[llvm-branch-commits] [llvm] [Vectorizer] fix GEPs incorrectly marked as "inbounds" (PR #120730)

[Florian Mayer via llvm-branch-commits]

https://github.com/fmayer updated https://github.com/llvm/llvm-project/pull/120730

>From 5987219575feabd0eefba5932c21b0eba8ae4fb7 Mon Sep 17 00:00:00 2001
From: Florian Mayer <fmayer at google.com>
Date: Fri, 20 Dec 2024 05:35:56 -0800
Subject: [PATCH 1/2] simplify

Created using spr 1.3.4
---
 llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp b/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
index 0768eccc8aeb35..ffd89466abeea9 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
@@ -1986,12 +1986,12 @@ void VPReverseVectorPointerRecipe::execute(VPTransformState &State) {
   // LastLane = 1 - RunTimeVF
   Value *LastLane = Builder.CreateSub(ConstantInt::get(IndexTy, 1), RunTimeVF);
   Value *Ptr = State.get(getOperand(0), VPLane(0));
-  Value *ResultPtr = Builder.CreateGEP(
-      IndexedTy, Ptr, NumElt, "",
-      getGEPNoWrapFlags().withoutInBounds().withoutNoUnsignedSignedWrap());
-  ResultPtr = Builder.CreateGEP(
-      IndexedTy, ResultPtr, LastLane, "",
-      getGEPNoWrapFlags().withoutInBounds().withoutNoUnsignedSignedWrap());
+  Value *ResultPtr =
+      Builder.CreateGEP(IndexedTy, Ptr, NumElt, "",
+                        getGEPNoWrapFlags().withoutNoUnsignedSignedWrap());
+  ResultPtr =
+      Builder.CreateGEP(IndexedTy, ResultPtr, LastLane, "",
+                        getGEPNoWrapFlags().withoutNoUnsignedSignedWrap());
 
   State.set(this, ResultPtr, /*IsScalar*/ true);
 }

>From e4e48cf7e0448f25ccdcdf7d7c262ac880853ddd Mon Sep 17 00:00:00 2001
From: Florian Mayer <fmayer at google.com>
Date: Fri, 20 Dec 2024 05:40:10 -0800
Subject: [PATCH 2/2] address comment

Created using spr 1.3.4
---
 llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp b/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
index ffd89466abeea9..f97cae215ec087 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
@@ -1986,12 +1986,10 @@ void VPReverseVectorPointerRecipe::execute(VPTransformState &State) {
   // LastLane = 1 - RunTimeVF
   Value *LastLane = Builder.CreateSub(ConstantInt::get(IndexTy, 1), RunTimeVF);
   Value *Ptr = State.get(getOperand(0), VPLane(0));
-  Value *ResultPtr =
-      Builder.CreateGEP(IndexedTy, Ptr, NumElt, "",
-                        getGEPNoWrapFlags().withoutNoUnsignedSignedWrap());
-  ResultPtr =
-      Builder.CreateGEP(IndexedTy, ResultPtr, LastLane, "",
-                        getGEPNoWrapFlags().withoutNoUnsignedSignedWrap());
+  // N.B. we deliberately do not use getGEPNoWrapFlags here, because this
+  // transform can invalidate `inbounds`.
+  Value *ResultPtr = Builder.CreateGEP(IndexedTy, Ptr, NumElt, "");
+  ResultPtr = Builder.CreateGEP(IndexedTy, ResultPtr, LastLane, "");
 
   State.set(this, ResultPtr, /*IsScalar*/ true);
 }