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[ARM] PR60663: Improve RTX costs for asm statements

Message ID 534D3CC1.9080504@arm.com
State New
Headers show

Commit Message

Kyrylo Tkachov April 15, 2014, 2:05 p.m. UTC 
On 15/04/14 14:55, Richard Earnshaw wrote:
> On 15/04/14 11:56, Kyrill Tkachov wrote:
>> Hi all,
>>
>> This patch relates to PR60663 where cse got confused due to asm statements being given a cost of zero in the arm backend. Jakub already put in a fix to cse for 4.9.0 (http://gcc.gnu.org/ml/gcc-patches/2014-04/msg00512.html) but we should still fix the costs in arm.
>>
>> This patch does that by estimating the number of instructions in the asm statement, adding the cost of the input operands and making sure that it's at least COSTS_N_INSNS (1).
>>
>> Tested and bootstrapped on arm-none-linux-gnueabihf.
>>
>> Ok for trunk?
>>
>> Thanks,
>> Kyrill
>>
>> 2014-04-15  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
>>
>> 	PR rtl-optimization/60663
>> 	* config/arm/arm.c (arm_new_rtx_costs): Improve ASM_OPERANDS case,
>> 	avoid 0 cost.
>>
> I'd be inclined to use 1 + number of operands, rather than MAX.
>
> OK with that change.

Thanks Richard,

I've committed this slightly modified version as version as r209419.

Kyrill

>
> R.
>
>> pr60663.patch
>>
>>
>> diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
>> index 91e4cd8..ce7ee82 100644
>> --- a/gcc/config/arm/arm.c
>> +++ b/gcc/config/arm/arm.c
>> @@ -10758,10 +10758,16 @@ arm_new_rtx_costs (rtx x, enum rtx_code code, enum rtx_code outer_code,
>>         return true;
>>   
>>       case ASM_OPERANDS:
>> -      /* Just a guess.  Cost one insn per input.  */
>> -      *cost = COSTS_N_INSNS (ASM_OPERANDS_INPUT_LENGTH (x));
>> -      return true;
>> +      {
>> +      /* Just a guess.  Guess number of instructions in the asm
>> +         plus one insn per input.  Always a minimum of COSTS_N_INSNS (1)
>> +         though (see PR60663).  */
>> +        int asm_length = asm_str_count (ASM_OPERANDS_TEMPLATE (x));
>> +        int num_operands = ASM_OPERANDS_INPUT_LENGTH (x);
>>   
>> +        *cost = COSTS_N_INSNS (MAX (1, asm_length + num_operands));
>> +        return true;
>> +      }
>>       default:
>>         if (mode != VOIDmode)
>>   	*cost = COSTS_N_INSNS (ARM_NUM_REGS (mode));
>>
diff mbox

Patch

diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
index e5cf503..773c353 100644
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -10670,10 +10670,16 @@  arm_new_rtx_costs (rtx x, enum rtx_code code, enum rtx_code outer_code,
       return true;
 
     case ASM_OPERANDS:
-      /* Just a guess.  Cost one insn per input.  */
-      *cost = COSTS_N_INSNS (ASM_OPERANDS_INPUT_LENGTH (x));
-      return true;
+      {
+      /* Just a guess.  Guess number of instructions in the asm
+         plus one insn per input.  Always a minimum of COSTS_N_INSNS (1)
+         though (see PR60663).  */
+        int asm_length = MAX (1, asm_str_count (ASM_OPERANDS_TEMPLATE (x)));
+        int num_operands = ASM_OPERANDS_INPUT_LENGTH (x);
 
+        *cost = COSTS_N_INSNS (asm_length + num_operands);
+        return true;
+      }
     default:
       if (mode != VOIDmode)
 	*cost = COSTS_N_INSNS (ARM_NUM_REGS (mode));