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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.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "loop-extract"
#include "llvm/Transforms/IPO.h"
#include "llvm/Instructions.h"
#include "llvm/Module.h"
#include "llvm/Pass.h"
#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Utils/FunctionUtils.h"
#include "llvm/ADT/Statistic.h"
using namespace llvm;
STATISTIC(NumExtracted, "Number of loops extracted");
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 VISIBILITY_HIDDEN LoopExtractor : public FunctionPass {
static char ID; // Pass identifcation, replacement for typeid
unsigned NumLoops;
LoopExtractor(unsigned numLoops = ~0)
: FunctionPass((intptr_t)&ID), NumLoops(numLoops) {}
virtual bool runOnFunction(Function &F);
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequiredID(BreakCriticalEdgesID);
AU.addRequiredID(LoopSimplifyID);
AU.addRequired<ETForest>();
AU.addRequired<DominatorTree>();
AU.addRequired<LoopInfo>();
}
};
char LoopExtractor::ID = 0;
RegisterPass<LoopExtractor>
X("loop-extract", "Extract loops into new functions");
/// SingleLoopExtractor - For bugpoint.
struct SingleLoopExtractor : public LoopExtractor {
static char ID; // Pass identifcation, replacement for typeid
SingleLoopExtractor() : LoopExtractor(1) {}
};
char SingleLoopExtractor::ID = 0;
RegisterPass<SingleLoopExtractor>
Y("loop-extract-single", "Extract at most one loop into a new function");
} // End anonymous namespace
// createLoopExtractorPass - This pass extracts all natural loops from the
// program into a function if it can.
//
FunctionPass *llvm::createLoopExtractorPass() { return new LoopExtractor(); }
bool LoopExtractor::runOnFunction(Function &F) {
LoopInfo &LI = getAnalysis<LoopInfo>();
// If this function has no loops, there is nothing to do.
if (LI.begin() == LI.end())
return false;
ETForest &EF = getAnalysis<ETForest>();
DominatorTree &DT = getAnalysis<DominatorTree>();
// If there is more than one top-level loop in this function, extract all of
// the loops.
bool Changed = false;
if (LI.end()-LI.begin() > 1) {
for (LoopInfo::iterator i = LI.begin(), e = LI.end(); i != e; ++i) {
if (NumLoops == 0) return Changed;
--NumLoops;
Changed |= ExtractLoop(EF, DT, *i) != 0;
++NumExtracted;
}
} else {
// Otherwise there is exactly one top-level loop. If this function is more
// than a minimal wrapper around the loop, extract the loop.
Loop *TLL = *LI.begin();
bool ShouldExtractLoop = false;
// Extract the loop if the entry block doesn't branch to the loop header.
TerminatorInst *EntryTI = F.getEntryBlock().getTerminator();
if (!isa<BranchInst>(EntryTI) ||
!cast<BranchInst>(EntryTI)->isUnconditional() ||
EntryTI->getSuccessor(0) != TLL->getHeader())
ShouldExtractLoop = true;
else {
// Check to see if any exits from the loop are more than just return
// blocks.
std::vector<BasicBlock*> ExitBlocks;
TLL->getExitBlocks(ExitBlocks);
for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i)
if (!isa<ReturnInst>(ExitBlocks[i]->getTerminator())) {
ShouldExtractLoop = true;
break;
}
}
if (ShouldExtractLoop) {
if (NumLoops == 0) return Changed;
--NumLoops;
Changed |= ExtractLoop(EF, DT, TLL) != 0;
++NumExtracted;
} else {
// Okay, this function is a minimal container around the specified loop.
// If we extract the loop, we will continue to just keep extracting it
// infinitely... so don't extract it. However, if the loop contains any
// subloops, extract them.
for (Loop::iterator i = TLL->begin(), e = TLL->end(); i != e; ++i) {
if (NumLoops == 0) return Changed;
--NumLoops;
Changed |= ExtractLoop(EF, DT, *i) != 0;
++NumExtracted;
}
}
}
return Changed;
}
// createSingleLoopExtractorPass - This pass extracts one natural loop from the
// program into a function if it can. This is used by bugpoint.
//
FunctionPass *llvm::createSingleLoopExtractorPass() {
return new SingleLoopExtractor();
}
namespace {
/// BlockExtractorPass - This pass is used by bugpoint to extract all blocks
/// from the module into their own functions except for those specified by the
/// BlocksToNotExtract list.
class BlockExtractorPass : public ModulePass {
std::vector<BasicBlock*> BlocksToNotExtract;
public:
static char ID; // Pass identifcation, replacement for typeid
BlockExtractorPass(std::vector<BasicBlock*> &B)
: ModulePass((intptr_t)&ID), BlocksToNotExtract(B) {}
BlockExtractorPass() : ModulePass((intptr_t)&ID) {}
bool runOnModule(Module &M);
};
char BlockExtractorPass::ID = 0;
RegisterPass<BlockExtractorPass>
XX("extract-blocks", "Extract Basic Blocks From Module (for bugpoint use)");
}
// createBlockExtractorPass - This pass extracts all blocks (except those
// specified in the argument list) from the functions in the module.
//
ModulePass *llvm::createBlockExtractorPass(std::vector<BasicBlock*> &BTNE) {
return new BlockExtractorPass(BTNE);
}
bool BlockExtractorPass::runOnModule(Module &M) {
std::set<BasicBlock*> TranslatedBlocksToNotExtract;
for (unsigned i = 0, e = BlocksToNotExtract.size(); i != e; ++i) {
BasicBlock *BB = BlocksToNotExtract[i];
Function *F = BB->getParent();
// Map the corresponding function in this module.
Function *MF = M.getFunction(F->getName());
assert(MF->getFunctionType() == F->getFunctionType() && "Wrong function?");
// Figure out which index the basic block is in its function.
Function::iterator BBI = MF->begin();
std::advance(BBI, std::distance(F->begin(), Function::iterator(BB)));
TranslatedBlocksToNotExtract.insert(BBI);
}
// Now that we know which blocks to not extract, figure out which ones we WANT
// to extract.
std::vector<BasicBlock*> BlocksToExtract;
for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F)
for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
if (!TranslatedBlocksToNotExtract.count(BB))
BlocksToExtract.push_back(BB);
for (unsigned i = 0, e = BlocksToExtract.size(); i != e; ++i)
ExtractBasicBlock(BlocksToExtract[i]);
return !BlocksToExtract.empty();
}
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