diff mbox series

Refactor wi::bswap as a function (instead of a method).

Message ID 005301d99195$e9524d60$bbf6e820$@nextmovesoftware.com
State New
Headers
Series Refactor wi::bswap as a function (instead of a method). |

Commit Message

Roger Sayle May 28, 2023, 6:55 p.m. UTC 
  This patch implements Richard Sandiford's suggestion from
https://gcc.gnu.org/pipermail/gcc-patches/2023-May/618215.html
that wi::bswap (and a new wi::bitreverse) should be functions,
and ideally only accessors are member functions.  This patch
implements the first step, moving/refactoring wi::bswap.

This patch has been tested on x86_64-pc-linux-gnu with make bootstrap
and make -k check, both with and without --target_board=unix{-m32}
with no new failures.  Ok for mainline?


2023-05-28  Roger Sayle  <roger@nextmovesoftware.com>

gcc/ChangeLog
        * fold-const-call.cc (fold_const_call_ss) <CFN_BUILT_IN_BSWAP*>:
        Update call to wi::bswap.
        * simplify-rtx.cc (simplify_const_unary_operation) <case BSWAP>:
        Update call to wi::bswap.
        * tree-ssa-ccp.cc (evaluate_stmt) <case BUILT_IN_BSWAP*>:
        Update calls to wi::bswap.

        * wide-int.cc (wide_int_storage::bswap): Remove/rename to...
        (wi::bswap_large): New function, with revised API.
        * wide-int.h (wi::bswap): New (template) function prototype.
        (wide_int_storage::bswap): Remove method.
        (sext_large, zext_large): Consistent indentation/line wrapping.
        (bswap_large): Prototype helper function containing implementation.
        (wi::bswap): New template wrapper around bswap_large.


Thanks,
Roger
--

Comments

Richard Sandiford May 30, 2023, 7:09 p.m. UTC | #1 
"Roger Sayle" <roger@nextmovesoftware.com> writes:
> This patch implements Richard Sandiford's suggestion from
> https://gcc.gnu.org/pipermail/gcc-patches/2023-May/618215.html
> that wi::bswap (and a new wi::bitreverse) should be functions,
> and ideally only accessors are member functions.  This patch
> implements the first step, moving/refactoring wi::bswap.
>
> This patch has been tested on x86_64-pc-linux-gnu with make bootstrap
> and make -k check, both with and without --target_board=unix{-m32}
> with no new failures.  Ok for mainline?

Thanks for doing this.  OK with a minor change:

> diff --git a/gcc/wide-int.h b/gcc/wide-int.h
> index 3d9b87c..a2b3371 100644
> --- a/gcc/wide-int.h
> +++ b/gcc/wide-int.h
> @@ -552,6 +552,7 @@ namespace wi
>    UNARY_FUNCTION sext (const T &, unsigned int);
>    UNARY_FUNCTION zext (const T &, unsigned int);
>    UNARY_FUNCTION set_bit (const T &, unsigned int);
> +  UNARY_FUNCTION bswap (const T &);
>  
>    BINARY_FUNCTION min (const T1 &, const T2 &, signop);
>    BINARY_FUNCTION smin (const T1 &, const T2 &);
> @@ -1086,9 +1087,6 @@ public:
>    static wide_int from_array (const HOST_WIDE_INT *, unsigned int,
>  			      unsigned int, bool = true);
>    static wide_int create (unsigned int);
> -
> -  /* FIXME: target-dependent, so should disappear.  */
> -  wide_int bswap () const;
>  };

I think the comment was referring to the fact that the function
swaps octets regardless of BITS_PER_UNIT.  That might be the right
behaviour, but it might not.  It's difficult to say when there are
no BITS_PER_UNIT!=8 targets left.

The patch is moving in the right direction by defining the function
outside the class.  If it turns out that BITS_PER_UNIT should matter,
we could later move the implementation to somewhere that is sensitive
to the target.

So...

