- Fix SelectionDAG to generate correct CFGs.
- Add a basic machine-level dead block eliminator.
These two have to go together, since many other parts of the code generator are unable to handle the unreachable blocks otherwise created.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@54333 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 196d3bf..6299bc4 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -1632,11 +1632,24 @@
}
SDValue BrCond = DAG.getNode(ISD::BRCOND, MVT::Other, getControlRoot(), Cond,
DAG.getBasicBlock(CB.TrueBB));
- if (CB.FalseBB == NextBlock)
+
+ // If the branch was constant folded, fix up the CFG.
+ if (BrCond.getOpcode() == ISD::BR) {
+ if (!DisableCorrectBranchFolding)
+ CurMBB->removeSuccessor(CB.FalseBB);
DAG.setRoot(BrCond);
- else
- DAG.setRoot(DAG.getNode(ISD::BR, MVT::Other, BrCond,
- DAG.getBasicBlock(CB.FalseBB)));
+ } else {
+ // Otherwise, go ahead and insert the false branch.
+ if (BrCond == getControlRoot())
+ if (!DisableCorrectBranchFolding)
+ CurMBB->removeSuccessor(CB.TrueBB);
+
+ if (CB.FalseBB == NextBlock)
+ DAG.setRoot(BrCond);
+ else
+ DAG.setRoot(DAG.getNode(ISD::BR, MVT::Other, BrCond,
+ DAG.getBasicBlock(CB.FalseBB)));
+ }
}
/// visitJumpTable - Emit JumpTable node in the current MBB