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to reflect the new license. We understand that people may be surprised that we're moving the header entirely to discuss the new license. We checked this carefully with the Foundation's lawyer and we believe this is the correct approach. Essentially, all code in the project is now made available by the LLVM project under our new license, so you will see that the license headers include that license only. Some of our contributors have contributed code under our old license, and accordingly, we have retained a copy of our old license notice in the top-level files in each project and repository. llvm-svn: 351636
64 lines
2.4 KiB
C++
64 lines
2.4 KiB
C++
//===-- GuardUtils.cpp - Utils for work with guards -------------*- 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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// Utils that are used to perform transformations related to guards and their
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// conditions.
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/Utils/GuardUtils.h"
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#include "llvm/IR/Function.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/IR/IRBuilder.h"
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#include "llvm/IR/MDBuilder.h"
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#include "llvm/Transforms/Utils/BasicBlockUtils.h"
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using namespace llvm;
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static cl::opt<uint32_t> PredicatePassBranchWeight(
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"guards-predicate-pass-branch-weight", cl::Hidden, cl::init(1 << 20),
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cl::desc("The probability of a guard failing is assumed to be the "
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"reciprocal of this value (default = 1 << 20)"));
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void llvm::makeGuardControlFlowExplicit(Function *DeoptIntrinsic,
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CallInst *Guard) {
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OperandBundleDef DeoptOB(*Guard->getOperandBundle(LLVMContext::OB_deopt));
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SmallVector<Value *, 4> Args(std::next(Guard->arg_begin()), Guard->arg_end());
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auto *CheckBB = Guard->getParent();
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auto *DeoptBlockTerm =
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SplitBlockAndInsertIfThen(Guard->getArgOperand(0), Guard, true);
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auto *CheckBI = cast<BranchInst>(CheckBB->getTerminator());
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// SplitBlockAndInsertIfThen inserts control flow that branches to
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// DeoptBlockTerm if the condition is true. We want the opposite.
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CheckBI->swapSuccessors();
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CheckBI->getSuccessor(0)->setName("guarded");
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CheckBI->getSuccessor(1)->setName("deopt");
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if (auto *MD = Guard->getMetadata(LLVMContext::MD_make_implicit))
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CheckBI->setMetadata(LLVMContext::MD_make_implicit, MD);
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MDBuilder MDB(Guard->getContext());
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CheckBI->setMetadata(LLVMContext::MD_prof,
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MDB.createBranchWeights(PredicatePassBranchWeight, 1));
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IRBuilder<> B(DeoptBlockTerm);
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auto *DeoptCall = B.CreateCall(DeoptIntrinsic, Args, {DeoptOB}, "");
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if (DeoptIntrinsic->getReturnType()->isVoidTy()) {
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B.CreateRetVoid();
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} else {
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DeoptCall->setName("deoptcall");
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B.CreateRet(DeoptCall);
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}
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DeoptCall->setCallingConv(Guard->getCallingConv());
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DeoptBlockTerm->eraseFromParent();
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}
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