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[mlir][LLVMIR] Handle anonymous TBAA roots during metadata emission #169167

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Merged
merged 1 commit into from
Nov 25, 2025
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Merged

[mlir][LLVMIR] Handle anonymous TBAA roots during metadata emission #169167

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20 changes: 14 additions & 6 deletions mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -677,10 +677,10 @@ llvm::Constant *mlir::LLVM::detail::getLLVMConstant(
}
}
}
// std::vector is used here to accomodate large number of elements that
// exceed SmallVector capacity.
std::vector<llvm::Constant *> constants(numElements, child);
return llvm::ConstantArray::get(arrayType, constants);
// std::vector is used here to accomodate large number of elements that
// exceed SmallVector capacity.
std::vector<llvm::Constant *> constants(numElements, child);
return llvm::ConstantArray::get(arrayType, constants);
}
}

Expand Down Expand Up @@ -2131,8 +2131,16 @@ LogicalResult ModuleTranslation::createTBAAMetadata() {
// LLVM metadata instances.
AttrTypeWalker walker;
walker.addWalk([&](TBAARootAttr root) {
tbaaMetadataMapping.insert(
{root, llvm::MDNode::get(ctx, llvm::MDString::get(ctx, root.getId()))});
llvm::MDNode *node;
if (StringAttr id = root.getId()) {
node = llvm::MDNode::get(ctx, llvm::MDString::get(ctx, id));
} else {
// Anonymous root nodes are self-referencing.
auto selfRef = llvm::MDNode::getTemporary(ctx, {});
node = llvm::MDNode::get(ctx, {selfRef.get()});
node->replaceOperandWith(0, node);
}
tbaaMetadataMapping.insert({root, node});
});

walker.addWalk([&](TBAATypeDescriptorAttr descriptor) {
Expand Down
21 changes: 21 additions & 0 deletions mlir/test/Target/LLVMIR/anonymous-tbaa.mlir
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Original file line number Diff line number Diff line change
@@ -0,0 +1,21 @@
// RUN: mlir-translate -mlir-to-llvmir -split-input-file %s | FileCheck %s

#tbaa_root_0 = #llvm.tbaa_root<>
#tbaa_type_desc_1 = #llvm.tbaa_type_desc<id = "omnipotent char", members = {<#tbaa_root_0, 0>}>
#tbaa_type_desc_2 = #llvm.tbaa_type_desc<id = "long long", members = {<#tbaa_type_desc_1, 0>}>
#tbaa_tag_3 = #llvm.tbaa_tag<access_type = #tbaa_type_desc_2, base_type = #tbaa_type_desc_2, offset = 0>

// CHECK: define void @tbaa_anonymous_root(ptr %{{.*}}) {
// CHECK: %{{.*}} = load i64, ptr %{{.*}}, align 4, !tbaa ![[TAG:[0-9]+]]
// CHECK: ret void
// CHECK: }
// CHECK: !llvm.module.flags = !{![[FLAGS:[0-9]+]]}
// CHECK: ![[FLAGS]] = !{i32 2, !"Debug Info Version", i32 3}
// CHECK: ![[TAG]] = !{![[TYPE:[0-9]+]], ![[TYPE]], i64 0}
// CHECK: ![[TYPE]] = !{!"long long", ![[BASE:[0-9]+]], i64 0}
// CHECK: ![[BASE]] = !{!"omnipotent char", ![[ROOT:[0-9]+]], i64 0}
// CHECK: ![[ROOT]] = distinct !{![[ROOT]]}
llvm.func @tbaa_anonymous_root(%arg0: !llvm.ptr) {
%0 = llvm.load %arg0 {tbaa = [#tbaa_tag_3]} : !llvm.ptr -> i64
llvm.return
}