[llvm] [SCEVExpander] Keep use flags when expanding adds to GEPs (PR #225148)

[Florian Hahn via llvm-commits]

https://github.com/fhahn updated https://github.com/llvm/llvm-project/pull/225148

>From 1c9987bf9a5ab05d53261cc98855980420c7338c Mon Sep 17 00:00:00 2001
From: Florian Hahn <flo at fhahn.com>
Date: Sun, 20 Sep 2026 15:54:00 +0100
Subject: [PATCH] [SCEVExpander] Keep use flags when expanding adds to GEPs

Update expandAddToGEP to accept and thread through operands as SCEVUse.

This properly use SCEVUse flags when expanding GEPs.
---
 llvm/include/llvm/Transforms/Utils/ScalarEvolutionExpander.h  | 2 +-
 llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp         | 4 ++--
 .../test/Transforms/IndVarSimplify/exit-value-nowrap-flags.ll | 2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/llvm/include/llvm/Transforms/Utils/ScalarEvolutionExpander.h b/llvm/include/llvm/Transforms/Utils/ScalarEvolutionExpander.h
index c98c0cb52fa9c..4470de17518db 100644
--- a/llvm/include/llvm/Transforms/Utils/ScalarEvolutionExpander.h
+++ b/llvm/include/llvm/Transforms/Utils/ScalarEvolutionExpander.h
@@ -487,7 +487,7 @@ class SCEVExpander : public SCEVUseVisitor<SCEVExpander, Value *> {
 
   /// Expand a SCEVAddExpr with a pointer type into a GEP instead of using
   /// ptrtoint+arithmetic+inttoptr.
-  Value *expandAddToGEP(const SCEV *Op, Value *V, SCEV::NoWrapFlags Flags);
+  Value *expandAddToGEP(SCEVUse Op, Value *V, SCEV::NoWrapFlags Flags);
 
   /// Find a previous Value in ExprValueMap for expand.
   /// DropPoisonGeneratingInsts is populated with instructions for which
diff --git a/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp b/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
index 93baf01173f98..3fc65a441d8cc 100644
--- a/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
+++ b/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
@@ -377,7 +377,7 @@ Value *SCEVExpander::InsertBinop(Instruction::BinaryOps Opcode,
 /// loop-invariant portions of expressions, after considering what
 /// can be folded using target addressing modes.
 ///
-Value *SCEVExpander::expandAddToGEP(const SCEV *Offset, Value *V,
+Value *SCEVExpander::expandAddToGEP(SCEVUse Offset, Value *V,
                                     SCEV::NoWrapFlags Flags) {
   assert(!isa<Instruction>(V) ||
          SE.DT.dominates(cast<Instruction>(V), &*Builder.GetInsertPoint()));
@@ -580,7 +580,7 @@ Value *SCEVExpander::visitAddExpr(SCEVUseT<const SCEVAddExpr *> S) {
       for (; I != E && I->first == CurLoop; ++I) {
         // If the operand is SCEVUnknown and not instructions, peek through
         // it, to enable more of it to be folded into the GEP.
-        const SCEV *X = I->second;
+        SCEVUse X = I->second;
         if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(X))
           if (!isa<Instruction>(U->getValue()))
             X = SE.getSCEV(U->getValue());
diff --git a/llvm/test/Transforms/IndVarSimplify/exit-value-nowrap-flags.ll b/llvm/test/Transforms/IndVarSimplify/exit-value-nowrap-flags.ll
index 959fa7aeda198..471abdd62362d 100644
--- a/llvm/test/Transforms/IndVarSimplify/exit-value-nowrap-flags.ll
+++ b/llvm/test/Transforms/IndVarSimplify/exit-value-nowrap-flags.ll
@@ -353,7 +353,7 @@ define ptr @ptr_step_mul_nuw(ptr %first, ptr %last) {
 ; CHECK-NEXT:    [[TMP3:%.*]] = sub i64 [[TMP2]], [[UMIN]]
 ; CHECK-NEXT:    [[TMP4:%.*]] = udiv i64 [[TMP3]], 24
 ; CHECK-NEXT:    [[TMP5:%.*]] = add i64 [[UMIN]], [[TMP4]]
-; CHECK-NEXT:    [[TMP6:%.*]] = mul i64 [[TMP5]], 24
+; CHECK-NEXT:    [[TMP6:%.*]] = mul nuw i64 [[TMP5]], 24
 ; CHECK-NEXT:    [[SCEVGEP:%.*]] = getelementptr nuw i8, ptr [[FIRST]], i64 [[TMP6]]
 ; CHECK-NEXT:    ret ptr [[SCEVGEP]]
 ; CHECK:       [[DONE]]: