[PATCH, V2] Do not enable -mblock-ops-vector-pair.

[PATCH, V2] Do not enable -mblock-ops-vector-pair.

[Michael Meissner]

Do not enable -mblock-ops-vector-pair.

Testing has shown that using the load vector pair and store vector pair
instructions for block moves has some performance issues on power10.

A patch on June 11th modified the code so that GCC would not set
-mblock-ops-vector-pair by default if we are tuning for power10, but it
would set the option if we were tuning for a different machine and have
load and store vector pair instructions enabled.

This patch eliminates the code setting -mblock-ops-vector-pair.  If you
want to generate load vector pair and store vector pair instructions for
block moves, you must use -mblock-ops-vector-pair.

2022-07-25   Michael Meissner  <meissner@linux.ibm.com>

gcc/

	* config/rs6000/rs6000.cc (rs6000_option_override_internal): Remove
	code setting -mblock-ops-vector-pair.

---
 gcc/config/rs6000/rs6000.cc | 11 -----------
 1 file changed, 11 deletions(-)

diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc
index 3ff16b8ae04..667f83b1dfd 100644
--- a/gcc/config/rs6000/rs6000.cc
+++ b/gcc/config/rs6000/rs6000.cc
@@ -4139,17 +4139,6 @@ rs6000_option_override_internal (bool global_init_p)
 	rs6000_isa_flags &= ~OPTION_MASK_BLOCK_OPS_UNALIGNED_VSX;
     }
 
-  if (!(rs6000_isa_flags_explicit & OPTION_MASK_BLOCK_OPS_VECTOR_PAIR))
-    {
-      /* Do not generate lxvp and stxvp on power10 since there are some
-	 performance issues.  */
-      if (TARGET_MMA && TARGET_EFFICIENT_UNALIGNED_VSX
-	  && rs6000_tune != PROCESSOR_POWER10)
-	rs6000_isa_flags |= OPTION_MASK_BLOCK_OPS_VECTOR_PAIR;
-      else
-	rs6000_isa_flags &= ~OPTION_MASK_BLOCK_OPS_VECTOR_PAIR;
-    }
-
   /* Use long double size to select the appropriate long double.  We use
      TYPE_PRECISION to differentiate the 3 different long double types.  We map
      128 into the precision used for TFmode.  */
-- 
2.35.3


-- 
Michael Meissner, IBM
PO Box 98, Ayer, Massachusetts, USA, 01432
email: meissner@linux.ibm.com

Ping: [PATCH, V2] Do not enable -mblock-ops-vector-pair.

[Michael Meissner]

Ping patch.

| Date: Mon, 25 Jul 2022 16:15:05 -0400
| Subject: [PATCH, V2] Do not enable -mblock-ops-vector-pair.
| Message-ID: <Yt75yUWKIqoWI5kZ@toto.the-meissners.org>

-- 
Michael Meissner, IBM
PO Box 98, Ayer, Massachusetts, USA, 01432
email: meissner@linux.ibm.com

Re: [PATCH, V2] Do not enable -mblock-ops-vector-pair.

[Segher Boessenkool]

Hi Mike,

On Mon, Jul 25, 2022 at 04:15:05PM -0400, Michael Meissner wrote:
> Testing has shown that using the load vector pair and store vector pair
> instructions for block moves has some performance issues on power10.

> This patch eliminates the code setting -mblock-ops-vector-pair.  If you
> want to generate load vector pair and store vector pair instructions for
> block moves, you must use -mblock-ops-vector-pair.
> 
> 2022-07-25   Michael Meissner  <meissner@linux.ibm.com>
> 
> gcc/
> 
> 	* config/rs6000/rs6000.cc (rs6000_option_override_internal): Remove
> 	code setting -mblock-ops-vector-pair.

Okay for trunk (and any backports you may need).  Thanks!


Segher