[FIX] Adjust the insert point for non-affine region PHIs

  If a non-affine region PHI is generated we should not move the insert
  point prior to the synthezised value in the same block as we might
  split that block at the insert point later on. Only if the incoming
  value should be placed in a different block we should change the
  insertion point.

llvm-svn: 265132

1 files changed, 7 insertions, 4 deletions

diff --git a/polly/lib/CodeGen/BlockGenerators.cpp b/polly/lib/CodeGen/BlockGenerators.cpp
index e643ada9eed..e980d375a17 100644
--- a/polly/lib/CodeGen/BlockGenerators.cpp
+++ b/polly/lib/CodeGen/BlockGenerators.cpp
@@ -1365,11 +1365,14 @@ void RegionGenerator::addOperandToPHI(ScopStmt &Stmt, const PHINode *PHI,
 
     Value *Op = PHI->getIncomingValueForBlock(IncomingBB);
 
-    BasicBlock *OldBlock = Builder.GetInsertBlock();
-    auto OldIP = Builder.GetInsertPoint();
-    Builder.SetInsertPoint(BBCopy->getTerminator());
+    // If the current insert block is different from the PHIs incoming block
+    // change it, otherwise do not.
+    auto IP = Builder.GetInsertPoint();
+    if (IP->getParent() != BBCopy)
+      Builder.SetInsertPoint(BBCopy->getTerminator());
     OpCopy = getNewValue(Stmt, Op, BBCopyMap, LTS, getLoopForStmt(Stmt));
-    Builder.SetInsertPoint(OldBlock, OldIP);
+    if (IP->getParent() != BBCopy)
+      Builder.SetInsertPoint(&*IP);
   } else {
 
     if (PHICopy->getBasicBlockIndex(BBCopy) >= 0)