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//===- LoopTransformWarning.cpp - ----------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// Emit warnings if forced code transformations have not been performed.
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/Scalar/WarnMissedTransforms.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/OptimizationRemarkEmitter.h"
#include "llvm/Transforms/Utils/LoopUtils.h"
using namespace llvm;
#define DEBUG_TYPE "transform-warning"
/// Emit warnings for forced (i.e. user-defined) loop transformations which have
/// still not been performed.
static void warnAboutLeftoverTransformations(Loop *L,
OptimizationRemarkEmitter *ORE) {
if (hasUnrollTransformation(L) == TM_ForcedByUser) {
LLVM_DEBUG(dbgs() << "Leftover unroll transformation\n");
ORE->emit(
DiagnosticInfoOptimizationFailure(DEBUG_TYPE,
"FailedRequestedUnrolling",
L->getStartLoc(), L->getHeader())
<< "loop not unrolled: the optimizer was unable to perform the "
"requested transformation; the transformation might be disabled or "
"specified as part of an unsupported transformation ordering");
}
if (hasUnrollAndJamTransformation(L) == TM_ForcedByUser) {
LLVM_DEBUG(dbgs() << "Leftover unroll-and-jam transformation\n");
ORE->emit(
DiagnosticInfoOptimizationFailure(DEBUG_TYPE,
"FailedRequestedUnrollAndJamming",
L->getStartLoc(), L->getHeader())
<< "loop not unroll-and-jammed: the optimizer was unable to perform "
"the requested transformation; the transformation might be disabled "
"or specified as part of an unsupported transformation ordering");
}
if (hasVectorizeTransformation(L) == TM_ForcedByUser) {
LLVM_DEBUG(dbgs() << "Leftover vectorization transformation\n");
std::optional<ElementCount> VectorizeWidth =
getOptionalElementCountLoopAttribute(L);
std::optional<int> InterleaveCount =
getOptionalIntLoopAttribute(L, "llvm.loop.interleave.count");
if (!VectorizeWidth || VectorizeWidth->isVector())
ORE->emit(
DiagnosticInfoOptimizationFailure(DEBUG_TYPE,
"FailedRequestedVectorization",
L->getStartLoc(), L->getHeader())
<< "loop not vectorized: the optimizer was unable to perform the "
"requested transformation; the transformation might be disabled "
"or specified as part of an unsupported transformation ordering");
else if (InterleaveCount.value_or(0) != 1)
ORE->emit(
DiagnosticInfoOptimizationFailure(DEBUG_TYPE,
"FailedRequestedInterleaving",
L->getStartLoc(), L->getHeader())
<< "loop not interleaved: the optimizer was unable to perform the "
"requested transformation; the transformation might be disabled "
"or specified as part of an unsupported transformation ordering");
}
if (hasDistributeTransformation(L) == TM_ForcedByUser) {
LLVM_DEBUG(dbgs() << "Leftover distribute transformation\n");
ORE->emit(
DiagnosticInfoOptimizationFailure(DEBUG_TYPE,
"FailedRequestedDistribution",
L->getStartLoc(), L->getHeader())
<< "loop not distributed: the optimizer was unable to perform the "
"requested transformation; the transformation might be disabled or "
"specified as part of an unsupported transformation ordering");
}
}
static void warnAboutLeftoverTransformations(Function *F, LoopInfo *LI,
OptimizationRemarkEmitter *ORE) {
for (auto *L : LI->getLoopsInPreorder())
warnAboutLeftoverTransformations(L, ORE);
}
// New pass manager boilerplate
PreservedAnalyses
WarnMissedTransformationsPass::run(Function &F, FunctionAnalysisManager &AM) {
// Do not warn about not applied transformations if optimizations are
// disabled.
if (F.hasOptNone())
return PreservedAnalyses::all();
auto &ORE = AM.getResult<OptimizationRemarkEmitterAnalysis>(F);
auto &LI = AM.getResult<LoopAnalysis>(F);
warnAboutLeftoverTransformations(&F, &LI, &ORE);
return PreservedAnalyses::all();
}
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