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llvm-mirror/lib/IR/LLVMContext.cpp
Akira Hatanaka 4055195f29 [ObjC][ARC] Use operand bundle 'clang.arc.attachedcall' instead of
explicitly emitting retainRV or claimRV calls in the IR

This reapplies ed4718eccb12bd42214ca4fb17d196d49561c0c7, which was reverted
because it was causing a miscompile. The bug that was causing the miscompile
has been fixed in 75805dce5ff874676f3559c069fcd6737838f5c0.

Original commit message:

Background:

This fixes a longstanding problem where llvm breaks ARC's autorelease
optimization (see the link below) by separating calls from the marker
instructions or retainRV/claimRV calls. The backend changes are in
https://reviews.llvm.org/D92569.

https://clang.llvm.org/docs/AutomaticReferenceCounting.html#arc-runtime-objc-autoreleasereturnvalue

What this patch does to fix the problem:

- The front-end adds operand bundle "clang.arc.attachedcall" to calls,
  which indicates the call is implicitly followed by a marker
  instruction and an implicit retainRV/claimRV call that consumes the
  call result. In addition, it emits a call to
  @llvm.objc.clang.arc.noop.use, which consumes the call result, to
  prevent the middle-end passes from changing the return type of the
  called function. This is currently done only when the target is arm64
  and the optimization level is higher than -O0.

- ARC optimizer temporarily emits retainRV/claimRV calls after the calls
  with the operand bundle in the IR and removes the inserted calls after
  processing the function.

- ARC contract pass emits retainRV/claimRV calls after the call with the
  operand bundle. It doesn't remove the operand bundle on the call since
  the backend needs it to emit the marker instruction. The retainRV and
  claimRV calls are emitted late in the pipeline to prevent optimization
  passes from transforming the IR in a way that makes it harder for the
  ARC middle-end passes to figure out the def-use relationship between
  the call and the retainRV/claimRV calls (which is the cause of
  PR31925).

- The function inliner removes an autoreleaseRV call in the callee if
  nothing in the callee prevents it from being paired up with the
  retainRV/claimRV call in the caller. It then inserts a release call if
  claimRV is attached to the call since autoreleaseRV+claimRV is
  equivalent to a release. If it cannot find an autoreleaseRV call, it
  tries to transfer the operand bundle to a function call in the callee.
  This is important since the ARC optimizer can remove the autoreleaseRV
  returning the callee result, which makes it impossible to pair it up
  with the retainRV/claimRV call in the caller. If that fails, it simply
  emits a retain call in the IR if retainRV is attached to the call and
  does nothing if claimRV is attached to it.

- SCCP refrains from replacing the return value of a call with a
  constant value if the call has the operand bundle. This ensures the
  call always has at least one user (the call to
  @llvm.objc.clang.arc.noop.use).

- This patch also fixes a bug in replaceUsesOfNonProtoConstant where
  multiple operand bundles of the same kind were being added to a call.

Future work:

- Use the operand bundle on x86-64.

- Fix the auto upgrader to convert call+retainRV/claimRV pairs into
  calls with the operand bundles.

rdar://71443534

Differential Revision: https://reviews.llvm.org/D92808
2021-03-04 11:22:30 -08:00

