[DirectX] Use an allow-list of DXIL compatible module metadata #165290
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@llvm/pr-subscribers-backend-directx Author: Finn Plummer (inbelic) ChangesThis pr introduces an allow-list for module metadata, this encompasses the llvm metadata nodes: Resolves: #164473. Full diff: https://github.com/llvm/llvm-project/pull/165290.diff 2 Files Affected:
diff --git a/llvm/lib/Target/DirectX/DXILTranslateMetadata.cpp b/llvm/lib/Target/DirectX/DXILTranslateMetadata.cpp
index 1e4797bbd05aa..be31da15581a3 100644
--- a/llvm/lib/Target/DirectX/DXILTranslateMetadata.cpp
+++ b/llvm/lib/Target/DirectX/DXILTranslateMetadata.cpp
@@ -364,6 +364,16 @@ static void cleanModuleFlags(Module &M) {
M.addModuleFlag(Flag.Behavior, Flag.Key->getString(), Flag.Val);
}
+using GlobalMDList = std::array<StringLiteral, 7>;
+
+// The following are compatible with DXIL but not emit with clang, they can
+// be added when applicable:
+// dx.typeAnnotations, dx.viewIDState, dx.dxrPayloadAnnotations
+static GlobalMDList CompatibleNamedModuleMDs = {
+ "llvm.ident", "llvm.module.flags", "dx.resources", "dx.valver",
+ "dx.shaderModel", "dx.version", "dx.entryPoints",
+};
+
static void translateGlobalMetadata(Module &M, DXILResourceMap &DRM,
DXILResourceTypeMap &DRTM,
const ModuleShaderFlags &ShaderFlags,
@@ -426,19 +436,17 @@ static void translateGlobalMetadata(Module &M, DXILResourceMap &DRM,
cleanModuleFlags(M);
- // dx.rootsignatures will have been parsed from its metadata form as its
- // binary form as part of the RootSignatureAnalysisWrapper, so safely
- // remove it as it is not recognized in DXIL
- if (NamedMDNode *RootSignature = M.getNamedMetadata("dx.rootsignatures"))
- RootSignature->eraseFromParent();
-
- // llvm.errno.tbaa was recently added but is not supported in LLVM 3.7 and
- // causes all tests using the DXIL Validator to fail.
- //
- // This is a temporary fix and should be replaced with a allowlist once
- // we have determined all metadata that the DXIL Validator allows
- if (NamedMDNode *ErrNo = M.getNamedMetadata("llvm.errno.tbaa"))
- ErrNo->eraseFromParent();
+ // Finally, strip all module metadata that is not explicitly specified in the
+ // allow-list
+ SmallVector<NamedMDNode *> ToStrip;
+
+ for (NamedMDNode &NamedMD : M.named_metadata())
+ if (!NamedMD.getName().starts_with("llvm.dbg.") &&
+ !llvm::is_contained(CompatibleNamedModuleMDs, NamedMD.getName()))
+ ToStrip.push_back(&NamedMD);
+
+ for (NamedMDNode *NamedMD : ToStrip)
+ NamedMD->eraseFromParent();
}
PreservedAnalyses DXILTranslateMetadata::run(Module &M,
diff --git a/llvm/test/CodeGen/DirectX/strip-module-md.ll b/llvm/test/CodeGen/DirectX/strip-module-md.ll
new file mode 100644
index 0000000000000..4d8b9ec935f6b
--- /dev/null
+++ b/llvm/test/CodeGen/DirectX/strip-module-md.ll
@@ -0,0 +1,75 @@
+; RUN: opt -S -dxil-translate-metadata < %s | FileCheck %s
+
+; Ensures that only metadata explictly specified on the allow list, or debug
+; related, metadata is emitted
+
+target triple = "dxil-unknown-shadermodel6.0-compute"
+
+; CHECK-NOT: !dx.rootsignatures
+; CHECK-NOT: !llvm.errno.tbaa
+
+; CHECK-DAG: !llvm.dbg.cu
+
+; CHECK-DAG: !llvm.module.flags = !{![[#DWARF_VER:]], ![[#DEBUG_VER:]]}
+; CHECK-DAG: !llvm.ident = !{![[#IDENT:]]}
+
+; CHECK-DAG: !dx.shaderModel
+; CHECK-DAG: !dx.version
+; CHECK-DAG: !dx.entryPoints
+; CHECK-DAG: !dx.valver
+; CHECK-DAG: !dx.resources
+
+; CHECK-NOT: !dx.rootsignatures
+; CHECK-NOT: !llvm.errno.tbaa
+
+; Check allowed llvm metadata structure to ensure it is still DXIL compatible
+; If this fails, please ensure that the updated form is DXIL compatible before
+; updating the test.
