rtlanal.c (commutative_operand_precedence): Correct comments.

	* rtlanal.c (commutative_operand_precedence): Correct comments.
	* simplify-rtx.c (simplify_plus_minus_op_data_cmp): Delete forward
	declaration.  Return an int.  Distinguish REG,REG return from
	others.
	(struct simplify_plus_minus_op_data): Make local to function.
	(simplify_plus_minus): Don't set canonicalized if merely sorting
	registers.  Avoid packing ops if nothing changes.  White space fixes.

From-SVN: r224768

3 files changed, 77 insertions, 46 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index e5a5764..540685b 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,13 @@
+2015-06-23  Alan Modra  <amodra@gmail.com>
+
+	* rtlanal.c (commutative_operand_precedence): Correct comments.
+	* simplify-rtx.c (simplify_plus_minus_op_data_cmp): Delete forward
+	declaration.  Return an int.  Distinguish REG,REG return from
+	others.
+	(struct simplify_plus_minus_op_data): Make local to function.
+	(simplify_plus_minus): Don't set canonicalized if merely sorting
+	registers.  Avoid packing ops if nothing changes.  White space fixes.
+
 2015-06-22  Pierre-Marie de Rodat  <derodat@adacore.com>
 
 	* gcc.c (default_compilers): Pass "-o %g.s" to cc1 for headers even if
diff --git a/gcc/rtlanal.c b/gcc/rtlanal.c
index d4a9eda..86b3b62 100644
--- a/gcc/rtlanal.c
+++ b/gcc/rtlanal.c
@@ -3132,17 +3132,16 @@ regno_use_in (unsigned int regno, rtx x)
 }
 
 /* Return a value indicating whether OP, an operand of a commutative
-   operation, is preferred as the first or second operand.  The higher
-   the value, the stronger the preference for being the first operand.
-   We use negative values to indicate a preference for the first operand
-   and positive values for the second operand.  */
+   operation, is preferred as the first or second operand.  The more
+   positive the value, the stronger the preference for being the first
+   operand.  */
 
 int
 commutative_operand_precedence (rtx op)
 {
   enum rtx_code code = GET_CODE (op);
 
-  /* Constants always come the second operand.  Prefer "nice" constants.  */
+  /* Constants always become the second operand.  Prefer "nice" constants.  */
   if (code == CONST_INT)
     return -8;
   if (code == CONST_WIDE_INT)
diff --git a/gcc/simplify-rtx.c b/gcc/simplify-rtx.c
index 521fecf..ca8310d 100644
--- a/gcc/simplify-rtx.c
+++ b/gcc/simplify-rtx.c
@@ -59,7 +59,6 @@ along with GCC; see the file COPYING3.  If not see
 
 static rtx neg_const_int (machine_mode, const_rtx);
 static bool plus_minus_operand_p (const_rtx);
-static bool simplify_plus_minus_op_data_cmp (rtx, rtx);
 static rtx simplify_plus_minus (enum rtx_code, machine_mode, rtx, rtx);
 static rtx simplify_immed_subreg (machine_mode, rtx, machine_mode,
 				  unsigned int);
@@ -4049,20 +4048,10 @@ simplify_const_binary_operation (enum rtx_code code, machine_mode mode,
 
 
 
-/* Simplify a PLUS or MINUS, at least one of whose operands may be another
-   PLUS or MINUS.
+/* Return a positive integer if X should sort after Y.  The value
+   returned is 1 if and only if X and Y are both regs.  */
 
-   Rather than test for specific case, we do this by a brute-force method
-   and do all possible simplifications until no more changes occur.  Then
-   we rebuild the operation.  */
-
-struct simplify_plus_minus_op_data
-{
-  rtx op;
-  short neg;
-};
-
-static bool
+static int
 simplify_plus_minus_op_data_cmp (rtx x, rtx y)
 {
   int result;
@@ -4070,20 +4059,33 @@ simplify_plus_minus_op_data_cmp (rtx x, rtx y)
   result = (commutative_operand_precedence (y)
 	    - commutative_operand_precedence (x));
   if (result)
-    return result > 0;
+    return result + result;
 
   /* Group together equal REGs to do more simplification.  */
   if (REG_P (x) && REG_P (y))
     return REGNO (x) > REGNO (y);
-  else
-    return false;
+
+  return 0;
 }
 
