MIPS/GAS: Simplify non-MIPS16 branch swapping sequence

Simplify non-MIPS16 branch swapping by copying the MIPS16 variant, which
sets the new position for the current instruction first and reduces the
calculation of the new position of the previous instruction.  Also refer
to previous instruction's frag and position via `delay' for consistency.

Reintroduce an explanatory comment, updated, previously removed with:

commit 1e91584932efd70020c8c98037d0cb93a0552a20
Author: Richard Sandiford <rdsandiford@googlemail.com>
Date:   Wed Mar 9 09:17:02 2005 +0000

<https://sourceware.org/ml/binutils/2005-03/msg00217.html>, ("Rework
MIPS nop-insertion code, add -mfix-vr4130 [5/11]").

	gas/
	* config/tc-mips.c (append_insn): Simplify non-MIPS16 branch
	swapping sequence.

diff --git a/gas/ChangeLog b/gas/ChangeLog
index 300d5ca..4459273 100644 (file)
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,5 +1,10 @@
 2016-06-30  Maciej W. Rozycki  <macro@imgtec.com>
 
+       * config/tc-mips.c (append_insn): Simplify non-MIPS16 branch
+       swapping sequence.
+
+2016-06-30  Maciej W. Rozycki  <macro@imgtec.com>
+
        PR gas/20312
        * write.c (subsegs_finish_section): Force no section padding to
        alignment on failed assembly, always set last frag's alignment

diff --git a/gas/config/tc-mips.c b/gas/config/tc-mips.c
index 092e7b4..77ba0c9 100644 (file)
--- a/gas/config/tc-mips.c
+++ b/gas/config/tc-mips.c
@@ -7537,9 +7537,10 @@ append_insn (struct mips_cl_insn *ip, expressionS *address_expr,
          }
        else
          {
-           move_insn (&delay, ip->frag,
-                      ip->where - branch_disp + insn_length (ip));
-           move_insn (ip, history[0].frag, history[0].where);
+           /* If this is not a relaxed branch and we are in the
+              same frag, then just swap the instructions.  */
+           move_insn (ip, delay.frag, delay.where);
+           move_insn (&delay, ip->frag, ip->where + insn_length (ip));
          }
        history[0] = *ip;
        delay.fixed_p = 1;