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If loop can be unswitched again, then do it yourself.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@40609 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Devang Patel 2007-07-30 23:07:10 +00:00
parent 42346f58d8
commit 6f62af6e64
1 changed files with 19 additions and 5 deletions
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22
lib/Transforms/Scalar/LoopUnswitch.cpp
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@ -70,12 +70,14 @@ namespace {
SmallPtrSet<Value *,8> UnswitchedVals;
bool OptimizeForSize;
bool redoLoop;
public:
static char ID; // Pass ID, replacement for typeid
LoopUnswitch(bool Os = false) :
LoopPass((intptr_t)&ID), OptimizeForSize(Os) {}
LoopPass((intptr_t)&ID), OptimizeForSize(Os), redoLoop(false) {}
bool runOnLoop(Loop *L, LPPassManager &LPM);
bool processLoop(Loop *L);
/// This transformation requires natural loop information & requires that
/// loop preheaders be inserted into the CFG...
@ -152,11 +154,23 @@ static Value *FindLIVLoopCondition(Value *Cond, Loop *L, bool &Changed) {
}
bool LoopUnswitch::runOnLoop(Loop *L, LPPassManager &LPM_Ref) {
assert(L->isLCSSAForm());
LI = &getAnalysis<LoopInfo>();
LPM = &LPM_Ref;
bool Changed = false;
do {
redoLoop = false;
Changed |= processLoop(L);
} while(redoLoop);
return Changed;
}
/// processLoop - Do actual work and unswitch loop if possible and profitable.
bool LoopUnswitch::processLoop(Loop *L) {
assert(L->isLCSSAForm());
bool Changed = false;
// Loop over all of the basic blocks in the loop. If we find an interior
// block that is branching on a loop-invariant condition, we can unswitch this
// loop.
@ -576,7 +590,7 @@ void LoopUnswitch::UnswitchTrivialCondition(Loop *L, Value *Cond,
OrigPH->getTerminator()->eraseFromParent();
// We need to reprocess this loop, it could be unswitched again.
LPM->redoLoop(L);
redoLoop = true;
// Now that we know that the loop is never entered when this condition is a
// particular value, rewrite the loop with this info. We know that this will
@ -740,7 +754,7 @@ void LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val,
OldBR->eraseFromParent();
LoopProcessWorklist.push_back(NewLoop);
LPM->redoLoop(L);
redoLoop = true;
// Now we rewrite the original code to know that the condition is true and the
// new code to know that the condition is false.