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more refactoring, no functionality change. 

llvm-svn: 26194
This commit is contained in:
Chris Lattner 2006-02-15 01:44:42 +00:00
parent aacc4c3b4c
commit 01db04efb0
1 changed files with 11 additions and 12 deletions
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23
llvm/lib/Transforms/Scalar/LoopUnswitch.cpp
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@ -77,7 +77,7 @@ namespace {
BasicBlock *SplitEdge(BasicBlock *From, BasicBlock *To);
void RewriteLoopBodyWithConditionConstant(Loop *L, Value *LIC,Constant *Val,
bool isEqual);
void UnswitchTrivialCondition(Loop *L, Value *Cond, bool EntersLoopOnCond,
void UnswitchTrivialCondition(Loop *L, Value *Cond, Constant *Val,
BasicBlock *ExitBlock);
};
RegisterOpt<LoopUnswitch> X("loop-unswitch", "Unswitch loops");
@ -154,7 +154,7 @@ static BasicBlock *FindTrivialLoopExitBlock(Loop *L, BasicBlock *Latch) {
/// runs when the condition is true, False if the loop body executes when the
/// condition is false. Otherwise, return null to indicate a complex condition.
static bool IsTrivialUnswitchCondition(Loop *L, Value *Cond,
bool *CondEntersLoop = 0,
Constant **Val = 0,
BasicBlock **LoopExit = 0) {
BasicBlock *Header = L->getHeader();
BranchInst *HeaderTerm = dyn_cast<BranchInst>(Header->getTerminator());
@ -170,9 +170,9 @@ static bool IsTrivialUnswitchCondition(Loop *L, Value *Cond,
// the loop.
BasicBlock *Latch = L->getLoopLatch();
if (HeaderTerm->getSuccessor(1) == Latch) {
if (CondEntersLoop) *CondEntersLoop = true;
if (Val) *Val = ConstantBool::True;
} else if (HeaderTerm->getSuccessor(0) == Latch)
if (CondEntersLoop) *CondEntersLoop = false;
if (Val) *Val = ConstantBool::False;
else
return false; // Doesn't branch to latch block.
@ -333,10 +333,10 @@ bool LoopUnswitch::UnswitchIfProfitable(Value *LoopCond, Constant *Val,Loop *L){
// If this is a trivial condition to unswitch (which results in no code
// duplication), do it now.
bool EntersLoopOnCond;
Constant *CondVal;
BasicBlock *ExitBlock;
if (IsTrivialUnswitchCondition(L, LoopCond, &EntersLoopOnCond, &ExitBlock)){
UnswitchTrivialCondition(L, LoopCond, EntersLoopOnCond, ExitBlock);
if (IsTrivialUnswitchCondition(L, LoopCond, &CondVal, &ExitBlock)){
UnswitchTrivialCondition(L, LoopCond, CondVal, ExitBlock);
NewLoop1 = L;
} else {
VersionLoop(LoopCond, Val, L, NewLoop1, NewLoop2);
@ -460,7 +460,7 @@ static void EmitPreheaderBranchOnCondition(Value *LIC, Constant *Val,
/// side-effects), unswitch it. This doesn't involve any code duplication, just
/// moving the conditional branch outside of the loop and updating loop info.
void LoopUnswitch::UnswitchTrivialCondition(Loop *L, Value *Cond,
bool EnterOnCond,
Constant *Val,
BasicBlock *ExitBlock) {
DEBUG(std::cerr << "loop-unswitch: Trivial-Unswitch loop %"
<< L->getHeader()->getName() << " [" << L->getBlocks().size()
@ -484,15 +484,14 @@ void LoopUnswitch::UnswitchTrivialCondition(Loop *L, Value *Cond,
// Okay, now we have a position to branch from and a position to branch to,
// insert the new conditional branch.
new BranchInst(EnterOnCond ? NewPH : NewExit, EnterOnCond ? NewExit : NewPH,
Cond, OrigPH->getTerminator());
EmitPreheaderBranchOnCondition(Cond, Val, NewPH, NewExit,
OrigPH->getTerminator());
OrigPH->getTerminator()->eraseFromParent();
// 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
// at least eliminate the old branch.
RewriteLoopBodyWithConditionConstant(L, Cond, ConstantBool::get(EnterOnCond),
true);
RewriteLoopBodyWithConditionConstant(L, Cond, Val, true);
++NumTrivial;
}