[PATCH] [RS6000] Change maddld match_operand from DI to GPR

[Segher Boessenkool]

Hi Lijia,

On Mon, Jun 24, 2019 at 01:00:05AM -0500, Li Jia He wrote:
> >From PowerPC ISA3.0, the description of `maddld RT, RA.RB, RC` is as follows:
> 64-bit RA and RB are multiplied and then the RC is signed extend to 128 bits,
> and add them together.
> 
> We only apply it to 64-bit mode (DI) when implementing maddld.  However, if we
> can guarantee that the result of the maddld operation will be limited to 32-bit
> mode (SI), we can still apply it to 32-bit mode (SI).

Great :-)  Just some testcase comments:

> diff --git a/gcc/testsuite/gcc.target/powerpc/maddld-1.c b/gcc/testsuite/gcc.target/powerpc/maddld-1.c
> new file mode 100644
> index 00000000000..06f5f5774d4
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/maddld-1.c
> @@ -0,0 +1,19 @@
> +/* { dg-do compile { target { powerpc*-*-* } } } */

powerpc* is the default in gcc.target/powerpc, so you can leave it out:

/* { dg-do compile } */

(and that is default itself, but it is good documentation for the target
tests, many of those are run tests).

> +/* { dg-require-effective-target powerpc_p9modulo_ok } */

You don't need this line, it tests if the assembler supports p9.

> +/* { dg-final { scan-assembler-times "maddld " 2 } } */
> +/* { dg-final { scan-assembler-not   "mulld "    } } */
> +/* { dg-final { scan-assembler-not   "add "      } } */

You can easier write this using \m and \M, a bit more exact even:

/* { dg-final { scan-assembler-times {\mmaddld\M} 2 } } */
/* { dg-final { scan-assembler-not   {\mmul} } } */
/* { dg-final { scan-assembler-not   {\madd} } } */

Which allows only the exact mnemonic "maddld", and disallows anything
starting with "mul" or "add".

Okay for trunk, with the testcase improvements please.  Thanks!


Segher