[PATCH] D145867: [X86][FP16] Optimize FMAXNUM/FMINNUM into SMAX/SMIN for FP16 emulation under fast math

[Phoebe Wang via Phabricator via llvm-commits]

pengfei planned changes to this revision.
pengfei added a comment.

The negative comparison is not correct.



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Comment at: llvm/lib/Target/X86/X86ISelLowering.cpp:53178
+      }
+      SDValue Res = DAG.getNode(MinMaxOp, DL, NVT, DAG.getBitcast(NVT, Op0),
+                                DAG.getBitcast(NVT, Op1));
----------------
LuoYuanke wrote:
> I forget the encoding of exponent. Is the result same for min(vXf16) and min(i16)?
Thanks for the reminding. Review it again, I found it is only correct to positive value. The reason is FP is represented in `Sign-Magnitude` while integer is `2’s Complement Code`. Let me try to think out some way to solve it.


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  https://reviews.llvm.org/D145867/new/

https://reviews.llvm.org/D145867