Besides removing phi cycles that reduce to a single value, also remove dead
phi cycles.  Adjust a few tests to keep dead instructions from being optimized
away.  This (together with my previous change for phi cycles) fixes Apple
radar 7627077.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@96057 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/CodeGen/X86/pre-split8.ll b/test/CodeGen/X86/pre-split8.ll
index ea4b949..0684bd0 100644
--- a/test/CodeGen/X86/pre-split8.ll
+++ b/test/CodeGen/X86/pre-split8.ll
@@ -20,7 +20,7 @@
 
 bb9.i:		; preds = %bb
 	%2 = fsub double %.rle4, %0		; <double> [#uses=0]
-	%3 = tail call double @asin(double 0.000000e+00) nounwind readonly		; <double> [#uses=0]
+	%3 = tail call double @asin(double %.rle4) nounwind readonly		; <double> [#uses=0]
 	%4 = fmul double 0.000000e+00, %0		; <double> [#uses=1]
 	%5 = tail call double @tan(double 0.000000e+00) nounwind readonly		; <double> [#uses=0]
 	%6 = fmul double %4, 0.000000e+00		; <double> [#uses=1]