotRetrieve, *this, | ||
| UsedAssumedInformation); | ||
| } | ||
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| // Returns true if FlatScratchInit is needed, i.e., no-flat-scratch-init is | ||
| // not to be set. | ||
| bool needFlatScratchInit(Attributor &A) { | ||
| assert(isAssumed(FLAT_SCRATCH_INIT)); // only called if the bit is still set | ||
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| // This is called on each callee; false means callee shouldn't have | ||
| // no-flat-scratch-init. | ||
| auto CheckForNoFlatScratchInit = [&](Instruction &I) { | ||
| const auto &CB = cast<CallBase>(I); | ||
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Contributor
There was a problem hiding this comment. I would hope FroAllCallLikeInstructions would have a CallBase typed argument to begin with |
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| const Function *Callee = CB.getCalledFunction(); | ||
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| // Callee == 0 for inline asm or indirect call with known callees. | ||
| // In the latter case, updateImpl() already checked the callees and we | ||
| // know their FLAT_SCRATCH_INIT bit is set. | ||
| // If function has indirect call with unknown callees, the bit is | ||
| // already removed in updateImpl() and execution won't reach here. | ||
| if (!Callee) | ||
| return true; | ||
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| return Callee->getIntrinsicID() != | ||
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Contributor
There was a problem hiding this comment. IIUC, this attribute should propagate from callee to caller, so you will need to check all function calls, and ask Attributor whether the callee needs it or not.
Contributor
Author
There was a problem hiding this comment.
Callees are already checked at the beginning of |
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| Intrinsic::amdgcn_addrspacecast_nonnull; | ||
| }; | ||
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| bool UsedAssumedInformation = false; | ||
| // If any callee is false (i.e. need FlatScratchInit), | ||
| // checkForAllCallLikeInstructions returns false, in which case this | ||
| // function returns true. | ||
| return !A.checkForAllCallLikeInstructions(CheckForNoFlatScratchInit, *this, | ||
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Contributor
There was a problem hiding this comment. This should look more like how the queue pointer is handled. This is just a slightly more complicated version of checkForQueuePtr. The instruction walk you put in initialize should be handled by checkForAllInstructions looking for addrspacecast
Collaborator
There was a problem hiding this comment. Doing it like QueuePtr is certainly more "canonical'. Seems more preferable than doing it in |
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| UsedAssumedInformation); | ||
| } | ||
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| bool constHasASCast(const Constant *C, | ||
| SmallPtrSetImpl<const Constant *> &Visited) { | ||
| if (!Visited.insert(C).second) | ||
| return false; | ||
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| if (const auto *CE = dyn_cast<ConstantExpr>(C)) | ||
| if (CE->getOpcode() == Instruction::AddrSpaceCast && | ||
| CE->getOperand(0)->getType()->getPointerAddressSpace() == | ||
| AMDGPUAS::PRIVATE_ADDRESS) | ||
| return true; | ||
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| for (const Use &U : C->operands()) { | ||
| const auto *OpC = dyn_cast<Constant>(U); | ||
| if (!OpC || !Visited.insert(OpC).second) | ||
| continue; | ||
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| if (constHasASCast(OpC, Visited)) | ||
| return true; | ||
| } | ||
| return false; | ||
| } | ||
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| }; | ||
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| AAAMDAttributes &AAAMDAttributes::createForPosition(const IRPosition &IRP, | ||
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Should use checkForAllInstructions instead of manually looking at all instructions