[LAA] Strip non-inbounds offset in getPointerDiff() (NFC)

[nikic]

I believe that this code doesn't care whether the offsets are known to be inbounds a priori. For the same reason the change is not testable, as the SCEV based fallback code will look through non-inbounds offsets anyway. So make it clear that there is no special inbounds requirement here.

[llvmbot]

@llvm/pr-subscribers-llvm-analysis

Author: Nikita Popov (nikic)

Changes

I believe that this code doesn't care whether the offsets are known to be inbounds a priori. For the same reason the change is not testable, as the SCEV based fallback code will look through non-inbounds offsets anyway. So make it clear that there is no special inbounds requirement here.

---

Full diff: https://github.com/llvm/llvm-project/pull/118665.diff

1 Files Affected:

• (modified) llvm/lib/Analysis/LoopAccessAnalysis.cpp (+4-4)

diff --git a/llvm/lib/Analysis/LoopAccessAnalysis.cpp b/llvm/lib/Analysis/LoopAccessAnalysis.cpp
index 71582d5d86549b..2c75d5625cb66d 100644
--- a/llvm/lib/Analysis/LoopAccessAnalysis.cpp
+++ b/llvm/lib/Analysis/LoopAccessAnalysis.cpp
@@ -1566,10 +1566,10 @@ std::optional<int> llvm::getPointersDiff(Type *ElemTyA, Value *PtrA,
   unsigned IdxWidth = DL.getIndexSizeInBits(ASA);
 
   APInt OffsetA(IdxWidth, 0), OffsetB(IdxWidth, 0);
-  const Value *PtrA1 =
-      PtrA->stripAndAccumulateInBoundsConstantOffsets(DL, OffsetA);
-  const Value *PtrB1 =
-      PtrB->stripAndAccumulateInBoundsConstantOffsets(DL, OffsetB);
+  const Value *PtrA1 = PtrA->stripAndAccumulateConstantOffsets(
+      DL, OffsetA, /*AllowNonInbounds=*/true);
+  const Value *PtrB1 = PtrB->stripAndAccumulateConstantOffsets(
+      DL, OffsetB, /*AllowNonInbounds=*/true);
 
   int Val;
   if (PtrA1 == PtrB1) {

[artagnon]

Sorry for the delay, but I think this LGTM, thanks!

[fhahn]

Looks good, thanks!