+
+; CHECK-DAG: ![[#IDENT]] = !{!"clang 22.0.0"}
+; CHECK-DAG: ![[#DWARF_VER]] = !{i32 2, !"Dwarf Version", i32 2}
+; CHECK-DAG: ![[#DEBUG_VER]] = !{i32 2, !"Debug Info Version", i32 3}
+
+; CHECK-NOT: !dx.rootsignatures
+; CHECK-NOT: !llvm.errno.tbaa
+
+@BufA.str = private unnamed_addr constant [5 x i8] c"BufA\00", align 1
+
+define void @main () #0 {
+entry:
+ %typed0 = call target("dx.TypedBuffer", <4 x float>, 1, 0, 0)
+ @llvm.dx.resource.handlefrombinding.tdx.TypedBuffer_v4f32_1_0_0(
+ i32 3, i32 5, i32 1, i32 0, ptr @BufA.str)
+ ret void
+}
+
+attributes #0 = { noinline nounwind "hlsl.numthreads"="1,1,1" "hlsl.shader"="compute" }
+
+; Incompatible
+!dx.rootsignatures = !{!2}
+!llvm.errno.tbaa = !{!5}
+
+; Compatible
+!llvm.dbg.cu = !{!8}
+!llvm.module.flags = !{!11, !12}
+!llvm.ident = !{!13}
+!dx.valver = !{!14}
+
+!2 = !{ ptr @main, !3, i32 2 }
+!3 = !{ !4 }
+!4 = !{ !"RootFlags", i32 1 }
+
+!5 = !{!6, !6, i64 0}
+!6 = !{!"omnipotent char", !7}
+!7 = !{!"Simple C/C++ TBAA"}
+
+!8 = distinct !DICompileUnit(language: DW_LANG_C99, file: !9, producer: "Some Compiler", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !10, splitDebugInlining: false, nameTableKind: None)
+!9 = !DIFile(filename: "hlsl.hlsl", directory: "/some-path")
+!10 = !{}
+
+!11 = !{i32 2, !"Dwarf Version", i32 2}
+!12 = !{i32 2, !"Debug Info Version", i32 3}
+
+!13 = !{!"clang 22.0.0"}
+
+!14 = !{i32 1, i32 1}
|
bob80905
approved these changes
Oct 27, 2025
| for (NamedMDNode &NamedMD : M.named_metadata()) | ||
| if (!NamedMD.getName().starts_with("llvm.dbg.") && | ||
| !llvm::is_contained(CompatibleNamedModuleMDs, NamedMD.getName())) | ||
| ToStrip.push_back(&NamedMD); |
There was a problem hiding this comment.
nit: Is the reason you don't erasefromparent right here because the for loop's iteration would skip over the next node?
I vaguely recall an std:: function that enabled deletion within a for loop without needing to make a separate list.
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Yep, it caused a crash when I removed it in place. Okay, sounds good. I will take look for it.
edit: it seems for this case for this case it isn't possible
Icohedron
approved these changes
Oct 29, 2025
Comment on lines
+372
to
+375
| static GlobalMDList CompatibleNamedModuleMDs = { | ||
| "llvm.ident", "llvm.module.flags", "dx.resources", "dx.valver", | ||
| "dx.shaderModel", "dx.version", "dx.entryPoints", | ||
| }; |
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This is a very nit-picky thing but I would put each element of the list on its own line.
One of the benefits is if there is a new commit, the diff will show the line(s) added or removed as opposed to a reviewer needing to scan for a change in a single line.
Suggested change
| static GlobalMDList CompatibleNamedModuleMDs = { | |
| "llvm.ident", "llvm.module.flags", "dx.resources", "dx.valver", | |
| "dx.shaderModel", "dx.version", "dx.entryPoints", | |
| }; | |
| static GlobalMDList CompatibleNamedModuleMDs = { | |
| "llvm.ident", | |
| "llvm.module.flags", | |
| "dx.resources", | |
| "dx.valver", | |
| "dx.shaderModel", | |
| "dx.version", | |
| "dx.entryPoints", | |
| }; |
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I agree, unfortunately clang-format does not :(
|
There seems to be a failing dxil-dis tests. |
this test checks that we can embed lots of string as metadata into DXIL bitcode and retrieve it again renaming the metadata to llvm.ident retains the testing with a DXIL compatible metadata node
the intent of this test is to ensure that the metadata written with the DXIL bitcode writer is correctly read back from being embedded in the DXIL removing the unrecognized metadata retains the test purpose
this test is redundant with respect to di-subprogram, so we can remove it without reducing test coverage
|
LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/65/builds/24691 Here is the relevant piece of the build log for the reference |
aokblast
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Oct 30, 2025
…165290) This pr introduces an allow-list for module metadata, this encompasses the llvm metadata nodes: `llvm.ident` and `llvm.module.flags`, as well as, the generated `dx.` options. Resolves: llvm#164473.
DEBADRIBASAK
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Nov 3, 2025
…165290) This pr introduces an allow-list for module metadata, this encompasses the llvm metadata nodes: `llvm.ident` and `llvm.module.flags`, as well as, the generated `dx.` options. Resolves: llvm#164473.
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This pr introduces an allow-list for module metadata, this encompasses the llvm metadata nodes:
llvm.identandllvm.module.flags, as well as, the generateddx.options.Resolves: #164473.