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llvm-capstone/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
Alexey Zhikhartsev 02077da7e7 Add jump-threading optimization for deterministic finite automata 
The current JumpThreading pass does not jump thread loops since it can
result in irreducible control flow that harms other optimizations. This
prevents switch statements inside a loop from being optimized to use
unconditional branches.

This code pattern occurs in the core_state_transition function of
Coremark. The state machine can be implemented manually with goto
statements resulting in a large runtime improvement, and this transform
makes the switch implementation match the goto version in performance.

This patch specifically targets switch statements inside a loop that
have the opportunity to be threaded. Once it identifies an opportunity,
it creates new paths that branch directly to the correct code block.
For example, the left CFG could be transformed to the right CFG:

```
          sw.bb                        sw.bb
        /   |   \                    /   |   \
   case1  case2  case3          case1  case2  case3
        \   |   /                /       |       \
        latch.bb             latch.2  latch.3  latch.1
         br sw.bb              /         |         \
                           sw.bb.2     sw.bb.3     sw.bb.1
                            br case2    br case3    br case1
```

Co-author: Justin Kreiner @jkreiner
Co-author: Ehsan Amiri @amehsan

Reviewed By: SjoerdMeijer

Differential Revision: https://reviews.llvm.org/D99205
2021-07-27 14:34:04 -04:00

1327 lines
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//===- PassManagerBuilder.cpp - Build Standard 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
//
//===----------------------------------------------------------------------===//
//
// This file defines the PassManagerBuilder class, which is used to set up a
// "standard" optimization sequence suitable for languages like C and C++.
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/IPO/PassManagerBuilder.h"
#include "llvm-c/Transforms/PassManagerBuilder.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Analysis/BasicAliasAnalysis.h"
#include "llvm/Analysis/CFLAndersAliasAnalysis.h"
#include "llvm/Analysis/CFLSteensAliasAnalysis.h"
#include "llvm/Analysis/GlobalsModRef.h"
#include "llvm/Analysis/InlineCost.h"
#include "llvm/Analysis/Passes.h"
#include "llvm/Analysis/ScopedNoAliasAA.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/TypeBasedAliasAnalysis.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/LegacyPassManager.h"
#include "llvm/IR/Verifier.h"
#include "llvm/InitializePasses.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/ManagedStatic.h"
#include "llvm/Target/CGPassBuilderOption.h"
#include "llvm/Transforms/AggressiveInstCombine/AggressiveInstCombine.h"
#include "llvm/Transforms/IPO.h"
#include "llvm/Transforms/IPO/Attributor.h"
#include "llvm/Transforms/IPO/ForceFunctionAttrs.h"
#include "llvm/Transforms/IPO/FunctionAttrs.h"
#include "llvm/Transforms/IPO/InferFunctionAttrs.h"
#include "llvm/Transforms/InstCombine/InstCombine.h"
#include "llvm/Transforms/Instrumentation.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Scalar/GVN.h"
#include "llvm/Transforms/Scalar/InstSimplifyPass.h"
#include "llvm/Transforms/Scalar/LICM.h"
#include "llvm/Transforms/Scalar/LoopUnrollPass.h"
#include "llvm/Transforms/Scalar/SCCP.h"
#include "llvm/Transforms/Scalar/SimpleLoopUnswitch.h"
#include "llvm/Transforms/Utils.h"
#include "llvm/Transforms/Vectorize.h"
#include "llvm/Transforms/Vectorize/LoopVectorize.h"
#include "llvm/Transforms/Vectorize/SLPVectorizer.h"
#include "llvm/Transforms/Vectorize/VectorCombine.h"
using namespace llvm;
namespace llvm {
cl::opt<bool> RunPartialInlining("enable-partial-inlining", cl::init(false),
cl::Hidden, cl::ZeroOrMore,
cl::desc("Run Partial inlinining pass"));
static cl::opt<bool>
UseGVNAfterVectorization("use-gvn-after-vectorization",
cl::init(false), cl::Hidden,
cl::desc("Run GVN instead of Early CSE after vectorization passes"));
cl::opt<bool> ExtraVectorizerPasses(
"extra-vectorizer-passes", cl::init(false), cl::Hidden,
cl::desc("Run cleanup optimization passes after vectorization."));
static cl::opt<bool>
RunLoopRerolling("reroll-loops", cl::Hidden,
cl::desc("Run the loop rerolling pass"));
cl::opt<bool> RunNewGVN("enable-newgvn", cl::init(false), cl::Hidden,
cl::desc("Run the NewGVN pass"));
// Experimental option to use CFL-AA
static cl::opt<::CFLAAType>
UseCFLAA("use-cfl-aa", cl::init(::CFLAAType::None), cl::Hidden,
cl::desc("Enable the new, experimental CFL alias analysis"),
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")));
cl::opt<bool> EnableLoopInterchange(
"enable-loopinterchange", cl::init(false), cl::Hidden,
cl::desc("Enable the experimental LoopInterchange Pass"));
cl::opt<bool> EnableUnrollAndJam("enable-unroll-and-jam", cl::init(false),
cl::Hidden,
cl::desc("Enable Unroll And Jam Pass"));
cl::opt<bool> EnableLoopFlatten("enable-loop-flatten", cl::init(false),
cl::Hidden,
cl::desc("Enable the LoopFlatten Pass"));
cl::opt<bool> EnableDFAJumpThreading("enable-dfa-jump-thread",
cl::desc("Enable DFA jump threading."),
cl::init(false), cl::Hidden);
static cl::opt<bool>
EnablePrepareForThinLTO("prepare-for-thinlto", cl::init(false), cl::Hidden,
cl::desc("Enable preparation for ThinLTO."));
static cl::opt<bool>
EnablePerformThinLTO("perform-thinlto", cl::init(false), cl::Hidden,
cl::desc("Enable performing ThinLTO."));
cl::opt<bool> EnableHotColdSplit("hot-cold-split", cl::init(false),
cl::ZeroOrMore, cl::desc("Enable hot-cold splitting pass"));
cl::opt<bool> EnableIROutliner("ir-outliner", cl::init(false), cl::Hidden,
cl::desc("Enable ir outliner pass"));
static cl::opt<bool> UseLoopVersioningLICM(
"enable-loop-versioning-licm", cl::init(false), cl::Hidden,
cl::desc("Enable the experimental Loop Versioning LICM pass"));
cl::opt<bool>
DisablePreInliner("disable-preinline", cl::init(false), cl::Hidden,
cl::desc("Disable pre-instrumentation inliner"));
cl::opt<int> PreInlineThreshold(
"preinline-threshold", cl::Hidden, cl::init(75), cl::ZeroOrMore,
cl::desc("Control the amount of inlining in pre-instrumentation inliner "
"(default = 75)"));
cl::opt<bool>
EnableGVNHoist("enable-gvn-hoist", cl::init(false), cl::ZeroOrMore,
cl::desc("Enable the GVN hoisting pass (default = off)"));
static cl::opt<bool>
DisableLibCallsShrinkWrap("disable-libcalls-shrinkwrap", cl::init(false),
cl::Hidden,
cl::desc("Disable shrink-wrap library calls"));
static cl::opt<bool> EnableSimpleLoopUnswitch(
"enable-simple-loop-unswitch", cl::init(false), cl::Hidden,
cl::desc("Enable the simple loop unswitch pass. Also enables independent "
"cleanup passes integrated into the loop pass manager pipeline."));
cl::opt<bool>
EnableGVNSink("enable-gvn-sink", cl::init(false), cl::ZeroOrMore,
cl::desc("Enable the GVN sinking pass (default = off)"));
// This option is used in simplifying testing SampleFDO optimizations for
// profile loading.
