xtensa: reimplement register spilling

Spilling windowed registers in userspace is much easier, more portable,
less error-prone and equally effective as in kernel. Now that register
spilling syscall is considered obsolete in the xtensa linux kernel
replace it with CALL12 followed by series of ENTRY in libgcc.

2015-08-18  Max Filippov  <jcmvbkbc@gmail.com>
libgcc/
	* config/xtensa/lib2funcs.S (__xtensa_libgcc_window_spill): Use
	CALL12 followed by series of ENTRY to spill windowed registers.
	(__xtensa_nonlocal_goto): Call __xtensa_libgcc_window_spill
	instead of making linux spill syscall.

From-SVN: r226962

diff --git a/libgcc/ChangeLog b/libgcc/ChangeLog
index 5ce8f7261eece11323536688f0150743ddb5dfaf..9b25699aa56e726ecd742285ba9fb7cb769a1d26 100644 (file)
--- a/libgcc/ChangeLog
+++ b/libgcc/ChangeLog
@@ -1,3 +1,10 @@
+2015-08-18  Max Filippov  <jcmvbkbc@gmail.com>
+
+       * config/xtensa/lib2funcs.S (__xtensa_libgcc_window_spill): Use
+       CALL12 followed by series of ENTRY to spill windowed registers.
+       (__xtensa_nonlocal_goto): Call __xtensa_libgcc_window_spill
+       instead of making linux spill syscall.
+
 2015-08-14  Yuri Rumyantsev  <ysrumyan@gmail.com>
 
        * config/i386/cpuinfo.c (enum processor_subtypes): Add skylake.

diff --git a/libgcc/config/xtensa/lib2funcs.S b/libgcc/config/xtensa/lib2funcs.S
index 4d451c8c71c8952e54baa0107a77252e5a18ac4a..ef0703f016e421665c1fa7b3a920f8dc34a53619 100644 (file)
--- a/libgcc/config/xtensa/lib2funcs.S
+++ b/libgcc/config/xtensa/lib2funcs.S
@@ -34,10 +34,29 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
        .global __xtensa_libgcc_window_spill
        .type   __xtensa_libgcc_window_spill,@function
 __xtensa_libgcc_window_spill:
-       entry   sp, 32
-       movi    a2, 0
-       syscall
+       entry   sp, 48
+#if XCHAL_NUM_AREGS > 16
+       call12  1f
+       retw
+       .align  4
+1:
+       .rept   (XCHAL_NUM_AREGS - 24) / 12
+       _entry  sp, 48
+       mov     a12, a0
+       .endr
+       _entry  sp, 16
+#if XCHAL_NUM_AREGS % 12 == 0
+       mov     a4, a4
+#elif XCHAL_NUM_AREGS % 12 == 4
+       mov     a8, a8
+#elif XCHAL_NUM_AREGS % 12 == 8
+       mov     a12, a12
+#endif
        retw
+#else
+       mov     a8, a8
+       retw
+#endif
        .size   __xtensa_libgcc_window_spill, .-__xtensa_libgcc_window_spill
 #endif
 
@@ -61,10 +80,7 @@ __xtensa_nonlocal_goto:
        entry   sp, 32
 
        /* Flush registers.  */
-       mov     a5, a2
-       movi    a2, 0
-       syscall
-       mov     a2, a5
+       call8   __xtensa_libgcc_window_spill
 
        /* Because the save area for a0-a3 is stored one frame below
           the one identified by a2, the only way to restore those