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[HLSL][RootSignature] Metadata generation of RootFlags, RootConstants, RootDescriptors #142010

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Merged
merged 9 commits into from
May 30, 2025
Merged

[HLSL][RootSignature] Metadata generation of RootFlags, RootConstants, RootDescriptors #142010

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34733d6
nfc: rename matches
inbelic May 26, 2025
2ee3b10
[HLSL][RootSignature] RootFlags metadata generation
inbelic May 29, 2025
33b5b05
[HLSL][RootSignature] RootConstants metadata generation
inbelic May 29, 2025
5875d8d
[HLSL][RootSignature] DescriptorTable metadata generation
inbelic May 29, 2025
e163ede
format
inbelic May 29, 2025
5501e5e
review: improve test case to specify values
inbelic May 29, 2025
079c6a6
review: fix formatting using array
inbelic May 30, 2025
2640b02
review: use else-if
inbelic May 30, 2025
ec94a3c
review: use SmallString/raw_svector_ostream
inbelic May 30, 2025
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56 changes: 49 additions & 7 deletions clang/test/CodeGenHLSL/RootSignature.hlsl
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Original file line number Diff line number Diff line change
@@ -1,16 +1,17 @@
// RUN: %clang_cc1 -triple dxil-pc-shadermodel6.3-library -emit-llvm -o - %s | FileCheck %s

// CHECK: !dx.rootsignatures = !{![[#FIRST_ENTRY:]], ![[#SECOND_ENTRY:]]}
// CHECK: !dx.rootsignatures = !{![[#EMPTY_ENTRY:]], ![[#DT_ENTRY:]],
// CHECK-SAME: ![[#RF_ENTRY:]], ![[#RC_ENTRY:]], ![[#RD_ENTRY:]]}

// CHECK: ![[#FIRST_ENTRY]] = !{ptr @FirstEntry, ![[#EMPTY:]]}
// CHECK: ![[#EMPTY_ENTRY]] = !{ptr @EmptyEntry, ![[#EMPTY:]]}
// CHECK: ![[#EMPTY]] = !{}

[shader("compute"), RootSignature("")]
[numthreads(1,1,1)]
void FirstEntry() {}
void EmptyEntry() {}

// CHECK: ![[#SECOND_ENTRY]] = !{ptr @SecondEntry, ![[#SECOND_RS:]]}
// CHECK: ![[#SECOND_RS]] = !{![[#TABLE:]]}
// CHECK: ![[#DT_ENTRY]] = !{ptr @DescriptorTableEntry, ![[#DT_RS:]]}
// CHECK: ![[#DT_RS]] = !{![[#TABLE:]]}
// CHECK: ![[#TABLE]] = !{!"DescriptorTable", i32 0, ![[#CBV:]], ![[#SRV:]]}
// CHECK: ![[#CBV]] = !{!"CBV", i32 1, i32 0, i32 0, i32 -1, i32 4}
// CHECK: ![[#SRV]] = !{!"SRV", i32 4, i32 42, i32 3, i32 32, i32 0}
Expand All @@ -22,10 +23,51 @@ void FirstEntry() {}
")"
[shader("compute"), RootSignature(SampleDescriptorTable)]
[numthreads(1,1,1)]
void SecondEntry() {}
void DescriptorTableEntry() {}

// CHECK: ![[#RF_ENTRY]] = !{ptr @RootFlagsEntry, ![[#RF_RS:]]}
// CHECK: ![[#RF_RS]] = !{![[#ROOT_FLAGS:]]}
// CHECK: ![[#ROOT_FLAGS]] = !{!"RootFlags", i32 2114}

#define SampleRootFlags \
"RootFlags( " \
" Deny_Vertex_Shader_Root_Access | Allow_Stream_Output | " \
" sampler_heap_directly_indexed " \
")"
[shader("compute"), RootSignature(SampleRootFlags)]
[numthreads(1,1,1)]
void RootFlagsEntry() {}

// CHECK: ![[#RC_ENTRY]] = !{ptr @RootConstantsEntry, ![[#RC_RS:]]}
// CHECK: ![[#RC_RS]] = !{![[#ROOT_CONSTANTS:]]}
// CHECK: ![[#ROOT_CONSTANTS]] = !{!"RootConstants", i32 5, i32 1, i32 2, i32 1}

#define SampleRootConstants \
"RootConstants(" \
" space = 2, " \
" visibility = Shader_Visibility_Pixel, " \
" b1, num32BitConstants = 1 " \
")"
[shader("compute"), RootSignature(SampleRootConstants)]
[numthreads(1,1,1)]
void RootConstantsEntry() {}

// CHECK: ![[#RD_ENTRY]] = !{ptr @RootDescriptorsEntry, ![[#RD_RS:]]}
// CHECK: ![[#RD_RS]] = !{![[#ROOT_CBV:]], ![[#ROOT_UAV:]], ![[#ROOT_SRV:]]}
// CHECK: ![[#ROOT_CBV]] = !{!"RootCBV", i32 0, i32 0, i32 0, i32 4}
// CHECK: ![[#ROOT_UAV]] = !{!"RootUAV", i32 0, i32 0, i32 0, i32 2}
// CHECK: ![[#ROOT_SRV]] = !{!"RootSRV", i32 0, i32 0, i32 0, i32 4}

