[SelectionDAG] Fix bugs in inverted condition splitting code.

Summary:
Fix two bugs in SelectionDAGBuilder::FindMergedConditions reported by
Mikael Holmen.  Handle non-canonicalized xor not operation
correctly (was assuming operand 0 was always the non-constant operand)
and check that the negated condition is also in the same block as the
original and/or instruction (as is done for and/or operands already)
before proceeding with optimization.

Reviewers: bogner, MatzeB, qcolombet

Subscribers: mcrosier, uabelho, llvm-commits

Differential Revision: https://reviews.llvm.org/D29680

llvm-svn: 294605

1 files changed, 6 insertions, 4 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 1cd4b48f3d6..5966069d31b 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -1638,10 +1638,12 @@ void SelectionDAGBuilder::FindMergedConditions(const Value *Cond,
   // Skip over not part of the tree and remember to invert op and operands at
   // next level.
   if (BinaryOperator::isNot(Cond) && Cond->hasOneUse()) {
-    Cond = cast<Instruction>(Cond)->getOperand(0);
-    FindMergedConditions(Cond, TBB, FBB, CurBB, SwitchBB, Opc, TProb, FProb,
-                         !InvertCond);
-    return;
+    const Value *CondOp = BinaryOperator::getNotArgument(Cond);
+    if (InBlock(CondOp, CurBB->getBasicBlock())) {
+      FindMergedConditions(CondOp, TBB, FBB, CurBB, SwitchBB, Opc, TProb, FProb,
+                           !InvertCond);
+      return;
+    }
   }
 
   const Instruction *BOp = dyn_cast<Instruction>(Cond);