[PATCH] D153084: AMDGPU: Partially fix not respecting dynamic denormal mode

Fri Jul 7 08:23:07 PDT 2023

arsenm added a comment.

In D153084#4475463 <https://reviews.llvm.org/D153084#4475463>, @rampitec wrote:

> In D153084#4475290 <https://reviews.llvm.org/D153084#4475290>, @arsenm wrote:
>
>> In D153084#4475241 <https://reviews.llvm.org/D153084#4475241>, @rampitec wrote:
>>
>>> It should be possible to logically separate it into 2 patches then: one reversing the flag but not changing the behavior, and then the fix itself?
>>
>> Yes, but it's kind of the same thing. I'd have to go spend the time to re-invert all the logic here and doesn't seem worth the effort
>
> Most of the patch is the logic inversion, I believe I have scanned it 3 times already. Could you please highlight the actual fix, or why does the inversion itself fixes it?

Because there's a 3rd option now, dynamic. It could be either mode. !IEEE doesn't imply denormals can be flushed, it has to be ==PreserveSign. This fixes illegally forming v_mad_f32 (see v_mac_f32_dynamic_ftz, this would be wrong if the function was called from an IEEE context if it used v_mad_f32)

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https://reviews.llvm.org/D153084