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//===-- go-llvm-cabi-irbuilders.h - IR builder helper classes -------------===//
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Assorted helper classes for IR building.
#include "go-llvm-bexpression.h"
#include "llvm/IR/IRBuilder.h"
class NameGen;
// Generic "no insert" builder
typedef llvm::IRBuilder<> LIRBuilder;
// Insertion helper for Bexpressions; inserts any instructions
// created by IRBuilder into the specified Bexpression's inst list.
class BexprInserter : public llvm::IRBuilderDefaultInserter {
BexprInserter() : expr_(nullptr) { }
void setDest(Bexpression *expr) { assert(!expr_); expr_ = expr; }
void InsertHelper(llvm::Instruction *I, const llvm::Twine &Name,
llvm::BasicBlock *BB,
llvm::BasicBlock::iterator InsertPt) const {
mutable Bexpression *expr_;
// Builder that appends to a specified Bexpression
class BexprLIRBuilder :
public llvm::IRBuilder<llvm::ConstantFolder, BexprInserter> {
typedef llvm::IRBuilder<llvm::ConstantFolder, BexprInserter> IRBuilderB;
BexprLIRBuilder(llvm::LLVMContext &context, Bexpression *expr) :
IRBuilderB(context, llvm::ConstantFolder()) {
// Many of the methods in the LLVM IRBuilder class (ex: CreateMemCpy)
// assume that you are appending to an existing basic block (which is
// typically not what we want to do in many cases in the bridge code).
// Furthermore it is required that the block in question be already
// parented within an llvm::Function (the IRBuilder code relies on
// being able to call getParent() to trace back up to the enclosing
// context).
// This builder works around this issue by creating a dummy basic
// block to capture any instructions generated, then when the builder
// is destroyed it detaches the instructions from the block so that
// they can be returned in a list. A dummy function has to be passed in
// as well in order to host the dummy BB, however the dummy block will
// be detached in the destructor.
class BlockLIRBuilder : public LIRBuilder {
BlockLIRBuilder(llvm::Function *dummyFcn, NameGen *namegen);
// Return the instructions generated by this builder. Note that
// this detaches them from the dummy block we emitted them into,
// hence is not intended to be invoked more than once.
std::vector<llvm::Instruction*> instructions();
std::unique_ptr<llvm::BasicBlock> dummyBlock_;
NameGen *namegen_;