350 lines
11 KiB
C++

//===-- LLVMContext.cpp - Implement LLVMContext ---------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This file implements LLVMContext, as a wrapper around the opaque
// class LLVMContextImpl.
//
//===----------------------------------------------------------------------===//
#include "llvm/IR/LLVMContext.h"
#include "LLVMContextImpl.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/Twine.h"
#include "llvm/IR/DiagnosticInfo.h"
#include "llvm/IR/DiagnosticPrinter.h"
#include "llvm/IR/LLVMRemarkStreamer.h"
#include "llvm/IR/Metadata.h"
#include "llvm/IR/Module.h"
#include "llvm/Remarks/RemarkStreamer.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include <cassert>
#include <cstdlib>
#include <string>
#include <utility>
using namespace llvm;
LLVMContext::LLVMContext() : pImpl(new LLVMContextImpl(*this)) {
// Create the fixed metadata kinds. This is done in the same order as the
// MD_* enum values so that they correspond.
std::pair<unsigned, StringRef> MDKinds[] = {
#define LLVM_FIXED_MD_KIND(EnumID, Name, Value) {EnumID, Name},
#include "llvm/IR/FixedMetadataKinds.def"
#undef LLVM_FIXED_MD_KIND
};
for (auto &MDKind : MDKinds) {
unsigned ID = getMDKindID(MDKind.second);
assert(ID == MDKind.first && "metadata kind id drifted");
(void)ID;
}
auto *DeoptEntry = pImpl->getOrInsertBundleTag("deopt");
assert(DeoptEntry->second == LLVMContext::OB_deopt &&
"deopt operand bundle id drifted!");
(void)DeoptEntry;
auto *FuncletEntry = pImpl->getOrInsertBundleTag("funclet");
assert(FuncletEntry->second == LLVMContext::OB_funclet &&
"funclet operand bundle id drifted!");
(void)FuncletEntry;
auto *GCTransitionEntry = pImpl->getOrInsertBundleTag("gc-transition");
assert(GCTransitionEntry->second == LLVMContext::OB_gc_transition &&
"gc-transition operand bundle id drifted!");
(void)GCTransitionEntry;
auto *CFGuardTargetEntry = pImpl->getOrInsertBundleTag("cfguardtarget");
assert(CFGuardTargetEntry->second == LLVMContext::OB_cfguardtarget &&
"cfguardtarget operand bundle id drifted!");
(void)CFGuardTargetEntry;
auto *PreallocatedEntry = pImpl->getOrInsertBundleTag("preallocated");
assert(PreallocatedEntry->second == LLVMContext::OB_preallocated &&
"preallocated operand bundle id drifted!");
(void)PreallocatedEntry;
auto *GCLiveEntry = pImpl->getOrInsertBundleTag("gc-live");
assert(GCLiveEntry->second == LLVMContext::OB_gc_live &&
"gc-transition operand bundle id drifted!");
(void)GCLiveEntry;
auto *ClangAttachedCall =
pImpl->getOrInsertBundleTag("clang.arc.attachedcall");
assert(ClangAttachedCall->second == LLVMContext::OB_clang_arc_attachedcall &&
"clang.arc.attachedcall operand bundle id drifted!");
(void)ClangAttachedCall;
SyncScope::ID SingleThreadSSID =
pImpl->getOrInsertSyncScopeID("singlethread");
assert(SingleThreadSSID == SyncScope::SingleThread &&
"singlethread synchronization scope ID drifted!");
(void)SingleThreadSSID;
SyncScope::ID SystemSSID =
pImpl->getOrInsertSyncScopeID("");
assert(SystemSSID == SyncScope::System &&
"system synchronization scope ID drifted!");
(void)SystemSSID;
}
LLVMContext::~LLVMContext() { delete pImpl; }
void LLVMContext::addModule(Module *M) {
pImpl->OwnedModules.insert(M);
}
void LLVMContext::removeModule(Module *M) {
pImpl->OwnedModules.erase(M);
}
//===----------------------------------------------------------------------===//
// Recoverable Backend Errors
//===----------------------------------------------------------------------===//
void LLVMContext::setDiagnosticHandlerCallBack(
