[PATCH][combine][obvious] Use std::swap instead of manually swapping

[Kyrill Tkachov]

Hi all,

This is another one of those std::swap patches, this time I was in the combine 
neighbourhood

Bootstrapped on x86_64 and tested on aarch64.
Precedents suggest these changes are considered obvious.
So I'll commit this in a couple of days unless someone objects.

Thanks,
Kyrill

2015-04-27  Kyrylo Tkachov  <kyrylo.tkac...@arm.com>

    * combine.c (simplify_if_then_else): Use std::swap instead
    of manually swapping.
    (known_cond): Likewise.
    (simplify_comparison): Likewise.

commit e8aa8f2ec22cf548bc05f0f8e56a13a2bdd1c228
Author: Kyrylo Tkachov <kyrylo.tkac...@arm.com>
Date:   Fri Apr 24 17:47:14 2015 +0100

    [combine][obvious] Use std::swap instead of manually swapping

diff --git a/gcc/combine.c b/gcc/combine.c
index 9f840cb..5f7cbc0 100644
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -6185,7 +6185,7 @@ simplify_if_then_else (rtx x)
       if (false_code == EQ)
 	{
 	  swapped = 1, true_code = EQ, false_code = NE;
-	  temp = true_rtx, true_rtx = false_rtx, false_rtx = temp;
+	  std::swap (true_rtx, false_rtx);
 	}
 
       /* If we are comparing against zero and the expression being tested has
@@ -6250,7 +6250,7 @@ simplify_if_then_else (rtx x)
       SUBST (XEXP (x, 1), false_rtx);
       SUBST (XEXP (x, 2), true_rtx);
 
-      temp = true_rtx, true_rtx = false_rtx, false_rtx = temp;
+      std::swap (true_rtx, false_rtx);
       cond = XEXP (x, 0);
 
       /* It is possible that the conditional has been simplified out.  */
@@ -9022,7 +9022,6 @@ static rtx
 known_cond (rtx x, enum rtx_code cond, rtx reg, rtx val)
 {
   enum rtx_code code = GET_CODE (x);
-  rtx temp;
   const char *fmt;
   int i, j;
 
@@ -9062,7 +9061,7 @@ known_cond (rtx x, enum rtx_code cond, rtx reg, rtx val)
   else if (COMPARISON_P (x) || COMMUTATIVE_ARITH_P (x))
     {
       if (rtx_equal_p (XEXP (x, 0), val))
-	cond = swap_condition (cond), temp = val, val = reg, reg = temp;
+	cond = swap_condition (cond), std::swap (val, reg);
 
       if (rtx_equal_p (XEXP (x, 0), reg) && rtx_equal_p (XEXP (x, 1), val))
 	{
@@ -11454,7 +11453,7 @@ simplify_comparison (enum rtx_code code, rtx *pop0, rtx *pop1)
      is already a constant integer.  */
   if (swap_commutative_operands_p (op0, op1))
     {
-      tem = op0, op0 = op1, op1 = tem;
+      std::swap (op0, op1);
       code = swap_condition (code);
     }
 
@@ -12341,7 +12340,7 @@ simplify_comparison (enum rtx_code code, rtx *pop0, rtx *pop1)
   /* We may have changed the comparison operands.  Re-canonicalize.  */
   if (swap_commutative_operands_p (op0, op1))
     {
-      tem = op0, op0 = op1, op1 = tem;
+      std::swap (op0, op1);
       code = swap_condition (code);
     }