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//===- TargetPassConfig.cpp - Target independent code generation passes ---===//
// The LLVM Compiler Infrastructure
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
// This file defines interfaces to access the target independent code
// generation passes provided by the LLVM backend.
#include "llvm/CodeGen/TargetPassConfig.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Analysis/BasicAliasAnalysis.h"
#include "llvm/Analysis/CFLAndersAliasAnalysis.h"
#include "llvm/Analysis/CFLSteensAliasAnalysis.h"
#include "llvm/Analysis/CallGraphSCCPass.h"
#include "llvm/Analysis/ScopedNoAliasAA.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/Analysis/TypeBasedAliasAnalysis.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachinePassRegistry.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/RegAllocRegistry.h"
#include "llvm/IR/IRPrintingPasses.h"
#include "llvm/IR/LegacyPassManager.h"
#include "llvm/IR/Verifier.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCTargetOptions.h"
#include "llvm/Pass.h"
#include "llvm/Support/CodeGen.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/Threading.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Utils.h"
#include "llvm/Transforms/Utils/SymbolRewriter.h"
#include <cassert>
#include <string>
using namespace llvm;
cl::opt<bool> EnableIPRA("enable-ipra", cl::init(false), cl::Hidden,
cl::desc("Enable interprocedural register allocation "
"to reduce load/store at procedure calls."));
static cl::opt<bool> DisablePostRASched("disable-post-ra", cl::Hidden,
cl::desc("Disable Post Regalloc Scheduler"));
static cl::opt<bool> DisableBranchFold("disable-branch-fold", cl::Hidden,
cl::desc("Disable branch folding"));
static cl::opt<bool> DisableTailDuplicate("disable-tail-duplicate", cl::Hidden,
cl::desc("Disable tail duplication"));
static cl::opt<bool> DisableEarlyTailDup("disable-early-taildup", cl::Hidden,
cl::desc("Disable pre-register allocation tail duplication"));
static cl::opt<bool> DisableBlockPlacement("disable-block-placement",
cl::Hidden, cl::desc("Disable probability-driven block placement"));
static cl::opt<bool> EnableBlockPlacementStats("enable-block-placement-stats",
cl::Hidden, cl::desc("Collect probability-driven block placement stats"));
static cl::opt<bool> DisableSSC("disable-ssc", cl::Hidden,
cl::desc("Disable Stack Slot Coloring"));
static cl::opt<bool> DisableMachineDCE("disable-machine-dce", cl::Hidden,
cl::desc("Disable Machine Dead Code Elimination"));
static cl::opt<bool> DisableEarlyIfConversion("disable-early-ifcvt", cl::Hidden,
cl::desc("Disable Early If-conversion"));
static cl::opt<bool> DisableMachineLICM("disable-machine-licm", cl::Hidden,
cl::desc("Disable Machine LICM"));
static cl::opt<bool> DisableMachineCSE("disable-machine-cse", cl::Hidden,
cl::desc("Disable Machine Common Subexpression Elimination"));
static cl::opt<cl::boolOrDefault> OptimizeRegAlloc(
"optimize-regalloc", cl::Hidden,
cl::desc("Enable optimized register allocation compilation path."));
static cl::opt<bool> DisablePostRAMachineLICM("disable-postra-machine-licm",
cl::desc("Disable Machine LICM"));
static cl::opt<bool> DisableMachineSink("disable-machine-sink", cl::Hidden,
cl::desc("Disable Machine Sinking"));
static cl::opt<bool> DisablePostRAMachineSink("disable-postra-machine-sink",
cl::desc("Disable PostRA Machine Sinking"));
static cl::opt<bool> DisableLSR("disable-lsr", cl::Hidden,
cl::desc("Disable Loop Strength Reduction Pass"));
static cl::opt<bool> DisableConstantHoisting("disable-constant-hoisting",
cl::Hidden, cl::desc("Disable ConstantHoisting"));
static cl::opt<bool> DisableCGP("disable-cgp", cl::Hidden,
cl::desc("Disable Codegen Prepare"));
static cl::opt<bool> DisableCopyProp("disable-copyprop", cl::Hidden,
cl::desc("Disable Copy Propagation pass"));
static cl::opt<bool> DisablePartialLibcallInlining("disable-partial-libcall-inlining",
cl::Hidden, cl::desc("Disable Partial Libcall Inlining"));
static cl::opt<bool> EnableImplicitNullChecks(
cl::desc("Fold null checks into faulting memory operations"),
cl::init(false), cl::Hidden);
static cl::opt<bool> DisableMergeICmps("disable-mergeicmps",
cl::desc("Disable MergeICmps Pass"),
cl::init(false), cl::Hidden);
static cl::opt<bool> PrintLSR("print-lsr-output", cl::Hidden,
cl::desc("Print LLVM IR produced by the loop-reduce pass"));
static cl::opt<bool> PrintISelInput("print-isel-input", cl::Hidden,
cl::desc("Print LLVM IR input to isel pass"));
static cl::opt<bool> PrintGCInfo("print-gc", cl::Hidden,
cl::desc("Dump garbage collector data"));
static cl::opt<bool> VerifyMachineCode("verify-machineinstrs", cl::Hidden,
cl::desc("Verify generated machine code"),
enum RunOutliner { AlwaysOutline, NeverOutline, TargetDefault };
// Enable or disable the MachineOutliner.