> @@ -2267,6 +2266,18 @@ wi::set_bit (const T &x, unsigned int bit)
>    return result;
>  }
>  
> +/* Byte swap the integer X.  */

...how about adding:

/* ??? This always swaps octets, regardless of BITS_PER_UNIT.  If the
   function should instead be sensitive to BITS_PER_UNIT, we should either
   pass that in or move the function to somewhere where the target
   configuration is available.  */

Feel free to reword to something you think is clearer.

OK with that or a similar change, thanks.

Richard

> +template <typename T>
> +inline WI_UNARY_RESULT (T)
> +wi::bswap (const T &x)
> +{
> +  WI_UNARY_RESULT_VAR (result, val, T, x);
> +  unsigned int precision = get_precision (result);
> +  WIDE_INT_REF_FOR (T) xi (x, precision);
> +  result.set_len (bswap_large (val, xi.val, xi.len, precision));
> +  return result;
> +}
> +
diff mbox series

Patch

diff --git a/gcc/fold-const-call.cc b/gcc/fold-const-call.cc
index 340cb66..663eae2 100644
--- a/gcc/fold-const-call.cc
+++ b/gcc/fold-const-call.cc
@@ -1060,7 +1060,8 @@  fold_const_call_ss (wide_int *result, combined_fn fn, const wide_int_ref &arg,
     case CFN_BUILT_IN_BSWAP32:
     case CFN_BUILT_IN_BSWAP64:
     case CFN_BUILT_IN_BSWAP128:
-      *result = wide_int::from (arg, precision, TYPE_SIGN (arg_type)).bswap ();
+      *result = wi::bswap (wide_int::from (arg, precision,
+					   TYPE_SIGN (arg_type)));
       return true;
 
     default:
diff --git a/gcc/simplify-rtx.cc b/gcc/simplify-rtx.cc
index d4aeebc..d93d632 100644
--- a/gcc/simplify-rtx.cc
+++ b/gcc/simplify-rtx.cc
@@ -2111,7 +2111,7 @@  simplify_const_unary_operation (enum rtx_code code, machine_mode mode,
 	  break;
 
 	case BSWAP:
-	  result = wide_int (op0).bswap ();
+	  result = wi::bswap (op0);
 	  break;
 
 	case TRUNCATE:
diff --git a/gcc/tree-ssa-ccp.cc b/gcc/tree-ssa-ccp.cc
index 6fb371c..26d5e44 100644
--- a/gcc/tree-ssa-ccp.cc
+++ b/gcc/tree-ssa-ccp.cc
@@ -2401,11 +2401,12 @@  evaluate_stmt (gimple *stmt)
 		  wide_int wval = wi::to_wide (val.value);
 		  val.value
 		    = wide_int_to_tree (type,
-					wide_int::from (wval, prec,
-							UNSIGNED).bswap ());
+					wi::bswap (wide_int::from (wval, prec,
+								   UNSIGNED)));
 		  val.mask
-		    = widest_int::from (wide_int::from (val.mask, prec,
-							UNSIGNED).bswap (),
+		    = widest_int::from (wi::bswap (wide_int::from (val.mask,
+								   prec,
+								   UNSIGNED)),
 					UNSIGNED);
 		  if (wi::sext (val.mask, prec) != -1)
 		    break;
diff --git a/gcc/wide-int.cc b/gcc/wide-int.cc
index c0987aa..1e4c046 100644
--- a/gcc/wide-int.cc
+++ b/gcc/wide-int.cc
@@ -731,16 +731,13 @@  wi::set_bit_large (HOST_WIDE_INT *val, const HOST_WIDE_INT *xval,
     }
 }
 
-/* bswap THIS.  */
-wide_int
-wide_int_storage::bswap () const
+/* Byte swap the integer represented by XVAL and LEN into VAL.  Return
+   the number of blocks in VAL.  Both XVAL and VAL have PRECISION bits.  */
+unsigned int
+wi::bswap_large (HOST_WIDE_INT *val, const HOST_WIDE_INT *xval,
+	         unsigned int len, unsigned int precision)
 {
-  wide_int result = wide_int::create (precision);
   unsigned int i, s;
-  unsigned int len = BLOCKS_NEEDED (precision);
-  unsigned int xlen = get_len ();
-  const HOST_WIDE_INT *xval = get_val ();
-  HOST_WIDE_INT *val = result.write_val ();
 