cl::opt<bool>
EnableCHR("enable-chr", cl::init(true), cl::Hidden,
cl::desc("Enable control height reduction optimization (CHR)"));
cl::opt<bool> FlattenedProfileUsed(
"flattened-profile-used", cl::init(false), cl::Hidden,
cl::desc("Indicate the sample profile being used is flattened, i.e., "
"no inline hierachy exists in the profile. "));
cl::opt<bool> EnableOrderFileInstrumentation(
"enable-order-file-instrumentation", cl::init(false), cl::Hidden,
cl::desc("Enable order file instrumentation (default = off)"));
cl::opt<bool> EnableMatrix(
"enable-matrix", cl::init(false), cl::Hidden,
cl::desc("Enable lowering of the matrix intrinsics"));
cl::opt<bool> EnableConstraintElimination(
"enable-constraint-elimination", cl::init(false), cl::Hidden,
cl::desc(
"Enable pass to eliminate conditions based on linear constraints."));
cl::opt<bool> EnableFunctionSpecialization(
"enable-function-specialization", cl::init(false), cl::Hidden,
cl::desc("Enable Function Specialization pass"));
cl::opt<AttributorRunOption> AttributorRun(
"attributor-enable", cl::Hidden, cl::init(AttributorRunOption::NONE),
cl::desc("Enable the attributor inter-procedural deduction pass."),
cl::values(clEnumValN(AttributorRunOption::ALL, "all",
"enable all attributor runs"),
clEnumValN(AttributorRunOption::MODULE, "module",
"enable module-wide attributor runs"),
clEnumValN(AttributorRunOption::CGSCC, "cgscc",
"enable call graph SCC attributor runs"),
clEnumValN(AttributorRunOption::NONE, "none",
"disable attributor runs")));
extern cl::opt<bool> EnableKnowledgeRetention;
} // namespace llvm
PassManagerBuilder::PassManagerBuilder() {
OptLevel = 2;
SizeLevel = 0;
LibraryInfo = nullptr;
Inliner = nullptr;
DisableUnrollLoops = false;
SLPVectorize = false;
LoopVectorize = true;
LoopsInterleaved = true;
RerollLoops = RunLoopRerolling;
NewGVN = RunNewGVN;
LicmMssaOptCap = SetLicmMssaOptCap;
LicmMssaNoAccForPromotionCap = SetLicmMssaNoAccForPromotionCap;
DisableGVNLoadPRE = false;
ForgetAllSCEVInLoopUnroll = ForgetSCEVInLoopUnroll;
VerifyInput = false;
VerifyOutput = false;
MergeFunctions = false;
PrepareForLTO = false;
EnablePGOInstrGen = false;
EnablePGOCSInstrGen = false;
EnablePGOCSInstrUse = false;
PGOInstrGen = "";
PGOInstrUse = "";
PGOSampleUse = "";
PrepareForThinLTO = EnablePrepareForThinLTO;
PerformThinLTO = EnablePerformThinLTO;
DivergentTarget = false;
CallGraphProfile = true;
}
PassManagerBuilder::~PassManagerBuilder() {
delete LibraryInfo;
delete Inliner;
}
/// Set of global extensions, automatically added as part of the standard set.
static ManagedStatic<
SmallVector<std::tuple<PassManagerBuilder::ExtensionPointTy,
PassManagerBuilder::ExtensionFn,
PassManagerBuilder::GlobalExtensionID>,
8>>
GlobalExtensions;
static PassManagerBuilder::GlobalExtensionID GlobalExtensionsCounter;
/// Check if GlobalExtensions is constructed and not empty.
/// Since GlobalExtensions is a managed static, calling 'empty()' will trigger
/// the construction of the object.
static bool GlobalExtensionsNotEmpty() {
return GlobalExtensions.isConstructed() && !GlobalExtensions->empty();
}
PassManagerBuilder::GlobalExtensionID
PassManagerBuilder::addGlobalExtension(PassManagerBuilder::ExtensionPointTy Ty,
PassManagerBuilder::ExtensionFn Fn) {
auto ExtensionID = GlobalExtensionsCounter++;
GlobalExtensions->push_back(std::make_tuple(Ty, std::move(Fn), ExtensionID));
return ExtensionID;
}
void PassManagerBuilder::removeGlobalExtension(
PassManagerBuilder::GlobalExtensionID ExtensionID) {
// RegisterStandardPasses may try to call this function after GlobalExtensions
// has already been destroyed; doing so should not generate an error.
if (!GlobalExtensions.isConstructed())
return;
auto GlobalExtension =
llvm::find_if(*GlobalExtensions, [ExtensionID](const auto &elem) {
return std::get<2>(elem) == ExtensionID;
});
assert(GlobalExtension != GlobalExtensions->end() &&
"The extension ID to be removed should always be valid.");
GlobalExtensions->erase(GlobalExtension);
}
void PassManagerBuilder::addExtension(ExtensionPointTy Ty, ExtensionFn Fn) {
Extensions.push_back(std::make_pair(Ty, std::move(Fn)));
}
void PassManagerBuilder::addExtensionsToPM(ExtensionPointTy ETy,
legacy::PassManagerBase &PM) const {
if (GlobalExtensionsNotEmpty()) {
for (auto &Ext : *GlobalExtensions) {
if (std::get<0>(Ext) == ETy)
std::get<1>(Ext)(*this, PM);
}
}
for (unsigned i = 0, e = Extensions.size(); i != e; ++i)
if (Extensions[i].first == ETy)
Extensions[i].second(*this, PM);
}
void PassManagerBuilder::addInitialAliasAnalysisPasses(
legacy::PassManagerBase &PM) const {
switch (UseCFLAA) {
case ::CFLAAType::Steensgaard:
PM.add(createCFLSteensAAWrapperPass());
break;
case ::CFLAAType::Andersen:
PM.add(createCFLAndersAAWrapperPass());
break;
case ::CFLAAType::Both:
PM.add(createCFLSteensAAWrapperPass());
PM.add(createCFLAndersAAWrapperPass());
break;
default:
break;
}
// Add TypeBasedAliasAnalysis before BasicAliasAnalysis so that
// BasicAliasAnalysis wins if they disagree. This is intended to help
// support "obvious" type-punning idioms.