static cl::opt<RunOutliner> EnableMachineOutliner(
"enable-machine-outliner", cl::desc("Enable the machine outliner"),
cl::Hidden, cl::ValueOptional, cl::init(TargetDefault),
cl::values(clEnumValN(AlwaysOutline, "always",
"Run on all functions guaranteed to be beneficial"),
clEnumValN(NeverOutline, "never", "Disable all outlining"),
// Sentinel value for unspecified option.
clEnumValN(AlwaysOutline, "", "")));
// Enable or disable FastISel. Both options are needed, because
// FastISel is enabled by default with -fast, and we wish to be
// able to enable or disable fast-isel independently from -O0.
static cl::opt<cl::boolOrDefault>
EnableFastISelOption("fast-isel", cl::Hidden,
cl::desc("Enable the \"fast\" instruction selector"));
static cl::opt<cl::boolOrDefault> EnableGlobalISelOption(
"global-isel", cl::Hidden,
cl::desc("Enable the \"global\" instruction selector"));
static cl::opt<std::string> PrintMachineInstrs(
"print-machineinstrs", cl::ValueOptional, cl::desc("Print machine instrs"),
cl::value_desc("pass-name"), cl::init("option-unspecified"), cl::Hidden);
static cl::opt<int> EnableGlobalISelAbort(
"global-isel-abort", cl::Hidden,
cl::desc("Enable abort calls when \"global\" instruction selection "
"fails to lower/select an instruction: 0 disable the abort, "
"1 enable the abort, and "
"2 disable the abort but emit a diagnostic on failure"),
// Temporary option to allow experimenting with MachineScheduler as a post-RA
// scheduler. Targets can "properly" enable this with
// substitutePass(&PostRASchedulerID, &PostMachineSchedulerID).
// Targets can return true in targetSchedulesPostRAScheduling() and
// insert a PostRA scheduling pass wherever it wants.
cl::opt<bool> MISchedPostRA("misched-postra", cl::Hidden,
cl::desc("Run MachineScheduler post regalloc (independent of preRA sched)"));
// Experimental option to run live interval analysis early.
static cl::opt<bool> EarlyLiveIntervals("early-live-intervals", cl::Hidden,
cl::desc("Run live interval analysis earlier in the pipeline"));
// Experimental option to use CFL-AA in codegen
enum class CFLAAType { None, Steensgaard, Andersen, Both };
static cl::opt<CFLAAType> UseCFLAA(
"use-cfl-aa-in-codegen", cl::init(CFLAAType::None), cl::Hidden,
cl::desc("Enable the new, experimental CFL alias analysis in CodeGen"),
cl::values(clEnumValN(CFLAAType::None, "none", "Disable CFL-AA"),
clEnumValN(CFLAAType::Steensgaard, "steens",
"Enable unification-based CFL-AA"),
clEnumValN(CFLAAType::Andersen, "anders",
"Enable inclusion-based CFL-AA"),
clEnumValN(CFLAAType::Both, "both",
"Enable both variants of CFL-AA")));
/// Option names for limiting the codegen pipeline.
/// Those are used in error reporting and we didn't want
/// to duplicate their names all over the place.
const char *StartAfterOptName = "start-after";
const char *StartBeforeOptName = "start-before";
const char *StopAfterOptName = "stop-after";
const char *StopBeforeOptName = "stop-before";
static cl::opt<std::string>
cl::desc("Resume compilation after a specific pass"),
cl::value_desc("pass-name"), cl::init(""), cl::Hidden);
static cl::opt<std::string>
cl::desc("Resume compilation before a specific pass"),
cl::value_desc("pass-name"), cl::init(""), cl::Hidden);
static cl::opt<std::string>
cl::desc("Stop compilation after a specific pass"),
cl::value_desc("pass-name"), cl::init(""), cl::Hidden);
static cl::opt<std::string>
cl::desc("Stop compilation before a specific pass"),
cl::value_desc("pass-name"), cl::init(""), cl::Hidden);
/// Allow standard passes to be disabled by command line options. This supports
/// simple binary flags that either suppress the pass or do nothing.
/// i.e. -disable-mypass=false has no effect.
/// These should be converted to boolOrDefault in order to use applyOverride.
static IdentifyingPassPtr applyDisable(IdentifyingPassPtr PassID,
bool Override) {
if (Override)
return IdentifyingPassPtr();
return PassID;
/// Allow standard passes to be disabled by the command line, regardless of who
/// is adding the pass.