   /* This is not a well defined operation if the precision is not a
      multiple of 8.  */
@@ -758,7 +755,7 @@  wide_int_storage::bswap () const
       unsigned int block = s / HOST_BITS_PER_WIDE_INT;
       unsigned int offset = s & (HOST_BITS_PER_WIDE_INT - 1);
 
-      byte = (safe_uhwi (xval, xlen, block) >> offset) & 0xff;
+      byte = (safe_uhwi (xval, len, block) >> offset) & 0xff;
 
       block = d / HOST_BITS_PER_WIDE_INT;
       offset = d & (HOST_BITS_PER_WIDE_INT - 1);
@@ -766,8 +763,7 @@  wide_int_storage::bswap () const
       val[block] |= byte << offset;
     }
 
-  result.set_len (canonize (val, len, precision));
-  return result;
+  return canonize (val, len, precision);
 }
 
 /* Fill VAL with a mask where the lower WIDTH bits are ones and the bits
diff --git a/gcc/wide-int.h b/gcc/wide-int.h
index 3d9b87c..a2b3371 100644
--- a/gcc/wide-int.h
+++ b/gcc/wide-int.h
@@ -552,6 +552,7 @@  namespace wi
   UNARY_FUNCTION sext (const T &, unsigned int);
   UNARY_FUNCTION zext (const T &, unsigned int);
   UNARY_FUNCTION set_bit (const T &, unsigned int);
+  UNARY_FUNCTION bswap (const T &);
 
   BINARY_FUNCTION min (const T1 &, const T2 &, signop);
   BINARY_FUNCTION smin (const T1 &, const T2 &);
@@ -1086,9 +1087,6 @@  public:
   static wide_int from_array (const HOST_WIDE_INT *, unsigned int,
 			      unsigned int, bool = true);
   static wide_int create (unsigned int);
-
-  /* FIXME: target-dependent, so should disappear.  */
-  wide_int bswap () const;
 };
 
 namespace wi
@@ -1743,13 +1741,14 @@  namespace wi
   int cmpu_large (const HOST_WIDE_INT *, unsigned int, unsigned int,
 		  const HOST_WIDE_INT *, unsigned int);
   unsigned int sext_large (HOST_WIDE_INT *, const HOST_WIDE_INT *,
-			   unsigned int,
-			   unsigned int, unsigned int);
+			   unsigned int, unsigned int, unsigned int);
   unsigned int zext_large (HOST_WIDE_INT *, const HOST_WIDE_INT *,
-			   unsigned int,
-			   unsigned int, unsigned int);
+			   unsigned int, unsigned int, unsigned int);
   unsigned int set_bit_large (HOST_WIDE_INT *, const HOST_WIDE_INT *,
 			      unsigned int, unsigned int, unsigned int);
+  unsigned int bswap_large (HOST_WIDE_INT *, const HOST_WIDE_INT *,
+			    unsigned int, unsigned int);
+  
   unsigned int lshift_large (HOST_WIDE_INT *, const HOST_WIDE_INT *,
 			     unsigned int, unsigned int, unsigned int);
   unsigned int lrshift_large (HOST_WIDE_INT *, const HOST_WIDE_INT *,
@@ -2267,6 +2266,18 @@  wi::set_bit (const T &x, unsigned int bit)
   return result;
 }
 
+/* Byte swap the integer X.  */
+template <typename T>
+inline WI_UNARY_RESULT (T)
+wi::bswap (const T &x)
+{
+  WI_UNARY_RESULT_VAR (result, val, T, x);
+  unsigned int precision = get_precision (result);
+  WIDE_INT_REF_FOR (T) xi (x, precision);
+  result.set_len (bswap_large (val, xi.val, xi.len, precision));
+  return result;
+}
+
 /* Return the mininum of X and Y, treating them both as having
    signedness SGN.  */
 template <typename T1, typename T2>