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remove the now dead condprop pass, PR3906.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86810 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2009-11-11 05:56:35 +00:00
parent b069c91191
commit f8fb7c26ee
6 changed files with 0 additions and 306 deletions
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3
include/llvm-c/Transforms/Scalar.h
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@ -31,9 +31,6 @@ void LLVMAddAggressiveDCEPass(LLVMPassManagerRef PM);
/** See llvm::createCFGSimplificationPass function. */
void LLVMAddCFGSimplificationPass(LLVMPassManagerRef PM);
/** See llvm::createCondPropagationPass function. */
void LLVMAddCondPropagationPass(LLVMPassManagerRef PM);
/** See llvm::createDeadStoreEliminationPass function. */
void LLVMAddDeadStoreEliminationPass(LLVMPassManagerRef PM);

1
include/llvm/LinkAllPasses.h
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@ -120,7 +120,6 @@ namespace {
(void) llvm::createTailDuplicationPass();
(void) llvm::createJumpThreadingPass();
(void) llvm::createUnifyFunctionExitNodesPass();
(void) llvm::createCondPropagationPass();
(void) llvm::createNullProfilerRSPass();
(void) llvm::createRSProfilingPass();
(void) llvm::createInstCountPass();

8
include/llvm/Transforms/Scalar.h
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@ -169,14 +169,6 @@ extern const PassInfo *const DemoteRegisterToMemoryID;
//
FunctionPass *createReassociatePass();
//===----------------------------------------------------------------------===//
//
// CondPropagationPass - This pass propagates information about conditional
// expressions through the program, allowing it to eliminate conditional
// branches in some cases.
//
FunctionPass *createCondPropagationPass();
//===----------------------------------------------------------------------===//
//
// TailDuplication - Eliminate unconditional branches through controlled code

1
lib/Transforms/Scalar/CMakeLists.txt
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@ -3,7 +3,6 @@ add_llvm_library(LLVMScalarOpts
ADCE.cpp
BasicBlockPlacement.cpp
CodeGenPrepare.cpp
CondPropagate.cpp
ConstantProp.cpp
DCE.cpp
DeadStoreElimination.cpp

