[PATCH, GCC, AARCH64] Add support for +profile extension

[Andre Vieira (lists)]

On 17/07/18 16:23, James Greenhalgh wrote:
> On Mon, Jul 09, 2018 at 08:20:53AM -0500, Andre Vieira (lists) wrote:
>> Hi,
>>
>> This patch adds support for the Statistical Profiling Extension (SPE) on
>> AArch64. Even though the compiler will not generate code any differently
>> given this extension, it will need to pass it on to the assembler in
>> order to let it correctly assemble inline asm containing accesses to the
>> extension's system registers.  The same applies when using the
>> preprocessor on an assembly file as this first must pass through cc1.
>>
>> I left the hwcaps string for SPE empty as the kernel does not define a
>> feature string for this extension.  The current effect of this is that
>> driver will disable profile feature bit in GCC.  This is OK though
>> because we don't, nor do we ever, enable this feature bit, as codegen is
>> not affect by the SPE support and more importantly the driver will still
>> pass the extension down to the assembler regardless.
> 
> Please make these conditions clear in the documentation. Something like.
> 
>> +@item profile
>> +Enable the Statistical Profiling extension.  This option only changes
>> +the behavior of the assembler, and does not change code generation.
> 
> Maybe worded better...
> 
>>
>> Boostrapped aarch64-none-linux-gnu and ran regression tests.
>>
>> Is it OK for trunk?
>>
>> gcc/ChangeLog:
>> 2018-07-09  Andre Vieira  <andre.simoesdiasvieira@arm.com>
>>
>> 	* config/aarch64/aarch64-option-extensions.def: New entry for profile
>> 	extension.
>> 	* config/aarch64/aarch64.h (AARCH64_FL_PROFILE): New.
>> 	* doc/invoke.texi (aarch64-feature-modifiers): New entry for profile
>> 	extension.
>>
>> gcc/testsuite/ChangeLog:
>> 2018-07-09 Andre Vieira <andre.simoesdiasvieira@arm.com>
>>
>> 	* gcc.target/aarch64/profile.c: New test.
> 
> This test will fail for targets with old assemblers. That isn't ideal, we
> don't normally add these assembler tests for new instructions for that
> reason. Personally I'd drop the test down to a compile-only and scan the
> assembler for "+profile".
> 
> OK with those changes.
> 

Committed with changes in r262882.

> Thanks,
> James
> 
> 
>> diff --git a/gcc/config/aarch64/aarch64-option-extensions.def b/gcc/config/aarch64/aarch64-option-extensions.def
>> index 5fe5e3f7dddf622a48a5b9458ef30449a886f395..69ab796a4e1a959b89ebb55b599919c442cfb088 100644
>> --- a/gcc/config/aarch64/aarch64-option-extensions.def
>> +++ b/gcc/config/aarch64/aarch64-option-extensions.def
>> @@ -105,4 +105,7 @@ AARCH64_OPT_EXTENSION("fp16fml", AARCH64_FL_F16FML, AARCH64_FL_FP | AARCH64_FL_F
>>     Disabling "sve" just disables "sve".  */
>>  AARCH64_OPT_EXTENSION("sve", AARCH64_FL_SVE, AARCH64_FL_FP | AARCH64_FL_SIMD | AARCH64_FL_F16, 0, "sve")
>>  
>> +/* Enabling/Disabling "profile" does not enable/disable any other feature.  */
>> +AARCH64_OPT_EXTENSION("profile", AARCH64_FL_PROFILE, 0, 0, "")
>> +
>>  #undef AARCH64_OPT_EXTENSION
>> diff --git a/gcc/config/aarch64/aarch64.h b/gcc/config/aarch64/aarch64.h
>> index f284e74bfb8c9bab2aa22cc6c5a67750cbbba3c2..c1218503bab19323eee1cca8b7e4bea8fbfcf573 100644
>> --- a/gcc/config/aarch64/aarch64.h
>> +++ b/gcc/config/aarch64/aarch64.h
>> @@ -158,6 +158,9 @@ extern unsigned aarch64_architecture_version;
>>  #define AARCH64_FL_SHA3	      (1 << 18)  /* Has ARMv8.4-a SHA3 and SHA512.  */
>>  #define AARCH64_FL_F16FML     (1 << 19)  /* Has ARMv8.4-a FP16 extensions.  */
>>  
>> +/* Statistical Profiling extensions.  */
>> +#define AARCH64_FL_PROFILE    (1 << 20)
>> +
>>  /* Has FP and SIMD.  */
>>  #define AARCH64_FL_FPSIMD     (AARCH64_FL_FP | AARCH64_FL_SIMD)
>>  
>> diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
>> index 56cd122b0d7b420e2b16ceb02907860879d3b9d7..4ca68a563297482afc75abed4a31c106af38caf7 100644
>> --- a/gcc/doc/invoke.texi
>> +++ b/gcc/doc/invoke.texi
>> @@ -14813,6 +14813,8 @@ instructions. Use of this option with architectures prior to Armv8.2-A is not su
>>  @item sm4
>>  Enable the sm3 and sm4 crypto extension.  This also enables Advanced SIMD instructions.
>>  Use of this option with architectures prior to Armv8.2-A is not supported.
>> +@item profile
>> +Enable the Statistical Profiling extension.
>>  
>>  @end table
>>  
>> diff --git a/gcc/testsuite/gcc.target/aarch64/profile.c b/gcc/testsuite/gcc.target/aarch64/profile.c
>> new file mode 100644
>> index 0000000000000000000000000000000000000000..db51b4746dd60009d784bc0b37ea99b2f120d856
>> --- /dev/null
>> +++ b/gcc/testsuite/gcc.target/aarch64/profile.c
>> @@ -0,0 +1,9 @@
>> +/* { dg-do assemble } */
>> +/* { dg-options "-std=gnu99 -march=armv8.2-a+profile" } */
>> +
>> +int foo (void)
>> +{
>> +  int ret;
>> +  asm ("mrs  %0, pmblimitr_el1" : "=r" (ret));
>> +  return ret;
>> +}
> 

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