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cbuffer A {
float a;
float b;
}
will be translated to a global variable with special address space.
Something like
struct CB_Ty {
float a;
float b;
};
__attribute__((address_space(3)))
CB_Ty A;
And all use of a and b will be replaced with A.a and A.b.
Only support none-legacy cbuffer layout now.
CodeGen for Resource binding will be in separate patch.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D130131
Files:
clang/lib/CodeGen/CGDecl.cpp
clang/lib/CodeGen/CGHLSLRuntime.cpp
clang/lib/CodeGen/CGHLSLRuntime.h
clang/lib/CodeGen/CodeGenModule.cpp
clang/test/CodeGenHLSL/cbuf.hlsl
Index: clang/test/CodeGenHLSL/cbuf.hlsl
===================================================================
--- /dev/null
+++ clang/test/CodeGenHLSL/cbuf.hlsl
@@ -0,0 +1,21 @@
+// RUN: %clang_dxc -Tlib_6_7 -fcgl -Fo - %s | FileCheck %s
+
+// CHECK: @[[CB:.+]] = external addrspace(4) constant { float, float }
+cbuffer A : register(b0, space1) {
+ float a;
+ float b;
+}
+
+// CHECK: @[[TB:.+]] = external addrspace(5) constant { float, float }
+tbuffer A : register(b2, space1) {
+ float c;
+ float d;
+}
+
+float foo() {
+// CHECK: load float, ptr addrspacecast (ptr addrspace(4) @[[CB]] to ptr), align 4
+// CHECK: load float, ptr addrspacecast (ptr addrspace(4) getelementptr inbounds ({ float, float }, ptr addrspace(4) @[[CB]], i32 0, i32 1) to ptr), align 4
+// CHECK: load float, ptr addrspacecast (ptr addrspace(5) @[[TB]] to ptr), align 4
+// CHECK: load float, ptr addrspacecast (ptr addrspace(5) getelementptr inbounds ({ float, float }, ptr addrspace(5) @[[TB]], i32 0, i32 1) to ptr), align 4
+ return a + b + c*d;
+}
Index: clang/lib/CodeGen/CodeGenModule.cpp
===================================================================
--- clang/lib/CodeGen/CodeGenModule.cpp
+++ clang/lib/CodeGen/CodeGenModule.cpp
@@ -6281,6 +6281,10 @@
DI->EmitAndRetainType(getContext().getEnumType(cast<EnumDecl>(D)));
break;
+ case Decl::HLSLBuffer:
+ getHLSLRuntime().addCBuffer(cast<HLSLBufferDecl>(D));
+ break;
+
default:
// Make sure we handled everything we should, every other kind is a
// non-top-level decl. FIXME: Would be nice to have an isTopLevelDeclKind
Index: clang/lib/CodeGen/CGHLSLRuntime.h
===================================================================
--- clang/lib/CodeGen/CGHLSLRuntime.h
+++ clang/lib/CodeGen/CGHLSLRuntime.h
@@ -15,21 +15,48 @@
#ifndef LLVM_CLANG_LIB_CODEGEN_CGHLSLRUNTIME_H
#define LLVM_CLANG_LIB_CODEGEN_CGHLSLRUNTIME_H
+#include "llvm/ADT/StringRef.h"
+
+namespace llvm {
+class GlobalVariable;
+class StructType;
+} // namespace llvm
+
namespace clang {
+class HLSLBufferDecl;
+class VarDecl;
+class DeclContext;
namespace CodeGen {
class CodeGenModule;
class CGHLSLRuntime {
+public:
+ struct CBuffer {
+ CBuffer(HLSLBufferDecl *D);
+ llvm::StringRef Name;
+ bool IsCBuffer;
+ unsigned Reg;
+ unsigned Space;
+ // Global variable and offset for each constant.
