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//===- LoopExtractor.cpp - Extract each loop into a new function ----------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// A pass wrapper around the ExtractLoop() scalar transformation to extract each
// top-level loop into its own new function. If the loop is the ONLY loop in a
// given function, it is not touched. This is a pass most useful for debugging
// via bugpoint.
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/IPO.h"
#include "llvm/Module.h"
#include "llvm/Pass.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Utils/FunctionUtils.h"
using namespace llvm;
namespace {
// FIXME: This is not a function pass, but the PassManager doesn't allow
// Module passes to require FunctionPasses, so we can't get loop info if we're
// not a function pass.
struct LoopExtractor : public FunctionPass {
unsigned NumLoops;
LoopExtractor(unsigned numLoops = ~0) : NumLoops(numLoops) {}
virtual bool runOnFunction(Function &F);
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<LoopInfo>();
AU.addRequiredID(LoopSimplifyID);
}
};
RegisterOpt<LoopExtractor>
X("loop-extract", "Extract loops into new functions");
/// SingleLoopExtractor - For bugpoint.
struct SingleLoopExtractor : public LoopExtractor {
SingleLoopExtractor() : LoopExtractor(1) {}
};
RegisterOpt<SingleLoopExtractor>
Y("loop-extract-single", "Extract at most one loop into a new function");
} // End anonymous namespace
bool LoopExtractor::runOnFunction(Function &F) {
LoopInfo &LI = getAnalysis<LoopInfo>();
// We don't want to keep extracting the only loop of a function into a new one
if (LI.begin() == LI.end() || LI.begin() + 1 == LI.end())
return false;
bool Changed = false;
// Try to move each loop out of the code into separate function
for (LoopInfo::iterator i = LI.begin(), e = LI.end(); i != e; ++i) {
if (NumLoops == 0) return Changed;
--NumLoops;
Changed |= (ExtractLoop(*i) != 0);
}
return Changed;
}
// createSingleLoopExtractorPass - This pass extracts one natural loop from the
// program into a function if it can. This is used by bugpoint.
//
Pass *llvm::createSingleLoopExtractorPass() {
return new SingleLoopExtractor();
}
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