PM.add(createTypeBasedAAWrapperPass());
PM.add(createScopedNoAliasAAWrapperPass());
}
void PassManagerBuilder::populateFunctionPassManager(
legacy::FunctionPassManager &FPM) {
addExtensionsToPM(EP_EarlyAsPossible, FPM);
// Add LibraryInfo if we have some.
if (LibraryInfo)
FPM.add(new TargetLibraryInfoWrapperPass(*LibraryInfo));
// The backends do not handle matrix intrinsics currently.
// Make sure they are also lowered in O0.
// FIXME: A lightweight version of the pass should run in the backend
// pipeline on demand.
if (EnableMatrix && OptLevel == 0)
FPM.add(createLowerMatrixIntrinsicsMinimalPass());
if (OptLevel == 0) return;
addInitialAliasAnalysisPasses(FPM);
// Lower llvm.expect to metadata before attempting transforms.
// Compare/branch metadata may alter the behavior of passes like SimplifyCFG.
FPM.add(createLowerExpectIntrinsicPass());
FPM.add(createCFGSimplificationPass());
FPM.add(createSROAPass());
FPM.add(createEarlyCSEPass());
}
// Do PGO instrumentation generation or use pass as the option specified.
void PassManagerBuilder::addPGOInstrPasses(legacy::PassManagerBase &MPM,
bool IsCS = false) {
if (IsCS) {
if (!EnablePGOCSInstrGen && !EnablePGOCSInstrUse)
return;
} else if (!EnablePGOInstrGen && PGOInstrUse.empty() && PGOSampleUse.empty())
return;
// Perform the preinline and cleanup passes for O1 and above.
// We will not do this inline for context sensitive PGO (when IsCS is true).
if (OptLevel > 0 && !DisablePreInliner && PGOSampleUse.empty() && !IsCS) {
// Create preinline pass. We construct an InlineParams object and specify
// the threshold here to avoid the command line options of the regular
// inliner to influence pre-inlining. The only fields of InlineParams we
// care about are DefaultThreshold and HintThreshold.
InlineParams IP;
IP.DefaultThreshold = PreInlineThreshold;
// FIXME: The hint threshold has the same value used by the regular inliner
// when not optimzing for size. This should probably be lowered after
// performance testing.
// Use PreInlineThreshold for both -Os and -Oz. Not running preinliner makes
// the instrumented binary unusably large. Even if PreInlineThreshold is not
// correct thresold for -Oz, it is better than not running preinliner.
IP.HintThreshold = SizeLevel > 0 ? PreInlineThreshold : 325;
MPM.add(createFunctionInliningPass(IP));
MPM.add(createSROAPass());
MPM.add(createEarlyCSEPass()); // Catch trivial redundancies
MPM.add(createCFGSimplificationPass()); // Merge & remove BBs
MPM.add(createInstructionCombiningPass()); // Combine silly seq's
addExtensionsToPM(EP_Peephole, MPM);
}
if ((EnablePGOInstrGen && !IsCS) || (EnablePGOCSInstrGen && IsCS)) {
MPM.add(createPGOInstrumentationGenLegacyPass(IsCS));
// Add the profile lowering pass.
InstrProfOptions Options;
if (!PGOInstrGen.empty())
Options.InstrProfileOutput = PGOInstrGen;
Options.DoCounterPromotion = true;
Options.UseBFIInPromotion = IsCS;
MPM.add(createLoopRotatePass());
MPM.add(createInstrProfilingLegacyPass(Options, IsCS));
}
if (!PGOInstrUse.empty())
MPM.add(createPGOInstrumentationUseLegacyPass(PGOInstrUse, IsCS));
// Indirect call promotion that promotes intra-module targets only.
// For ThinLTO this is done earlier due to interactions with globalopt
// for imported functions. We don't run this at -O0.
if (OptLevel > 0 && !IsCS)
MPM.add(
createPGOIndirectCallPromotionLegacyPass(false, !PGOSampleUse.empty()));
}
void PassManagerBuilder::addFunctionSimplificationPasses(
legacy::PassManagerBase &MPM) {
// Start of function pass.
// Break up aggregate allocas, using SSAUpdater.
assert(OptLevel >= 1 && "Calling function optimizer with no optimization level!");
MPM.add(createSROAPass());
MPM.add(createEarlyCSEPass(true /* Enable mem-ssa. */)); // Catch trivial redundancies
if (EnableKnowledgeRetention)
MPM.add(createAssumeSimplifyPass());
if (OptLevel > 1) {
if (EnableGVNHoist)
MPM.add(createGVNHoistPass());
if (EnableGVNSink) {
MPM.add(createGVNSinkPass());
MPM.add(createCFGSimplificationPass());
}
}
if (EnableConstraintElimination)
MPM.add(createConstraintEliminationPass());
if (OptLevel > 1) {
// Speculative execution if the target has divergent branches; otherwise nop.
MPM.add(createSpeculativeExecutionIfHasBranchDivergencePass());
MPM.add(createJumpThreadingPass()); // Thread jumps.
MPM.add(createCorrelatedValuePropagationPass()); // Propagate conditionals
}
MPM.add(createCFGSimplificationPass()); // Merge & remove BBs
// Combine silly seq's
if (OptLevel > 2)
MPM.add(createAggressiveInstCombinerPass());
MPM.add(createInstructionCombiningPass());
if (SizeLevel == 0 && !DisableLibCallsShrinkWrap)
MPM.add(createLibCallsShrinkWrapPass());
addExtensionsToPM(EP_Peephole, MPM);
// Optimize memory intrinsic calls based on the profiled size information.
if (SizeLevel == 0)
MPM.add(createPGOMemOPSizeOptLegacyPass());
// TODO: Investigate the cost/benefit of tail call elimination on debugging.
if (OptLevel > 1)
MPM.add(createTailCallEliminationPass()); // Eliminate tail calls
MPM.add(createCFGSimplificationPass()); // Merge & remove BBs
MPM.add(createReassociatePass()); // Reassociate expressions
// Begin the loop pass pipeline.
if (EnableSimpleLoopUnswitch) {
// The simple loop unswitch pass relies on separate cleanup passes. Schedule
// them first so when we re-process a loop they run before other loop
// passes.
MPM.add(createLoopInstSimplifyPass());
MPM.add(createLoopSimplifyCFGPass());
}
// Try to remove as much code from the loop header as possible,
// to reduce amount of IR that will have to be duplicated.
// TODO: Investigate promotion cap for O1.
MPM.add(createLICMPass(LicmMssaOptCap, LicmMssaNoAccForPromotionCap));
// Rotate Loop - disable header duplication at -Oz
MPM.add(createLoopRotatePass(SizeLevel == 2 ? 0 : -1, PrepareForLTO));
// TODO: Investigate promotion cap for O1.
MPM.add(createLICMPass(LicmMssaOptCap, LicmMssaNoAccForPromotionCap));
if (EnableSimpleLoopUnswitch)
MPM.add(createSimpleLoopUnswitchLegacyPass());
else
MPM.add(createLoopUnswitchPass(SizeLevel || OptLevel < 3, DivergentTarget));
// FIXME: We break the loop pass pipeline here in order to do full
// simplifycfg. Eventually loop-simplifycfg should be enhanced to replace the
// need for this.
