[PATCH] rs6000: Change bitwise xor to inequality operator [PR106907]

[PATCH] rs6000: Change bitwise xor to inequality operator [PR106907]

[P Jeevitha]

PR106907 has few warnings spotted from cppcheck. Here we have
warnings for precedence clarification since boolean results are
used in bitwise operation. Bitwise xor performed on bool
is similar to checking inequality. So changed to inequality
operator (!=) instead of bitwise xor (^). And fixed comment indentation

2023-06-12  Jeevitha Palanisamy  <jeevitha@linux.ibm.com>

gcc/
	PR target/106907
	* config/rs6000/rs6000.cc (altivec_expand_vec_perm_const): Change bitwise
	xor to inequality and fix comment indentation.


diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc
index ea68ca6faef..ea7efda8dcd 100644
--- a/gcc/config/rs6000/rs6000.cc
+++ b/gcc/config/rs6000/rs6000.cc
@@ -23396,10 +23396,10 @@ altivec_expand_vec_perm_const (rtx target, rtx op0, rtx op1,
 		      && GET_MODE (XEXP (op0, 0)) != V8HImode)))
 	    continue;
 
-          /* For little-endian, the two input operands must be swapped
-             (or swapped back) to ensure proper right-to-left numbering
-             from 0 to 2N-1.  */
-	  if (swapped ^ !BYTES_BIG_ENDIAN
+	  /* For little-endian, the two input operands must be swapped
+	     (or swapped back) to ensure proper right-to-left numbering
+	     from 0 to 2N-1.  */
+	  if (swapped != !BYTES_BIG_ENDIAN
 	      && icode != CODE_FOR_vsx_xxpermdi_v16qi)
 	    std::swap (op0, op1);
 	  if (imode != V16QImode)

Re: [PATCH] rs6000: Change bitwise xor to inequality operator [PR106907]

[Peter Bergner]

On 6/12/23 6:18 AM, P Jeevitha wrote:
> Bitwise xor performed on bool
> is similar to checking inequality. So changed to inequality
> operator (!=) instead of bitwise xor (^).
[snip'
> -	  if (swapped ^ !BYTES_BIG_ENDIAN
[snip]
> +	  if (swapped != !BYTES_BIG_ENDIAN

I know Andreas mentioned using "swapped != !BYTES_BIG_ENDIAN" in
the bugzilla, but that's the same as "swapped == BYTES_BIG_ENDIAN",
and it doesn't contain a double-negative and seems a little clearer.

It's up to Segher though...and if we go with this, then the ChangeLog
entry needs to be updated slightly since we're no longer testing for
inequality.

Peter

Re: [PING^1][PATCH] rs6000: Change bitwise xor to inequality operator [PR106907]

[jeevitha]

Ping!

please review.

Thanks & Regards
Jeevitha

On 16/06/23 9:55 am, Peter Bergner wrote:
> On 6/12/23 6:18 AM, P Jeevitha wrote:
>> Bitwise xor performed on bool
>> is similar to checking inequality. So changed to inequality
>> operator (!=) instead of bitwise xor (^).
> [snip'
>> -	  if (swapped ^ !BYTES_BIG_ENDIAN
> [snip]
>> +	  if (swapped != !BYTES_BIG_ENDIAN
> 
> I know Andreas mentioned using "swapped != !BYTES_BIG_ENDIAN" in
> the bugzilla, but that's the same as "swapped == BYTES_BIG_ENDIAN",
> and it doesn't contain a double-negative and seems a little clearer.
> 
> It's up to Segher though...and if we go with this, then the ChangeLog
> entry needs to be updated slightly since we're no longer testing for
> inequality.
> 
> Peter
>