package/gcc/5.4.0/871-xtensa-reimplement-register-spilling.patch

   1 From 40507bf199440082ed69b777986d50c31efe2520 Mon Sep 17 00:00:00 2001
   2 From: Max Filippov <jcmvbkbc@gmail.com>
   3 Date: Mon, 10 Aug 2015 21:35:20 +0300
   4 Subject: [PATCH 1/3] xtensa: reimplement register spilling
   5
   6 Spilling windowed registers in userspace is much easier, more portable,
   7 less error-prone and equally effective as in kernel. Now that register
   8 spilling syscall is considered obsolete in the xtensa linux kernel
   9 replace it with CALL12 followed by series of ENTRY in libgcc.
  10
  11 2015-08-18  Max Filippov  <jcmvbkbc@gmail.com>
  12 libgcc/
  13         * config/xtensa/lib2funcs.S (__xtensa_libgcc_window_spill): Use
  14         CALL12 followed by series of ENTRY to spill windowed registers.
  15         (__xtensa_nonlocal_goto): Call __xtensa_libgcc_window_spill
  16         instead of making linux spill syscall.
  17
  18 Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
  19 ---
  20 Backported from: r226962
  21
  22  libgcc/config/xtensa/lib2funcs.S | 30 +++++++++++++++++++++++-------
  23  1 file changed, 23 insertions(+), 7 deletions(-)
  24
  25 diff --git a/libgcc/config/xtensa/lib2funcs.S b/libgcc/config/xtensa/lib2funcs.S
  26 index 4d451c8..ef0703f 100644
  27 --- a/libgcc/config/xtensa/lib2funcs.S
  28 +++ b/libgcc/config/xtensa/lib2funcs.S
  29 @@ -34,10 +34,29 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  30         .global __xtensa_libgcc_window_spill
  31         .type   __xtensa_libgcc_window_spill,@function
  32  __xtensa_libgcc_window_spill:
  33 -       entry   sp, 32
  34 -       movi    a2, 0
  35 -       syscall
  36 +       entry   sp, 48
  37 +#if XCHAL_NUM_AREGS > 16
  38 +       call12  1f
  39 +       retw
  40 +       .align  4
  41 +1:
  42 +       .rept   (XCHAL_NUM_AREGS - 24) / 12
  43 +       _entry  sp, 48
  44 +       mov     a12, a0
  45 +       .endr
  46 +       _entry  sp, 16
  47 +#if XCHAL_NUM_AREGS % 12 == 0
  48 +       mov     a4, a4
  49 +#elif XCHAL_NUM_AREGS % 12 == 4
  50 +       mov     a8, a8
  51 +#elif XCHAL_NUM_AREGS % 12 == 8
  52 +       mov     a12, a12
  53 +#endif
  54         retw
  55 +#else
  56 +       mov     a8, a8
  57 +       retw
  58 +#endif
  59         .size   __xtensa_libgcc_window_spill, .-__xtensa_libgcc_window_spill
  60  #endif
  61
  62 @@ -61,10 +80,7 @@ __xtensa_nonlocal_goto:
  63         entry   sp, 32
  64
  65         /* Flush registers.  */
  66 -       mov     a5, a2
  67 -       movi    a2, 0
  68 -       syscall
  69 -       mov     a2, a5
  70 +       call8   __xtensa_libgcc_window_spill
  71
  72         /* Because the save area for a0-a3 is stored one frame below
  73            the one identified by a2, the only way to restore those
  74 --
  75 1.8.1.4
  76