llvm/llvm/lib/Transforms/Coroutines/CoroEarly.cpp

//===- CoroEarly.cpp - Coroutine Early Function Pass ----------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//

#include "llvm/Transforms/Coroutines/CoroEarly.h"
#include "CoroInternal.h"
#include "llvm/IR/DIBuilder.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/InstIterator.h"
#include "llvm/IR/Module.h"
#include "llvm/Transforms/Coroutines/CoroShape.h"

usingnamespacellvm;

#define DEBUG_TYPE …

namespace {
// Created on demand if the coro-early pass has work to do.
class Lowerer : public coro::LowererBase { … };
}

// Replace a direct call to coro.resume or coro.destroy with an indirect call to
// an address returned by coro.subfn.addr intrinsic. This is done so that
// CGPassManager recognizes devirtualization when CoroElide pass replaces a call
// to coro.subfn.addr with an appropriate function address.
void Lowerer::lowerResumeOrDestroy(CallBase &CB,
                                   CoroSubFnInst::ResumeKind Index) { … }

// Coroutine promise field is always at the fixed offset from the beginning of
// the coroutine frame. i8* coro.promise(i8*, i1 from) intrinsic adds an offset
// to a passed pointer to move from coroutine frame to coroutine promise and
// vice versa. Since we don't know exactly which coroutine frame it is, we build
// a coroutine frame mock up starting with two function pointers, followed by a
// properly aligned coroutine promise field.
// TODO: Handle the case when coroutine promise alloca has align override.
void Lowerer::lowerCoroPromise(CoroPromiseInst *Intrin) { … }

// When a coroutine reaches final suspend point, it zeros out ResumeFnAddr in
// the coroutine frame (it is UB to resume from a final suspend point).
// The llvm.coro.done intrinsic is used to check whether a coroutine is
// suspended at the final suspend point or not.
void Lowerer::lowerCoroDone(IntrinsicInst *II) { … }

static void buildDebugInfoForNoopResumeDestroyFunc(Function *NoopFn) { … }

void Lowerer::lowerCoroNoop(IntrinsicInst *II) { … }

// Prior to CoroSplit, calls to coro.begin needs to be marked as NoDuplicate,
// as CoroSplit assumes there is exactly one coro.begin. After CoroSplit,
// NoDuplicate attribute will be removed from coro.begin otherwise, it will
// interfere with inlining.
static void setCannotDuplicate(CoroIdInst *CoroId) { … }

void Lowerer::lowerEarlyIntrinsics(Function &F) { … }

static bool declaresCoroEarlyIntrinsics(const Module &M) { … }

PreservedAnalyses CoroEarlyPass::run(Module &M, ModuleAnalysisManager &) { … }