Re: [PATCH-2, rs6000] Implement 32bit inline lrint [PR88558]

["Kewen.Lin" <linkw@linux.ibm.com>]

Hi Haochen,

on 2023/8/25 14:44, HAO CHEN GUI wrote:
> Hi,
>   This patch implements 32bit inline lrint by "fctiw". It depends on
> the patch1 to do SImode move from FP register on P7.
> 
>   Bootstrapped and tested on powerpc64-linux BE and LE with no regressions.
> 
> Thanks
> Gui Haochen
> 
> ChangeLog
> rs6000: support 32bit inline lrint
> 
> gcc/
> 	PR target/88558
> 	* config/rs6000/rs6000.md (lrint<mode>di2): Remove TARGET_FPRND
> 	from insn condition.
> 	(lrint<mode>si2): New insn pattern for 32bit lrint.
> 
> gcc/testsuite/
> 	PR target/106769
> 	* gcc.target/powerpc/pr88558.h: New.
> 	* gcc.target/powerpc/pr88558-p7.c: New.
> 	* gcc.target/powerpc/pr88558-p8v.c: New.
> 
> patch.diff
> diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
> index fd263e8dfe3..b36304de8c6 100644
> --- a/gcc/config/rs6000/rs6000.md
> +++ b/gcc/config/rs6000/rs6000.md
> @@ -6655,10 +6655,18 @@ (define_insn "lrint<mode>di2"
>    [(set (match_operand:DI 0 "gpc_reg_operand" "=d")
>  	(unspec:DI [(match_operand:SFDF 1 "gpc_reg_operand" "<rreg2>")]
>  		   UNSPEC_FCTID))]
> -  "TARGET_HARD_FLOAT && TARGET_FPRND"
> +  "TARGET_HARD_FLOAT"
>    "fctid %0,%1"
>    [(set_attr "type" "fp")])
> 
> +(define_insn "lrint<mode>si2"
> +  [(set (match_operand:SI 0 "gpc_reg_operand" "=d")
> +	(unspec:SI [(match_operand:SFDF 1 "gpc_reg_operand" "<rreg2>")]
> +		   UNSPEC_FCTIW))]

It surprises me that we have UNSPEC_FCTIW but it's unused before. :)

> +  "TARGET_HARD_FLOAT && TARGET_POPCNTD"
> +  "fctiw %0,%1"
> +  [(set_attr "type" "fp")])
> +
>  (define_insn "btrunc<mode>2"
>    [(set (match_operand:SFDF 0 "gpc_reg_operand" "=d,wa")
>  	(unspec:SFDF [(match_operand:SFDF 1 "gpc_reg_operand" "d,wa")]
> diff --git a/gcc/testsuite/gcc.target/powerpc/pr88558-p7.c b/gcc/testsuite/gcc.target/powerpc/pr88558-p7.c
> new file mode 100644
> index 00000000000..6437c55fa61
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/pr88558-p7.c
> @@ -0,0 +1,10 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fno-math-errno -mdejagnu-cpu=power7" } */

Nit: Maybe add one comment for why -fno-math-errno is needed,
such as: "-fno-math-errno is required to make {i,l,ll}rint inlined".

> +
> +#include "pr88558.h"
> +
> +/* { dg-final { scan-assembler-times {\mfctid\M} 2 { target lp64 } } } */
> +/* { dg-final { scan-assembler-times {\mfctid\M} 1 { target ilp32 } } } */
> +/* { dg-final { scan-assembler-times {\mfctiw\M} 1 { target lp64 } } } */
> +/* { dg-final { scan-assembler-times {\mfctiw\M} 2 { target ilp32 } } } */
> +/* { dg-final { scan-assembler-times {\mstfiwx\M} 1 } } */

Shouldn't we also expect different expected count for stfiwx for lp64 and ilp32?
1 for lp64 and 2 for ilp32? no?

> diff --git a/gcc/testsuite/gcc.target/powerpc/pr88558-p8v.c b/gcc/testsuite/gcc.target/powerpc/pr88558-p8v.c
> new file mode 100644
> index 00000000000..fd22123ffb6
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/pr88558-p8v.c

Nit: Maybe just name this with "-p8.c" instead of "-p8v.c".

> @@ -0,0 +1,24 @@
> +/* { dg-do compile } */
> +/* { dg-require-effective-target powerpc_p8vector_ok } */
> +/* { dg-options "-O2 -fno-math-errno -mdejagnu-cpu=power8" } */
> +
> +long int foo (double a)
> +{
> +  return __builtin_lrint (a);
> +}
> +
> +long long bar (double a)
> +{
> +  return __builtin_llrint (a);
> +}
> +
> +int baz (double a)
> +{
> +  return __builtin_irint (a);
> +}

I think you want to use #include "pr88558.h" here, wrong revision?

> +
> +/* { dg-final { scan-assembler-times {\mfctid\M} 2 { target lp64 } } } */
> +/* { dg-final { scan-assembler-times {\mfctid\M} 1 { target ilp32 } } } */
> +/* { dg-final { scan-assembler-times {\mfctiw\M} 1 { target lp64 } } } */
> +/* { dg-final { scan-assembler-times {\mfctiw\M} 2 { target ilp32 } } } */
> +/* { dg-final { scan-assembler-times {\mmfvsrwz\M} 1 } } */

Similar question on mfvsrwz counts (to the above stfiwx).

> diff --git a/gcc/testsuite/gcc.target/powerpc/pr88558.h b/gcc/testsuite/gcc.target/powerpc/pr88558.h
> new file mode 100644
> index 00000000000..0cc0c68dd4e
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/pr88558.h
> @@ -0,0 +1,14 @@
> +long int foo (double a)
> +{
> +  return __builtin_lrint (a);
> +}
> +
> +long long bar (double a)
> +{
> +  return __builtin_llrint (a);
> +}
> +
> +int baz (double a)
> +{
> +  return __builtin_irint (a);
> +}
> 

The PR also mentioned lrintf, I think we can also add some cases for
the coverage?

BR,
Kewen