[PATCH] aarch64: Replace manual swapping idiom with std::swap in aarch64.cc

[Richard Ball via Gcc-patches]

Replace manual swapping idiom with std::swap in aarch64.cc
gcc/config/aarch64/aarch64.cc has a few manual swapping idioms of the form:

x = in0, in0 = in1, in1 = x;

The preferred way is using the standard:

std::swap (in0, in1);

We should just fix these to use std::swap.
This will also allow us to eliminate the x temporary rtx.

gcc/ChangeLog:

        * config/aarch64/aarch64.cc (aarch64_evpc_trn): Use std:swap.
        (aarch64_evpc_uzp): Likewise.
        (aarch64_evpc_zip): Likewise.

---


diff --git a/gcc/config/aarch64/aarch64.cc b/gcc/config/aarch64/aarch64.cc
index 
d049f9a9819628a73bfd57114c3b89d848da7d9c..b75a032c2f2c55d71bcb6b4b6ef1bd7f42a97235 
100644
--- a/gcc/config/aarch64/aarch64.cc
+++ b/gcc/config/aarch64/aarch64.cc
@@ -23498,7 +23498,7 @@ aarch64_evpc_trn (struct expand_vec_perm_d *d)
 {
   HOST_WIDE_INT odd;
   poly_uint64 nelt = d->perm.length ();
-  rtx out, in0, in1, x;
+  rtx out, in0, in1;
   machine_mode vmode = d->vmode;

   if (GET_MODE_UNIT_SIZE (vmode) > 8)
@@ -23522,7 +23522,7 @@ aarch64_evpc_trn (struct expand_vec_perm_d *d)
      at the head of aarch64-sve.md for details.  */
   if (BYTES_BIG_ENDIAN && d->vec_flags == VEC_ADVSIMD)
     {
-      x = in0, in0 = in1, in1 = x;
+      std::swap (in0, in1);
       odd = !odd;
     }
   out = d->target;
@@ -23592,7 +23592,7 @@ static bool
 aarch64_evpc_uzp (struct expand_vec_perm_d *d)
 {
   HOST_WIDE_INT odd;
-  rtx out, in0, in1, x;
+  rtx out, in0, in1;
   machine_mode vmode = d->vmode;

   if (GET_MODE_UNIT_SIZE (vmode) > 8)
@@ -23615,7 +23615,7 @@ aarch64_evpc_uzp (struct expand_vec_perm_d *d)
      at the head of aarch64-sve.md for details.  */
   if (BYTES_BIG_ENDIAN && d->vec_flags == VEC_ADVSIMD)
     {
-      x = in0, in0 = in1, in1 = x;
+      std::swap (in0, in1);
       odd = !odd;
     }
   out = d->target;
@@ -23631,7 +23631,7 @@ aarch64_evpc_zip (struct expand_vec_perm_d *d)
 {
   unsigned int high;
   poly_uint64 nelt = d->perm.length ();
-  rtx out, in0, in1, x;
+  rtx out, in0, in1;
   machine_mode vmode = d->vmode;

   if (GET_MODE_UNIT_SIZE (vmode) > 8)
@@ -23656,7 +23656,7 @@ aarch64_evpc_zip (struct expand_vec_perm_d *d)
      at the head of aarch64-sve.md for details.  */
   if (BYTES_BIG_ENDIAN && d->vec_flags == VEC_ADVSIMD)
     {
-      x = in0, in0 = in1, in1 = x;
+      std::swap (in0, in1);
       high = !high;
     }
   out = d->target;