[llvm-branch-commits] [llvm] release/23.x: [GlobalsAA] Handle self-referencing stores in `AnalyzeUsesOfPointer` (#213631) (PR #231127)

[via llvm-branch-commits]

https://github.com/llvmbot created https://github.com/llvm/llvm-project/pull/231127

Backport 2b3dd2dc32be01ebb74c15d919822538db0292db

Requested by: @nikic

>From b68c9ca7b3237fdd4f034419fb2f98304364fb20 Mon Sep 17 00:00:00 2001
From: Antonio Frighetto <me at antoniofrighetto.com>
Date: Tue, 4 Aug 2026 08:47:01 +0200
Subject: [PATCH] [GlobalsAA] Handle self-referencing stores in
 `AnalyzeUsesOfPointer` (#213631)

Correctly recognize that a global address does escape when it is stored
into itself. Such globals were previously incorrectly marked as
non-address-taken.

Fixes: https://github.com/llvm/llvm-project/issues/213232.
(cherry picked from commit 2b3dd2dc32be01ebb74c15d919822538db0292db)
---
 llvm/lib/Analysis/GlobalsModRef.cpp              |  3 ++-
 .../Analysis/GlobalsModRef/self-addresstaken.ll  | 16 ++++++++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)
 create mode 100644 llvm/test/Analysis/GlobalsModRef/self-addresstaken.ll

diff --git a/llvm/lib/Analysis/GlobalsModRef.cpp b/llvm/lib/Analysis/GlobalsModRef.cpp
index 1a0ae25b2b6b3..6471cc0d52cbd 100644
--- a/llvm/lib/Analysis/GlobalsModRef.cpp
+++ b/llvm/lib/Analysis/GlobalsModRef.cpp
@@ -328,7 +328,8 @@ bool GlobalsAAResult::AnalyzeUsesOfPointer(Value *V,
       if (Readers)
         Readers->insert(LI->getParent()->getParent());
     } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
-      if (V == SI->getOperand(1)) {
+      // Check the pointer operand use of the store.
+      if (&U == &SI->getOperandUse(1)) {
         if (Writers)
           Writers->insert(SI->getParent()->getParent());
       } else if (SI->getOperand(1) != OkayStoreDest) {
diff --git a/llvm/test/Analysis/GlobalsModRef/self-addresstaken.ll b/llvm/test/Analysis/GlobalsModRef/self-addresstaken.ll
new file mode 100644
index 0000000000000..57fd8259f6790
--- /dev/null
+++ b/llvm/test/Analysis/GlobalsModRef/self-addresstaken.ll
@@ -0,0 +1,16 @@
+; RUN: opt < %s -passes='require<globals-aa>,aa-eval' -print-all-alias-modref-info -disable-output 2>&1 | FileCheck %s
+
+; Ensure @g is correctly marked as address taken when it is stored into itself.
+
+ at g = internal global ptr null
+
+; CHECK-LABEL: self_addresstaken
+; CHECK:       MayAlias:	ptr* %p, ptr* @g
+
+define ptr @self_addresstaken() {
+  store ptr @g, ptr @g, align 8
+  %p = load ptr, ptr @g, align 8
+  store ptr null, ptr %p, align 8
+  %q = load ptr, ptr @g, align 8
+  ret ptr %q
+}