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[SPIR-V][Codegen] Represent the property of the target to declare and use typed pointers and update MachineVerifier to use it #110270

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[SPIR-V][Codegen] Represent the property of the target to declare and use typed pointers and update MachineVerifier to use it #110270

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6 changes: 6 additions & 0 deletions llvm/include/llvm/CodeGen/TargetLowering.h
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Expand Up @@ -455,6 +455,12 @@ class TargetLoweringBase {
return true;
}

/// Return true if the target can handle the declaration and use of pointers
/// that specify the type of data they point to, meaning that interpretation
/// of the data type is not left to instructions that utilize the pointer, but
/// encoded by the pointer declaration.
virtual bool hasTypedPointer() const { return false; }
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Should this bit be in the Subtarget/Target info?

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I don't know what is the best option. After some reflection I decided that the notion of typed pointers seems to be more of a target lowering property than property of the SPIRV target machine itself, especially given the recent appearance of untyped pointers (https://htmlpreview.github.io/?https://github.com/KhronosGroup/SPIRV-Registry/blob/main/extensions/KHR/SPV_KHR_untyped_pointers.html) that do not specify the type of data they point to. Although we can't lower without typed pointers at the moment, probably this property belongs to lowering rather than to target machine. I'm not 100% sure though.


/// Return true if the @llvm.experimental.vector.partial.reduce.* intrinsic
/// should be expanded using generic code in SelectionDAGBuilder.
virtual bool
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4 changes: 3 additions & 1 deletion llvm/lib/CodeGen/MachineVerifier.cpp
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Expand Up @@ -1294,7 +1294,9 @@ void MachineVerifier::verifyPreISelGenericInstruction(const MachineInstr *MI) {
report("bitcast sizes must match", MI);

if (SrcTy == DstTy)
report("bitcast must change the type", MI);
if (!SrcTy.isPointer() ||
!MF->getSubtarget().getTargetLowering()->hasTypedPointer())
report("bitcast must change the type", MI);

break;
}
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3 changes: 3 additions & 0 deletions llvm/lib/Target/SPIRV/SPIRVISelLowering.h
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Expand Up @@ -41,6 +41,9 @@ class SPIRVTargetLowering : public TargetLowering {
// prevent creation of jump tables
bool areJTsAllowed(const Function *) const override { return false; }

// allow for typed pointers
bool hasTypedPointer() const override { return true; }

// This is to prevent sexts of non-i64 vector indices which are generated
// within general IRTranslator hence type generation for it is omitted.
MVT getVectorIdxTy(const DataLayout &DL) const override {
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15 changes: 15 additions & 0 deletions llvm/test/MachineVerifier/SPIRV/test_typedptr_bitcast.mir
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@@ -0,0 +1,15 @@
#RUN: llc -mtriple=spirv64-unknown-unknown -o - -global-isel -run-pass=none -verify-machineinstrs %s 2>&1 | FileCheck %s

---
name: test_typedptr_bitcast
legalized: true
regBankSelected: false
selected: false
tracksRegLiveness: true
liveins:
body: |
bb.0:
; CHECK-NOT: Bad machine code: bitcast must change the type
%0:_(p0) = G_IMPLICIT_DEF
%1:_(p0) = G_BITCAST %0
...
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