Re: [PATCH v3 2/9] Introduce rtx_alloca, alloca_raw_REG and alloca_rtx_fmt_*

[Ilya Leoshkevich <iii at linux dot ibm dot com>]

> Am 06.09.2019 um 14:40 schrieb Richard Sandiford <richard.sandiford@arm.com>:
> 
> Ilya Leoshkevich <iii@linux.ibm.com> writes:
>> One of the next patches in series needs to frequently pass short-lived
>> fake rtxes to the back-end in order to test its capabilities.  In order
>> to reduce the load on GC, it is beneficial to allocate these rtxes on
>> stack.
>> 
>> Provide the macro counterparts of gen_* functions required by the next
>> patch in series.
>> 
>> gcc/ChangeLog:
>> 
>> 2019-08-27  Ilya Leoshkevich  <iii@linux.ibm.com>
>> 
>> 	PR target/77918
>> 	* emit-rtl.c (gen_raw_REG): Use init_raw_REG.
>> 	(init_raw_REG): New function.
>> 	* gengenrtl.c (gendef): Emit init_* functions and alloca_*
>> 	macros.
>> 	* rtl.c (rtx_alloc_stat_v): Use rtx_init.
>> 	* rtl.h (rtx_init): New function.
>> 	(rtx_alloca): New function.
>> 	(init_raw_REG): New function.
>> 	(alloca_raw_REG): New macro.
>> ---
>> gcc/emit-rtl.c  | 15 +++++++++---
>> gcc/gengenrtl.c | 64 +++++++++++++++++++++++++++++++++++++------------
>> gcc/rtl.c       |  7 +-----
>> gcc/rtl.h       | 12 ++++++++++
>> 4 files changed, 74 insertions(+), 24 deletions(-)
>> 
>> diff --git a/gcc/emit-rtl.c b/gcc/emit-rtl.c
>> index a667cdab94e..ecfa3735bba 100644
>> --- a/gcc/emit-rtl.c
>> +++ b/gcc/emit-rtl.c
>> @@ -466,20 +466,29 @@ set_mode_and_regno (rtx x, machine_mode mode, unsigned int regno)
>>   set_regno_raw (x, regno, nregs);
>> }
>> 
>> -/* Generate a new REG rtx.  Make sure ORIGINAL_REGNO is set properly, and
>> +/* Initialize a REG rtx.  Make sure ORIGINAL_REGNO is set properly, and
>>    don't attempt to share with the various global pieces of rtl (such as
>>    frame_pointer_rtx).  */
>> 
>> rtx
>> -gen_raw_REG (machine_mode mode, unsigned int regno)
>> +init_raw_REG (rtx x, machine_mode mode, unsigned int regno)
>> {
>> -  rtx x = rtx_alloc (REG MEM_STAT_INFO);
>>   set_mode_and_regno (x, mode, regno);
>>   REG_ATTRS (x) = NULL;
>>   ORIGINAL_REGNO (x) = regno;
>>   return x;
>> }
>> 
>> +/* Generate a new REG rtx.  */
>> +
>> +rtx
>> +gen_raw_REG (machine_mode mode, unsigned int regno)
>> +{
>> +  rtx x = rtx_alloc (REG MEM_STAT_INFO);
>> +  init_raw_REG (x, mode, regno);
>> +  return x;
>> +}
>> +
> 
> I think we should keep the gen_raw_REG comment the same (including
> the "Make sure..." bit).  The point is to contrast gen_raw_REG with
> gen_rtx_REG, which does various bits of sharing.
> 
> Maybe the comment above init_raw_REG can instead be just:
> 
> /* Initialize a fresh REG rtx with mode MODE and register REGNO.  */
> 
>> [...]
>> @@ -266,16 +261,55 @@ gendef (const char *format)
>>     else
>>       printf ("  %s (rt, %d) = arg%d;\n", accessor_from_format (*p), i, j++);
>> 
>> -  puts ("\n  return rt;\n}\n");
>> +  puts ("  return rt;\n}\n");
>> +
>> +  /* Write the definition of the gen function name and the types
>> +     of the arguments.  */
>> +
>> +  puts ("static inline rtx");
>> +  printf ("gen_rtx_fmt_%s_stat (RTX_CODE code, machine_mode mode", format);
>> +  for (p = format, i = 0; *p != 0; p++)
>> +    if (*p != '0')
>> +      printf (",\n\t%sarg%d", type_from_format (*p), i++);
>> +  puts (" MEM_STAT_DECL)");
>> +
>> +  /* Now write out the body of the function itself, which allocates
>> +     the memory and initializes it.  */
>> +  puts ("{");
>> +  puts ("  rtx rt;\n");
>> +
>> +  puts ("  rt = rtx_alloc (code PASS_MEM_STAT);");
>> +  printf ("  init_rtx_fmt_%s (rt, mode", format);
>> +  for (p = format, i = 0; *p != 0; p++)
>> +    if (*p != '0')
>> +      printf (", arg%d", i++);
>> +  puts (");\n");
>> +
>> +  puts ("  return rt;\n}\n");
> 
> Might as well make it:
> 
>  printf ("  return init_rtx_fmt_%s (rt, mode", format);
> 
> and drop the separate return, for consistency with the new
> alloca code.
> 
> OK with those changes, thanks.

I've made the changes and committed the patch:

https://gcc.gnu.org/viewcvs/gcc?view=revision&revision=276303

Thanks for the review!