Ping.
I have incorporated review comments from Peter in this revised patch. The
comment was to remove -mvsx option from dg-options as this is implied by
-mcpu=power8.
Ok for trunk?
Regards,
Surya
On 09/01/25 8:53 pm, Surya Kumari Jangala wrote:
> Ping
>
> On 02/12/24 2:20 pm, Surya Kumari Jangala wrote:
>> I have incorporated review comments in this patch.
>>
>> Regards,
>> Surya
>>
>>
>> rs6000: Inefficient vector splat of small V2DI constants [PR107757]
>>
>> On P8, for vector splat of double word constants, specifically -1 and 1,
>> gcc generates inefficient code. For -1, gcc generates two instructions
>> (vspltisw and vupkhsw) whereas only one instruction (vspltisw) is
>> sufficient. For constant 1, gcc generates a load of the constant from
>> .rodata instead of the instructions vspltisw and vupkhsw.
>>
>> The routine vspltisw_vupkhsw_constant_p() returns true if the constant
>> can be synthesized with instructions vspltisw and vupkhsw. However, for
>> constant 1, this routine returns false.
>>
>> For constant -1, this routine returns true. Vector splat of -1 can be
>> done with only one instruction, i.e., vspltisw. We do not need two
>> instructions. Hence this routine should return false for -1.
>>
>> With this patch, gcc generates only one instruction (vspltisw)
>> for -1. And for constant 1, this patch generates two instructions
>> (vspltisw and vupkhsw).
>>
>> 2024-11-20 Surya Kumari Jangala <jskum...@linux.ibm.com>
>>
>> gcc/
>> PR target/107757
>> * config/rs6000/rs6000.cc (vspltisw_vupkhsw_constant_p):
>> Return false for -1 and return true for 1.
>>
>> gcc/testsuite/
>> PR target/107757
>> * gcc.target/powerpc/pr107757-1.c: New.
>> * gcc.target/powerpc/pr107757-2.c: New.
>> ---
>> gcc/config/rs6000/rs6000.cc | 2 +-
>> gcc/testsuite/gcc.target/powerpc/pr107757-1.c | 14 ++++++++++++++
>> gcc/testsuite/gcc.target/powerpc/pr107757-2.c | 13 +++++++++++++
>> 3 files changed, 28 insertions(+), 1 deletion(-)
>> create mode 100644 gcc/testsuite/gcc.target/powerpc/pr107757-1.c
>> create mode 100644 gcc/testsuite/gcc.target/powerpc/pr107757-2.c
>>
>> diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc
>> index 02a2f1152db..d0c528f4d5f 100644
>> --- a/gcc/config/rs6000/rs6000.cc
>> +++ b/gcc/config/rs6000/rs6000.cc
>> @@ -6652,7 +6652,7 @@ vspltisw_vupkhsw_constant_p (rtx op, machine_mode
>> mode, int *constant_ptr)
>> return false;
>>
>> value = INTVAL (elt);
>> - if (value == 0 || value == 1
>> + if (value == 0 || value == -1
>> || !EASY_VECTOR_15 (value))
>> return false;
>>
>> diff --git a/gcc/testsuite/gcc.target/powerpc/pr107757-1.c
>> b/gcc/testsuite/gcc.target/powerpc/pr107757-1.c
>> new file mode 100644
>> index 00000000000..49076fba255
>> --- /dev/null
>> +++ b/gcc/testsuite/gcc.target/powerpc/pr107757-1.c
>> @@ -0,0 +1,14 @@
>> +/* { dg-do compile } */
>> +/* { dg-options "-mdejagnu-cpu=power8 -O2" } */
>> +/* { dg-require-effective-target powerpc_vsx } */
>> +/* { dg-final { scan-assembler {\mvspltisw\M} } } */
>> +/* { dg-final { scan-assembler {\mvupkhsw\M} } } */
>> +/* { dg-final { scan-assembler-not {\mlvx\M} } } */
>> +
>> +#include <altivec.h>
>> +
>> +vector long long
>> +foo ()
>> +{
>> + return vec_splats (1LL);
>> +}
>> diff --git a/gcc/testsuite/gcc.target/powerpc/pr107757-2.c
>> b/gcc/testsuite/gcc.target/powerpc/pr107757-2.c
>> new file mode 100644
>> index 00000000000..4955696f11d
>> --- /dev/null
>> +++ b/gcc/testsuite/gcc.target/powerpc/pr107757-2.c
>> @@ -0,0 +1,13 @@
>> +/* { dg-do compile } */
>> +/* { dg-options "-mdejagnu-cpu=power8 -O2" } */
>> +/* { dg-require-effective-target powerpc_vsx } */
>> +/* { dg-final { scan-assembler {\mvspltisw\M} } } */
>> +/* { dg-final { scan-assembler-not {\mvupkhsw\M} } } */
>> +
>> +#include <altivec.h>
>> +
>> +vector long long
>> +foo ()
>> +{
>> + return vec_splats (~0LL);
>> +}
>
