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a3238969e5
Fix two issues: * If a constant is used in another constant, we need to insert newly created instructions to worklist so that constant used in them will be converted. * Set debug info of original instruction to newly created instructions.
111 lines
3.6 KiB
C++
111 lines
3.6 KiB
C++
//===- ReplaceConstant.cpp - Replace LLVM constant expression--------------===//
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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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// This file implements a utility function for replacing LLVM constant
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// expressions by instructions.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/IR/ReplaceConstant.h"
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#include "llvm/ADT/SetVector.h"
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#include "llvm/IR/Constants.h"
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#include "llvm/IR/Instructions.h"
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namespace llvm {
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static bool isExpandableUser(User *U) {
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return isa<ConstantExpr>(U) || isa<ConstantAggregate>(U);
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}
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static SmallVector<Instruction *, 4> expandUser(Instruction *InsertPt,
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Constant *C) {
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SmallVector<Instruction *, 4> NewInsts;
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if (auto *CE = dyn_cast<ConstantExpr>(C)) {
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NewInsts.push_back(CE->getAsInstruction(InsertPt));
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} else if (isa<ConstantStruct>(C) || isa<ConstantArray>(C)) {
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Value *V = PoisonValue::get(C->getType());
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for (auto [Idx, Op] : enumerate(C->operands())) {
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V = InsertValueInst::Create(V, Op, Idx, "", InsertPt);
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NewInsts.push_back(cast<Instruction>(V));
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}
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} else if (isa<ConstantVector>(C)) {
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Type *IdxTy = Type::getInt32Ty(C->getContext());
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Value *V = PoisonValue::get(C->getType());
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for (auto [Idx, Op] : enumerate(C->operands())) {
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V = InsertElementInst::Create(V, Op, ConstantInt::get(IdxTy, Idx), "",
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InsertPt);
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NewInsts.push_back(cast<Instruction>(V));
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}
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} else {
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llvm_unreachable("Not an expandable user");
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}
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return NewInsts;
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}
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bool convertUsersOfConstantsToInstructions(ArrayRef<Constant *> Consts) {
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// Find all expandable direct users of Consts.
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SmallVector<Constant *> Stack;
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for (Constant *C : Consts)
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for (User *U : C->users())
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if (isExpandableUser(U))
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Stack.push_back(cast<Constant>(U));
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// Include transitive users.
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SetVector<Constant *> ExpandableUsers;
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while (!Stack.empty()) {
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Constant *C = Stack.pop_back_val();
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if (!ExpandableUsers.insert(C))
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continue;
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for (auto *Nested : C->users())
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if (isExpandableUser(Nested))
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Stack.push_back(cast<Constant>(Nested));
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}
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// Find all instructions that use any of the expandable users
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SetVector<Instruction *> InstructionWorklist;
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for (Constant *C : ExpandableUsers)
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for (User *U : C->users())
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if (auto *I = dyn_cast<Instruction>(U))
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InstructionWorklist.insert(I);
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// Replace those expandable operands with instructions
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bool Changed = false;
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while (!InstructionWorklist.empty()) {
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Instruction *I = InstructionWorklist.pop_back_val();
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DebugLoc Loc = I->getDebugLoc();
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for (Use &U : I->operands()) {
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auto *BI = I;
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if (auto *Phi = dyn_cast<PHINode>(I)) {
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BasicBlock *BB = Phi->getIncomingBlock(U);
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BasicBlock::iterator It = BB->getFirstInsertionPt();
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assert(It != BB->end() && "Unexpected empty basic block");
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BI = &*It;
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}
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if (auto *C = dyn_cast<Constant>(U.get())) {
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if (ExpandableUsers.contains(C)) {
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Changed = true;
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auto NewInsts = expandUser(BI, C);
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for (auto *NI : NewInsts)
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NI->setDebugLoc(Loc);
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InstructionWorklist.insert(NewInsts.begin(), NewInsts.end());
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U.set(NewInsts.back());
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}
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}
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}
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}
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for (Constant *C : Consts)
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C->removeDeadConstantUsers();
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return Changed;
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}
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} // namespace llvm
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