MPM.add(createCFGSimplificationPass());
MPM.add(createInstructionCombiningPass());
// We resume loop passes creating a second loop pipeline here.
if (EnableLoopFlatten) {
MPM.add(createLoopFlattenPass()); // Flatten loops
MPM.add(createLoopSimplifyCFGPass());
}
MPM.add(createLoopIdiomPass()); // Recognize idioms like memset.
MPM.add(createIndVarSimplifyPass()); // Canonicalize indvars
addExtensionsToPM(EP_LateLoopOptimizations, MPM);
MPM.add(createLoopDeletionPass()); // Delete dead loops
if (EnableLoopInterchange)
MPM.add(createLoopInterchangePass()); // Interchange loops
// Unroll small loops and perform peeling.
MPM.add(createSimpleLoopUnrollPass(OptLevel, DisableUnrollLoops,
ForgetAllSCEVInLoopUnroll));
addExtensionsToPM(EP_LoopOptimizerEnd, MPM);
// This ends the loop pass pipelines.
// Break up allocas that may now be splittable after loop unrolling.
MPM.add(createSROAPass());
if (OptLevel > 1) {
MPM.add(createMergedLoadStoreMotionPass()); // Merge ld/st in diamonds
MPM.add(NewGVN ? createNewGVNPass()
: createGVNPass(DisableGVNLoadPRE)); // Remove redundancies
}
MPM.add(createSCCPPass()); // Constant prop with SCCP
if (EnableConstraintElimination)
MPM.add(createConstraintEliminationPass());
// Delete dead bit computations (instcombine runs after to fold away the dead
// computations, and then ADCE will run later to exploit any new DCE
// opportunities that creates).
MPM.add(createBitTrackingDCEPass()); // Delete dead bit computations
// Run instcombine after redundancy elimination to exploit opportunities
// opened up by them.
MPM.add(createInstructionCombiningPass());
addExtensionsToPM(EP_Peephole, MPM);
if (OptLevel > 1) {
if (EnableDFAJumpThreading && SizeLevel == 0)
MPM.add(createDFAJumpThreadingPass());
MPM.add(createJumpThreadingPass()); // Thread jumps
MPM.add(createCorrelatedValuePropagationPass());
}
MPM.add(createAggressiveDCEPass()); // Delete dead instructions
MPM.add(createMemCpyOptPass()); // Remove memcpy / form memset
// TODO: Investigate if this is too expensive at O1.
if (OptLevel > 1) {
MPM.add(createDeadStoreEliminationPass()); // Delete dead stores
MPM.add(createLICMPass(LicmMssaOptCap, LicmMssaNoAccForPromotionCap));
}
addExtensionsToPM(EP_ScalarOptimizerLate, MPM);
if (RerollLoops)
MPM.add(createLoopRerollPass());
// Merge & remove BBs and sink & hoist common instructions.
MPM.add(createCFGSimplificationPass(
SimplifyCFGOptions().hoistCommonInsts(true).sinkCommonInsts(true)));
// Clean up after everything.
MPM.add(createInstructionCombiningPass());
addExtensionsToPM(EP_Peephole, MPM);
if (EnableCHR && OptLevel >= 3 &&
(!PGOInstrUse.empty() || !PGOSampleUse.empty() || EnablePGOCSInstrGen))
MPM.add(createControlHeightReductionLegacyPass());
}
/// FIXME: Should LTO cause any differences to this set of passes?
void PassManagerBuilder::addVectorPasses(legacy::PassManagerBase &PM,
bool IsFullLTO) {
PM.add(createLoopVectorizePass(!LoopsInterleaved, !LoopVectorize));
if (IsFullLTO) {
// The vectorizer may have significantly shortened a loop body; unroll
// again. Unroll small loops to hide loop backedge latency and saturate any
// parallel execution resources of an out-of-order processor. We also then
// need to clean up redundancies and loop invariant code.
// FIXME: It would be really good to use a loop-integrated instruction
// combiner for cleanup here so that the unrolling and LICM can be pipelined
// across the loop nests.
// We do UnrollAndJam in a separate LPM to ensure it happens before unroll
if (EnableUnrollAndJam && !DisableUnrollLoops)
PM.add(createLoopUnrollAndJamPass(OptLevel));
PM.add(createLoopUnrollPass(OptLevel, DisableUnrollLoops,
ForgetAllSCEVInLoopUnroll));
PM.add(createWarnMissedTransformationsPass());
}
if (!IsFullLTO) {
// Eliminate loads by forwarding stores from the previous iteration to loads
// of the current iteration.
PM.add(createLoopLoadEliminationPass());
}
// Cleanup after the loop optimization passes.
PM.add(createInstructionCombiningPass());
if (OptLevel > 1 && ExtraVectorizerPasses) {
// At higher optimization levels, try to clean up any runtime overlap and
// alignment checks inserted by the vectorizer. We want to track correlated
// runtime checks for two inner loops in the same outer loop, fold any
// common computations, hoist loop-invariant aspects out of any outer loop,
// and unswitch the runtime checks if possible. Once hoisted, we may have
// dead (or speculatable) control flows or more combining opportunities.
PM.add(createEarlyCSEPass());
PM.add(createCorrelatedValuePropagationPass());
PM.add(createInstructionCombiningPass());
PM.add(createLICMPass(LicmMssaOptCap, LicmMssaNoAccForPromotionCap));
PM.add(createLoopUnswitchPass(SizeLevel || OptLevel < 3, DivergentTarget));
PM.add(createCFGSimplificationPass());
PM.add(createInstructionCombiningPass());
}
// Now that we've formed fast to execute loop structures, we do further
// optimizations. These are run afterward as they might block doing complex
// analyses and transforms such as what are needed for loop vectorization.
// Cleanup after loop vectorization, etc. Simplification passes like CVP and
// GVN, loop transforms, and others have already run, so it's now better to
// convert to more optimized IR using more aggressive simplify CFG options.
// The extra sinking transform can create larger basic blocks, so do this
// before SLP vectorization.
PM.add(createCFGSimplificationPass(SimplifyCFGOptions()
.forwardSwitchCondToPhi(true)
.convertSwitchToLookupTable(true)
.needCanonicalLoops(false)
.hoistCommonInsts(true)
.sinkCommonInsts(true)));
if (IsFullLTO) {
PM.add(createSCCPPass()); // Propagate exposed constants
PM.add(createInstructionCombiningPass()); // Clean up again
PM.add(createBitTrackingDCEPass());
}
// Optimize parallel scalar instruction chains into SIMD instructions.
if (SLPVectorize) {
PM.add(createSLPVectorizerPass());
if (OptLevel > 1 && ExtraVectorizerPasses)
PM.add(createEarlyCSEPass());
}
// Enhance/cleanup vector code.
PM.add(createVectorCombinePass());
if (!IsFullLTO) {
addExtensionsToPM(EP_Peephole, PM);
PM.add(createInstructionCombiningPass());
if (EnableUnrollAndJam && !DisableUnrollLoops) {
// Unroll and Jam. We do this before unroll but need to be in a separate
// loop pass manager in order for the outer loop to be processed by
// unroll and jam before the inner loop is unrolled.
