Teach CodeGenPrep to look past bitcast when it's duplicating return instruction
into predecessor blocks to enable tail call optimization.
rdar://11958338
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160894 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/CodeGenPrepare.cpp b/lib/Transforms/Scalar/CodeGenPrepare.cpp
index f425cd0..4b4a8c5 100644
--- a/lib/Transforms/Scalar/CodeGenPrepare.cpp
+++ b/lib/Transforms/Scalar/CodeGenPrepare.cpp
@@ -645,10 +645,18 @@
if (!TLI)
return false;
+ PHINode *PN = 0;
+ BitCastInst *BCI = 0;
Value *V = RI->getReturnValue();
- PHINode *PN = V ? dyn_cast<PHINode>(V) : NULL;
- if (V && !PN)
- return false;
+ if (V) {
+ BCI = dyn_cast<BitCastInst>(V);
+ if (BCI)
+ V = BCI->getOperand(0);
+
+ PN = dyn_cast<PHINode>(V);
+ if (!PN)
+ return false;
+ }
BasicBlock *BB = RI->getParent();
if (PN && PN->getParent() != BB)
@@ -666,6 +674,9 @@
if (PN) {
BasicBlock::iterator BI = BB->begin();
do { ++BI; } while (isa<DbgInfoIntrinsic>(BI));
+ if (&*BI == BCI)
+ // Also skip over the bitcast.
+ ++BI;
if (&*BI != RI)
return false;
} else {