[gcc/devel/c++-modules] MIPS: Fix __builtin_longjmp (PR 64242)

[Nathan Sidwell <nathan@gcc.gnu.org>]

https://gcc.gnu.org/g:68e605c93d57c17f07edd50f7e1c80f9216befd2

commit 68e605c93d57c17f07edd50f7e1c80f9216befd2
Author: Andrew Pinski <apinski@marvell.com>
Date:   Tue Aug 25 14:17:52 2020 +0800

    MIPS: Fix __builtin_longjmp (PR 64242)
    
    The problem here is mips has its own builtin_longjmp
    pattern and it was not fixed when expand_builtin_longjmp
    was fixed.  We need to read the new fp and gp before
    restoring the stack as the buffer might be a local
    variable.
    
    2020-08-25  Andrew Pinski  <apinski@marvell.com>
    
    gcc/ChangeLog:
    
            PR middle-end/64242
            * config/mips/mips.md (builtin_longjmp): Restore the frame
            pointer and stack pointer and gp.

Diff:
---
 gcc/config/mips/mips.md | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/gcc/config/mips/mips.md b/gcc/config/mips/mips.md
index 6383a31a5e3..2e75a720fa9 100644
--- a/gcc/config/mips/mips.md
+++ b/gcc/config/mips/mips.md
@@ -6562,9 +6562,19 @@
 
   /* This bit is similar to expand_builtin_longjmp except that it
      restores $gp as well.  */
-  mips_emit_move (hard_frame_pointer_rtx, fp);
   mips_emit_move (pv, lab);
+  /* Restore the frame pointer and stack pointer and gp.  We must use a
+     temporary since the setjmp buffer may be a local.  */
+  fp = copy_to_reg (fp);
+  gpv = copy_to_reg (gpv);
   emit_stack_restore (SAVE_NONLOCAL, stack);
+
+  /* Ensure the frame pointer move is not optimized.  */
+  emit_insn (gen_blockage ());
+  emit_clobber (hard_frame_pointer_rtx);
+  emit_clobber (frame_pointer_rtx);
+  emit_clobber (gp);
+  mips_emit_move (hard_frame_pointer_rtx, fp);
   mips_emit_move (gp, gpv);
   emit_use (hard_frame_pointer_rtx);
   emit_use (stack_pointer_rtx);