PM.add(createLoopUnrollAndJamPass(OptLevel));
}
// Unroll small loops
PM.add(createLoopUnrollPass(OptLevel, DisableUnrollLoops,
ForgetAllSCEVInLoopUnroll));
if (!DisableUnrollLoops) {
// LoopUnroll may generate some redundency to cleanup.
PM.add(createInstructionCombiningPass());
// Runtime unrolling will introduce runtime check in loop prologue. If the
// unrolled loop is a inner loop, then the prologue will be inside the
// outer loop. LICM pass can help to promote the runtime check out if the
// checked value is loop invariant.
PM.add(createLICMPass(LicmMssaOptCap, LicmMssaNoAccForPromotionCap));
}
PM.add(createWarnMissedTransformationsPass());
}
// After vectorization and unrolling, assume intrinsics may tell us more
// about pointer alignments.
PM.add(createAlignmentFromAssumptionsPass());
if (IsFullLTO)
PM.add(createInstructionCombiningPass());
}
void PassManagerBuilder::populateModulePassManager(
legacy::PassManagerBase &MPM) {
// Whether this is a default or *LTO pre-link pipeline. The FullLTO post-link
// is handled separately, so just check this is not the ThinLTO post-link.
bool DefaultOrPreLinkPipeline = !PerformThinLTO;
MPM.add(createAnnotation2MetadataLegacyPass());
if (!PGOSampleUse.empty()) {
MPM.add(createPruneEHPass());
// In ThinLTO mode, when flattened profile is used, all the available
// profile information will be annotated in PreLink phase so there is
// no need to load the profile again in PostLink.
if (!(FlattenedProfileUsed && PerformThinLTO))
MPM.add(createSampleProfileLoaderPass(PGOSampleUse));
}
// Allow forcing function attributes as a debugging and tuning aid.
MPM.add(createForceFunctionAttrsLegacyPass());
// If all optimizations are disabled, just run the always-inline pass and,
// if enabled, the function merging pass.
if (OptLevel == 0) {
addPGOInstrPasses(MPM);
if (Inliner) {
MPM.add(Inliner);
Inliner = nullptr;
}
// FIXME: The BarrierNoopPass is a HACK! The inliner pass above implicitly
// creates a CGSCC pass manager, but we don't want to add extensions into
// that pass manager. To prevent this we insert a no-op module pass to reset
// the pass manager to get the same behavior as EP_OptimizerLast in non-O0
// builds. The function merging pass is
if (MergeFunctions)
MPM.add(createMergeFunctionsPass());
else if (GlobalExtensionsNotEmpty() || !Extensions.empty())
MPM.add(createBarrierNoopPass());
if (PerformThinLTO) {
MPM.add(createLowerTypeTestsPass(nullptr, nullptr, true));
// Drop available_externally and unreferenced globals. This is necessary
// with ThinLTO in order to avoid leaving undefined references to dead
// globals in the object file.
MPM.add(createEliminateAvailableExternallyPass());
MPM.add(createGlobalDCEPass());
}
addExtensionsToPM(EP_EnabledOnOptLevel0, MPM);
if (PrepareForLTO || PrepareForThinLTO) {
MPM.add(createCanonicalizeAliasesPass());
// Rename anon globals to be able to export them in the summary.
// This has to be done after we add the extensions to the pass manager
// as there could be passes (e.g. Adddress sanitizer) which introduce
// new unnamed globals.
MPM.add(createNameAnonGlobalPass());
}
MPM.add(createAnnotationRemarksLegacyPass());
return;
}
// Add LibraryInfo if we have some.
if (LibraryInfo)
MPM.add(new TargetLibraryInfoWrapperPass(*LibraryInfo));
addInitialAliasAnalysisPasses(MPM);
// For ThinLTO there are two passes of indirect call promotion. The
// first is during the compile phase when PerformThinLTO=false and
// intra-module indirect call targets are promoted. The second is during
// the ThinLTO backend when PerformThinLTO=true, when we promote imported
// inter-module indirect calls. For that we perform indirect call promotion
// earlier in the pass pipeline, here before globalopt. Otherwise imported
// available_externally functions look unreferenced and are removed.
if (PerformThinLTO) {
MPM.add(createPGOIndirectCallPromotionLegacyPass(/*InLTO = */ true,
!PGOSampleUse.empty()));
MPM.add(createLowerTypeTestsPass(nullptr, nullptr, true));
}
// For SamplePGO in ThinLTO compile phase, we do not want to unroll loops
// as it will change the CFG too much to make the 2nd profile annotation
// in backend more difficult.
bool PrepareForThinLTOUsingPGOSampleProfile =
PrepareForThinLTO && !PGOSampleUse.empty();
if (PrepareForThinLTOUsingPGOSampleProfile)
DisableUnrollLoops = true;
// Infer attributes about declarations if possible.
MPM.add(createInferFunctionAttrsLegacyPass());
// Infer attributes on declarations, call sites, arguments, etc.
if (AttributorRun & AttributorRunOption::MODULE)
MPM.add(createAttributorLegacyPass());
addExtensionsToPM(EP_ModuleOptimizerEarly, MPM);
if (OptLevel > 2)
MPM.add(createCallSiteSplittingPass());
// Propage constant function arguments by specializing the functions.
if (OptLevel > 2 && EnableFunctionSpecialization)
MPM.add(createFunctionSpecializationPass());
MPM.add(createIPSCCPPass()); // IP SCCP
MPM.add(createCalledValuePropagationPass());
MPM.add(createGlobalOptimizerPass()); // Optimize out global vars
// Promote any localized global vars.
MPM.add(createPromoteMemoryToRegisterPass());
MPM.add(createDeadArgEliminationPass()); // Dead argument elimination
MPM.add(createInstructionCombiningPass()); // Clean up after IPCP & DAE
addExtensionsToPM(EP_Peephole, MPM);
MPM.add(createCFGSimplificationPass()); // Clean up after IPCP & DAE
// For SamplePGO in ThinLTO compile phase, we do not want to do indirect
// call promotion as it will change the CFG too much to make the 2nd
// profile annotation in backend more difficult.
// PGO instrumentation is added during the compile phase for ThinLTO, do
// not run it a second time
if (DefaultOrPreLinkPipeline && !PrepareForThinLTOUsingPGOSampleProfile)
addPGOInstrPasses(MPM);
// Create profile COMDAT variables. Lld linker wants to see all variables
// before the LTO/ThinLTO link since it needs to resolve symbols/comdats.
if (!PerformThinLTO && EnablePGOCSInstrGen)
MPM.add(createPGOInstrumentationGenCreateVarLegacyPass(PGOInstrGen));
// We add a module alias analysis pass here. In part due to bugs in the
// analysis infrastructure this "works" in that the analysis stays alive
// for the entire SCC pass run below.
MPM.add(createGlobalsAAWrapperPass());
// Start of CallGraph SCC passes.
