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Avoid non-trivial loop unswitching while optimizing for size.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@37446 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Devang Patel 2007-06-06 00:21:03 +00:00
parent 1405d008d8
commit 743f7e8839
2 changed files with 13 additions and 4 deletions
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2
include/llvm/Transforms/Scalar.h
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@ -127,7 +127,7 @@ LoopPass *createLoopStrengthReducePass(const TargetLowering *TLI = 0);
//
// LoopUnswitch - This pass is a simple loop unswitching pass.
//
LoopPass *createLoopUnswitchPass();
LoopPass *createLoopUnswitchPass(bool Os = false);
//===----------------------------------------------------------------------===//
//

15
lib/Transforms/Scalar/LoopUnswitch.cpp
View File

@ -67,10 +67,12 @@ namespace {
// after RewriteLoopBodyWithConditionConstant rewrites first loop.
std::vector<Loop*> LoopProcessWorklist;
SmallPtrSet<Value *,8> UnswitchedVals;
bool OptimizeForSize;
public:
static char ID; // Pass ID, replacement for typeid
LoopUnswitch() : LoopPass((intptr_t)&ID) {}
LoopUnswitch(bool Os = false) :
LoopPass((intptr_t)&ID), OptimizeForSize(Os) {}
bool runOnLoop(Loop *L, LPPassManager &LPM);
@ -116,7 +118,9 @@ namespace {
RegisterPass<LoopUnswitch> X("loop-unswitch", "Unswitch loops");
}
LoopPass *llvm::createLoopUnswitchPass() { return new LoopUnswitch(); }
LoopPass *llvm::createLoopUnswitchPass(bool Os) {
return new LoopUnswitch(Os);
}
/// FindLIVLoopCondition - Cond is a condition that occurs in L. If it is
/// invariant in the loop, or has an invariant piece, return the invariant.
@ -359,6 +363,11 @@ unsigned LoopUnswitch::getLoopUnswitchCost(Loop *L, Value *LIC) {
bool LoopUnswitch::UnswitchIfProfitable(Value *LoopCond, Constant *Val,Loop *L){
// Check to see if it would be profitable to unswitch this loop.
unsigned Cost = getLoopUnswitchCost(L, LoopCond);
// Do not do non-trivial unswitch while optimizing for size.
if (Cost && OptimizeForSize)
return false;
if (Cost > Threshold) {
// FIXME: this should estimate growth by the amount of code shared by the
// resultant unswitched loops.