/// StandardID is the pass identified in the standard pass pipeline and provided
/// to addPass(). It may be a target-specific ID in the case that the target
/// directly adds its own pass, but in that case we harmlessly fall through.
/// TargetID is the pass that the target has configured to override StandardID.
/// StandardID may be a pseudo ID. In that case TargetID is the name of the real
/// pass to run. This allows multiple options to control a single pass depending
/// on where in the pipeline that pass is added.
static IdentifyingPassPtr overridePass(AnalysisID StandardID,
IdentifyingPassPtr TargetID) {
if (StandardID == &PostRASchedulerID)
return applyDisable(TargetID, DisablePostRASched);
if (StandardID == &BranchFolderPassID)
return applyDisable(TargetID, DisableBranchFold);
if (StandardID == &TailDuplicateID)
return applyDisable(TargetID, DisableTailDuplicate);
if (StandardID == &EarlyTailDuplicateID)
return applyDisable(TargetID, DisableEarlyTailDup);
if (StandardID == &MachineBlockPlacementID)
return applyDisable(TargetID, DisableBlockPlacement);
if (StandardID == &StackSlotColoringID)
return applyDisable(TargetID, DisableSSC);
if (StandardID == &DeadMachineInstructionElimID)
return applyDisable(TargetID, DisableMachineDCE);
if (StandardID == &EarlyIfConverterID)
return applyDisable(TargetID, DisableEarlyIfConversion);
if (StandardID == &EarlyMachineLICMID)
return applyDisable(TargetID, DisableMachineLICM);
if (StandardID == &MachineCSEID)
return applyDisable(TargetID, DisableMachineCSE);
if (StandardID == &MachineLICMID)
return applyDisable(TargetID, DisablePostRAMachineLICM);
if (StandardID == &MachineSinkingID)
return applyDisable(TargetID, DisableMachineSink);
if (StandardID == &PostRAMachineSinkingID)
return applyDisable(TargetID, DisablePostRAMachineSink);
if (StandardID == &MachineCopyPropagationID)
return applyDisable(TargetID, DisableCopyProp);
return TargetID;
/// TargetPassConfig
INITIALIZE_PASS(TargetPassConfig, "targetpassconfig",
"Target Pass Configuration", false, false)
char TargetPassConfig::ID = 0;
namespace {
struct InsertedPass {
AnalysisID TargetPassID;
IdentifyingPassPtr InsertedPassID;
bool VerifyAfter;
bool PrintAfter;
InsertedPass(AnalysisID TargetPassID, IdentifyingPassPtr InsertedPassID,
bool VerifyAfter, bool PrintAfter)
: TargetPassID(TargetPassID), InsertedPassID(InsertedPassID),
VerifyAfter(VerifyAfter), PrintAfter(PrintAfter) {}
Pass *getInsertedPass() const {
assert(InsertedPassID.isValid() && "Illegal Pass ID!");
if (InsertedPassID.isInstance())
return InsertedPassID.getInstance();
Pass *NP = Pass::createPass(InsertedPassID.getID());
assert(NP && "Pass ID not registered");
return NP;
} // end anonymous namespace
namespace llvm {
class PassConfigImpl {
// List of passes explicitly substituted by this target. Normally this is
// empty, but it is a convenient way to suppress or replace specific passes
// that are part of a standard pass pipeline without overridding the entire
// pipeline. This mechanism allows target options to inherit a standard pass's
// user interface. For example, a target may disable a standard pass by
// default by substituting a pass ID of zero, and the user may still enable
// that standard pass with an explicit command line option.
DenseMap<AnalysisID,IdentifyingPassPtr> TargetPasses;
/// Store the pairs of <AnalysisID, AnalysisID> of which the second pass
/// is inserted after each instance of the first one.
SmallVector<InsertedPass, 4> InsertedPasses;
} // end namespace llvm
// Out of line virtual method.
TargetPassConfig::~TargetPassConfig() {
delete Impl;
static const PassInfo *getPassInfo(StringRef PassName) {
if (PassName.empty())
return nullptr;
const PassRegistry &PR = *PassRegistry::getPassRegistry();
const PassInfo *PI = PR.getPassInfo(PassName);
if (!PI)
report_fatal_error(Twine('\"') + Twine(PassName) +
Twine("\" pass is not registered."));
return PI;
static AnalysisID getPassIDFromName(StringRef PassName) {
const PassInfo *PI = getPassInfo(PassName);
return PI ? PI->getTypeInfo() : nullptr;
void TargetPassConfig::setStartStopPasses() {
StartBefore = getPassIDFromName(StartBeforeOpt);
StartAfter = getPassIDFromName(StartAfterOpt);
StopBefore = getPassIDFromName(StopBeforeOpt);
StopAfter = getPassIDFromName(StopAfterOpt);
if (StartBefore && StartAfter)
report_fatal_error(Twine(StartBeforeOptName) + Twine(" and ") +
Twine(StartAfterOptName) + Twine(" specified!"));
if (StopBefore && StopAfter)
report_fatal_error(Twine(StopBeforeOptName) + Twine(" and ") +
Twine(StopAfterOptName) + Twine(" specified!"));
Started = (StartAfter == nullptr) && (StartBefore == nullptr);
// Out of line constructor provides default values for pass options and
// registers all common codegen passes.
