Changes in directory llvm/lib/CodeGen:
IfConversion.cpp updated: 1.19 -> 1.20
---
Log message:
Ifcvt triangle: don't ifcvt 'true' BB if it has other predecessors; don't merge
'false' BB if it has other predecessors.
---
Diffs of the changes: (+18 -3)
IfConversion.cpp | 21 ++++++++++++++++++---
1 files changed, 18 insertions(+), 3 deletions(-)
Index: llvm/lib/CodeGen/IfConversion.cpp
diff -u llvm/lib/CodeGen/IfConversion.cpp:1.19
llvm/lib/CodeGen/IfConversion.cpp:1.20
--- llvm/lib/CodeGen/IfConversion.cpp:1.19 Thu May 31 19:55:26 2007
+++ llvm/lib/CodeGen/IfConversion.cpp Fri Jun 1 02:41:07 2007
@@ -460,14 +460,29 @@
if (!TrueBBI.isPredicable)
return false;
+ // FIXME: Consider duplicating if BB is small.
+ if (BBI.TrueBB->pred_size() > 1)
+ return false;
+
// Predicate the 'true' block after removing its branch.
TrueBBI.NonPredSize -= TII->RemoveBranch(*BBI.TrueBB);
PredicateBlock(TrueBBI, BBI.BrCond);
- // Join the 'true' and 'false' blocks by copying the instructions
- // from the 'false' block to the 'true' block.
+ // If 'true' block has a 'false' successor, add a early exit branch to it.
+ if (TrueBBI.FalseBB) {
+ std::vector<MachineOperand> RevCond(TrueBBI.BrCond);
+ if (TII->ReverseBranchCondition(RevCond))
+ assert(false && "Unable to reverse branch condition!");
+ TII->InsertBranch(*BBI.TrueBB, TrueBBI.FalseBB, NULL, RevCond);
+ }
+
+ // Join the 'true' and 'false' blocks if the 'false' block has no other
+ // predecessors. Otherwise, add a unconditional branch from 'true' to
'false'.
BBInfo &FalseBBI = BBAnalysis[BBI.FalseBB->getNumber()];
- MergeBlocks(TrueBBI, FalseBBI);
+ if (FalseBBI.BB->pred_size() == 2)
+ MergeBlocks(TrueBBI, FalseBBI);
+ else
+ InsertUncondBranch(TrueBBI.BB, FalseBBI.BB, TII);
// Now merge the entry of the triangle with the true block.
BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB);
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