[llvm] [LAA] Strip non-inbounds offset in getPointerDiff() (NFC) (PR #118665)

[Nikita Popov via llvm-commits]

https://github.com/nikic created https://github.com/llvm/llvm-project/pull/118665

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.

>From 551d49b6ebdddedb3867ec4e23d8245243b8e168 Mon Sep 17 00:00:00 2001
From: Nikita Popov <npopov at redhat.com>
Date: Wed, 4 Dec 2024 17:08:50 +0100
Subject: [PATCH] [LAA] Strip non-inbounds offset in getPointerDiff() (NFC)

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 offset anyway. So make it clear that there is no
special inbounds requirement here.
---
 llvm/lib/Analysis/LoopAccessAnalysis.cpp | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

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) {