DiagnosticHandler::DiagnosticHandlerTy DiagnosticHandler,
void *DiagnosticContext, bool RespectFilters) {
pImpl->DiagHandler->DiagHandlerCallback = DiagnosticHandler;
pImpl->DiagHandler->DiagnosticContext = DiagnosticContext;
pImpl->RespectDiagnosticFilters = RespectFilters;
}
void LLVMContext::setDiagnosticHandler(std::unique_ptr<DiagnosticHandler> &&DH,
bool RespectFilters) {
pImpl->DiagHandler = std::move(DH);
pImpl->RespectDiagnosticFilters = RespectFilters;
}
void LLVMContext::setDiagnosticsHotnessRequested(bool Requested) {
pImpl->DiagnosticsHotnessRequested = Requested;
}
bool LLVMContext::getDiagnosticsHotnessRequested() const {
return pImpl->DiagnosticsHotnessRequested;
}
void LLVMContext::setDiagnosticsHotnessThreshold(Optional<uint64_t> Threshold) {
pImpl->DiagnosticsHotnessThreshold = Threshold;
}
uint64_t LLVMContext::getDiagnosticsHotnessThreshold() const {
return pImpl->DiagnosticsHotnessThreshold.getValueOr(UINT64_MAX);
}
bool LLVMContext::isDiagnosticsHotnessThresholdSetFromPSI() const {
return !pImpl->DiagnosticsHotnessThreshold.hasValue();
}
remarks::RemarkStreamer *LLVMContext::getMainRemarkStreamer() {
return pImpl->MainRemarkStreamer.get();
}
const remarks::RemarkStreamer *LLVMContext::getMainRemarkStreamer() const {
return const_cast<LLVMContext *>(this)->getMainRemarkStreamer();
}
void LLVMContext::setMainRemarkStreamer(
std::unique_ptr<remarks::RemarkStreamer> RemarkStreamer) {
pImpl->MainRemarkStreamer = std::move(RemarkStreamer);
}
LLVMRemarkStreamer *LLVMContext::getLLVMRemarkStreamer() {
return pImpl->LLVMRS.get();
}
const LLVMRemarkStreamer *LLVMContext::getLLVMRemarkStreamer() const {
return const_cast<LLVMContext *>(this)->getLLVMRemarkStreamer();
}
void LLVMContext::setLLVMRemarkStreamer(
std::unique_ptr<LLVMRemarkStreamer> RemarkStreamer) {
pImpl->LLVMRS = std::move(RemarkStreamer);
}
DiagnosticHandler::DiagnosticHandlerTy
LLVMContext::getDiagnosticHandlerCallBack() const {
return pImpl->DiagHandler->DiagHandlerCallback;
}
void *LLVMContext::getDiagnosticContext() const {
return pImpl->DiagHandler->DiagnosticContext;
}
void LLVMContext::setYieldCallback(YieldCallbackTy Callback, void *OpaqueHandle)
{
pImpl->YieldCallback = Callback;
pImpl->YieldOpaqueHandle = OpaqueHandle;
}
void LLVMContext::yield() {
if (pImpl->YieldCallback)
pImpl->YieldCallback(this, pImpl->YieldOpaqueHandle);
}
void LLVMContext::emitError(const Twine &ErrorStr) {
diagnose(DiagnosticInfoInlineAsm(ErrorStr));
}
void LLVMContext::emitError(const Instruction *I, const Twine &ErrorStr) {
assert (I && "Invalid instruction");
diagnose(DiagnosticInfoInlineAsm(*I, ErrorStr));
}
static bool isDiagnosticEnabled(const DiagnosticInfo &DI) {
// Optimization remarks are selective. They need to check whether the regexp
// pattern, passed via one of the -pass-remarks* flags, matches the name of
// the pass that is emitting the diagnostic. If there is no match, ignore the
// diagnostic and return.
//
// Also noisy remarks are only enabled if we have hotness information to sort
// them.
if (auto *Remark = dyn_cast<DiagnosticInfoOptimizationBase>(&DI))
return Remark->isEnabled() &&
(!Remark->isVerbose() || Remark->getHotness());
return true;
}
const char *
LLVMContext::getDiagnosticMessagePrefix(DiagnosticSeverity Severity) {
switch (Severity) {
case DS_Error:
return "error";
case DS_Warning:
return "warning";
case DS_Remark:
return "remark";
case DS_Note:
return "note";
}
llvm_unreachable("Unknown DiagnosticSeverity");