+ std::vector<std::pair<llvm::GlobalVariable *, unsigned>> Constants;
+ llvm::StructType *LayoutStruct = nullptr;
+ };
+
protected:
CodeGenModule &CGM;
public:
CGHLSLRuntime(CodeGenModule &CGM) : CGM(CGM) {}
virtual ~CGHLSLRuntime() {}
-
+ void addCBuffer(HLSLBufferDecl *D);
void finishCodeGen();
+
+private:
+ void addConstant(VarDecl *D, CBuffer &CB);
+ void addCBufferDecls(DeclContext *DC, CBuffer &CB);
+ SmallVector<CBuffer> CBuffers;
};
} // namespace CodeGen
Index: clang/lib/CodeGen/CGHLSLRuntime.cpp
===================================================================
--- clang/lib/CodeGen/CGHLSLRuntime.cpp
+++ clang/lib/CodeGen/CGHLSLRuntime.cpp
@@ -13,7 +13,9 @@
//===----------------------------------------------------------------------===//
#include "CGHLSLRuntime.h"
+#include "CGDebugInfo.h"
#include "CodeGenModule.h"
+
#include "clang/Basic/TargetOptions.h"
#include "llvm/IR/Metadata.h"
#include "llvm/IR/Module.h"
@@ -23,6 +25,7 @@
using namespace llvm;
namespace {
+
void addDxilValVersion(StringRef ValVersionStr, llvm::Module &M) {
// The validation of ValVersionStr is done at HLSLToolChain::TranslateArgs.
// Assume ValVersionStr is legal here.
@@ -42,11 +45,138 @@
StringRef DxilValKey = "dx.valver";
M.addModuleFlag(llvm::Module::ModFlagBehavior::AppendUnique, DxilValKey, Val);
}
+
+void layoutCBuffer(CGHLSLRuntime::CBuffer &CB, const DataLayout &DL) {
+ // FIXME: support legacy cbuffer layout.
+ std::vector<llvm::Type *> EltTys;
+ for (auto &Const : CB.Constants) {
+ auto *GV = Const.first;
+ Const.second = EltTys.size();
+ auto *Ty = GV->getValueType();
+ EltTys.emplace_back(Ty);
+ }
+ CB.LayoutStruct = llvm::StructType::get(EltTys[0]->getContext(), EltTys);
+}
+
+GlobalVariable *replaceCBuffer(CGHLSLRuntime::CBuffer &CB) {
+ const unsigned CBufferAddressSpace = 4;
+ const unsigned TBufferAddressSpace = 5;
+ // Create global variable for CB.
+ GlobalVariable *CBGV = new GlobalVariable(
+ CB.LayoutStruct, /*isConstant*/ true,
+ GlobalValue::LinkageTypes::ExternalLinkage, nullptr, CB.Name + ".cb.",
+ GlobalValue::NotThreadLocal,
+ CB.IsCBuffer ? CBufferAddressSpace : TBufferAddressSpace);
+
+ IRBuilder<> B(CBGV->getContext());
+ Value *ZeroIdx = B.getInt32(0);
+ // Replace Const use with CB use.
+ for (auto &Const : CB.Constants) {
+ auto *EltTy = CB.LayoutStruct->getElementType(Const.second);
+ auto *GV = Const.first;
+ unsigned Offset = Const.second;
+
+ Value *GEP =
+ B.CreateGEP(CB.LayoutStruct, CBGV, {ZeroIdx, B.getInt32(Offset)});
+
+ auto *GVTy = GV->getValueType();
+ assert(EltTy == GVTy && "constant type mismatch");
+
+ // Cast address space.
+ GEP = B.CreateAddrSpaceCast(GEP, GVTy->getPointerTo());
+ // Replace.
+ GV->replaceAllUsesWith(GEP);
+ // Erase GV.
+ GV->removeDeadConstantUsers();
+ GV->eraseFromParent();
+ }
+ return CBGV;
+}
+
+void addResourceBinding(GlobalVariable *GV, CGHLSLRuntime::CBuffer &CB) {
+ // FIXME: add resource binding to GV.
