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[PATCH] Fix PR84521


This fixes and simplifies the setjmp and non-local goto implementation.
Currently the virtual frame pointer is saved when using __builtin_setjmp or
a non-local goto.  Depending on whether a frame pointer is used, this may
either save SP or FP with an immediate offset.  However the goto or longjmp
always updates the hard frame pointer.

A receiver veneer in the original function then assigns the hard frame pointer
to the virtual frame pointer, which should, if it works correctly, again assign
SP or FP.  However the special elimination code in eliminate_regs_in_insn
doesn't do this correctly unless the frame pointer is used, and even if it
worked by writing SP, the frame pointer would still be corrupted.

A much simpler implementation is to always save and restore the hard frame
pointer.  This avoids 2 redundant instructions which add/subtract the virtual
frame offset.  A large amount of code can be removed as a result, including all
implementations of TARGET_BUILTIN_SETJMP_FRAME_VALUE (all of which already use
the hard frame pointer).  The expansion of nonlocal_goto on PA can be simplied
to just restore the hard frame pointer. 

This fixes the most obvious issues, however there are still issues on targets
which define HARD_FRAME_POINTER_IS_FRAME_POINTER (arm, mips, xtensa).
Each function could have a different hard frame pointer, so a non-local goto
may restore the wrong frame pointer (TARGET_BUILTIN_SETJMP_FRAME_VALUE could
be useful for this).

The i386 TARGET_BUILTIN_SETJMP_FRAME_VALUE was incorrect: if stack_realign_fp
is true, it would save the hard frame pointer value but restore the virtual
frame pointer which according to ix86_initial_elimination_offset can have a
non-zero offset from the hard frame pointer.

The ia64 implementation of nonlocal_goto seems incorrect since the helper
function moves the the frame pointer value into the static chain register
(so this patch does nothing to make it better or worse).

AArch64 bootstrap OK, new test passes on AArch64, x86-64 and Arm.

ChangeLog:
2018-12-13  Wilco Dijkstra  <wdijkstr@arm.com>

gcc/
	PR middle-end/84521
	* builtins.c (expand_builtin_setjmp_setup): Save hard_frame_pointer_rtx.
	(expand_builtin_setjmp_receiver): Do not emit sfp = fp move since we restore fp.
	* function.c (expand_function_start): Save hard_frame_pointer_rtx for non-local goto.
	* lra-eliminations.c (eliminate_regs_in_insn): Remove sfp = fp elimination code.
	(remove_reg_equal_offset_note): Remove unused function.
	* reload1.c (eliminate_regs_in_insn): Remove sfp = fp elimination code.
	* config/arc/arc.c (TARGET_BUILTIN_SETJMP_FRAME_VALUE): Remove.
	(arc_builtin_setjmp_frame_value): Remove function.
	* config/avr/avr.c  (TARGET_BUILTIN_SETJMP_FRAME_VALUE): Remove.
	(avr_builtin_setjmp_frame_value): Remove function.
	* config/i386/i386.c (TARGET_BUILTIN_SETJMP_FRAME_VALUE): Remove.
	(ix86_builtin_setjmp_frame_value): Remove function.
	* config/pa/pa.md (nonlocal_goto): Remove FP adjustment.
	* config/sparc/sparc.c (TARGET_BUILTIN_SETJMP_FRAME_VALUE): Remove.
	(sparc_builtin_setjmp_frame_value): Remove function.
	* config/vax/vax.c (TARGET_BUILTIN_SETJMP_FRAME_VALUE): Remove.
	(vax_builtin_setjmp_frame_value): Remove function.

testsuite/
	PR middle-end/84521
	* gcc.c-torture/execute/pr84521.c: New test.

---
diff --git a/gcc/builtins.c b/gcc/builtins.c
index 2ef9c9afcc69fcb775dc6a6fff550025bdc76337..55b78adbc3df8c970083e6d9b548a8ca7dc52600 100644
--- a/gcc/builtins.c
+++ b/gcc/builtins.c
@@ -982,7 +982,7 @@ expand_builtin_setjmp_setup (rtx buf_addr, rtx receiver_label)
 
   mem = gen_rtx_MEM (Pmode, buf_addr);
   set_mem_alias_set (mem, setjmp_alias_set);
-  emit_move_insn (mem, targetm.builtin_setjmp_frame_value ());
+  emit_move_insn (mem, hard_frame_pointer_rtx);
 
   mem = gen_rtx_MEM (Pmode, plus_constant (Pmode, buf_addr,
 					   GET_MODE_SIZE (Pmode))),
@@ -1024,31 +1024,6 @@ expand_builtin_setjmp_receiver (rtx receiver_label)
   if (chain && REG_P (chain))
     emit_clobber (chain);
 
