RE: [PATCH,gcc/MIPS] Make loongson3a use fused madd.d

[Matthew Fortune]

Paul Hua <paul.hua...@gmail.com> writes:
> Loongson3a has 4 operand fused madd instrcution. This patch set
> loongson3a use fused madd.d.

Hi Paul,

Thanks for the fix. I was vaguely aware that this was wrong for
loongson-3a but never confirmed it.

I suspect this change is mechanical enough that it can bypass
copyright assignment but I'd need a global maintainer to comment.

I've sent you copyright assignment paperwork separately.

Two comments on the patch:

> ChangeLog :
> 
> *** gcc/ChangeLog ***
> 
> 2016-11-03 Chenghua Xu <paul.hua...@gmail.com>
> 
>     config/mips/
>     * mips.h: Set loongson3a use fused madd.d.

The changelog needs to reference what was changed rather than the
effect of the change:

        * config/mips/mips.h (ISA_HAS_FUSED_MADD4): Enable for
        TARGET_LOONGSON_3A.
        (ISA_HAS_UNFUSED_MADD4): Exclude TARGET_LOONGSON_3A.


>diff --git a/gcc/config/mips/mips.h b/gcc/config/mips/mips.h
>index 81862a9..5076a2b 100644
>--- a/gcc/config/mips/mips.h
>+++ b/gcc/config/mips/mips.h
>@@ -1056,11 +1056,11 @@ struct mips_cpu_info {
> 
> /* ISA has 4 operand fused madd instructions of the form
>    'd = [+-] (a * b [+-] c)'.  */
>-#define ISA_HAS_FUSED_MADD4   TARGET_MIPS8000
>+#define ISA_HAS_FUSED_MADD4   (TARGET_MIPS8000 || TARGET_LOONGSON_3A)
> 
> /* ISA has 4 operand unfused madd instructions of the form
>    'd = [+-] (a * b [+-] c)'.  */
>-#define ISA_HAS_UNFUSED_MADD4 (ISA_HAS_FP4 && !TARGET_MIPS8000)
>+#define ISA_HAS_UNFUSED_MADD4 (ISA_HAS_FP4 && !TARGET_MIPS8000 && 
>!TARGET_LOONGSON_3A)

Please split this line and move && !TARGET_LOONGSON_3A to the next line
under ISA_HAS_FP4.

> 
> /* ISA has 3 operand r6 fused madd instructions of the form
>    'c = c [+-] (a * b)'.  */

Thanks,
Matthew