llvm-project/llvm/tools/llvm-reduce/DeltaManager.cpp
Matt Arsenault e66592509b
llvm-reduce: Add values to return reduction (#132686)
In void functions, try to replace instruction uses
with a new non-void return. If the return type matches
the instruction, also try to directly return it.

This handles most of the cases, but doesn't try to handle
all of the weird exception related terminators.

Also doesn't try to replace argument uses, although it could. We
could also handle cases where we can insert a simple cast to an
original return value. I didn't think too hard about where to put this
in the default pass order. In many cases it obviates the need for most
of the CFG folds, but I've left it near the end initially.

I also think this is too aggressive about removing dead code, and
should leave existing dead code alone. I'm also not sure why we have
both "removeUnreachableBlocks" and EliminateUnreachableBlocks" in Utils.

Fixes #66039, fixes #107327
2025-05-02 16:11:14 +02:00

201 lines
6.2 KiB
C++

//===- DeltaManager.cpp - Runs Delta Passes to reduce Input ---------------===//
//
// 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 calls each specialized Delta pass in order to reduce the input IR
// file.
//
//===----------------------------------------------------------------------===//
#include "DeltaManager.h"
#include "DeltaPass.h"
#include "TestRunner.h"
#include "deltas/ReduceAliases.h"
#include "deltas/ReduceArguments.h"
#include "deltas/ReduceAttributes.h"
#include "deltas/ReduceBasicBlocks.h"
#include "deltas/ReduceDIMetadata.h"
#include "deltas/ReduceDbgRecords.h"
#include "deltas/ReduceDistinctMetadata.h"
#include "deltas/ReduceFunctionBodies.h"
#include "deltas/ReduceFunctions.h"
#include "deltas/ReduceGlobalObjects.h"
#include "deltas/ReduceGlobalValues.h"
#include "deltas/ReduceGlobalVarInitializers.h"
#include "deltas/ReduceGlobalVars.h"
#include "deltas/ReduceIRReferences.h"
#include "deltas/ReduceInstructionFlags.h"
#include "deltas/ReduceInstructionFlagsMIR.h"
#include "deltas/ReduceInstructions.h"
#include "deltas/ReduceInstructionsMIR.h"
#include "deltas/ReduceInvokes.h"
#include "deltas/ReduceMemoryOperations.h"
#include "deltas/ReduceMetadata.h"
#include "deltas/ReduceModuleData.h"
#include "deltas/ReduceOpcodes.h"
#include "deltas/ReduceOperandBundles.h"
#include "deltas/ReduceOperands.h"
#include "deltas/ReduceOperandsSkip.h"
#include "deltas/ReduceOperandsToArgs.h"
#include "deltas/ReduceRegisterDefs.h"
#include "deltas/ReduceRegisterMasks.h"
#include "deltas/ReduceRegisterUses.h"
#include "deltas/ReduceSpecialGlobals.h"
#include "deltas/ReduceTargetFeaturesAttr.h"
#include "deltas/ReduceUsingSimplifyCFG.h"
#include "deltas/ReduceValuesToReturn.h"
#include "deltas/ReduceVirtualRegisters.h"
#include "deltas/RunIRPasses.h"
#include "deltas/SimplifyInstructions.h"
#include "deltas/StripDebugInfo.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/Support/CommandLine.h"
using namespace llvm;
using SmallStringSet = SmallSet<StringRef, 8>;
extern cl::OptionCategory LLVMReduceOptions;
static cl::list<std::string>
DeltaPasses("delta-passes",
cl::desc("Delta passes to run, separated by commas. By "
"default, run all delta passes."),
cl::cat(LLVMReduceOptions), cl::CommaSeparated);
