9357c5906c
Currently we handle 0-sized arrays in multiple places, non-uniformly, either via `SPIRVLegalizeZeroSizeArrays` or via `SPIRVPrepareGlobals`. For AMDGCN flavoured SPIR-V we have a singular, simpler solution: set all 0-sized arrays to be `UINT64_MAX` sized. This is an unambiguous token that we can use during reverse translation to restore the intended 0 size.
95 lines
2.6 KiB
C++
95 lines
2.6 KiB
C++
//===-- SPIRVPrepareGlobals.cpp - Prepare IR SPIRV globals ------*- C++ -*-===//
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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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//
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// The pass transforms IR globals that cannot be trivially mapped to SPIRV
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// into something that is trival to lower.
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//
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//===----------------------------------------------------------------------===//
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#include "SPIRV.h"
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#include "SPIRVUtils.h"
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/IR/Module.h"
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#include "llvm/Support/Debug.h"
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#define DEBUG_TYPE "spirv-prepare-globals"
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using namespace llvm;
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namespace {
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struct SPIRVPrepareGlobals : public ModulePass {
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static char ID;
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SPIRVPrepareGlobals() : ModulePass(ID) {}
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StringRef getPassName() const override {
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return "SPIRV prepare global variables";
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}
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bool runOnModule(Module &M) override;
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};
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// The backend does not support GlobalAlias. Replace aliases with their aliasees
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// when possible and remove them from the module.
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bool tryReplaceAliasWithAliasee(GlobalAlias &GA) {
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// According to the lang ref, aliases cannot be replaced if either the alias
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// or the aliasee are interposable. We only replace in the case that both
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// are not interposable.
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if (GA.isInterposable()) {
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LLVM_DEBUG(dbgs() << "Skipping interposable alias: " << GA.getName()
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<< "\n");
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return false;
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}
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auto *AO = dyn_cast<GlobalObject>(GA.getAliasee());
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if (!AO) {
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LLVM_DEBUG(dbgs() << "Skipping alias whose aliasee is not a GlobalObject: "
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<< GA.getName() << "\n");
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return false;
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}
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if (AO->isInterposable()) {
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LLVM_DEBUG(dbgs() << "Skipping interposable aliasee: " << AO->getName()
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<< "\n");
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return false;
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}
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LLVM_DEBUG(dbgs() << "Replacing alias " << GA.getName()
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<< " with aliasee: " << AO->getName() << "\n");
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GA.replaceAllUsesWith(AO);
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if (GA.isDiscardableIfUnused()) {
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GA.eraseFromParent();
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}
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return true;
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}
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bool SPIRVPrepareGlobals::runOnModule(Module &M) {
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bool Changed = false;
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for (GlobalAlias &GA : make_early_inc_range(M.aliases())) {
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Changed |= tryReplaceAliasWithAliasee(GA);
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}
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return Changed;
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}
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char SPIRVPrepareGlobals::ID = 0;
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} // namespace
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INITIALIZE_PASS(SPIRVPrepareGlobals, "prepare-globals",
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"SPIRV prepare global variables", false, false)
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namespace llvm {
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ModulePass *createSPIRVPrepareGlobalsPass() {
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return new SPIRVPrepareGlobals();
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}
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} // namespace llvm
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