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//===- LoopPassManager.cpp - Loop pass management -------------------------===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
#include "llvm/Transforms/Scalar/LoopPassManager.h"
#include "llvm/Analysis/LoopInfo.h"
using namespace llvm;
// Explicit template instantiations and specialization defininitions for core
// template typedefs.
namespace llvm {
template class PassManager<Loop, LoopAnalysisManager,
LoopStandardAnalysisResults &, LPMUpdater &>;
/// Explicitly specialize the pass manager's run method to handle loop nest
/// structure updates.
template <>
PassManager<Loop, LoopAnalysisManager, LoopStandardAnalysisResults &,
LPMUpdater &>::run(Loop &L, LoopAnalysisManager &AM,
LoopStandardAnalysisResults &AR, LPMUpdater &U) {
PreservedAnalyses PA = PreservedAnalyses::all();
if (DebugLogging)
dbgs() << "Starting Loop pass manager run.\n";
// Request PassInstrumentation from analysis manager, will use it to run
// instrumenting callbacks for the passes later.
PassInstrumentation PI = AM.getResult<PassInstrumentationAnalysis>(L, AR);
for (auto &Pass : Passes) {
if (DebugLogging)
dbgs() << "Running pass: " << Pass->name() << " on " << L;
// Check the PassInstrumentation's BeforePass callbacks before running the
// pass, skip its execution completely if asked to (callback returns false).
if (!PI.runBeforePass<Loop>(*Pass, L))
PreservedAnalyses PassPA = Pass->run(L, AM, AR, U);
// do not pass deleted Loop into the instrumentation
if (U.skipCurrentLoop())
PI.runAfterPass<Loop>(*Pass, L);
// If the loop was deleted, abort the run and return to the outer walk.
if (U.skipCurrentLoop()) {
#ifndef NDEBUG
// Verify the loop structure and LCSSA form before visiting the loop.
assert(L.isRecursivelyLCSSAForm(AR.DT, AR.LI) &&
"Loops must remain in LCSSA form!");
// Update the analysis manager as each pass runs and potentially
// invalidates analyses.
AM.invalidate(L, PassPA);
// Finally, we intersect the final preserved analyses to compute the
// aggregate preserved set for this pass manager.
// FIXME: Historically, the pass managers all called the LLVM context's
// yield function here. We don't have a generic way to acquire the
// context and it isn't yet clear what the right pattern is for yielding
// in the new pass manager so it is currently omitted.
// ...getContext().yield();
// Invalidation for the current loop should be handled above, and other loop
// analysis results shouldn't be impacted by runs over this loop. Therefore,
// the remaining analysis results in the AnalysisManager are preserved. We
// mark this with a set so that we don't need to inspect each one
// individually.
// FIXME: This isn't correct! This loop and all nested loops' analyses should
// be preserved, but unrolling should invalidate the parent loop's analyses.
if (DebugLogging)
dbgs() << "Finished Loop pass manager run.\n";
return PA;
PrintLoopPass::PrintLoopPass() : OS(dbgs()) {}
PrintLoopPass::PrintLoopPass(raw_ostream &OS, const std::string &Banner)
: OS(OS), Banner(Banner) {}
PreservedAnalyses PrintLoopPass::run(Loop &L, LoopAnalysisManager &,
LoopStandardAnalysisResults &,
LPMUpdater &) {
printLoop(L, OS, Banner);
return PreservedAnalyses::all();