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//===- LoopAnalysisManager.cpp - Loop analysis management -----------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/LoopAnalysisManager.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/MemorySSA.h"
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/PassManagerImpl.h"
#include <optional>
using namespace llvm;
namespace llvm {
// Explicit template instantiations and specialization definitions for core
// template typedefs.
template class AllAnalysesOn<Loop>;
template class AnalysisManager<Loop, LoopStandardAnalysisResults &>;
template class InnerAnalysisManagerProxy<LoopAnalysisManager, Function>;
template class OuterAnalysisManagerProxy<FunctionAnalysisManager, Loop,
LoopStandardAnalysisResults &>;
bool LoopAnalysisManagerFunctionProxy::Result::invalidate(
Function &F, const PreservedAnalyses &PA,
FunctionAnalysisManager::Invalidator &Inv) {
// First compute the sequence of IR units covered by this proxy. We will want
// to visit this in postorder, but because this is a tree structure we can do
// this by building a preorder sequence and walking it backwards. We also
// want siblings in forward program order to match the LoopPassManager so we
// get the preorder with siblings reversed.
SmallVector<Loop *, 4> PreOrderLoops = LI->getLoopsInReverseSiblingPreorder();
// If this proxy or the loop info is going to be invalidated, we also need
// to clear all the keys coming from that analysis. We also completely blow
// away the loop analyses if any of the standard analyses provided by the
// loop pass manager go away so that loop analyses can freely use these
// without worrying about declaring dependencies on them etc.
// FIXME: It isn't clear if this is the right tradeoff. We could instead make
// loop analyses declare any dependencies on these and use the more general
// invalidation logic below to act on that.
auto PAC = PA.getChecker<LoopAnalysisManagerFunctionProxy>();
bool invalidateMemorySSAAnalysis = false;
if (MSSAUsed)
invalidateMemorySSAAnalysis = Inv.invalidate<MemorySSAAnalysis>(F, PA);
if (!(PAC.preserved() || PAC.preservedSet<AllAnalysesOn<Function>>()) ||
Inv.invalidate<AAManager>(F, PA) ||
Inv.invalidate<AssumptionAnalysis>(F, PA) ||
Inv.invalidate<DominatorTreeAnalysis>(F, PA) ||
Inv.invalidate<LoopAnalysis>(F, PA) ||
Inv.invalidate<ScalarEvolutionAnalysis>(F, PA) ||
invalidateMemorySSAAnalysis) {
// Note that the LoopInfo may be stale at this point, however the loop
// objects themselves remain the only viable keys that could be in the
// analysis manager's cache. So we just walk the keys and forcibly clear
// those results. Note that the order doesn't matter here as this will just
// directly destroy the results without calling methods on them.
for (Loop *L : PreOrderLoops) {
// NB! `L` may not be in a good enough state to run Loop::getName.
InnerAM->clear(*L, "<possibly invalidated loop>");
}
// We also need to null out the inner AM so that when the object gets
// destroyed as invalid we don't try to clear the inner AM again. At that
// point we won't be able to reliably walk the loops for this function and
// only clear results associated with those loops the way we do here.
// FIXME: Making InnerAM null at this point isn't very nice. Most analyses
// try to remain valid during invalidation. Maybe we should add an
// `IsClean` flag?
InnerAM = nullptr;
// Now return true to indicate this *is* invalid and a fresh proxy result
// needs to be built. This is especially important given the null InnerAM.
return true;
}
// Directly check if the relevant set is preserved so we can short circuit
// invalidating loops.
bool AreLoopAnalysesPreserved =
PA.allAnalysesInSetPreserved<AllAnalysesOn<Loop>>();
// Since we have a valid LoopInfo we can actually leave the cached results in
// the analysis manager associated with the Loop keys, but we need to
// propagate any necessary invalidation logic into them. We'd like to
// invalidate things in roughly the same order as they were put into the
// cache and so we walk the preorder list in reverse to form a valid
// postorder.
for (Loop *L : reverse(PreOrderLoops)) {
std::optional<PreservedAnalyses> InnerPA;
// Check to see whether the preserved set needs to be adjusted based on
// function-level analysis invalidation triggering deferred invalidation
// for this loop.
if (auto *OuterProxy =
InnerAM->getCachedResult<FunctionAnalysisManagerLoopProxy>(*L))
for (const auto &OuterInvalidationPair :
OuterProxy->getOuterInvalidations()) {
AnalysisKey *OuterAnalysisID = OuterInvalidationPair.first;
const auto &InnerAnalysisIDs = OuterInvalidationPair.second;
if (Inv.invalidate(OuterAnalysisID, F, PA)) {
if (!InnerPA)
InnerPA = PA;
for (AnalysisKey *InnerAnalysisID : InnerAnalysisIDs)
InnerPA->abandon(InnerAnalysisID);
}
}
// Check if we needed a custom PA set. If so we'll need to run the inner
// invalidation.
if (InnerPA) {
InnerAM->invalidate(*L, *InnerPA);
continue;
}
// Otherwise we only need to do invalidation if the original PA set didn't
// preserve all Loop analyses.
if (!AreLoopAnalysesPreserved)
InnerAM->invalidate(*L, PA);
}
// Return false to indicate that this result is still a valid proxy.
return false;
}
template <>
LoopAnalysisManagerFunctionProxy::Result
LoopAnalysisManagerFunctionProxy::run(Function &F,
FunctionAnalysisManager &AM) {
return Result(*InnerAM, AM.getResult<LoopAnalysis>(F));
}
}
PreservedAnalyses llvm::getLoopPassPreservedAnalyses() {
PreservedAnalyses PA;
PA.preserve<DominatorTreeAnalysis>();
PA.preserve<LoopAnalysis>();
PA.preserve<LoopAnalysisManagerFunctionProxy>();
PA.preserve<ScalarEvolutionAnalysis>();
return PA;
}
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