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The uniformity analysis treated an undef argument to phi to be distinct from any other argument, equivalent to calling PHINode::hasConstantValue() instead of PHINode::hasConstantOrUndefValue(). Such a phi was reported as divergent. This is different from the older divergence analysis which treats such a phi as uniform. Fixed uniformity analysis to match the older behaviour. The original behaviour was added to DivergenceAnalysis in D19013. But it is not clear if relying on the undef value is safe. The defined values are not constant per se; they just happen to be uniform and the non-constant uniform value may not dominate the PHI. Reviewed By: ruiling Differential Revision: https://reviews.llvm.org/D144254
104 lines
3.1 KiB
C++
104 lines
3.1 KiB
C++
//===- SSAContext.cpp -------------------------------------------*- 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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/// \file
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///
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/// This file defines a specialization of the GenericSSAContext<X>
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/// template class for LLVM IR.
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///
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//===----------------------------------------------------------------------===//
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#include "llvm/IR/SSAContext.h"
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#include "llvm/IR/Argument.h"
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#include "llvm/IR/BasicBlock.h"
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#include "llvm/IR/Function.h"
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#include "llvm/IR/Instruction.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/Support/raw_ostream.h"
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using namespace llvm;
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Value *SSAContext::ValueRefNull = nullptr;
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void SSAContext::setFunction(Function &Fn) { F = &Fn; }
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BasicBlock *SSAContext::getEntryBlock(Function &F) {
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return &F.getEntryBlock();
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}
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const BasicBlock *SSAContext::getEntryBlock(const Function &F) {
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return &F.getEntryBlock();
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}
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void SSAContext::appendBlockDefs(SmallVectorImpl<Value *> &defs,
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BasicBlock &block) {
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for (auto &instr : block.instructionsWithoutDebug(/*SkipPseudoOp=*/true)) {
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if (instr.isTerminator())
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break;
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if (instr.getType()->isVoidTy())
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continue;
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auto *def = &instr;
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defs.push_back(def);
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}
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}
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void SSAContext::appendBlockDefs(SmallVectorImpl<const Value *> &defs,
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const BasicBlock &block) {
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for (auto &instr : block) {
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if (instr.isTerminator())
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break;
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defs.push_back(&instr);
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}
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}
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void SSAContext::appendBlockTerms(SmallVectorImpl<Instruction *> &terms,
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BasicBlock &block) {
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terms.push_back(block.getTerminator());
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}
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void SSAContext::appendBlockTerms(SmallVectorImpl<const Instruction *> &terms,
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const BasicBlock &block) {
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terms.push_back(block.getTerminator());
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}
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const BasicBlock *SSAContext::getDefBlock(const Value *value) const {
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if (const auto *instruction = dyn_cast<Instruction>(value))
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return instruction->getParent();
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return nullptr;
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}
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bool SSAContext::comesBefore(const Instruction *lhs, const Instruction *rhs) {
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return lhs->comesBefore(rhs);
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}
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bool SSAContext::isConstantOrUndefValuePhi(const Instruction &Instr) {
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if (auto *Phi = dyn_cast<PHINode>(&Instr))
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return Phi->hasConstantOrUndefValue();
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return false;
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}
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Printable SSAContext::print(const Value *V) const {
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return Printable([V](raw_ostream &Out) { V->print(Out); });
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}
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Printable SSAContext::print(const Instruction *Inst) const {
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return print(cast<Value>(Inst));
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}
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Printable SSAContext::print(const BasicBlock *BB) const {
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if (!BB)
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return Printable([](raw_ostream &Out) { Out << "<nullptr>"; });
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if (BB->hasName())
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return Printable([BB](raw_ostream &Out) { Out << BB->getName(); });
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return Printable([BB](raw_ostream &Out) {
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ModuleSlotTracker MST{BB->getParent()->getParent(), false};
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MST.incorporateFunction(*BB->getParent());
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Out << MST.getLocalSlot(BB);
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});
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}
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