TargetPassConfig::TargetPassConfig(LLVMTargetMachine &TM, PassManagerBase &pm)
: ImmutablePass(ID), PM(&pm), TM(&TM) {
Impl = new PassConfigImpl();
// Register all target independent codegen passes to activate their PassIDs,
// including this pass itself.
// Also register alias analysis passes required by codegen passes.
if (StringRef(PrintMachineInstrs.getValue()).equals(""))
TM.Options.PrintMachineCode = true;
if (EnableIPRA.getNumOccurrences())
TM.Options.EnableIPRA = EnableIPRA;
else {
// If not explicitly specified, use target default.
TM.Options.EnableIPRA = TM.useIPRA();
if (TM.Options.EnableIPRA)
CodeGenOpt::Level TargetPassConfig::getOptLevel() const {
return TM->getOptLevel();
/// Insert InsertedPassID pass after TargetPassID.
void TargetPassConfig::insertPass(AnalysisID TargetPassID,
IdentifyingPassPtr InsertedPassID,
bool VerifyAfter, bool PrintAfter) {
assert(((!InsertedPassID.isInstance() &&
TargetPassID != InsertedPassID.getID()) ||
(InsertedPassID.isInstance() &&
TargetPassID != InsertedPassID.getInstance()->getPassID())) &&
"Insert a pass after itself!");
Impl->InsertedPasses.emplace_back(TargetPassID, InsertedPassID, VerifyAfter,
/// createPassConfig - Create a pass configuration object to be used by
/// addPassToEmitX methods for generating a pipeline of CodeGen passes.
/// Targets may override this to extend TargetPassConfig.
TargetPassConfig *LLVMTargetMachine::createPassConfig(PassManagerBase &PM) {
return new TargetPassConfig(*this, PM);
: ImmutablePass(ID) {
report_fatal_error("Trying to construct TargetPassConfig without a target "
"machine. Scheduling a CodeGen pass without a target "
"triple set?");
bool TargetPassConfig::hasLimitedCodeGenPipeline() const {
return StartBefore || StartAfter || StopBefore || StopAfter;
TargetPassConfig::getLimitedCodeGenPipelineReason(const char *Separator) const {
if (!hasLimitedCodeGenPipeline())
return std::string();
std::string Res;
static cl::opt<std::string> *PassNames[] = {&StartAfterOpt, &StartBeforeOpt,
&StopAfterOpt, &StopBeforeOpt};
static const char *OptNames[] = {StartAfterOptName, StartBeforeOptName,
StopAfterOptName, StopBeforeOptName};
bool IsFirst = true;
for (int Idx = 0; Idx < 4; ++Idx)
if (!PassNames[Idx]->empty()) {
if (!IsFirst)
Res += Separator;
IsFirst = false;
Res += OptNames[Idx];
return Res;
// Helper to verify the analysis is really immutable.
void TargetPassConfig::setOpt(bool &Opt, bool Val) {
assert(!Initialized && "PassConfig is immutable");
Opt = Val;
void TargetPassConfig::substitutePass(AnalysisID StandardID,
IdentifyingPassPtr TargetID) {
Impl->TargetPasses[StandardID] = TargetID;
IdentifyingPassPtr TargetPassConfig::getPassSubstitution(AnalysisID ID) const {
DenseMap<AnalysisID, IdentifyingPassPtr>::const_iterator
I = Impl->TargetPasses.find(ID);
if (I == Impl->TargetPasses.end())
return ID;
return I->second;
bool TargetPassConfig::isPassSubstitutedOrOverridden(AnalysisID ID) const {
IdentifyingPassPtr TargetID = getPassSubstitution(ID);
IdentifyingPassPtr FinalPtr = overridePass(ID, TargetID);
return !FinalPtr.isValid() || FinalPtr.isInstance() ||
FinalPtr.getID() != ID;
/// Add a pass to the PassManager if that pass is supposed to be run. If the
/// Started/Stopped flags indicate either that the compilation should start at
/// a later pass or that it should stop after an earlier pass, then do not add
/// the pass. Finally, compare the current pass against the StartAfter
/// and StopAfter options and change the Started/Stopped flags accordingly.
void TargetPassConfig::addPass(Pass *P, bool verifyAfter, bool printAfter) {
assert(!Initialized && "PassConfig is immutable");
// Cache the Pass ID here in case the pass manager finds this pass is
// redundant with ones already scheduled / available, and deletes it.
// Fundamentally, once we add the pass to the manager, we no longer own it
// and shouldn't reference it.