static cl::list<std::string>
SkipDeltaPasses("skip-delta-passes",
cl::desc("Delta passes to not run, separated by commas. By "
"default, run all delta passes."),
cl::cat(LLVMReduceOptions), cl::CommaSeparated);
// Generate two separate Pass lists: IR_Passes and MIR_Passes
static const DeltaPass IR_Passes[] = {
#undef DELTA_PASS_IR
#undef DELTA_PASS_MIR
#define DELTA_PASS_IR(NAME, FUNC, DESC) {NAME, FUNC, DESC},
#include "DeltaPasses.def"
#undef DELTA_PASS_IR
};
static const DeltaPass MIR_Passes[] = {
#undef DELTA_PASS_IR
#undef DELTA_PASS_MIR
#define DELTA_PASS_MIR(NAME, FUNC, DESC) {NAME, FUNC, DESC},
#include "DeltaPasses.def"
#undef DELTA_PASS_MIR
};
static void runAllDeltaPasses(TestRunner &Tester,
const SmallStringSet &SkipPass) {
if (Tester.getProgram().isMIR()) {
for (const DeltaPass &Pass : MIR_Passes) {
if (!SkipPass.count(Pass.Name)) {
runDeltaPass(Tester, Pass);
}
}
} else {
for (const DeltaPass &Pass : IR_Passes) {
if (!SkipPass.count(Pass.Name)) {
runDeltaPass(Tester, Pass);
}
}
}
}
static void runDeltaPassName(TestRunner &Tester, StringRef PassName) {
if (Tester.getProgram().isMIR()) {
for (const DeltaPass &Pass : MIR_Passes) {
if (PassName == Pass.Name) {
runDeltaPass(Tester, Pass);
return;
}
}
} else {
for (const DeltaPass &Pass : IR_Passes) {
if (PassName == Pass.Name) {
runDeltaPass(Tester, Pass);
return;
}
}
}
// We should have errored on unrecognized passes before trying to run
// anything.
llvm_unreachable("unknown delta pass");
}
void llvm::printDeltaPasses(raw_ostream &OS) {
OS << "Delta passes (pass to `--delta-passes=` as a comma separated list):\n";
OS << " IR:\n";
for (const DeltaPass &Pass : IR_Passes) {
OS << " " << Pass.Name << '\n';
}
OS << " MIR:\n";
for (const DeltaPass &Pass : MIR_Passes) {
OS << " " << Pass.Name << '\n';
}
}
// Built a set of available delta passes.
static void collectPassNames(const TestRunner &Tester,
SmallStringSet &NameSet) {
for (const DeltaPass &Pass : MIR_Passes) {
NameSet.insert(Pass.Name);
}
for (const DeltaPass &Pass : IR_Passes) {
NameSet.insert(Pass.Name);
}
}
/// Verify all requested or skipped passes are valid names, and return them in a
/// set.
static SmallStringSet handlePassList(const TestRunner &Tester,
const cl::list<std::string> &PassList) {
SmallStringSet AllPasses;
collectPassNames(Tester, AllPasses);
SmallStringSet PassSet;
for (StringRef PassName : PassList) {
if (!AllPasses.count(PassName)) {
errs() << "unknown pass \"" << PassName << "\"\n";
exit(1);
}
PassSet.insert(PassName);
}
return PassSet;
}
void llvm::runDeltaPasses(TestRunner &Tester, int MaxPassIterations) {
uint64_t OldComplexity = Tester.getProgram().getComplexityScore();
SmallStringSet RunPassSet, SkipPassSet;
if (!DeltaPasses.empty())
RunPassSet = handlePassList(Tester, DeltaPasses);
if (!SkipDeltaPasses.empty())
SkipPassSet = handlePassList(Tester, SkipDeltaPasses);
for (int Iter = 0; Iter < MaxPassIterations; ++Iter) {
if (DeltaPasses.empty()) {
runAllDeltaPasses(Tester, SkipPassSet);
} else {
for (StringRef PassName : DeltaPasses) {
if (!SkipPassSet.count(PassName))
runDeltaPassName(Tester, PassName);
}
}
uint64_t NewComplexity = Tester.getProgram().getComplexityScore();
if (NewComplexity >= OldComplexity)
break;
OldComplexity = NewComplexity;
}
}