}
void LLVMContext::diagnose(const DiagnosticInfo &DI) {
if (auto *OptDiagBase = dyn_cast<DiagnosticInfoOptimizationBase>(&DI))
if (LLVMRemarkStreamer *RS = getLLVMRemarkStreamer())
RS->emit(*OptDiagBase);
// If there is a report handler, use it.
if (pImpl->DiagHandler &&
(!pImpl->RespectDiagnosticFilters || isDiagnosticEnabled(DI)) &&
pImpl->DiagHandler->handleDiagnostics(DI))
return;
if (!isDiagnosticEnabled(DI))
return;
// Otherwise, print the message with a prefix based on the severity.
DiagnosticPrinterRawOStream DP(errs());
errs() << getDiagnosticMessagePrefix(DI.getSeverity()) << ": ";
DI.print(DP);
errs() << "\n";
if (DI.getSeverity() == DS_Error)
exit(1);
}
void LLVMContext::emitError(unsigned LocCookie, const Twine &ErrorStr) {
diagnose(DiagnosticInfoInlineAsm(LocCookie, ErrorStr));
}
//===----------------------------------------------------------------------===//
// Metadata Kind Uniquing
//===----------------------------------------------------------------------===//
/// Return a unique non-zero ID for the specified metadata kind.
unsigned LLVMContext::getMDKindID(StringRef Name) const {
// If this is new, assign it its ID.
return pImpl->CustomMDKindNames.insert(
std::make_pair(
Name, pImpl->CustomMDKindNames.size()))
.first->second;
}
/// getHandlerNames - Populate client-supplied smallvector using custom
/// metadata name and ID.
void LLVMContext::getMDKindNames(SmallVectorImpl<StringRef> &Names) const {
Names.resize(pImpl->CustomMDKindNames.size());
for (StringMap<unsigned>::const_iterator I = pImpl->CustomMDKindNames.begin(),
E = pImpl->CustomMDKindNames.end(); I != E; ++I)
Names[I->second] = I->first();
}
void LLVMContext::getOperandBundleTags(SmallVectorImpl<StringRef> &Tags) const {
pImpl->getOperandBundleTags(Tags);
}
StringMapEntry<uint32_t> *
LLVMContext::getOrInsertBundleTag(StringRef TagName) const {
return pImpl->getOrInsertBundleTag(TagName);
}
uint32_t LLVMContext::getOperandBundleTagID(StringRef Tag) const {
return pImpl->getOperandBundleTagID(Tag);
}
SyncScope::ID LLVMContext::getOrInsertSyncScopeID(StringRef SSN) {
return pImpl->getOrInsertSyncScopeID(SSN);
}
void LLVMContext::getSyncScopeNames(SmallVectorImpl<StringRef> &SSNs) const {
pImpl->getSyncScopeNames(SSNs);
}
void LLVMContext::setGC(const Function &Fn, std::string GCName) {
auto It = pImpl->GCNames.find(&Fn);
if (It == pImpl->GCNames.end()) {
pImpl->GCNames.insert(std::make_pair(&Fn, std::move(GCName)));
return;
}
It->second = std::move(GCName);
}
const std::string &LLVMContext::getGC(const Function &Fn) {
return pImpl->GCNames[&Fn];
}
void LLVMContext::deleteGC(const Function &Fn) {
pImpl->GCNames.erase(&Fn);
}
bool LLVMContext::shouldDiscardValueNames() const {
return pImpl->DiscardValueNames;
}
bool LLVMContext::isODRUniquingDebugTypes() const { return !!pImpl->DITypeMap; }
void LLVMContext::enableDebugTypeODRUniquing() {
if (pImpl->DITypeMap)
return;
pImpl->DITypeMap.emplace();
}
void LLVMContext::disableDebugTypeODRUniquing() { pImpl->DITypeMap.reset(); }
void LLVMContext::setDiscardValueNames(bool Discard) {
pImpl->DiscardValueNames = Discard;
}
OptPassGate &LLVMContext::getOptPassGate() const {
return pImpl->getOptPassGate();
}
void LLVMContext::setOptPassGate(OptPassGate& OPG) {
pImpl->setOptPassGate(OPG);
}
const DiagnosticHandler *LLVMContext::getDiagHandlerPtr() const {
return pImpl->DiagHandler.get();
}
std::unique_ptr<DiagnosticHandler> LLVMContext::getDiagnosticHandler() {
return std::move(pImpl->DiagHandler);
}