AnalysisID PassID = P->getPassID();
if (StartBefore == PassID)
Started = true;
if (StopBefore == PassID)
Stopped = true;
if (Started && !Stopped) {
std::string Banner;
// Construct banner message before PM->add() as that may delete the pass.
if (AddingMachinePasses && (printAfter || verifyAfter))
Banner = std::string("After ") + std::string(P->getPassName());
if (AddingMachinePasses) {
if (printAfter)
if (verifyAfter)
// Add the passes after the pass P if there is any.
for (auto IP : Impl->InsertedPasses) {
if (IP.TargetPassID == PassID)
addPass(IP.getInsertedPass(), IP.VerifyAfter, IP.PrintAfter);
} else {
delete P;
if (StopAfter == PassID)
Stopped = true;
if (StartAfter == PassID)
Started = true;
if (Stopped && !Started)
report_fatal_error("Cannot stop compilation after pass that is not run");
/// Add a CodeGen pass at this point in the pipeline after checking for target
/// and command line overrides.
/// addPass cannot return a pointer to the pass instance because is internal the
/// PassManager and the instance we create here may already be freed.
AnalysisID TargetPassConfig::addPass(AnalysisID PassID, bool verifyAfter,
bool printAfter) {
IdentifyingPassPtr TargetID = getPassSubstitution(PassID);
IdentifyingPassPtr FinalPtr = overridePass(PassID, TargetID);
if (!FinalPtr.isValid())
return nullptr;
Pass *P;
if (FinalPtr.isInstance())
P = FinalPtr.getInstance();
else {
P = Pass::createPass(FinalPtr.getID());
if (!P)
llvm_unreachable("Pass ID not registered");
AnalysisID FinalID = P->getPassID();
addPass(P, verifyAfter, printAfter); // Ends the lifetime of P.
return FinalID;
void TargetPassConfig::printAndVerify(const std::string &Banner) {
void TargetPassConfig::addPrintPass(const std::string &Banner) {
if (TM->shouldPrintMachineCode())
PM->add(createMachineFunctionPrinterPass(dbgs(), Banner));
void TargetPassConfig::addVerifyPass(const std::string &Banner) {
bool Verify = VerifyMachineCode;
if (VerifyMachineCode == cl::BOU_UNSET)
Verify = TM->isMachineVerifierClean();
if (Verify)
/// Add common target configurable passes that perform LLVM IR to IR transforms
/// following machine independent optimization.
void TargetPassConfig::addIRPasses() {
switch (UseCFLAA) {
case CFLAAType::Steensgaard:
case CFLAAType::Andersen:
case CFLAAType::Both:
// Basic AliasAnalysis support.
// Add TypeBasedAliasAnalysis before BasicAliasAnalysis so that
// BasicAliasAnalysis wins if they disagree. This is intended to help
// support "obvious" type-punning idioms.
// Before running any passes, run the verifier to determine if the input
// coming from the front-end and/or optimizer is valid.
if (!DisableVerify)
// Run loop strength reduction before anything else.
if (getOptLevel() != CodeGenOpt::None && !DisableLSR) {
if (PrintLSR)
addPass(createPrintFunctionPass(dbgs(), "\n\n*** Code after LSR ***\n"));
if (getOptLevel() != CodeGenOpt::None) {
// The MergeICmpsPass tries to create memcmp calls by grouping sequences of
// loads and compares. ExpandMemCmpPass then tries to expand those calls
// into optimally-sized loads and compares. The transforms are enabled by a
// target lowering hook.
if (!DisableMergeICmps)
// Run GC lowering passes for builtin collectors
// TODO: add a pass insertion point here
// Make sure that no unreachable blocks are instruction selected.
// Prepare expensive constants for SelectionDAG.
if (getOptLevel() != CodeGenOpt::None && !DisableConstantHoisting)
if (getOptLevel() != CodeGenOpt::None && !DisablePartialLibcallInlining)
// Instrument function entry and exit, e.g. with calls to mcount().
// Add scalarization of target's unsupported masked memory intrinsics pass.
// the unsupported intrinsic will be replaced with a chain of basic blocks,
// that stores/loads element one-by-one if the appropriate mask bit is set.
// Expand reduction intrinsics into shuffle sequences if the target wants to.
/// Turn exception handling constructs into something the code generators can
/// handle.
void TargetPassConfig::addPassesToHandleExceptions() {
const MCAsmInfo *MCAI = TM->getMCAsmInfo();
assert(MCAI && "No MCAsmInfo");
switch (MCAI->getExceptionHandlingType()) {
case ExceptionHandling::SjLj:
// SjLj piggy-backs on dwarf for this bit. The cleanups done apply to both
// Dwarf EH prepare needs to be run after SjLj prepare. Otherwise,
// catch info can get misplaced when a selector ends up more than one block
// removed from the parent invoke(s). This could happen when a landing
// pad is shared by multiple invokes and is also a target of a normal
// edge from elsewhere.
case ExceptionHandling::DwarfCFI:
case ExceptionHandling::ARM:
case ExceptionHandling::WinEH:
// We support using both GCC-style and MSVC-style exceptions on Windows, so
// add both preparation passes. Each pass will only actually run if it
// recognizes the personality function.
case ExceptionHandling::Wasm:
// Wasm EH uses Windows EH instructions, but it does not need to demote PHIs
// on catchpads and cleanuppads because it does not outline them into
// funclets. Catchswitch blocks are not lowered in SelectionDAG, so we
// should remove PHIs there.
case ExceptionHandling::None:
// The lower invoke pass may create unreachable code. Remove it.
