[llvm-branch-commits] [llvm] release/21.x: [DSE] Remove `uninitialized` from `allockind` when creating dummy zeroed variant function (#149336) (PR #149468)

[Tobias Hieta via llvm-branch-commits]

https://github.com/tru updated https://github.com/llvm/llvm-project/pull/149468

>From 186df07d013b5c3f158d22f3e7687723fbcc775b Mon Sep 17 00:00:00 2001
From: clubby789 <jamie at hill-daniel.co.uk>
Date: Fri, 18 Jul 2025 08:30:23 +0100
Subject: [PATCH] [DSE] Remove `uninitialized` from `allockind` when creating
 dummy zeroed variant function (#149336)

cc https://github.com/llvm/llvm-project/pull/138299

rustc sets `allockind("uninitialized")` - if we copy the attributes
as-is when creating a dummy function, Verify complains about
`allockind("uninitialized,zeroed")` conflicting, so we need to clear the
flag.

Co-authored-by: Jamie Hill-Daniel <jamie at osec.io>
(cherry picked from commit 74c396afb26dec74c0b799e218c63f1a26e90d21)
---
 llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp         | 1 +
 llvm/test/Transforms/DeadStoreElimination/zeroed-missing.ll | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp b/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
index 85dd9a1bf7161..0f63ed0166cf4 100644
--- a/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
+++ b/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
@@ -2079,6 +2079,7 @@ struct DSEState {
       AllocFnKind AllocKind =
           Attrs.getFnAttr(Attribute::AllocKind).getAllocKind() |
           AllocFnKind::Zeroed;
+      AllocKind &= ~AllocFnKind::Uninitialized;
       Attrs =
           Attrs.addFnAttribute(Ctx, Attribute::getWithAllocKind(Ctx, AllocKind))
               .removeFnAttribute(Ctx, "alloc-variant-zeroed");
diff --git a/llvm/test/Transforms/DeadStoreElimination/zeroed-missing.ll b/llvm/test/Transforms/DeadStoreElimination/zeroed-missing.ll
index e390d4bdca632..303afc207c023 100644
--- a/llvm/test/Transforms/DeadStoreElimination/zeroed-missing.ll
+++ b/llvm/test/Transforms/DeadStoreElimination/zeroed-missing.ll
@@ -12,6 +12,6 @@ define ptr @undeclared_customalloc(i64 %size, i64 %align) {
   ret ptr %call
 }
 
-declare ptr @customalloc2(i64, i64) allockind("alloc") "alloc-family"="customalloc2" "alloc-variant-zeroed"="customalloc2_zeroed"
+declare ptr @customalloc2(i64, i64) allockind("alloc,uninitialized") "alloc-family"="customalloc2" "alloc-variant-zeroed"="customalloc2_zeroed"
 ; CHECK-DAG: declare ptr @customalloc2_zeroed(i64, i64) #[[CA2ATTR:[0-9]+]]
 ; CHECK-DAG: attributes #[[CA2ATTR]] = { allockind("alloc,zeroed") "alloc-family"="customalloc2" }