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[DSE] Remove uninitialized from allockind when creating dummy zeroed variant function #149336

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Merged
merged 1 commit into from
Jul 18, 2025

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clubby789
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cc #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.

@clubby789 clubby789 changed the title Remove uninitialized from allockind when creating dummy zeroed variant function [DSE] Remove uninitialized from allockind when creating dummy zeroed variant function Jul 17, 2025
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llvmbot commented Jul 17, 2025

@llvm/pr-subscribers-llvm-transforms

Author: None (clubby789)

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cc #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.


Full diff: https://github.com/llvm/llvm-project/pull/149336.diff

2 Files Affected:

  • (modified) llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp (+1)
  • (modified) llvm/test/Transforms/DeadStoreElimination/zeroed-missing.ll (+1-1)
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" }

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LGTM

@nikic nikic merged commit 74c396a into llvm:main Jul 18, 2025
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@nikic nikic added this to the LLVM 21.x Release milestone Jul 18, 2025
@github-project-automation github-project-automation bot moved this to Needs Triage in LLVM Release Status Jul 18, 2025
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nikic commented Jul 18, 2025

/cherry-pick 74c396a

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llvmbot commented Jul 18, 2025

/pull-request #149468

@llvmbot llvmbot moved this from Needs Triage to Done in LLVM Release Status Jul 18, 2025
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4 participants