+}
+
} // namespace
+void CGHLSLRuntime::addConstant(VarDecl *D, CBuffer &CB) {
+ if (D->getStorageClass() == SC_Static) {
+ // For static inside cbuffer, take as global static.
+ // Don't add to cbuffer.
+ CGM.EmitGlobal(D);
+ return;
+ }
+
+ auto *GV = cast<GlobalVariable>(CGM.GetAddrOfGlobalVar(D));
+ // Add debug info for constVal.
+ if (CGDebugInfo *DI = CGM.getModuleDebugInfo())
+ if (CGM.getCodeGenOpts().getDebugInfo() >=
+ codegenoptions::DebugInfoKind::LimitedDebugInfo)
+ DI->EmitGlobalVariable(cast<GlobalVariable>(GV), D);
+
+ // FIXME: support packoffset.
+ uint32_t Offset = 0;
+ bool HasUserOffset = false;
+
+ unsigned LowerBound = HasUserOffset ? Offset : UINT_MAX;
+ CB.Constants.emplace_back(std::make_pair(GV, LowerBound));
+}
+
+void CGHLSLRuntime::addCBufferDecls(DeclContext *DC, CBuffer &CB) {
+ for (Decl *it : DC->decls()) {
+ if (VarDecl *ConstDecl = dyn_cast<VarDecl>(it)) {
+ addConstant(ConstDecl, CB);
+ } else if (isa<EmptyDecl>(*it)) {
+ // Nothing to do for this declaration.
+ } else if (isa<CXXRecordDecl>(it)) {
+ // Nothing to do for this declaration.
+ } else if (isa<FunctionDecl>(it)) {
+ // A function within an cbuffer is effectively a top-level function,
+ // as it only refers to globally scoped declarations.
+ CGM.EmitTopLevelDecl(it);
+ } else if (NamespaceDecl *ND = dyn_cast<NamespaceDecl>(it)) {
+ addCBufferDecls(ND, CB);
+ } else {
+ HLSLBufferDecl *Inner = dyn_cast<HLSLBufferDecl>(it);
+ if (!Inner) {
+ DiagnosticsEngine &Diags = CGM.getDiags();
+ unsigned DiagID = Diags.getCustomDiagID(DiagnosticsEngine::Error,
+ "invalid decl inside cbuffer");
+ Diags.Report(it->getLocation(), DiagID);
+ return;
+ }
+ addCBuffer(Inner);
+ }
+ }
+}
+
+void CGHLSLRuntime::addCBuffer(HLSLBufferDecl *D) {
+ CBuffers.emplace_back(CBuffer(D));
+ addCBufferDecls(D, CBuffers.back());
+}
+
void CGHLSLRuntime::finishCodeGen() {
auto &TargetOpts = CGM.getTarget().getTargetOpts();
llvm::Module &M = CGM.getModule();
addDxilValVersion(TargetOpts.DxilValidatorVersion, M);
+ auto &DL = M.getDataLayout();
+ for (auto &CB : CBuffers) {
+ layoutCBuffer(CB, DL);
+ auto *GV = replaceCBuffer(CB);
+ M.getGlobalList().push_back(GV);
+ addResourceBinding(GV, CB);
+ }
+}
+
+CGHLSLRuntime::CBuffer::CBuffer(HLSLBufferDecl *D) {
+ Name = D->getName();
+ IsCBuffer = D->isCBuffer();
+ if (auto *Binding = D->getAttr<HLSLResourceBindingAttr>()) {
+ Reg = Binding->getID();
+ Space = Binding->getSpace();
+ } else {
+ Reg = UINT_MAX;
+ Space = 0;
+ }
}
Index: clang/lib/CodeGen/CGDecl.cpp
===================================================================
--- clang/lib/CodeGen/CGDecl.cpp
+++ clang/lib/CodeGen/CGDecl.cpp
@@ -128,6 +128,7 @@
case Decl::Concept:
case Decl::LifetimeExtendedTemporary:
case Decl::RequiresExprBody:
+ case Decl::HLSLBuffer:
// None of these decls require codegen support.
return;
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