[llvm-branch-commits] [llvm] [AMDGPU] Fold provably out-of-bounds raw buffer loads/stores (PR #227402)

[Matt Arsenault via llvm-branch-commits]

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@@ -1175,6 +1175,80 @@ static Instruction *foldConstantIntoDotAccumulator(IntrinsicInst &II,
   return IC.replaceOperand(II, AccIdx, NewAcc);
 }
 
+// Check raw buffer access is OOB or not. For partial OOB access, just bail out.
+static bool isRawBufferAccessDefinitelyOOB(const GCNSubtarget *ST, Value *Rsrc,
+                                           Value *OffsetV, Value *SOffsetV,
+                                           Value *AuxV, uint64_t Payload,
+                                           const DataLayout &DL) {
+  using OOBModel = GCNSubtarget::AMDGPUBufferOOBModel;
+  std::optional<OOBModel> Model = ST->getBufferOOBModel();
+  std::optional<unsigned> NumRecordsWidth =
+      ST->getBufferResourceNumRecordsWidth();
+  if (!Model || !NumRecordsWidth)
+    return false;
+
+  auto *AuxC = dyn_cast<ConstantInt>(AuxV);
+  if (!AuxC)
+    return false;
+
+  uint64_t Offset = computeKnownBits(OffsetV, DL).getMinValue().getZExtValue();
+  uint64_t SOffset =
+      computeKnownBits(SOffsetV, DL).getMinValue().getZExtValue();
+
+  uint64_t Aux = AuxC->getZExtValue();
+  if (Aux & AMDGPU::CPol::VOLATILE)
+    return false;
+
+  // The resource descriptor must also be a compile-time constant.
+  const APInt *StrideAP, *NumRecAP, *FlagsAP;
+  if (!match(Rsrc, m_Intrinsic<Intrinsic::amdgcn_make_buffer_rsrc>(
+                       m_Value(), m_APInt(StrideAP), m_APInt(NumRecAP),
+                       m_APInt(FlagsAP))))
+    return false;
+
+  uint64_t StrideRaw = StrideAP->getZExtValue();
+  uint64_t Stride = StrideRaw & 0x3fff;
+  uint64_t Flags = FlagsAP->getZExtValue();
+  uint64_t NumRecordsMask = maskTrailingOnes<uint64_t>(*NumRecordsWidth);
+  uint64_t NumRecords =
+      NumRecAP->zextOrTrunc(64).getZExtValue() & NumRecordsMask;
+
+  switch (*Model) {
+  case OOBModel::Gfx9:
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arsenm wrote:

It would be nicer if these were named according to the behavior instead of the targets with the behavior 

https://github.com/llvm/llvm-project/pull/227402