289
lib/Transforms/Scalar/CondPropagate.cpp
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@ -1,289 +0,0 @@
//===-- CondPropagate.cpp - Propagate Conditional Expressions -------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This pass propagates information about conditional expressions through the
// program, allowing it to eliminate conditional branches in some cases.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "condprop"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Instructions.h"
#include "llvm/IntrinsicInst.h"
#include "llvm/Pass.h"
#include "llvm/Type.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/SmallVector.h"
using namespace llvm;
STATISTIC(NumBrThread, "Number of CFG edges threaded through branches");
STATISTIC(NumSwThread, "Number of CFG edges threaded through switches");
namespace {
struct CondProp : public FunctionPass {
static char ID; // Pass identification, replacement for typeid
CondProp() : FunctionPass(&ID) {}
virtual bool runOnFunction(Function &F);
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequiredID(BreakCriticalEdgesID);
//AU.addRequired<DominanceFrontier>();
}
private:
bool MadeChange;
SmallVector<BasicBlock *, 4> DeadBlocks;
void SimplifyBlock(BasicBlock *BB);
void SimplifyPredecessors(BranchInst *BI);
void SimplifyPredecessors(SwitchInst *SI);
void RevectorBlockTo(BasicBlock *FromBB, BasicBlock *ToBB);
bool RevectorBlockTo(BasicBlock *FromBB, Value *Cond, BranchInst *BI);
};
}
char CondProp::ID = 0;
static RegisterPass<CondProp> X("condprop", "Conditional Propagation");
FunctionPass *llvm::createCondPropagationPass() {
return new CondProp();
}
bool CondProp::runOnFunction(Function &F) {
bool EverMadeChange = false;
DeadBlocks.clear();
// While we are simplifying blocks, keep iterating.
do {
MadeChange = false;
for (Function::iterator BB = F.begin(), E = F.end(); BB != E;)
SimplifyBlock(BB++);
EverMadeChange = EverMadeChange || MadeChange;
} while (MadeChange);
if (EverMadeChange) {
while (!DeadBlocks.empty()) {
BasicBlock *BB = DeadBlocks.back(); DeadBlocks.pop_back();
DeleteDeadBlock(BB);
}
}
return EverMadeChange;
}
void CondProp::SimplifyBlock(BasicBlock *BB) {
if (BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator())) {
// If this is a conditional branch based on a phi node that is defined in
// this block, see if we can simplify predecessors of this block.
if (BI->isConditional() && isa<PHINode>(BI->getCondition()) &&
cast<PHINode>(BI->getCondition())->getParent() == BB)
SimplifyPredecessors(BI);
} else if (SwitchInst *SI = dyn_cast<SwitchInst>(BB->getTerminator())) {
if (isa<PHINode>(SI->getCondition()) &&
cast<PHINode>(SI->getCondition())->getParent() == BB)
SimplifyPredecessors(SI);
}
// If possible, simplify the terminator of this block.
if (ConstantFoldTerminator(BB))
MadeChange = true;
// If this block ends with an unconditional branch and the only successor has
// only this block as a predecessor, merge the two blocks together.
if (BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator()))
if (BI->isUnconditional() && BI->getSuccessor(0)->getSinglePredecessor() &&
BB != BI->getSuccessor(0)) {
BasicBlock *Succ = BI->getSuccessor(0);
// If Succ has any PHI nodes, they are all single-entry PHI's. Eliminate
// them.
FoldSingleEntryPHINodes(Succ);
// Remove BI.
BI->eraseFromParent();
// Move over all of the instructions.
BB->getInstList().splice(BB->end(), Succ->getInstList());
// Any phi nodes that had entries for Succ now have entries from BB.
Succ->replaceAllUsesWith(BB);
// Succ is now dead, but we cannot delete it without potentially
// invalidating iterators elsewhere. Just insert an unreachable
// instruction in it and delete this block later on.
new UnreachableInst(BB->getContext(), Succ);
DeadBlocks.push_back(Succ);
MadeChange = true;
}
}
// SimplifyPredecessors(branches) - We know that BI is a conditional branch
// based on a PHI node defined in this block. If the phi node contains constant
// operands, then the blocks corresponding to those operands can be modified to
// jump directly to the destination instead of going through this block.
void CondProp::SimplifyPredecessors(BranchInst *BI) {
// TODO: We currently only handle the most trival case, where the PHI node has
// one use (the branch), and is the only instruction besides the branch and dbg
// intrinsics in the block.
PHINode *PN = cast<PHINode>(BI->getCondition());
if (PN->getNumIncomingValues() == 1) {
// Eliminate single-entry PHI nodes.
FoldSingleEntryPHINodes(PN->getParent());
return;
}
if (!PN->hasOneUse()) return;
BasicBlock *BB = BI->getParent();
if (&*BB->begin() != PN)
return;
BasicBlock::iterator BBI = BB->begin();
BasicBlock::iterator BBE = BB->end();
while (BBI != BBE && isa<DbgInfoIntrinsic>(++BBI)) /* empty */;
if (&*BBI != BI)
return;
// Ok, we have this really simple case, walk the PHI operands, looking for
// constants. Walk from the end to remove operands from the end when
// possible, and to avoid invalidating "i".
for (unsigned i = PN->getNumIncomingValues(); i != 0; --i) {
Value *InVal = PN->getIncomingValue(i-1);
