78 lines · cpp
1//===- CBuffer.cpp - HLSL constant buffer handling ------------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8 9#include "llvm/Frontend/HLSL/CBuffer.h"10#include "llvm/Frontend/HLSL/HLSLResource.h"11#include "llvm/IR/DerivedTypes.h"12#include "llvm/IR/Metadata.h"13#include "llvm/IR/Module.h"14 15using namespace llvm;16using namespace llvm::hlsl;17 18static SmallVector<size_t>19getMemberOffsets(const DataLayout &DL, GlobalVariable *Handle,20 llvm::function_ref<bool(Type *)> IsPadding) {21 SmallVector<size_t> Offsets;22 23 auto *HandleTy = cast<TargetExtType>(Handle->getValueType());24 assert((HandleTy->getName().ends_with(".CBuffer") ||25 HandleTy->getName() == "spirv.VulkanBuffer") &&26 "Not a cbuffer type");27 assert(HandleTy->getNumTypeParameters() == 1 && "Expected layout type");28 auto *LayoutTy = cast<StructType>(HandleTy->getTypeParameter(0));29 30 const StructLayout *SL = DL.getStructLayout(LayoutTy);31 for (int I = 0, E = LayoutTy->getNumElements(); I < E; ++I)32 if (!IsPadding(LayoutTy->getElementType(I)))33 Offsets.push_back(SL->getElementOffset(I));34 35 return Offsets;36}37 38std::optional<CBufferMetadata>39CBufferMetadata::get(Module &M, llvm::function_ref<bool(Type *)> IsPadding) {40 NamedMDNode *CBufMD = M.getNamedMetadata("hlsl.cbs");41 if (!CBufMD)42 return std::nullopt;43 44 std::optional<CBufferMetadata> Result({CBufMD});45 46 for (const MDNode *MD : CBufMD->operands()) {47 assert(MD->getNumOperands() && "Invalid cbuffer metadata");48 49 // For an unused cbuffer, the handle may have been optimized out50 Metadata *OpMD = MD->getOperand(0);51 if (!OpMD)52 continue;53 54 auto *Handle =55 cast<GlobalVariable>(cast<ValueAsMetadata>(OpMD)->getValue());56 CBufferMapping &Mapping = Result->Mappings.emplace_back(Handle);57 58 SmallVector<size_t> MemberOffsets =59 getMemberOffsets(M.getDataLayout(), Handle, IsPadding);60 61 for (int I = 1, E = MD->getNumOperands(); I < E; ++I) {62 Metadata *OpMD = MD->getOperand(I);63 // Some members may be null if they've been optimized out.64 if (!OpMD)65 continue;66 auto *V = cast<GlobalVariable>(cast<ValueAsMetadata>(OpMD)->getValue());67 Mapping.Members.emplace_back(V, MemberOffsets[I - 1]);68 }69 }70 71 return Result;72}73 74void CBufferMetadata::eraseFromModule() {75 // Remove the cbs named metadata76 MD->eraseFromParent();77}78