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don't bother calling ConstantFoldInstruction unless there is a use of the

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instruction (which disqualifies stores, unreachable, etc) and at least the
first operand is a constant.  This filters out a lot of obvious cases that
can't be folded.  Also, switch the IRBuilder to a TargetFolder, which tries
harder.

llvm-svn: 84170
This commit is contained in:
Chris Lattner 2009-10-15 04:13:44 +00:00
parent a12f6e8f78
commit ddfa3af584
1 changed files with 25 additions and 22 deletions
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47
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -56,6 +56,7 @@
#include "llvm/Support/IRBuilder.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/PatternMatch.h"
#include "llvm/Support/TargetFolder.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallVector.h"
@ -186,7 +187,7 @@ namespace {
/// Builder - This is an IRBuilder that automatically inserts new
/// instructions into the worklist when they are created.
typedef IRBuilder<true, ConstantFolder, InstCombineIRInserter> BuilderTy;
typedef IRBuilder<true, TargetFolder, InstCombineIRInserter> BuilderTy;
BuilderTy *Builder;
static char ID; // Pass identification, replacement for typeid
@ -12704,14 +12705,15 @@ static void AddReachableCodeToWorklist(BasicBlock *BB,
}
// ConstantProp instruction if trivially constant.
if (Constant *C = ConstantFoldInstruction(Inst, BB->getContext(), TD)) {
DEBUG(errs() << "IC: ConstFold to: " << *C << " from: "
<< *Inst << '\n');
Inst->replaceAllUsesWith(C);
++NumConstProp;
Inst->eraseFromParent();
continue;
}
if (!Inst->use_empty() && isa<Constant>(Inst->getOperand(0)))
if (Constant *C = ConstantFoldInstruction(Inst, BB->getContext(), TD)) {
DEBUG(errs() << "IC: ConstFold to: " << *C << " from: "
<< *Inst << '\n');
Inst->replaceAllUsesWith(C);
++NumConstProp;
Inst->eraseFromParent();
continue;
}
InstrsForInstCombineWorklist.push_back(Inst);
}
@ -12757,7 +12759,6 @@ static void AddReachableCodeToWorklist(BasicBlock *BB,
bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) {
MadeIRChange = false;
TD = getAnalysisIfAvailable<TargetData>();
DEBUG(errs() << "\n\nINSTCOMBINE ITERATION #" << Iteration << " on "
<< F.getNameStr() << "\n");
@ -12810,16 +12811,17 @@ bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) {
}
// Instruction isn't dead, see if we can constant propagate it.
if (Constant *C = ConstantFoldInstruction(I, F.getContext(), TD)) {
DEBUG(errs() << "IC: ConstFold to: " << *C << " from: " << *I << '\n');
if (!I->use_empty() && isa<Constant>(I->getOperand(0)))
if (Constant *C = ConstantFoldInstruction(I, F.getContext(), TD)) {
DEBUG(errs() << "IC: ConstFold to: " << *C << " from: " << *I << '\n');
// Add operands to the worklist.
ReplaceInstUsesWith(*I, C);
++NumConstProp;
EraseInstFromFunction(*I);
MadeIRChange = true;
continue;
}
// Add operands to the worklist.
ReplaceInstUsesWith(*I, C);
++NumConstProp;
EraseInstFromFunction(*I);
MadeIRChange = true;
continue;
}
if (TD) {
// See if we can constant fold its operands.
@ -12927,12 +12929,13 @@ bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) {
bool InstCombiner::runOnFunction(Function &F) {
MustPreserveLCSSA = mustPreserveAnalysisID(LCSSAID);
Context = &F.getContext();
TD = getAnalysisIfAvailable<TargetData>();
/// Builder - This is an IRBuilder that automatically inserts new
/// instructions into the worklist when they are created.
IRBuilder<true, ConstantFolder, InstCombineIRInserter>
TheBuilder(F.getContext(), ConstantFolder(F.getContext()),
IRBuilder<true, TargetFolder, InstCombineIRInserter>
TheBuilder(F.getContext(), TargetFolder(TD, F.getContext()),
InstCombineIRInserter(Worklist));
Builder = &TheBuilder;