/// Add pass to prepare the LLVM IR for code generation. This should be done
/// before exception handling preparation passes.
void TargetPassConfig::addCodeGenPrepare() {
if (getOptLevel() != CodeGenOpt::None && !DisableCGP)
/// Add common passes that perform LLVM IR to IR transforms in preparation for
/// instruction selection.
void TargetPassConfig::addISelPrepare() {
// Force codegen to run according to the callgraph.
if (requiresCodeGenSCCOrder())
addPass(new DummyCGSCCPass);
// Add both the safe stack and the stack protection passes: each of them will
// only protect functions that have corresponding attributes.
if (PrintISelInput)
dbgs(), "\n\n*** Final LLVM Code input to ISel ***\n"));
// All passes which modify the LLVM IR are now complete; run the verifier
// to ensure that the IR is valid.
if (!DisableVerify)
bool TargetPassConfig::addCoreISelPasses() {
// Enable FastISel with -fast-isel, but allow that to be overridden.
TM->setO0WantsFastISel(EnableFastISelOption != cl::BOU_FALSE);
if (EnableFastISelOption == cl::BOU_TRUE ||
(TM->getOptLevel() == CodeGenOpt::None && TM->getO0WantsFastISel()))
// Ask the target for an instruction selector.
// Explicitly enabling fast-isel should override implicitly enabled
// global-isel.
if (EnableGlobalISelOption == cl::BOU_TRUE ||
(EnableGlobalISelOption == cl::BOU_UNSET &&
TM->Options.EnableGlobalISel && EnableFastISelOption != cl::BOU_TRUE)) {
if (addIRTranslator())
return true;
if (addLegalizeMachineIR())
return true;
// Before running the register bank selector, ask the target if it
// wants to run some passes.
if (addRegBankSelect())
return true;
if (addGlobalInstructionSelect())
return true;
// Pass to reset the MachineFunction if the ISel failed.
reportDiagnosticWhenGlobalISelFallback(), isGlobalISelAbortEnabled()));
// Provide a fallback path when we do not want to abort on
// not-yet-supported input.
if (!isGlobalISelAbortEnabled() && addInstSelector())
return true;
} else if (addInstSelector())
return true;
return false;
bool TargetPassConfig::addISelPasses() {
if (TM->useEmulatedTLS())
return addCoreISelPasses();
/// -regalloc=... command line option.
static FunctionPass *useDefaultRegisterAllocator() { return nullptr; }
static cl::opt<RegisterRegAlloc::FunctionPassCtor, false,
RegAlloc("regalloc", cl::Hidden, cl::init(&useDefaultRegisterAllocator),
cl::desc("Register allocator to use"));
/// Add the complete set of target-independent postISel code generator passes.
/// This can be read as the standard order of major LLVM CodeGen stages. Stages
/// with nontrivial configuration or multiple passes are broken out below in
/// add%Stage routines.
/// Any TargetPassConfig::addXX routine may be overriden by the Target. The
/// addPre/Post methods with empty header implementations allow injecting
/// target-specific fixups just before or after major stages. Additionally,
/// targets have the flexibility to change pass order within a stage by
/// overriding default implementation of add%Stage routines below. Each
/// technique has maintainability tradeoffs because alternate pass orders are
/// not well supported. addPre/Post works better if the target pass is easily
/// tied to a common pass. But if it has subtle dependencies on multiple passes,
/// the target should override the stage instead.
/// TODO: We could use a single addPre/Post(ID) hook to allow pass injection
/// before/after any target-independent pass. But it's currently overkill.
void TargetPassConfig::addMachinePasses() {
AddingMachinePasses = true;
// Insert a machine instr printer pass after the specified pass.
if (!StringRef(PrintMachineInstrs.getValue()).equals("") &&
!StringRef(PrintMachineInstrs.getValue()).equals("option-unspecified")) {
const PassRegistry *PR = PassRegistry::getPassRegistry();
const PassInfo *TPI = PR->getPassInfo(PrintMachineInstrs.getValue());
const PassInfo *IPI = PR->getPassInfo(StringRef("machineinstr-printer"));
assert (TPI && IPI && "Pass ID not registered!");
const char *TID = (const char *)(TPI->getTypeInfo());
const char *IID = (const char *)(IPI->getTypeInfo());
insertPass(TID, IID);
// Print the instruction selected machine code...
printAndVerify("After Instruction Selection");
// Expand pseudo-instructions emitted by ISel.
