llvm/llvm/lib/Transforms/Coroutines/CoroAnnotationElide.cpp

//===- CoroAnnotationElide.cpp - Elide attributed safe coroutine calls ----===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// \file
// This pass transforms all Call or Invoke instructions that are annotated
// "coro_elide_safe" to call the `.noalloc` variant of coroutine instead.
// The frame of the callee coroutine is allocated inside the caller. A pointer
// to the allocated frame will be passed into the `.noalloc` ramp function.
//
//===----------------------------------------------------------------------===//

#include "llvm/Transforms/Coroutines/CoroAnnotationElide.h"

#include "llvm/Analysis/LazyCallGraph.h"
#include "llvm/Analysis/OptimizationRemarkEmitter.h"
#include "llvm/IR/Analysis.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/InstIterator.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/PassManager.h"
#include "llvm/Transforms/Utils/CallGraphUpdater.h"

#include <cassert>

usingnamespacellvm;

#define DEBUG_TYPE …

static Instruction *getFirstNonAllocaInTheEntryBlock(Function *F) { … }

// Create an alloca in the caller, using FrameSize and FrameAlign as the callee
// coroutine's activation frame.
static Value *allocateFrameInCaller(Function *Caller, uint64_t FrameSize,
                                    Align FrameAlign) { … }

// Given a call or invoke instruction to the elide safe coroutine, this function
// does the following:
//  - Allocate a frame for the callee coroutine in the caller using alloca.
//  - Replace the old CB with a new Call or Invoke to `NewCallee`, with the
//    pointer to the frame as an additional argument to NewCallee.
static void processCall(CallBase *CB, Function *Caller, Function *NewCallee,
                        uint64_t FrameSize, Align FrameAlign) { … }

PreservedAnalyses CoroAnnotationElidePass::run(Function &F,
                                               FunctionAnalysisManager &FAM) { … }