Fix PR3016, a bug which can occur do to an invalid assumption:

we assumed a CFG structure that would be valid when all code in 
the function is reachable, but not all code is necessarily 
reachable.  Do a simple, but horrible, CFG walk to check for this
case.

llvm-svn: 62487

1 files changed, 30 insertions, 0 deletions

diff --git a/llvm/test/Transforms/SimplifyCFG/2009-01-18-PHIPropCrash.ll b/llvm/test/Transforms/SimplifyCFG/2009-01-18-PHIPropCrash.ll
new file mode 100644
index 00000000000..692ef748262
--- /dev/null
+++ b/llvm/test/Transforms/SimplifyCFG/2009-01-18-PHIPropCrash.ll
@@ -0,0 +1,30 @@
+; RUN: llvm-as < %s | opt -simplifycfg | llvm-dis
+; PR3016
+; Dead use caused invariant violation.
+
+define i32 @func_105(i1 %tmp5, i1 %tmp7) nounwind {
+BB:
+	br i1 true, label %BB2, label %BB1
+
+BB1:		; preds = %BB
+	br label %BB2
+
+BB2:		; preds = %BB1, %BB
+	%tmp3 = phi i1 [ true, %BB ], [ false, %BB1 ]		; <i1> [#uses=1]
+	br label %BB9
+
+BB9:		; preds = %BB11, %BB2
+	%tmp10 = phi i32 [ 0, %BB2 ], [ %tmp12, %BB11 ]		; <i32> [#uses=1]
+	br i1 %tmp5, label %BB11, label %BB13
+
+BB11:		; preds = %BB13, %BB9
+	%tmp12 = phi i32 [ 0, %BB13 ], [ %tmp10, %BB9 ]		; <i32> [#uses=2]
+	br i1 %tmp3, label %BB9, label %BB20
+
+BB13:		; preds = %BB13, %BB9
+	%tmp14 = phi i32 [ 0, %BB9 ], [ %tmp14, %BB13 ]		; <i32> [#uses=1]
+	br i1 %tmp7, label %BB13, label %BB11
+
+BB20:		; preds = %BB11
+	ret i32 %tmp12
+}