[PATCH] bug fix for PR20020: anti-dependency-breaker causes miscompilation

[hfinkel at anl.gov]

LGTM; thanks!

================
Comment at: test/CodeGen/X86/pr20020.ll:73
@@ +72,2 @@
+
+attributes #0 = { nounwind ssp uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
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Please remove any unneeded attributes.

http://reviews.llvm.org/D4351