[mlir][LLVMIR] Handle anonymous TBAA roots during metadata emission #169167
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@llvm/pr-subscribers-mlir-llvm Author: Men-cotton (Men-cotton) ChangesFixes: #160721 Now Full diff: https://github.com/llvm/llvm-project/pull/169167.diff 2 Files Affected:
diff --git a/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp b/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
index caecc0f774155..412a5f76d5753 100644
--- a/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
+++ b/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
@@ -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);
}
}
@@ -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) {
diff --git a/mlir/test/Target/LLVMIR/anonymous-tbaa.mlir b/mlir/test/Target/LLVMIR/anonymous-tbaa.mlir
new file mode 100644
index 0000000000000..b54bfe47e0807
--- /dev/null
+++ b/mlir/test/Target/LLVMIR/anonymous-tbaa.mlir
@@ -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
+}
|
Member
|
@llvm/pr-subscribers-mlir Author: Men-cotton (Men-cotton) ChangesFixes: #160721 Now Full diff: https://github.com/llvm/llvm-project/pull/169167.diff 2 Files Affected:
diff --git a/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp b/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
index caecc0f774155..412a5f76d5753 100644
--- a/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
+++ b/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
@@ -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);
}
}
@@ -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) {
diff --git a/mlir/test/Target/LLVMIR/anonymous-tbaa.mlir b/mlir/test/Target/LLVMIR/anonymous-tbaa.mlir
new file mode 100644
index 0000000000000..b54bfe47e0807
--- /dev/null
+++ b/mlir/test/Target/LLVMIR/anonymous-tbaa.mlir
@@ -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
+}
|
Dinistro
approved these changes
Nov 24, 2025
gysit
reviewed
Nov 24, 2025
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gysit
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gysit
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Are you sure an anonymous TBAA root is represent with a self referencing node?
The language reference seems to hint that an empty node should be used:
https://llvm.org/docs/LangRef.html#representation
Or am I misreading something?
Contributor
Author
|
Thanks for reviewing, @gysit ! You are right about the LangRef description. However, I noticed that My implementation matches that pattern to be consistent with how LLVM typically builds anonymous roots. That said, if you prefer to strictly follow the LangRef text (using |
Contributor
Ah, if the actual implementation differs from the language reference then the implementation takes preference. |
gysit
approved these changes
Nov 24, 2025
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gysit
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gysit
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Thanks for clarifying!
LGTM
Contributor
Author
|
I don't have write access. Could you please merge this? |
Collaborator
|
LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/169/builds/17432 Here is the relevant piece of the build log for the reference |
Contributor
Author
|
At least, I found that the same failure was reported in the pull request #167767. |
Contributor
Author
|
I've been looking into the post-merge CI failure. It appears to be a pre-existing issue in the Here is a summary of my investigation:
Given that my patch only touches MLIR, it seems highly unlikely to be the root cause of this JITLink test failure. It appears to be an intermittent issue that was present before my patch landed. |
Contributor
|
Yeah, this does not look related in any way. |
aadeshps-mcw
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to aadeshps-mcw/llvm-project
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Nov 26, 2025
…lvm#169167) This commit enhances MLIR's TBAA export with support for anonymous TBAA roots. The import for this was around for a bit but the export was missing. Fixes: llvm#160721
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Fixes: #160721
Now
build/bin/mlir-translate -mlir-to-llvmir mlir/test/Dialect/LLVMIR/tbaa-roundtrip.mlirpasses.