[clang] 3091b98 - [CIR] Add noundef to __cxx_global_array_dtor parameter (#191529)

[via cfe-commits]

Author: adams381
Date: 2026-04-16T12:08:19-05:00
New Revision: 3091b9811305b98cf45aaf6ed7b5c2c910b24a6f

URL: https://github.com/llvm/llvm-project/commit/3091b9811305b98cf45aaf6ed7b5c2c910b24a6f
DIFF: https://github.com/llvm/llvm-project/commit/3091b9811305b98cf45aaf6ed7b5c2c910b24a6f.diff

LOG: [CIR] Add noundef to __cxx_global_array_dtor parameter (#191529)

The synthetic __cxx_global_array_dtor helper created by
LoweringPrepare was missing noundef on its ptr parameter,
causing a mismatch with classic codegen.

Added: 
    

Modified: 
    clang/lib/CIR/Dialect/Transforms/LoweringPrepare.cpp
    clang/test/CIR/CodeGen/global-array-dtor.cpp
    clang/test/CIR/CodeGen/global-init.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/CIR/Dialect/Transforms/LoweringPrepare.cpp b/clang/lib/CIR/Dialect/Transforms/LoweringPrepare.cpp
index 9015fe483a7df..ec032a92591d7 100644
--- a/clang/lib/CIR/Dialect/Transforms/LoweringPrepare.cpp
+++ b/clang/lib/CIR/Dialect/Transforms/LoweringPrepare.cpp
@@ -910,6 +910,16 @@ cir::FuncOp LoweringPreparePass::getOrCreateDtorFunc(CIRBaseBuilderTy &builder,
   cir::FuncOp dtorFunc =
       buildRuntimeFunction(builder, fnName, op.getLoc(), fnType,
                            cir::GlobalLinkageKind::InternalLinkage);
+
+  SmallVector<mlir::NamedAttribute> paramAttrs;
+  paramAttrs.push_back(
+      builder.getNamedAttr("llvm.noundef", builder.getUnitAttr()));
+  SmallVector<mlir::Attribute> argAttrDicts;
+  argAttrDicts.push_back(
+      mlir::DictionaryAttr::get(builder.getContext(), paramAttrs));
+  dtorFunc.setArgAttrsAttr(
+      mlir::ArrayAttr::get(builder.getContext(), argAttrDicts));
+
   mlir::Block *entryBB = dtorFunc.addEntryBlock();
 
   // Move everything from the dtor region into the helper function.

diff  --git a/clang/test/CIR/CodeGen/global-array-dtor.cpp b/clang/test/CIR/CodeGen/global-array-dtor.cpp
index 49c8e279c2678..ef2a313546fcd 100644
--- a/clang/test/CIR/CodeGen/global-array-dtor.cpp
+++ b/clang/test/CIR/CodeGen/global-array-dtor.cpp
@@ -55,7 +55,7 @@ ArrayDtor arrDtor[16];
 // CIR:   %[[HANDLE:.*]] = cir.get_global @__dso_handle : !cir.ptr<i8>
 // CIR:   cir.call @__cxa_atexit(%[[DTOR_CAST]], %[[ARR_CAST]], %[[HANDLE]]) : (!cir.ptr<!cir.func<(!cir.ptr<!void>)>>, !cir.ptr<!void>, !cir.ptr<i8>) -> ()
 
-// LLVM: define internal void @__cxx_global_array_dtor(ptr %[[ARR_ARG:.*]]) {
+// LLVM: define internal void @__cxx_global_array_dtor(ptr noundef %[[ARR_ARG:.*]]) {
 // LLVM:   %[[BEGIN:.*]] = getelementptr %struct.ArrayDtor, ptr %[[ARR_ARG]], i32 0
 // LLVM:   %[[END:.*]] = getelementptr %struct.ArrayDtor, ptr %[[BEGIN]], i64 16
 // LLVM:   %[[CUR_ADDR:.*]] = alloca ptr

diff  --git a/clang/test/CIR/CodeGen/global-init.cpp b/clang/test/CIR/CodeGen/global-init.cpp
index 7ef21cab24940..47cad1bd724dd 100644
--- a/clang/test/CIR/CodeGen/global-init.cpp
+++ b/clang/test/CIR/CodeGen/global-init.cpp
@@ -216,7 +216,7 @@ ArrayDtor arrDtor[16];
 // CIR:   %[[HANDLE:.*]] = cir.get_global @__dso_handle : !cir.ptr<i8>
 // CIR:   cir.call @__cxa_atexit(%[[DTOR_CAST]], %[[ARR_CAST]], %[[HANDLE]]) : (!cir.ptr<!cir.func<(!cir.ptr<!void>)>>, !cir.ptr<!void>, !cir.ptr<i8>) -> ()
 
-// LLVM: define internal void @__cxx_global_array_dtor(ptr %[[ARR_ARG:.*]]) {
+// LLVM: define internal void @__cxx_global_array_dtor(ptr noundef %[[ARR_ARG:.*]]) {
 // LLVM:   %[[BEGIN:.*]] = getelementptr %struct.ArrayDtor, ptr %[[ARR_ARG]], i32 0
 // LLVM:   %[[END:.*]] = getelementptr %struct.ArrayDtor, ptr %[[BEGIN]], i64 16
 // LLVM:   %[[CUR_ADDR:.*]] = alloca ptr