// Add passes that optimize machine instructions in SSA form.
if (getOptLevel() != CodeGenOpt::None) {
} else {
// If the target requests it, assign local variables to stack slots relative
// to one another and simplify frame index references where possible.
addPass(&LocalStackSlotAllocationID, false);
if (TM->Options.EnableIPRA)
// Run pre-ra passes.
// Run register allocation and passes that are tightly coupled with it,
// including phi elimination and scheduling.
if (getOptimizeRegAlloc())
else {
if (RegAlloc != &useDefaultRegisterAllocator &&
RegAlloc != &createFastRegisterAllocator)
report_fatal_error("Must use fast (default) register allocator for unoptimized regalloc.");
// Run post-ra passes.
// Insert prolog/epilog code. Eliminate abstract frame index references...
if (getOptLevel() != CodeGenOpt::None) {
// Prolog/Epilog inserter needs a TargetMachine to instantiate. But only
// do so if it hasn't been disabled, substituted, or overridden.
if (!isPassSubstitutedOrOverridden(&PrologEpilogCodeInserterID))
/// Add passes that optimize machine instructions after register allocation.
if (getOptLevel() != CodeGenOpt::None)
// Expand pseudo instructions before second scheduling pass.
// Run pre-sched2 passes.
if (EnableImplicitNullChecks)
// Second pass scheduler.
// Let Target optionally insert this pass by itself at some other
// point.
if (getOptLevel() != CodeGenOpt::None &&
!TM->targetSchedulesPostRAScheduling()) {
if (MISchedPostRA)
// GC
if (addGCPasses()) {
if (PrintGCInfo)
addPass(createGCInfoPrinter(dbgs()), false, false);
// Basic block placement.
if (getOptLevel() != CodeGenOpt::None)
if (TM->Options.EnableIPRA)
// Collect register usage information and produce a register mask of
// clobbered registers, to be used to optimize call sites.
addPass(&FuncletLayoutID, false);
addPass(&StackMapLivenessID, false);
addPass(&LiveDebugValuesID, false);
// Insert before XRay Instrumentation.
addPass(&FEntryInserterID, false);
addPass(&XRayInstrumentationID, false);
addPass(&PatchableFunctionID, false);
if (TM->Options.EnableMachineOutliner && getOptLevel() != CodeGenOpt::None &&
EnableMachineOutliner != NeverOutline) {
bool RunOnAllFunctions = (EnableMachineOutliner == AlwaysOutline);
bool AddOutliner = RunOnAllFunctions ||
if (AddOutliner)
// Add passes that directly emit MI after all other MI passes.
AddingMachinePasses = false;
/// Add passes that optimize machine instructions in SSA form.
void TargetPassConfig::addMachineSSAOptimization() {
// Pre-ra tail duplication.
// Optimize PHIs before DCE: removing dead PHI cycles may make more
// instructions dead.
addPass(&OptimizePHIsID, false);
// This pass merges large allocas. StackSlotColoring is a different pass
// which merges spill slots.
addPass(&StackColoringID, false);
// If the target requests it, assign local variables to stack slots relative
// to one another and simplify frame index references where possible.
addPass(&LocalStackSlotAllocationID, false);
// With optimization, dead code should already be eliminated. However
// there is one known exception: lowered code for arguments that are only
// used by tail calls, where the tail calls reuse the incoming stack
// arguments directly (see t11 in test/CodeGen/X86/sibcall.ll).
// Allow targets to insert passes that improve instruction level parallelism,
// like if-conversion. Such passes will typically need dominator trees and
// loop info, just like LICM and CSE below.
addPass(&EarlyMachineLICMID, false);
addPass(&MachineCSEID, false);
// Clean-up the dead code that may have been generated by peephole
// rewriting.
/// Register Allocation Pass Configuration
bool TargetPassConfig::getOptimizeRegAlloc() const {
switch (OptimizeRegAlloc) {
case cl::BOU_UNSET: return getOptLevel() != CodeGenOpt::None;
case cl::BOU_TRUE: return true;
case cl::BOU_FALSE: return false;
llvm_unreachable("Invalid optimize-regalloc state");
/// RegisterRegAlloc's global Registry tracks allocator registration.
MachinePassRegistry RegisterRegAlloc::Registry;
/// A dummy default pass factory indicates whether the register allocator is
/// overridden on the command line.
static llvm::once_flag InitializeDefaultRegisterAllocatorFlag;
static RegisterRegAlloc
"pick register allocator based on -O option",
static void initializeDefaultRegisterAllocatorOnce() {
RegisterRegAlloc::FunctionPassCtor Ctor = RegisterRegAlloc::getDefault();
if (!Ctor) {
Ctor = RegAlloc;
/// Instantiate the default register allocator pass for this target for either
/// the optimized or unoptimized allocation path. This will be added to the pass
/// manager by addFastRegAlloc in the unoptimized case or addOptimizedRegAlloc
/// in the optimized case.
