Re: [AArch64][PR65139] use clobber with match_scratch for aarch64_lshr_sisd_or_int_3

[Kugan]

On 15/04/15 22:32, Jakub Jelinek wrote:
> On Wed, Apr 15, 2015 at 01:18:36PM +0100, Richard Earnshaw wrote:
>> On 14/04/15 22:41, Kugan wrote:
>>> This patch uses clobber with match_scratch instead of earlyclobber for
>>> aarch64_lshr_sisd_or_int_<mode>3 so that RA can have more freedom in
>>> selecting suitable register, as discussed in
>>> http://thread.gmane.org/gmane.comp.gcc.patches/336162 and reported in
>>> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65139.
>>>
>>> This is based on Maxim's patch. I have bootstrapped and regression
>>> tested on aarch64-linux-gnu with no new regressions. Is this OK for trunk?
>>>
>>> Thanks,
>>> Kugan
>>>
>>> gcc/ChangeLog:
>>>
>>> 2015-04-15  Kugan Vivekanandarajah  <kug...@linaro.org>
>>>         Maxim Kuvyrkov  <maxim.kuvyr...@linaro.org>
>>>
>>>     PR target/65139
>>>     * config/aarch64/aarch64.md (<optab><mode>3): Expand lshr with
>>>      gen_aarch64_lshr_sisd_or_int_<mode>3.
>>>     (*aarch64_lshr_sisd_or_int_<mode>3): Rename to
>>>      aarch64_lshr_sisd_or_int_<mode>3 and use clobber with
>>>      match_scratch instead of early clobber.
>>>
>>
>> +    if (strcmp ("<optab>", "lshr") == 0)
>> +      {
>>
>>
>> This can't be the best way to match the operation type.  Yes, I know that
>> the comparison is a compile time invariant, but there must be an attribute
>> of optab (or one can be created for it) that would make the test trivial and
>> not rely on the compiler optimizing the strcmp away.
> 
> Perhaps just
>   if (<CODE> == LSHIFTRT)
>     {

Thanks. I have now changed it as above and reran the regression.

Richard, is this OK to you?

Kugan

diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md
index 534a862..4a16529 100644
--- a/gcc/config/aarch64/aarch64.md
+++ b/gcc/config/aarch64/aarch64.md
@@ -3277,6 +3277,12 @@
            DONE;
           }
       }
+
+    if (<CODE> == LSHIFTRT)
+      {
+        emit_insn (gen_aarch64_lshr_sisd_or_int_<mode>3 (operands[0], 
operands[1], operands[2]));
+        DONE;
+      }
   }
 )
 
@@ -3361,11 +3367,12 @@
 )
 
 ;; Logical right shift using SISD or Integer instruction
-(define_insn "*aarch64_lshr_sisd_or_int_<mode>3"
-  [(set (match_operand:GPI 0 "register_operand" "=w,&w,r")
+(define_insn "aarch64_lshr_sisd_or_int_<mode>3"
+  [(set (match_operand:GPI 0 "register_operand" "=w,w,r")
         (lshiftrt:GPI
           (match_operand:GPI 1 "register_operand" "w,w,r")
-          (match_operand:QI 2 "aarch64_reg_or_shift_imm_<mode>" 
"Us<cmode>,w,rUs<cmode>")))]
+          (match_operand:QI 2 "aarch64_reg_or_shift_imm_<mode>" 
"Us<cmode>,w,rUs<cmode>")))
+   (clobber (match_scratch:QI 3 "=X,w,X"))]
   ""
   "@
    ushr\t%<rtn>0<vas>, %<rtn>1<vas>, %2
@@ -3379,30 +3386,28 @@
   [(set (match_operand:DI 0 "aarch64_simd_register")
         (lshiftrt:DI
            (match_operand:DI 1 "aarch64_simd_register")
-           (match_operand:QI 2 "aarch64_simd_register")))]
+           (match_operand:QI 2 "aarch64_simd_register")))
+   (clobber (match_scratch:QI 3))]
   "TARGET_SIMD && reload_completed"
   [(set (match_dup 3)
         (unspec:QI [(match_dup 2)] UNSPEC_SISD_NEG))
    (set (match_dup 0)
         (unspec:DI [(match_dup 1) (match_dup 3)] UNSPEC_SISD_USHL))]
-  {
-    operands[3] = gen_lowpart (QImode, operands[0]);
-  }
+  ""
 )
 
 (define_split
   [(set (match_operand:SI 0 "aarch64_simd_register")
         (lshiftrt:SI
            (match_operand:SI 1 "aarch64_simd_register")
-           (match_operand:QI 2 "aarch64_simd_register")))]
+           (match_operand:QI 2 "aarch64_simd_register")))
+   (clobber (match_scratch:QI 3))]
   "TARGET_SIMD && reload_completed"
   [(set (match_dup 3)
         (unspec:QI [(match_dup 2)] UNSPEC_SISD_NEG))
    (set (match_dup 0)
         (unspec:SI [(match_dup 1) (match_dup 3)] UNSPEC_USHL_2S))]
-  {
-    operands[3] = gen_lowpart (QImode, operands[0]);
-  }
+  ""
 )
 
 ;; Arithmetic right shift using SISD or Integer instruction