[LLVMdev] 65bit integer math

[Villmow, Micah]

I have a test case(attached as fc_long.ll) that when run through the
optimizer produces 65bit integer math(fc_long-opt.ll).

 

Now I understand that llvm can have any length integer, but I consider
turning a 64bit mul into multiple 65 bit instructions to be a 'bad'
optimization. This eventually expands to a 128bit multiply
call(__multi3) which I have absolutely no interest in supporting. So I'm
wondering what optimization might be the culprit here so I can disable
it in this situation.

 

Micah

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