MPM.add(createPruneEHPass()); // Remove dead EH info
bool RunInliner = false;
if (Inliner) {
MPM.add(Inliner);
Inliner = nullptr;
RunInliner = true;
}
// Infer attributes on declarations, call sites, arguments, etc. for an SCC.
if (AttributorRun & AttributorRunOption::CGSCC)
MPM.add(createAttributorCGSCCLegacyPass());
// Try to perform OpenMP specific optimizations. This is a (quick!) no-op if
// there are no OpenMP runtime calls present in the module.
if (OptLevel > 1)
MPM.add(createOpenMPOptCGSCCLegacyPass());
MPM.add(createPostOrderFunctionAttrsLegacyPass());
if (OptLevel > 2)
MPM.add(createArgumentPromotionPass()); // Scalarize uninlined fn args
addExtensionsToPM(EP_CGSCCOptimizerLate, MPM);
addFunctionSimplificationPasses(MPM);
// FIXME: This is a HACK! The inliner pass above implicitly creates a CGSCC
// pass manager that we are specifically trying to avoid. To prevent this
// we must insert a no-op module pass to reset the pass manager.
MPM.add(createBarrierNoopPass());
if (RunPartialInlining)
MPM.add(createPartialInliningPass());
if (OptLevel > 1 && !PrepareForLTO && !PrepareForThinLTO)
// Remove avail extern fns and globals definitions if we aren't
// compiling an object file for later LTO. For LTO we want to preserve
// these so they are eligible for inlining at link-time. Note if they
// are unreferenced they will be removed by GlobalDCE later, so
// this only impacts referenced available externally globals.
// Eventually they will be suppressed during codegen, but eliminating
// here enables more opportunity for GlobalDCE as it may make
// globals referenced by available external functions dead
// and saves running remaining passes on the eliminated functions.
MPM.add(createEliminateAvailableExternallyPass());
// CSFDO instrumentation and use pass. Don't invoke this for Prepare pass
// for LTO and ThinLTO -- The actual pass will be called after all inlines
// are performed.
// Need to do this after COMDAT variables have been eliminated,
// (i.e. after EliminateAvailableExternallyPass).
if (!(PrepareForLTO || PrepareForThinLTO))
addPGOInstrPasses(MPM, /* IsCS */ true);
if (EnableOrderFileInstrumentation)
MPM.add(createInstrOrderFilePass());
MPM.add(createReversePostOrderFunctionAttrsPass());
// The inliner performs some kind of dead code elimination as it goes,
// but there are cases that are not really caught by it. We might
// at some point consider teaching the inliner about them, but it
// is OK for now to run GlobalOpt + GlobalDCE in tandem as their
// benefits generally outweight the cost, making the whole pipeline
// faster.
if (RunInliner) {
MPM.add(createGlobalOptimizerPass());
MPM.add(createGlobalDCEPass());
}
// If we are planning to perform ThinLTO later, let's not bloat the code with
// unrolling/vectorization/... now. We'll first run the inliner + CGSCC passes
// during ThinLTO and perform the rest of the optimizations afterward.
if (PrepareForThinLTO) {
// Ensure we perform any last passes, but do so before renaming anonymous
// globals in case the passes add any.
addExtensionsToPM(EP_OptimizerLast, MPM);
MPM.add(createCanonicalizeAliasesPass());
// Rename anon globals to be able to export them in the summary.
MPM.add(createNameAnonGlobalPass());
return;
}
if (PerformThinLTO)
// Optimize globals now when performing ThinLTO, this enables more
// optimizations later.
MPM.add(createGlobalOptimizerPass());
// Scheduling LoopVersioningLICM when inlining is over, because after that
// we may see more accurate aliasing. Reason to run this late is that too
// early versioning may prevent further inlining due to increase of code
// size. By placing it just after inlining other optimizations which runs
// later might get benefit of no-alias assumption in clone loop.
if (UseLoopVersioningLICM) {
MPM.add(createLoopVersioningLICMPass()); // Do LoopVersioningLICM
MPM.add(createLICMPass(LicmMssaOptCap, LicmMssaNoAccForPromotionCap));
}
// We add a fresh GlobalsModRef run at this point. This is particularly
// useful as the above will have inlined, DCE'ed, and function-attr
// propagated everything. We should at this point have a reasonably minimal
// and richly annotated call graph. By computing aliasing and mod/ref
// information for all local globals here, the late loop passes and notably
// the vectorizer will be able to use them to help recognize vectorizable
// memory operations.
//
// Note that this relies on a bug in the pass manager which preserves
// a module analysis into a function pass pipeline (and throughout it) so
// long as the first function pass doesn't invalidate the module analysis.
// Thus both Float2Int and LoopRotate have to preserve AliasAnalysis for
// this to work. Fortunately, it is trivial to preserve AliasAnalysis
// (doing nothing preserves it as it is required to be conservatively
// correct in the face of IR changes).
MPM.add(createGlobalsAAWrapperPass());
MPM.add(createFloat2IntPass());
MPM.add(createLowerConstantIntrinsicsPass());
if (EnableMatrix) {
MPM.add(createLowerMatrixIntrinsicsPass());
// CSE the pointer arithmetic of the column vectors. This allows alias
// analysis to establish no-aliasing between loads and stores of different
// columns of the same matrix.
MPM.add(createEarlyCSEPass(false));
}
addExtensionsToPM(EP_VectorizerStart, MPM);
// Re-rotate loops in all our loop nests. These may have fallout out of
// rotated form due to GVN or other transformations, and the vectorizer relies
// on the rotated form. Disable header duplication at -Oz.
MPM.add(createLoopRotatePass(SizeLevel == 2 ? 0 : -1, PrepareForLTO));
// Distribute loops to allow partial vectorization. I.e. isolate dependences
// into separate loop that would otherwise inhibit vectorization. This is
// currently only performed for loops marked with the metadata
// llvm.loop.distribute=true or when -enable-loop-distribute is specified.
MPM.add(createLoopDistributePass());
addVectorPasses(MPM, /* IsFullLTO */ false);
// FIXME: We shouldn't bother with this anymore.
MPM.add(createStripDeadPrototypesPass()); // Get rid of dead prototypes
// GlobalOpt already deletes dead functions and globals, at -O2 try a
// late pass of GlobalDCE. It is capable of deleting dead cycles.
if (OptLevel > 1) {
MPM.add(createGlobalDCEPass()); // Remove dead fns and globals.
MPM.add(createConstantMergePass()); // Merge dup global constants
}
// See comment in the new PM for justification of scheduling splitting at
// this stage (\ref buildModuleSimplificationPipeline).
if (EnableHotColdSplit && !(PrepareForLTO || PrepareForThinLTO))
MPM.add(createHotColdSplittingPass());
if (EnableIROutliner)
MPM.add(createIROutlinerPass());
if (MergeFunctions)
MPM.add(createMergeFunctionsPass());
// Add Module flag "CG Profile" based on Branch Frequency Information.
if (CallGraphProfile)
MPM.add(createCGProfileLegacyPass());
// LoopSink pass sinks instructions hoisted by LICM, which serves as a
// canonicalization pass that enables other optimizations. As a result,
// LoopSink pass needs to be a very late IR pass to avoid undoing LICM
// result too early.
