Changes in directory llvm/lib/Transforms/Scalar:
LoopUnswitch.cpp updated: 1.29 -> 1.30
---
Log message:
initial trivial support for folding branches that have now-constant
destinations.
---
Diffs of the changes: (+34 -3)
LoopUnswitch.cpp | 37 ++++++++++++++++++++++++++++++++++---
1 files changed, 34 insertions(+), 3 deletions(-)
Index: llvm/lib/Transforms/Scalar/LoopUnswitch.cpp
diff -u llvm/lib/Transforms/Scalar/LoopUnswitch.cpp:1.29
llvm/lib/Transforms/Scalar/LoopUnswitch.cpp:1.30
--- llvm/lib/Transforms/Scalar/LoopUnswitch.cpp:1.29 Fri Feb 17 18:55:32 2006
+++ llvm/lib/Transforms/Scalar/LoopUnswitch.cpp Fri Feb 17 19:27:45 2006
@@ -76,12 +76,14 @@
unsigned getLoopUnswitchCost(Loop *L, Value *LIC);
void VersionLoop(Value *LIC, Constant *OnVal,
Loop *L, Loop *&Out1, Loop *&Out2);
+ void UnswitchTrivialCondition(Loop *L, Value *Cond, Constant *Val,
+ bool EntersWhenTrue, BasicBlock *ExitBlock);
BasicBlock *SplitEdge(BasicBlock *From, BasicBlock *To);
BasicBlock *SplitBlock(BasicBlock *Old, Instruction *SplitPt);
void RewriteLoopBodyWithConditionConstant(Loop *L, Value *LIC,Constant
*Val,
bool isEqual);
- void UnswitchTrivialCondition(Loop *L, Value *Cond, Constant *Val,
- bool EntersWhenTrue, BasicBlock *ExitBlock);
+ bool TryToRemoveEdge(TerminatorInst *TI, unsigned SuccNo,
+ std::vector<Instruction*> &Worklist);
};
RegisterOpt<LoopUnswitch> X("loop-unswitch", "Unswitch loops");
}
@@ -717,7 +719,25 @@
++NumSimplify;
}
-
+/// TryToRemoveEdge - Determine whether this is a case where we're smart enough
+/// to remove the specified edge from the CFG and know how to update loop
+/// information. If it is, update SSA and the loop information for the future
+/// change, then return true. If not, return false.
+bool LoopUnswitch::TryToRemoveEdge(TerminatorInst *TI, unsigned DeadSuccNo,
+ std::vector<Instruction*> &Worklist) {
+ BasicBlock *BB = TI->getParent(), *Succ = TI->getSuccessor(DeadSuccNo);
+ Loop *BBLoop = LI->getLoopFor(BB);
+ Loop *SuccLoop = LI->getLoopFor(Succ);
+
+ // If this edge is not in a loop, or if this edge is leaving a loop to a
+ // non-loop area, this is trivial.
+ if (SuccLoop == 0) {
+ Succ->removePredecessor(BB, true);
+ return true;
+ }
+
+ return false;
+}
// RewriteLoopBodyWithConditionConstant - We know either that the value LIC has
// the value specified by Val in the specified loop, or we know it does NOT
have
@@ -875,7 +895,18 @@
// Remove Succ from the loop tree.
LI->removeBlock(Succ);
Succ->eraseFromParent();
+ ++NumSimplify;
break;
+ } else if (ConstantBool *CB =
dyn_cast<ConstantBool>(BI->getCondition())){
+ // Conditional branch.
+ if (TryToRemoveEdge(BI, CB->getValue(), Worklist)) {
+ DEBUG(std::cerr << "Folded branch: " << *BI);
+ new BranchInst(BI->getSuccessor(!CB->getValue()), BI);
+ BI->eraseFromParent();
+ RemoveFromWorklist(BI, Worklist);
+ ++NumSimplify;
+ break;
+ }
}
break;
}
_______________________________________________
llvm-commits mailing list
llvm-commits@cs.uiuc.edu
http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
