[llvm-commits] [llvm] r168711 - in /llvm/trunk: lib/Analysis/ScalarEvolution.cpp test/Transforms/IndVarSimplify/eliminate-comparison.ll

[Chris Lattner]

On Nov 29, 2012, at 11:04 AM, Benjamin Kramer <benny.kra at gmail.com> wrote:
>> 
>> Hi Ben,
>> 
>> Thanks for the fix. But why didn't you go for the more obvious fix?
>> 
>> -      return CmpInst::isFalseWhenEqual(Pred);
>> +      return CmpInst::isFalseWhenEqual(FoundPred);
>> 
>> As an example, invert the predicate in your test case:
>> 
>> %tmp76 = icmp ne i32 %sext34, %sext21
>> 
>> In this case, I think the following compare should be eliminated, but won't be with your fix:
>> 
>> %tmp46 = icmp slt i32 %__key8.0, 10
>> 
>> -Andy
> 
> Hah, sometimes you're too blind to see the obvious. I'll fix this, thanks for the review.
> 
> The original patch is still safe for 3.2, it only misses a potential optimization.

I'd prefer to have Andy approve whichever patch makes the most sense for 3.2.  Andy, what do you think?

-Chris