/// A target that uses the standard regalloc pass order for fast or optimized
/// allocation may still override this for per-target regalloc
/// selection. But -regalloc=... always takes precedence.
FunctionPass *TargetPassConfig::createTargetRegisterAllocator(bool Optimized) {
if (Optimized)
return createGreedyRegisterAllocator();
return createFastRegisterAllocator();
/// Find and instantiate the register allocation pass requested by this target
/// at the current optimization level. Different register allocators are
/// defined as separate passes because they may require different analysis.
/// This helper ensures that the regalloc= option is always available,
/// even for targets that override the default allocator.
/// FIXME: When MachinePassRegistry register pass IDs instead of function ptrs,
/// this can be folded into addPass.
FunctionPass *TargetPassConfig::createRegAllocPass(bool Optimized) {
// Initialize the global default.
RegisterRegAlloc::FunctionPassCtor Ctor = RegisterRegAlloc::getDefault();
if (Ctor != useDefaultRegisterAllocator)
return Ctor();
// With no -regalloc= override, ask the target for a regalloc pass.
return createTargetRegisterAllocator(Optimized);
/// Return true if the default global register allocator is in use and
/// has not be overriden on the command line with '-regalloc=...'
bool TargetPassConfig::usingDefaultRegAlloc() const {
return RegAlloc.getNumOccurrences() == 0;
/// Add the minimum set of target-independent passes that are required for
/// register allocation. No coalescing or scheduling.
void TargetPassConfig::addFastRegAlloc(FunctionPass *RegAllocPass) {
addPass(&PHIEliminationID, false);
addPass(&TwoAddressInstructionPassID, false);
if (RegAllocPass)
/// Add standard target-independent passes that are tightly coupled with
/// optimized register allocation, including coalescing, machine instruction
/// scheduling, and register allocation itself.
void TargetPassConfig::addOptimizedRegAlloc(FunctionPass *RegAllocPass) {
addPass(&DetectDeadLanesID, false);
addPass(&ProcessImplicitDefsID, false);
// LiveVariables currently requires pure SSA form.
// FIXME: Once TwoAddressInstruction pass no longer uses kill flags,
// LiveVariables can be removed completely, and LiveIntervals can be directly
// computed. (We still either need to regenerate kill flags after regalloc, or
// preferably fix the scavenger to not depend on them).
addPass(&LiveVariablesID, false);
// Edge splitting is smarter with machine loop info.
addPass(&MachineLoopInfoID, false);
addPass(&PHIEliminationID, false);
// Eventually, we want to run LiveIntervals before PHI elimination.
if (EarlyLiveIntervals)
addPass(&LiveIntervalsID, false);
addPass(&TwoAddressInstructionPassID, false);
// The machine scheduler may accidentally create disconnected components
// when moving subregister definitions around, avoid this by splitting them to
// separate vregs before. Splitting can also improve reg. allocation quality.
// PreRA instruction scheduling.
if (RegAllocPass) {
// Add the selected register allocation pass.
// Allow targets to change the register assignments before rewriting.
// Finally rewrite virtual registers.
// Perform stack slot coloring and post-ra machine LICM.
// FIXME: Re-enable coloring with register when it's capable of adding
// kill markers.
// Copy propagate to forward register uses and try to eliminate COPYs that
// were not coalesced.
// Run post-ra machine LICM to hoist reloads / remats.
// FIXME: can this move into MachineLateOptimization?
/// Post RegAlloc Pass Configuration
/// Add passes that optimize machine instructions after register allocation.
void TargetPassConfig::addMachineLateOptimization() {
// Branch folding must be run after regalloc and prolog/epilog insertion.
// Tail duplication.
// Note that duplicating tail just increases code size and degrades
// performance for targets that require Structured Control Flow.
// In addition it can also make CFG irreducible. Thus we disable it.
if (!TM->requiresStructuredCFG())
// Copy propagation.
/// Add standard GC passes.
bool TargetPassConfig::addGCPasses() {
addPass(&GCMachineCodeAnalysisID, false);
return true;
/// Add standard basic block placement passes.
void TargetPassConfig::addBlockPlacement() {
if (addPass(&MachineBlockPlacementID)) {
// Run a separate pass to collect block placement statistics.
if (EnableBlockPlacementStats)
/// GlobalISel Configuration
bool TargetPassConfig::isGlobalISelAbortEnabled() const {
if (EnableGlobalISelAbort.getNumOccurrences() > 0)
return EnableGlobalISelAbort == 1;
// When no abort behaviour is specified, we don't abort if the target says
// that GISel is enabled.
return !TM->Options.EnableGlobalISel;
bool TargetPassConfig::reportDiagnosticWhenGlobalISelFallback() const {
return EnableGlobalISelAbort == 2;