If succ has succ itself as one of the predecessors then do

not merge current bb and succ even if bb's terminator is
unconditional branch to succ.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@45305 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 62 insertions, 2 deletions

diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp
index 1305fd92c7..ee283a04c5 100644
--- a/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -110,10 +110,10 @@ static bool CanPropagatePredecessorsForPHIs(BasicBlock *BB, BasicBlock *Succ) {
   // update the PHI nodes correctly.
   if (!isa<PHINode>(BB->begin()) || Succ->getSinglePredecessor()) return true;
 
-  // If the predecessors of Succ are only BB and Succ itself, handle it.
+  // If the predecessors of Succ are only BB, handle it.
   bool IsSafe = true;
   for (pred_iterator PI = pred_begin(Succ), E = pred_end(Succ); PI != E; ++PI)
-    if (*PI != Succ && *PI != BB) {
+    if (*PI != BB) {
       IsSafe = false;
       break;
     }
diff --git a/test/Transforms/SimplifyCFG/2007-12-21-Crash.ll b/test/Transforms/SimplifyCFG/2007-12-21-Crash.ll
new file mode 100644
index 0000000000..31a22f55ec
--- /dev/null
+++ b/test/Transforms/SimplifyCFG/2007-12-21-Crash.ll
@@ -0,0 +1,60 @@
+; RUN:  llvm-as < %s | opt -std-compile-opts -disable-output
+
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
+
+define i32 @bork() {
+entry:
+	%retval = alloca i32		; <i32*> [#uses=2]
+	%opt = alloca i32		; <i32*> [#uses=3]
+	%undo = alloca i32		; <i32*> [#uses=3]
+	%tmp = alloca i32		; <i32*> [#uses=3]
+	%"alloca point" = bitcast i32 0 to i32		; <i32> [#uses=0]
+	store i32 0, i32* %undo, align 4
+	br label %bb5
+
+bb:		; preds = %bb5
+	%tmp1 = load i32* %opt, align 4		; <i32> [#uses=1]
+	switch i32 %tmp1, label %bb4 [
+		 i32 102, label %bb3
+		 i32 110, label %bb2
+	]
+
+bb2:		; preds = %bb
+	store i32 1, i32* %undo, align 4
+	br label %bb3
+
+bb3:		; preds = %bb2, %bb
+	br label %bb5
+
+bb4:		; preds = %bb
+	store i32 258, i32* %tmp, align 4
+	br label %bb13
+
+bb5:		; preds = %bb3, %entry
+	%tmp6 = call i32 (...)* @foo( ) nounwind 		; <i32> [#uses=1]
+	store i32 %tmp6, i32* %opt, align 4
+	%tmp7 = load i32* %opt, align 4		; <i32> [#uses=1]
+	%tmp8 = icmp ne i32 %tmp7, -1		; <i1> [#uses=1]
+	%tmp89 = zext i1 %tmp8 to i8		; <i8> [#uses=1]
+	%toBool = icmp ne i8 %tmp89, 0		; <i1> [#uses=1]
+	br i1 %toBool, label %bb, label %bb10
+
+bb10:		; preds = %bb5
+	%tmp11 = load i32* %undo, align 4		; <i32> [#uses=1]
+	%tmp12 = call i32 (...)* @bar( i32 %tmp11 ) nounwind 		; <i32> [#uses=0]
+	store i32 1, i32* %tmp, align 4
+	br label %bb13
+
+bb13:		; preds = %bb10, %bb4
+	%tmp14 = load i32* %tmp, align 4		; <i32> [#uses=1]
+	store i32 %tmp14, i32* %retval, align 4
+	br label %return
+
+return:		; preds = %bb13
+	%retval15 = load i32* %retval		; <i32> [#uses=1]
+	ret i32 %retval15
+}
+
+declare i32 @foo(...)
+
+declare i32 @bar(...)