if (!RevectorBlockTo(PN->getIncomingBlock(i-1), InVal, BI))
continue;
++NumBrThread;
// If there were two predecessors before this simplification, or if the
// PHI node contained all the same value except for the one we just
// substituted, the PHI node may be deleted. Don't iterate through it the
// last time.
if (BI->getCondition() != PN) return;
}
}
// SimplifyPredecessors(switch) - We know that SI is switch based on a PHI node
// defined in this block. If the phi node contains constant operands, then the
// blocks corresponding to those operands can be modified to jump directly to
// the destination instead of going through this block.
void CondProp::SimplifyPredecessors(SwitchInst *SI) {
// TODO: We currently only handle the most trival case, where the PHI node has
// one use (the branch), and is the only instruction besides the branch and
// dbg intrinsics in the block.
PHINode *PN = cast<PHINode>(SI->getCondition());
if (!PN->hasOneUse()) return;
BasicBlock *BB = SI->getParent();
if (&*BB->begin() != PN)
return;
BasicBlock::iterator BBI = BB->begin();
BasicBlock::iterator BBE = BB->end();
while (BBI != BBE && isa<DbgInfoIntrinsic>(++BBI)) /* empty */;
if (&*BBI != SI)
return;
// Ok, we have this really simple case, walk the PHI operands, looking for
// constants. Walk from the end to remove operands from the end when
// possible, and to avoid invalidating "i".
for (unsigned i = PN->getNumIncomingValues(); i != 0; --i)
if (ConstantInt *CI = dyn_cast<ConstantInt>(PN->getIncomingValue(i-1))) {
BasicBlock *PredBB = PN->getIncomingBlock(i-1);
if (isa<BranchInst>(PredBB->getTerminator())) {
// If we have a constant, forward the edge from its current to its
// ultimate destination.
unsigned DestCase = SI->findCaseValue(CI);
RevectorBlockTo(PredBB, SI->getSuccessor(DestCase));
++NumSwThread;
// If there were two predecessors before this simplification, or if the
// PHI node contained all the same value except for the one we just
// substituted, the PHI node may be deleted. Don't iterate through it the
// last time.
if (SI->getCondition() != PN) return;
}
}
}
// RevectorBlockTo - Revector the unconditional branch at the end of FromBB to
// the ToBB block, which is one of the successors of its current successor.
void CondProp::RevectorBlockTo(BasicBlock *FromBB, BasicBlock *ToBB) {
BranchInst *FromBr = cast<BranchInst>(FromBB->getTerminator());
assert(FromBr->isUnconditional() && "FromBB should end with uncond br!");
// Get the old block we are threading through.
BasicBlock *OldSucc = FromBr->getSuccessor(0);
// OldSucc had multiple successors. If ToBB has multiple predecessors, then
// the edge between them would be critical, which we already took care of.
// If ToBB has single operand PHI node then take care of it here.
FoldSingleEntryPHINodes(ToBB);
// Update PHI nodes in OldSucc to know that FromBB no longer branches to it.
OldSucc->removePredecessor(FromBB);
// Change FromBr to branch to the new destination.
FromBr->setSuccessor(0, ToBB);
MadeChange = true;
}
bool CondProp::RevectorBlockTo(BasicBlock *FromBB, Value *Cond, BranchInst *BI){
BranchInst *FromBr = cast<BranchInst>(FromBB->getTerminator());
if (!FromBr->isUnconditional())
return false;
// Get the old block we are threading through.
BasicBlock *OldSucc = FromBr->getSuccessor(0);
// If the condition is a constant, simply revector the unconditional branch at
// the end of FromBB to one of the successors of its current successor.
if (ConstantInt *CB = dyn_cast<ConstantInt>(Cond)) {
BasicBlock *ToBB = BI->getSuccessor(CB->isZero());
// OldSucc had multiple successors. If ToBB has multiple predecessors, then
// the edge between them would be critical, which we already took care of.
// If ToBB has single operand PHI node then take care of it here.
FoldSingleEntryPHINodes(ToBB);
// Update PHI nodes in OldSucc to know that FromBB no longer branches to it.
OldSucc->removePredecessor(FromBB);
// Change FromBr to branch to the new destination.
FromBr->setSuccessor(0, ToBB);
} else {
BasicBlock *Succ0 = BI->getSuccessor(0);
// Do not perform transform if the new destination has PHI nodes. The
// transform will add new preds to the PHI's.
if (isa<PHINode>(Succ0->begin()))
return false;
BasicBlock *Succ1 = BI->getSuccessor(1);
if (isa<PHINode>(Succ1->begin()))
return false;
// Insert the new conditional branch.
BranchInst::Create(Succ0, Succ1, Cond, FromBr);
FoldSingleEntryPHINodes(Succ0);
FoldSingleEntryPHINodes(Succ1);
// Update PHI nodes in OldSucc to know that FromBB no longer branches to it.
OldSucc->removePredecessor(FromBB);
// Delete the old branch.
FromBr->eraseFromParent();
}
MadeChange = true;
return true;
}

4
lib/Transforms/Scalar/Scalar.cpp
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@ -26,10 +26,6 @@ void LLVMAddCFGSimplificationPass(LLVMPassManagerRef PM) {
unwrap(PM)->add(createCFGSimplificationPass());
}
void LLVMAddCondPropagationPass(LLVMPassManagerRef PM) {
unwrap(PM)->add(createCondPropagationPass());
}
void LLVMAddDeadStoreEliminationPass(LLVMPassManagerRef PM) {
unwrap(PM)->add(createDeadStoreEliminationPass());
}