0bb1af478a
Fixes #139023. This PR essentially removes unused global variables: - Restores the `GlobalDCE` Legacy pass and adds it to the DirectX backend after the finalize linkage pass - Converts external global variables with no usage to internal linkage in the finalize linkage pass - (so they can be removed by `GlobalDCE`) - Makes the `dxil-finalize-linkage` pass usable using the new pass manager flag syntax - Adds tests to `finalize_linkage.ll` that make sure unused global variables are removed - Adds a use for variable `@CBV` in `opaque-value_as_metadata.ll` so it isn't removed - Changes the `scalar-data.ll` run command to avoid removing its global variables --------- Co-authored-by: Farzon Lotfi <farzonlotfi@microsoft.com>
79 lines
2.3 KiB
C++
79 lines
2.3 KiB
C++
//===- DXILFinalizeLinkage.cpp - Finalize linkage of functions ------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "DXILFinalizeLinkage.h"
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#include "DirectX.h"
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#include "llvm/IR/Function.h"
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#include "llvm/IR/GlobalValue.h"
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#include "llvm/IR/Metadata.h"
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#include "llvm/IR/Module.h"
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#define DEBUG_TYPE "dxil-finalize-linkage"
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using namespace llvm;
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static bool finalizeLinkage(Module &M) {
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bool MadeChange = false;
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// Convert private globals and external globals with no usage to internal
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// linkage.
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for (GlobalVariable &GV : M.globals())
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if (GV.hasPrivateLinkage() || (GV.hasExternalLinkage() && GV.use_empty())) {
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GV.setLinkage(GlobalValue::InternalLinkage);
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MadeChange = true;
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}
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SmallVector<Function *> Funcs;
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// Collect non-entry and non-exported functions to set to internal linkage.
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for (Function &EF : M.functions()) {
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if (EF.isIntrinsic())
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continue;
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if (EF.hasExternalLinkage() && EF.hasDefaultVisibility())
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continue;
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if (EF.hasFnAttribute("hlsl.shader"))
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continue;
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Funcs.push_back(&EF);
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}
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for (Function *F : Funcs) {
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if (F->getLinkage() == GlobalValue::ExternalLinkage) {
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F->setLinkage(GlobalValue::InternalLinkage);
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MadeChange = true;
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}
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if (F->isDefTriviallyDead()) {
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M.getFunctionList().erase(F);
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MadeChange = true;
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}
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}
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return MadeChange;
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}
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PreservedAnalyses DXILFinalizeLinkage::run(Module &M,
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ModuleAnalysisManager &AM) {
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if (finalizeLinkage(M))
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return PreservedAnalyses::none();
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return PreservedAnalyses::all();
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}
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bool DXILFinalizeLinkageLegacy::runOnModule(Module &M) {
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return finalizeLinkage(M);
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}
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char DXILFinalizeLinkageLegacy::ID = 0;
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INITIALIZE_PASS_BEGIN(DXILFinalizeLinkageLegacy, DEBUG_TYPE,
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"DXIL Finalize Linkage", false, false)
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INITIALIZE_PASS_END(DXILFinalizeLinkageLegacy, DEBUG_TYPE,
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"DXIL Finalize Linkage", false, false)
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ModulePass *llvm::createDXILFinalizeLinkageLegacyPass() {
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return new DXILFinalizeLinkageLegacy();
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}
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