MPM.add(createLoopSinkPass());
// Get rid of LCSSA nodes.
MPM.add(createInstSimplifyLegacyPass());
// This hoists/decomposes div/rem ops. It should run after other sink/hoist
// passes to avoid re-sinking, but before SimplifyCFG because it can allow
// flattening of blocks.
MPM.add(createDivRemPairsPass());
// LoopSink (and other loop passes since the last simplifyCFG) might have
// resulted in single-entry-single-exit or empty blocks. Clean up the CFG.
MPM.add(createCFGSimplificationPass());
addExtensionsToPM(EP_OptimizerLast, MPM);
if (PrepareForLTO) {
MPM.add(createCanonicalizeAliasesPass());
// Rename anon globals to be able to handle them in the summary
MPM.add(createNameAnonGlobalPass());
}
MPM.add(createAnnotationRemarksLegacyPass());
}
void PassManagerBuilder::addLTOOptimizationPasses(legacy::PassManagerBase &PM) {
// Load sample profile before running the LTO optimization pipeline.
if (!PGOSampleUse.empty()) {
PM.add(createPruneEHPass());
PM.add(createSampleProfileLoaderPass(PGOSampleUse));
}
// Remove unused virtual tables to improve the quality of code generated by
// whole-program devirtualization and bitset lowering.
PM.add(createGlobalDCEPass());
// Provide AliasAnalysis services for optimizations.
addInitialAliasAnalysisPasses(PM);
// Allow forcing function attributes as a debugging and tuning aid.
PM.add(createForceFunctionAttrsLegacyPass());
// Infer attributes about declarations if possible.
PM.add(createInferFunctionAttrsLegacyPass());
if (OptLevel > 1) {
// Split call-site with more constrained arguments.
PM.add(createCallSiteSplittingPass());
// Indirect call promotion. This should promote all the targets that are
// left by the earlier promotion pass that promotes intra-module targets.
// This two-step promotion is to save the compile time. For LTO, it should
// produce the same result as if we only do promotion here.
PM.add(
createPGOIndirectCallPromotionLegacyPass(true, !PGOSampleUse.empty()));
// Propage constant function arguments by specializing the functions.
if (EnableFunctionSpecialization)
PM.add(createFunctionSpecializationPass());
// Propagate constants at call sites into the functions they call. This
// opens opportunities for globalopt (and inlining) by substituting function
// pointers passed as arguments to direct uses of functions.
PM.add(createIPSCCPPass());
// Attach metadata to indirect call sites indicating the set of functions
// they may target at run-time. This should follow IPSCCP.
PM.add(createCalledValuePropagationPass());
// Infer attributes on declarations, call sites, arguments, etc.
if (AttributorRun & AttributorRunOption::MODULE)
PM.add(createAttributorLegacyPass());
}
// Infer attributes about definitions. The readnone attribute in particular is
// required for virtual constant propagation.
PM.add(createPostOrderFunctionAttrsLegacyPass());
PM.add(createReversePostOrderFunctionAttrsPass());
// Split globals using inrange annotations on GEP indices. This can help
// improve the quality of generated code when virtual constant propagation or
// control flow integrity are enabled.
PM.add(createGlobalSplitPass());
// Apply whole-program devirtualization and virtual constant propagation.
PM.add(createWholeProgramDevirtPass(ExportSummary, nullptr));
// That's all we need at opt level 1.
if (OptLevel == 1)
return;
// Now that we internalized some globals, see if we can hack on them!
PM.add(createGlobalOptimizerPass());
// Promote any localized global vars.
PM.add(createPromoteMemoryToRegisterPass());
// Linking modules together can lead to duplicated global constants, only
// keep one copy of each constant.
PM.add(createConstantMergePass());
// Remove unused arguments from functions.
PM.add(createDeadArgEliminationPass());
// Reduce the code after globalopt and ipsccp. Both can open up significant
// simplification opportunities, and both can propagate functions through
// function pointers. When this happens, we often have to resolve varargs
// calls, etc, so let instcombine do this.
if (OptLevel > 2)
PM.add(createAggressiveInstCombinerPass());
PM.add(createInstructionCombiningPass());
addExtensionsToPM(EP_Peephole, PM);
// Inline small functions
bool RunInliner = Inliner;
if (RunInliner) {
PM.add(Inliner);
Inliner = nullptr;
}
PM.add(createPruneEHPass()); // Remove dead EH info.
// CSFDO instrumentation and use pass.
addPGOInstrPasses(PM, /* IsCS */ true);
// Infer attributes on declarations, call sites, arguments, etc. for an SCC.
if (AttributorRun & AttributorRunOption::CGSCC)
PM.add(createAttributorCGSCCLegacyPass());
// Try to perform OpenMP specific optimizations. This is a (quick!) no-op if
// there are no OpenMP runtime calls present in the module.
if (OptLevel > 1)
PM.add(createOpenMPOptCGSCCLegacyPass());
// Optimize globals again if we ran the inliner.
if (RunInliner)
PM.add(createGlobalOptimizerPass());
PM.add(createGlobalDCEPass()); // Remove dead functions.
// If we didn't decide to inline a function, check to see if we can
// transform it to pass arguments by value instead of by reference.
PM.add(createArgumentPromotionPass());
// The IPO passes may leave cruft around. Clean up after them.
PM.add(createInstructionCombiningPass());
addExtensionsToPM(EP_Peephole, PM);
PM.add(createJumpThreadingPass(/*FreezeSelectCond*/ true));
// Break up allocas
PM.add(createSROAPass());
// LTO provides additional opportunities for tailcall elimination due to
// link-time inlining, and visibility of nocapture attribute.
if (OptLevel > 1)
PM.add(createTailCallEliminationPass());
// Infer attributes on declarations, call sites, arguments, etc.
PM.add(createPostOrderFunctionAttrsLegacyPass()); // Add nocapture.
// Run a few AA driven optimizations here and now, to cleanup the code.
PM.add(createGlobalsAAWrapperPass()); // IP alias analysis.
PM.add(createLICMPass(LicmMssaOptCap, LicmMssaNoAccForPromotionCap));
PM.add(NewGVN ? createNewGVNPass()
: createGVNPass(DisableGVNLoadPRE)); // Remove redundancies.
PM.add(createMemCpyOptPass()); // Remove dead memcpys.
// Nuke dead stores.
PM.add(createDeadStoreEliminationPass());
PM.add(createMergedLoadStoreMotionPass()); // Merge ld/st in diamonds.
// More loops are countable; try to optimize them.
if (EnableLoopFlatten)
PM.add(createLoopFlattenPass());
PM.add(createIndVarSimplifyPass());
PM.add(createLoopDeletionPass());
if (EnableLoopInterchange)
PM.add(createLoopInterchangePass());
if (EnableConstraintElimination)
PM.add(createConstraintEliminationPass());
// Unroll small loops and perform peeling.
