DAGCombine: visitXOR can replace a node without returning it, bail out in that case.

Fixes the crash reported in PR15608.

llvm-svn: 178429

2 files changed, 36 insertions, 3 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 44d43a1d076..d1f476e6447 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -6823,9 +6823,9 @@ SDValue DAGCombiner::visitBRCOND(SDNode *N) {
                              MVT::Other, Chain, Tmp, N2);
         }
 
-        // visitXOR has changed XOR's operands.
-        Op0 = TheXor->getOperand(0);
-        Op1 = TheXor->getOperand(1);
+        // visitXOR has changed XOR's operands or replaced the XOR completely,
+        // bail out.
+        return SDValue(N, 0);
       }
     }
 
diff --git a/llvm/test/CodeGen/X86/2013-01-09-DAGCombineBug.ll b/llvm/test/CodeGen/X86/2013-01-09-DAGCombineBug.ll
index db7ec8ae26c..1b417e54a2f 100644
--- a/llvm/test/CodeGen/X86/2013-01-09-DAGCombineBug.ll
+++ b/llvm/test/CodeGen/X86/2013-01-09-DAGCombineBug.ll
@@ -39,3 +39,36 @@ define void @t() nounwind uwtable ssp {
 ; <label>:11                                      ; preds = %11, %4
   br label %11
 }
+
+; PR15608
+@global = external constant [2 x i8]
+
+define void @PR15608() {
+bb:
+  br label %bb3
+
+bb1:                                              ; No predecessors!
+  br i1 icmp ult (i64 xor (i64 zext (i1 trunc (i192 lshr (i192 or (i192 shl (i192 zext (i64 trunc (i128 lshr (i128 trunc (i384 lshr (i384 or (i384 shl (i384 zext (i64 ptrtoint ([2 x i8]* @global to i64) to i384), i384 192), i384 425269881901436522087161771558896140289), i384 128) to i128), i128 64) to i64) to i192), i192 64), i192 1), i192 128) to i1) to i64), i64 1), i64 1), label %bb2, label %bb3
+
+bb2:                                              ; preds = %bb1
+  unreachable
+
+bb3:                                              ; preds = %bb1, %bb
+  br i1 xor (i1 trunc (i192 lshr (i192 or (i192 shl (i192 zext (i64 trunc (i128 lshr (i128 trunc (i384 lshr (i384 or (i384 shl (i384 zext (i64 ptrtoint ([2 x i8]* @global to i64) to i384), i384 192), i384 425269881901436522087161771558896140289), i384 128) to i128), i128 64) to i64) to i192), i192 64), i192 1), i192 128) to i1), i1 trunc (i192 lshr (i192 or (i192 and (i192 or (i192 shl (i192 zext (i64 trunc (i128 lshr (i128 trunc (i384 lshr (i384 or (i384 shl (i384 zext (i64 ptrtoint ([2 x i8]* @global to i64) to i384), i384 192), i384 425269881901436522087161771558896140289), i384 128) to i128), i128 64) to i64) to i192), i192 64), i192 1), i192 -340282366920938463463374607431768211457), i192 shl (i192 zext (i1 trunc (i192 lshr (i192 or (i192 shl (i192 zext (i64 trunc (i128 lshr (i128 trunc (i384 lshr (i384 or (i384 shl (i384 zext (i64 ptrtoint ([2 x i8]* @global to i64) to i384), i384 192), i384 425269881901436522087161771558896140289), i384 128) to i128), i128 64) to i64) to i192), i192 64), i192 1), i192 128) to i1) to i192), i192 128)), i192 128) to i1)), label %bb7, label %bb4
+
+bb4:                                              ; preds = %bb6, %bb3
+  %tmp = phi i1 [ true, %bb6 ], [ trunc (i192 lshr (i192 or (i192 and (i192 or (i192 shl (i192 zext (i64 trunc (i128 lshr (i128 trunc (i384 lshr (i384 or (i384 shl (i384 zext (i64 ptrtoint ([2 x i8]* @global to i64) to i384), i384 192), i384 425269881901436522087161771558896140289), i384 128) to i128), i128 64) to i64) to i192), i192 64), i192 1), i192 -340282366920938463463374607431768211457), i192 shl (i192 zext (i1 trunc (i192 lshr (i192 or (i192 shl (i192 zext (i64 trunc (i128 lshr (i128 trunc (i384 lshr (i384 or (i384 shl (i384 zext (i64 ptrtoint ([2 x i8]* @global to i64) to i384), i384 192), i384 425269881901436522087161771558896140289), i384 128) to i128), i128 64) to i64) to i192), i192 64), i192 1), i192 128) to i1) to i192), i192 128)), i192 128) to i1), %bb3 ]
+  br i1 false, label %bb8, label %bb5
+
+bb5:                                              ; preds = %bb4
+  br i1 %tmp, label %bb8, label %bb6
+
+bb6:                                              ; preds = %bb5
+  br i1 false, label %bb8, label %bb4
+
+bb7:                                              ; preds = %bb3
+  unreachable
+
+bb8:                                              ; preds = %bb6, %bb5, %bb4
+  unreachable
+}