#define SampleRootDescriptors \
"CBV(b0), " \
"UAV(u0), " \
"SRV(t0)"
[shader("compute"), RootSignature(SampleRootDescriptors)]
[numthreads(1,1,1)]
void RootDescriptorsEntry() {}

// Sanity test to ensure no root is added for this function as there is only
// two entries in !dx.roosignatures
[shader("compute")]
[numthreads(1,1,1)]
void ThirdEntry() {}
void NoRSEntry() {}
3 changes: 3 additions & 0 deletions llvm/include/llvm/Frontend/HLSL/HLSLRootSignature.h
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Original file line number Diff line number Diff line change
Expand Up @@ -188,6 +188,9 @@ class MetadataBuilder {

private:
/// Define the various builders for the different metadata types
MDNode *BuildRootFlags(const RootFlags &Flags);
MDNode *BuildRootConstants(const RootConstants &Constants);
MDNode *BuildRootDescriptor(const RootDescriptor &Descriptor);
MDNode *BuildDescriptorTable(const DescriptorTable &Table);
MDNode *BuildDescriptorTableClause(const DescriptorTableClause &Clause);

Expand Down
46 changes: 46 additions & 0 deletions llvm/lib/Frontend/HLSL/HLSLRootSignature.cpp
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Expand Up @@ -171,6 +171,12 @@ void dumpRootElements(raw_ostream &OS, ArrayRef<RootElement> Elements) {
MDNode *MetadataBuilder::BuildRootSignature() {
for (const RootElement &Element : Elements) {
MDNode *ElementMD = nullptr;
if (const auto &Flags = std::get_if<RootFlags>(&Element))
ElementMD = BuildRootFlags(*Flags);
if (const auto &Constants = std::get_if<RootConstants>(&Element))
ElementMD = BuildRootConstants(*Constants);
if (const auto &Descriptor = std::get_if<RootDescriptor>(&Element))
ElementMD = BuildRootDescriptor(*Descriptor);
if (const auto &Clause = std::get_if<DescriptorTableClause>(&Element))
ElementMD = BuildDescriptorTableClause(*Clause);
if (const auto &Table = std::get_if<DescriptorTable>(&Element))
Expand All @@ -187,6 +193,46 @@ MDNode *MetadataBuilder::BuildRootSignature() {
return MDNode::get(Ctx, GeneratedMetadata);
}

MDNode *MetadataBuilder::BuildRootFlags(const RootFlags &Flags) {
IRBuilder<> Builder(Ctx);
return MDNode::get(Ctx, {
MDString::get(Ctx, "RootFlags"),
ConstantAsMetadata::get(
Builder.getInt32(llvm::to_underlying(Flags))),
});
}

MDNode *MetadataBuilder::BuildRootConstants(const RootConstants &Constants) {
IRBuilder<> Builder(Ctx);
return MDNode::get(
Ctx, {
MDString::get(Ctx, "RootConstants"),
ConstantAsMetadata::get(
Builder.getInt32(llvm::to_underlying(Constants.Visibility))),
ConstantAsMetadata::get(Builder.getInt32(Constants.Reg.Number)),
ConstantAsMetadata::get(Builder.getInt32(Constants.Space)),
ConstantAsMetadata::get(
Builder.getInt32(Constants.Num32BitConstants)),
});
}

MDNode *MetadataBuilder::BuildRootDescriptor(const RootDescriptor &Descriptor) {
IRBuilder<> Builder(Ctx);
std::string Name;
llvm::raw_string_ostream OS(Name);
OS << "Root" << ClauseType(llvm::to_underlying(Descriptor.Type));
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It'll be slightly more efficient to use SmallString<16> and raw_svector_ostream here to avoid a heap allocation. Also I find it a bit clearer to use Name directly below instead of OS.str().

Note also that this does actually point out a bit of an inefficiency with how we've implemented only operator<< for these simple enum stringifying functions. If we had a function like getClauseTypeName returning static StringRef for these we could avoid this work entirely, and the operator<< could still exist for where it's useful and simply call this function in its implementation. It might be worth coming back to this in a follow up change.

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Sounds good. I have a note for a clean-up to do define the stringifying functions for the enums. Further, the pattern used here was propagated from descriptor tables, so I will update the other uses accordingly.

return MDNode::get(
Ctx, {
MDString::get(Ctx, OS.str()),
ConstantAsMetadata::get(Builder.getInt32(
llvm::to_underlying(Descriptor.Visibility))),
ConstantAsMetadata::get(Builder.getInt32(Descriptor.Reg.Number)),
ConstantAsMetadata::get(Builder.getInt32(Descriptor.Space)),
ConstantAsMetadata::get(
Builder.getInt32(llvm::to_underlying(Descriptor.Flags))),
});
}

MDNode *MetadataBuilder::BuildDescriptorTable(const DescriptorTable &Table) {
IRBuilder<> Builder(Ctx);
SmallVector<Metadata *> TableOperands;
Expand Down
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