PM.add(createSimpleLoopUnrollPass(OptLevel, DisableUnrollLoops,
ForgetAllSCEVInLoopUnroll));
PM.add(createLoopDistributePass());
addVectorPasses(PM, /* IsFullLTO */ true);
addExtensionsToPM(EP_Peephole, PM);
PM.add(createJumpThreadingPass(/*FreezeSelectCond*/ true));
}
void PassManagerBuilder::addLateLTOOptimizationPasses(
legacy::PassManagerBase &PM) {
// See comment in the new PM for justification of scheduling splitting at
// this stage (\ref buildLTODefaultPipeline).
if (EnableHotColdSplit)
PM.add(createHotColdSplittingPass());
// Delete basic blocks, which optimization passes may have killed.
PM.add(
createCFGSimplificationPass(SimplifyCFGOptions().hoistCommonInsts(true)));
// Drop bodies of available externally objects to improve GlobalDCE.
PM.add(createEliminateAvailableExternallyPass());
// Now that we have optimized the program, discard unreachable functions.
PM.add(createGlobalDCEPass());
// FIXME: this is profitable (for compiler time) to do at -O0 too, but
// currently it damages debug info.
if (MergeFunctions)
PM.add(createMergeFunctionsPass());
}
void PassManagerBuilder::populateThinLTOPassManager(
legacy::PassManagerBase &PM) {
PerformThinLTO = true;
if (LibraryInfo)
PM.add(new TargetLibraryInfoWrapperPass(*LibraryInfo));
if (VerifyInput)
PM.add(createVerifierPass());
if (ImportSummary) {
// This pass imports type identifier resolutions for whole-program
// devirtualization and CFI. It must run early because other passes may
// disturb the specific instruction patterns that these passes look for,
// creating dependencies on resolutions that may not appear in the summary.
//
// For example, GVN may transform the pattern assume(type.test) appearing in
// two basic blocks into assume(phi(type.test, type.test)), which would
// transform a dependency on a WPD resolution into a dependency on a type
// identifier resolution for CFI.
//
// Also, WPD has access to more precise information than ICP and can
// devirtualize more effectively, so it should operate on the IR first.
PM.add(createWholeProgramDevirtPass(nullptr, ImportSummary));
PM.add(createLowerTypeTestsPass(nullptr, ImportSummary));
}
populateModulePassManager(PM);
if (VerifyOutput)
PM.add(createVerifierPass());
PerformThinLTO = false;
}
void PassManagerBuilder::populateLTOPassManager(legacy::PassManagerBase &PM) {
if (LibraryInfo)
PM.add(new TargetLibraryInfoWrapperPass(*LibraryInfo));
if (VerifyInput)
PM.add(createVerifierPass());
addExtensionsToPM(EP_FullLinkTimeOptimizationEarly, PM);
if (OptLevel != 0)
addLTOOptimizationPasses(PM);
else {
// The whole-program-devirt pass needs to run at -O0 because only it knows
// about the llvm.type.checked.load intrinsic: it needs to both lower the
// intrinsic itself and handle it in the summary.
PM.add(createWholeProgramDevirtPass(ExportSummary, nullptr));
}
// Create a function that performs CFI checks for cross-DSO calls with targets
// in the current module.
PM.add(createCrossDSOCFIPass());
// Lower type metadata and the type.test intrinsic. This pass supports Clang's
// control flow integrity mechanisms (-fsanitize=cfi*) and needs to run at
// link time if CFI is enabled. The pass does nothing if CFI is disabled.
PM.add(createLowerTypeTestsPass(ExportSummary, nullptr));
// Run a second time to clean up any type tests left behind by WPD for use
// in ICP (which is performed earlier than this in the regular LTO pipeline).
PM.add(createLowerTypeTestsPass(nullptr, nullptr, true));
if (OptLevel != 0)
addLateLTOOptimizationPasses(PM);
addExtensionsToPM(EP_FullLinkTimeOptimizationLast, PM);
PM.add(createAnnotationRemarksLegacyPass());
if (VerifyOutput)
PM.add(createVerifierPass());
}
LLVMPassManagerBuilderRef LLVMPassManagerBuilderCreate() {
PassManagerBuilder *PMB = new PassManagerBuilder();
return wrap(PMB);
}
void LLVMPassManagerBuilderDispose(LLVMPassManagerBuilderRef PMB) {
PassManagerBuilder *Builder = unwrap(PMB);
delete Builder;
}
void
LLVMPassManagerBuilderSetOptLevel(LLVMPassManagerBuilderRef PMB,
unsigned OptLevel) {
PassManagerBuilder *Builder = unwrap(PMB);
Builder->OptLevel = OptLevel;
}
void
LLVMPassManagerBuilderSetSizeLevel(LLVMPassManagerBuilderRef PMB,
unsigned SizeLevel) {
PassManagerBuilder *Builder = unwrap(PMB);
Builder->SizeLevel = SizeLevel;
}
void
LLVMPassManagerBuilderSetDisableUnitAtATime(LLVMPassManagerBuilderRef PMB,
LLVMBool Value) {
// NOTE: The DisableUnitAtATime switch has been removed.
}
void
LLVMPassManagerBuilderSetDisableUnrollLoops(LLVMPassManagerBuilderRef PMB,
LLVMBool Value) {
PassManagerBuilder *Builder = unwrap(PMB);
Builder->DisableUnrollLoops = Value;
}
void
LLVMPassManagerBuilderSetDisableSimplifyLibCalls(LLVMPassManagerBuilderRef PMB,
LLVMBool Value) {
// NOTE: The simplify-libcalls pass has been removed.
}
void
LLVMPassManagerBuilderUseInlinerWithThreshold(LLVMPassManagerBuilderRef PMB,
unsigned Threshold) {
PassManagerBuilder *Builder = unwrap(PMB);
Builder->Inliner = createFunctionInliningPass(Threshold);
}
void
LLVMPassManagerBuilderPopulateFunctionPassManager(LLVMPassManagerBuilderRef PMB,
LLVMPassManagerRef PM) {
PassManagerBuilder *Builder = unwrap(PMB);
legacy::FunctionPassManager *FPM = unwrap<legacy::FunctionPassManager>(PM);
Builder->populateFunctionPassManager(*FPM);
}
void
LLVMPassManagerBuilderPopulateModulePassManager(LLVMPassManagerBuilderRef PMB,
LLVMPassManagerRef PM) {
PassManagerBuilder *Builder = unwrap(PMB);
legacy::PassManagerBase *MPM = unwrap(PM);
Builder->populateModulePassManager(*MPM);
}
void LLVMPassManagerBuilderPopulateLTOPassManager(LLVMPassManagerBuilderRef PMB,
LLVMPassManagerRef PM,
LLVMBool Internalize,
LLVMBool RunInliner) {
PassManagerBuilder *Builder = unwrap(PMB);
legacy::PassManagerBase *LPM = unwrap(PM);
// A small backwards compatibility hack. populateLTOPassManager used to take
// an RunInliner option.
if (RunInliner && !Builder->Inliner)
Builder->Inliner = createFunctionInliningPass();
Builder->populateLTOPassManager(*LPM);
}
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