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081c34b725
must be called in the pass's constructor. This function uses static dependency declarations to recursively initialize the pass's dependencies. Clients that only create passes through the createFooPass() APIs will require no changes. Clients that want to use the CommandLine options for passes will need to manually call the appropriate initialization functions in PassInitialization.h before parsing commandline arguments. I have tested this with all standard configurations of clang and llvm-gcc on Darwin. It is possible that there are problems with the static dependencies that will only be visible with non-standard options. If you encounter any crash in pass registration/creation, please send the testcase to me directly. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@116820 91177308-0d34-0410-b5e6-96231b3b80d8
84 lines
3.0 KiB
C++
84 lines
3.0 KiB
C++
//===- GEPSplitter.cpp - Split complex GEPs into simple ones --------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This function breaks GEPs with more than 2 non-zero operands into smaller
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// GEPs each with no more than 2 non-zero operands. This exposes redundancy
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// between GEPs with common initial operand sequences.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "split-geps"
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/Constants.h"
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#include "llvm/Function.h"
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#include "llvm/Instructions.h"
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#include "llvm/Pass.h"
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using namespace llvm;
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namespace {
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class GEPSplitter : public FunctionPass {
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virtual bool runOnFunction(Function &F);
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virtual void getAnalysisUsage(AnalysisUsage &AU) const;
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public:
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static char ID; // Pass identification, replacement for typeid
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explicit GEPSplitter() : FunctionPass(ID) {
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initializeGEPSplitterPass(*PassRegistry::getPassRegistry());
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}
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};
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}
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char GEPSplitter::ID = 0;
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INITIALIZE_PASS(GEPSplitter, "split-geps",
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"split complex GEPs into simple GEPs", false, false)
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FunctionPass *llvm::createGEPSplitterPass() {
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return new GEPSplitter();
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}
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bool GEPSplitter::runOnFunction(Function &F) {
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bool Changed = false;
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// Visit each GEP instruction.
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for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I)
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for (BasicBlock::iterator II = I->begin(), IE = I->end(); II != IE; )
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if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(II++)) {
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unsigned NumOps = GEP->getNumOperands();
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// Ignore GEPs which are already simple.
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if (NumOps <= 2)
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continue;
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bool FirstIndexIsZero = isa<ConstantInt>(GEP->getOperand(1)) &&
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cast<ConstantInt>(GEP->getOperand(1))->isZero();
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if (NumOps == 3 && FirstIndexIsZero)
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continue;
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// The first index is special and gets expanded with a 2-operand GEP
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// (unless it's zero, in which case we can skip this).
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Value *NewGEP = FirstIndexIsZero ?
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GEP->getOperand(0) :
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GetElementPtrInst::Create(GEP->getOperand(0), GEP->getOperand(1),
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"tmp", GEP);
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// All remaining indices get expanded with a 3-operand GEP with zero
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// as the second operand.
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Value *Idxs[2];
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Idxs[0] = ConstantInt::get(Type::getInt64Ty(F.getContext()), 0);
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for (unsigned i = 2; i != NumOps; ++i) {
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Idxs[1] = GEP->getOperand(i);
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NewGEP = GetElementPtrInst::Create(NewGEP, Idxs, Idxs+2, "tmp", GEP);
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}
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GEP->replaceAllUsesWith(NewGEP);
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GEP->eraseFromParent();
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Changed = true;
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}
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return Changed;
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}
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void GEPSplitter::getAnalysisUsage(AnalysisUsage &AU) const {
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AU.setPreservesCFG();
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}
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