fix two problems with machine sinking:
1. Sinking would crash when the first instruction of a block was
sunk due to iterator problems.
2. Instructions could be sunk to their current block, causing an
infinite loop.
This fixes PR3968
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@68787 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/CodeGen/Generic/2009-04-10-SinkCrash.ll b/test/CodeGen/Generic/2009-04-10-SinkCrash.ll
new file mode 100644
index 0000000..3637a06
--- /dev/null
+++ b/test/CodeGen/Generic/2009-04-10-SinkCrash.ll
@@ -0,0 +1,16 @@
+; RUN: llvm-as < %s | llc
+
+define void @QRiterate(i32 %p.1, double %tmp.212) nounwind {
+entry:
+ br i1 false, label %shortcirc_next.1, label %exit.1.critedge
+
+shortcirc_next.1: ; preds = %shortcirc_next.1, %entry
+ %tmp.213 = fcmp une double %tmp.212, 0.000000e+00 ; <i1> [#uses=1]
+ br i1 %tmp.213, label %shortcirc_next.1, label %exit.1
+
+exit.1.critedge: ; preds = %entry
+ ret void
+
+exit.1: ; preds = %shortcirc_next.1
+ ret void
+}