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Simplify control flow a bit, note that unswitch preserves canonical loop form

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llvm-svn: 26098
This commit is contained in:
Chris Lattner 2006-02-09 22:15:42 +00:00
parent d491020c15
commit 602fc20596
1 changed files with 12 additions and 10 deletions
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22
lib/Transforms/Scalar/LoopUnswitch.cpp
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@ -59,12 +59,13 @@ namespace {
///
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequiredID(LoopSimplifyID);
AU.addPreservedID(LoopSimplifyID);
AU.addRequired<LoopInfo>();
AU.addPreserved<LoopInfo>();
}
private:
void VersionLoop(Value *LIC, Loop *L);
void VersionLoop(Value *LIC, Loop *L, Loop *&Out1, Loop *&Out2);
BasicBlock *SplitBlock(BasicBlock *BB, bool SplitAtTop);
void RewriteLoopBodyWithConditionConstant(Loop *L, Value *LIC, bool Val);
};
@ -172,11 +173,13 @@ bool LoopUnswitch::visitLoop(Loop *L) {
}
//std::cerr << "BEFORE:\n"; LI->dump();
VersionLoop(BI->getCondition(), L);
Loop *First = 0, *Second = 0;
VersionLoop(BI->getCondition(), L, First, Second);
//std::cerr << "AFTER:\n"; LI->dump();
// FIXME: Why return here? What if we have:
// "for () { if (iv1) { if (iv2) { } } }" ?
// Try to unswitch each of our new loops now!
if (First) visitLoop(First);
if (Second) visitLoop(Second);
return true;
}
@ -247,8 +250,9 @@ static Loop *CloneLoop(Loop *L, Loop *PL, std::map<const Value*, Value*> &VM,
/// VersionLoop - We determined that the loop is profitable to unswitch and
/// contains a branch on a loop invariant condition. Split it into loop
/// versions and test the condition outside of either loop.
void LoopUnswitch::VersionLoop(Value *LIC, Loop *L) {
/// versions and test the condition outside of either loop. Return the loops
/// created as Out1/Out2.
void LoopUnswitch::VersionLoop(Value *LIC, Loop *L, Loop *&Out1, Loop *&Out2) {
Function *F = L->getHeader()->getParent();
DEBUG(std::cerr << "loop-unswitch: Unswitching loop %"
@ -324,10 +328,8 @@ void LoopUnswitch::VersionLoop(Value *LIC, Loop *L) {
RewriteLoopBodyWithConditionConstant(L, LIC, true);
RewriteLoopBodyWithConditionConstant(NewLoop, LIC, false);
++NumUnswitched;
// Try to unswitch each of our new loops now!
visitLoop(L);
visitLoop(NewLoop);
Out1 = L;
Out2 = NewLoop;
}
// RewriteLoopBodyWithConditionConstant - We know that the boolean value LIC has