[PATCH] Fix another infinite loop in InstCombine

[Steven Wu]

Sorry I forget to add llvm-commits for the first try. Since David has already reviewed it, I will not create a new review. 

Steven

> On Dec 11, 2014, at 8:24 PM, David Majnemer <david.majnemer at gmail.com> wrote:
> 
> LGTM with tweaks
> 
> 
> ================
> Comment at: test/Transforms/InstCombine/fpcast.ll:84-86
> @@ +83,5 @@
> +; CHECK-NEXT: %[[fext:.*]]  = fpext float %V to double
> +; CHECK-NEXT: %[[frem:.*]]  = frem double %fext, 1.000000e-01
> +; CHECK-NEXT: %[[trunc:.*]] = fptrunc double %frem to float
> +; CHECK-NEXT: ret float %trunc
> +}
> ----------------
> this should be:
> ; CHECK-NEXT: %[[frem:.*]]  = frem double %[[fext]], 1.000000e-01
> ; CHECK-NEXT: %[[trunc:.*]] = fptrunc double %[[frem]] to float
> ; CHECK-NEXT: ret float %[[trunc]]
> 
> http://reviews.llvm.org/D6634
> 
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