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Avoid non-trivial loop unswitching while optimizing for size.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@37446 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -127,7 +127,7 @@ LoopPass *createLoopStrengthReducePass(const TargetLowering *TLI = 0);
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//
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// LoopUnswitch - This pass is a simple loop unswitching pass.
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//
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LoopPass *createLoopUnswitchPass();
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LoopPass *createLoopUnswitchPass(bool Os = false);
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//===----------------------------------------------------------------------===//
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//
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@ -67,10 +67,12 @@ namespace {
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// after RewriteLoopBodyWithConditionConstant rewrites first loop.
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std::vector<Loop*> LoopProcessWorklist;
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SmallPtrSet<Value *,8> UnswitchedVals;
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bool OptimizeForSize;
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public:
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static char ID; // Pass ID, replacement for typeid
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LoopUnswitch() : LoopPass((intptr_t)&ID) {}
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LoopUnswitch(bool Os = false) :
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LoopPass((intptr_t)&ID), OptimizeForSize(Os) {}
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bool runOnLoop(Loop *L, LPPassManager &LPM);
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@ -116,7 +118,9 @@ namespace {
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RegisterPass<LoopUnswitch> X("loop-unswitch", "Unswitch loops");
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}
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LoopPass *llvm::createLoopUnswitchPass() { return new LoopUnswitch(); }
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LoopPass *llvm::createLoopUnswitchPass(bool Os) {
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return new LoopUnswitch(Os);
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}
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/// FindLIVLoopCondition - Cond is a condition that occurs in L. If it is
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/// invariant in the loop, or has an invariant piece, return the invariant.
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@ -359,6 +363,11 @@ unsigned LoopUnswitch::getLoopUnswitchCost(Loop *L, Value *LIC) {
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bool LoopUnswitch::UnswitchIfProfitable(Value *LoopCond, Constant *Val,Loop *L){
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// Check to see if it would be profitable to unswitch this loop.
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unsigned Cost = getLoopUnswitchCost(L, LoopCond);
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// Do not do non-trivial unswitch while optimizing for size.
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if (Cost && OptimizeForSize)
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return false;
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if (Cost > Threshold) {
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// FIXME: this should estimate growth by the amount of code shared by the
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// resultant unswitched loops.
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