+/* Simplify and canonicalize a PLUS or MINUS, at least one of whose
+   operands may be another PLUS or MINUS.
+
+   Rather than test for specific case, we do this by a brute-force method
+   and do all possible simplifications until no more changes occur.  Then
+   we rebuild the operation.
+
+   May return NULL_RTX when no changes were made.  */
+
 static rtx
 simplify_plus_minus (enum rtx_code code, machine_mode mode, rtx op0,
 		     rtx op1)
 {
-  struct simplify_plus_minus_op_data ops[16];
+  struct simplify_plus_minus_op_data
+  {
+    rtx op;
+    short neg;
+  } ops[16];
   rtx result, tem;
   int n_ops = 2;
   int changed, n_constants, canonicalized = 0;
@@ -4124,7 +4126,18 @@ simplify_plus_minus (enum rtx_code code, machine_mode mode, rtx op0,
 
 	      ops[i].op = XEXP (this_op, 0);
 	      changed = 1;
-	      canonicalized |= this_neg || i != n_ops - 2;
+	      /* If this operand was negated then we will potentially
+		 canonicalize the expression.  Similarly if we don't
+		 place the operands adjacent we're re-ordering the
+		 expression and thus might be performing a
+		 canonicalization.  Ignore register re-ordering.
+		 ??? It might be better to shuffle the ops array here,
+		 but then (plus (plus (A, B), plus (C, D))) wouldn't
+		 be seen as non-canonical.  */
+	      if (this_neg
+		  || (i != n_ops - 2
+		      && !(REG_P (ops[i].op) && REG_P (ops[n_ops - 1].op))))
+		canonicalized = 1;
 	      break;
 
 	    case NEG:
@@ -4145,7 +4158,7 @@ simplify_plus_minus (enum rtx_code code, machine_mode mode, rtx op0,
 		  ops[n_ops].neg = this_neg;
 		  n_ops++;
 		  changed = 1;
-	          canonicalized = 1;
+		  canonicalized = 1;
 		}
 	      break;
 
@@ -4158,7 +4171,7 @@ simplify_plus_minus (enum rtx_code code, machine_mode mode, rtx op0,
 		  ops[i].op = XEXP (this_op, 0);
 		  ops[i].neg = !this_neg;
 		  changed = 1;
-	          canonicalized = 1;
+		  canonicalized = 1;
 		}
 	      break;
 
@@ -4169,7 +4182,7 @@ simplify_plus_minus (enum rtx_code code, machine_mode mode, rtx op0,
 		  ops[i].op = neg_const_int (mode, this_op);
 		  ops[i].neg = 0;
 		  changed = 1;
-	          canonicalized = 1;
+		  canonicalized = 1;
 		}
 	      break;
 
@@ -4213,23 +4226,29 @@ simplify_plus_minus (enum rtx_code code, machine_mode mode, rtx op0,
     }
 
   /* Now simplify each pair of operands until nothing changes.  */
-  do
+  while (1)
     {
       /* Insertion sort is good enough for a small array.  */
       for (i = 1; i < n_ops; i++)
-        {
-          struct simplify_plus_minus_op_data save;
-          j = i - 1;
-          if (!simplify_plus_minus_op_data_cmp (ops[j].op, ops[i].op))
+	{
+	  struct simplify_plus_minus_op_data save;
+	  int cmp;
+
+	  j = i - 1;
+	  cmp = simplify_plus_minus_op_data_cmp (ops[j].op, ops[i].op);
+	  if (cmp <= 0)
 	    continue;
+	  /* Just swapping registers doesn't count as canonicalization.  */
+	  if (cmp != 1)
+	    canonicalized = 1;
 
-          canonicalized = 1;
-          save = ops[i];
-          do
+	  save = ops[i];
+	  do
 	    ops[j + 1] = ops[j];
-          while (j-- && simplify_plus_minus_op_data_cmp (ops[j].op, save.op));
-          ops[j + 1] = save;
-        }
+	  while (j--
+		 && simplify_plus_minus_op_data_cmp (ops[j].op, save.op) > 0);
+	  ops[j + 1] = save;
+	}
 
       changed = 0;
       for (i = n_ops - 1; i > 0; i--)
@@ -4258,7 +4277,8 @@ simplify_plus_minus (enum rtx_code code, machine_mode mode, rtx op0,
 
 		    tem_lhs = GET_CODE (lhs) == CONST ? XEXP (lhs, 0) : lhs;
 		    tem_rhs = GET_CODE (rhs) == CONST ? XEXP (rhs, 0) : rhs;
-		    tem = simplify_binary_operation (ncode, mode, tem_lhs, tem_rhs);
+		    tem = simplify_binary_operation (ncode, mode, tem_lhs,
+						     tem_rhs);
 
 		    if (tem && !CONSTANT_P (tem))
 		      tem = gen_rtx_CONST (GET_MODE (tem), tem);
@@ -4296,20 +4316,22 @@ simplify_plus_minus (enum rtx_code code, machine_mode mode, rtx op0,
 	      }
 	  }
 
-      /* If nothing changed, fail.  */
-      if (!canonicalized)
-        return NULL_RTX;
+      if (!changed)
+	break;
 
       /* Pack all the operands to the lower-numbered entries.  */
       for (i = 0, j = 0; j < n_ops; j++)
-        if (ops[j].op)
-          {
+	if (ops[j].op)
+	  {
 	    ops[i] = ops[j];
 	    i++;
-          }
+	  }
       n_ops = i;
     }
-  while (changed);
+
+  /* If nothing changed, fail.  */
+  if (!canonicalized)
+    return NULL_RTX;
 
   /* Create (minus -C X) instead of (neg (const (plus X C))).  */
   if (n_ops == 2