-  /* Now put in the code to restore the frame pointer, and argument
-     pointer, if needed.  */
-  if (! targetm.have_nonlocal_goto ())
-    {
-      /* First adjust our frame pointer to its actual value.  It was
-	 previously set to the start of the virtual area corresponding to
-	 the stacked variables when we branched here and now needs to be
-	 adjusted to the actual hardware fp value.
-
-	 Assignments to virtual registers are converted by
-	 instantiate_virtual_regs into the corresponding assignment
-	 to the underlying register (fp in this case) that makes
-	 the original assignment true.
-	 So the following insn will actually be decrementing fp by
-	 TARGET_STARTING_FRAME_OFFSET.  */
-      emit_move_insn (virtual_stack_vars_rtx, hard_frame_pointer_rtx);
-
-      /* Restoring the frame pointer also modifies the hard frame pointer.
-	 Mark it used (so that the previous assignment remains live once
-	 the frame pointer is eliminated) and clobbered (to represent the
-	 implicit update from the assignment).  */
-      emit_use (hard_frame_pointer_rtx);
-      emit_clobber (hard_frame_pointer_rtx);
-    }
-
   if (!HARD_FRAME_POINTER_IS_ARG_POINTER && fixed_regs[ARG_POINTER_REGNUM])
     {
       /* If the argument pointer can be eliminated in favor of the
diff --git a/gcc/config/arc/arc.c b/gcc/config/arc/arc.c
index 55175215bfed6e166a92ae046b36487662c36dd0..9058729a76e7f85f188ed0323190549ddd886fa9 100644
--- a/gcc/config/arc/arc.c
+++ b/gcc/config/arc/arc.c
@@ -689,8 +689,6 @@ static rtx arc_legitimize_address_0 (rtx, rtx, machine_mode mode);
 
 #undef TARGET_MODES_TIEABLE_P
 #define TARGET_MODES_TIEABLE_P arc_modes_tieable_p
-#undef TARGET_BUILTIN_SETJMP_FRAME_VALUE
-#define TARGET_BUILTIN_SETJMP_FRAME_VALUE arc_builtin_setjmp_frame_value
 
 /* Try to keep the (mov:DF _, reg) as early as possible so
    that the d<add/sub/mul>h-lr insns appear together and can
@@ -10964,28 +10962,6 @@ compact_memory_operand_p (rtx op, machine_mode mode,
   return false;
 }
 
-/* Return the frame pointer value to be backed up in the setjmp buffer.  */
-
-static rtx
-arc_builtin_setjmp_frame_value (void)
-{
-  /* We always want to preserve whatever value is currently in the frame
-     pointer register.  For frames that are using the frame pointer the new
-     value of the frame pointer register will have already been computed
-     (as part of the prologue).  For frames that are not using the frame
-     pointer it is important that we backup whatever value is in the frame
-     pointer register, as earlier (more outer) frames may have placed a
-     value into the frame pointer register.  It might be tempting to try
-     and use `frame_pointer_rtx` here, however, this is not what we want.
-     For frames that are using the frame pointer this will give the
-     correct value.  However, for frames that are not using the frame
-     pointer this will still give the value that _would_ have been the
-     frame pointer value for this frame (if the use of the frame pointer
-     had not been removed).  We really do want the raw frame pointer
-     register value.  */
-  return gen_raw_REG (Pmode, FRAME_POINTER_REGNUM);
-}
-
 /* Return nonzero if a jli call should be generated for a call from
    the current function to DECL.  */
 
diff --git a/gcc/config/avr/avr.c b/gcc/config/avr/avr.c
index 81c35e7fbc2b06bc06cc7fb7406694bbe48860e5..4fdc38649eb9dc88d33b17f64fe09ffe22f57d1c 100644
--- a/gcc/config/avr/avr.c
+++ b/gcc/config/avr/avr.c
@@ -1302,22 +1302,6 @@ avr_build_builtin_va_list (void)
 }
 
 
-/* Implement `TARGET_BUILTIN_SETJMP_FRAME_VALUE'.  */
-/* Actual start of frame is virtual_stack_vars_rtx this is offset from
-   frame pointer by +TARGET_STARTING_FRAME_OFFSET.
-   Using saved frame = virtual_stack_vars_rtx - TARGET_STARTING_FRAME_OFFSET
-   avoids creating add/sub of offset in nonlocal goto and setjmp.  */
-
-static rtx
-avr_builtin_setjmp_frame_value (void)
-{
-  rtx xval = gen_reg_rtx (Pmode);
-  emit_insn (gen_subhi3 (xval, virtual_stack_vars_rtx,
-                         gen_int_mode (avr_starting_frame_offset (), Pmode)));
-  return xval;
-}
-
-
 /* Return contents of MEM at frame pointer + stack size + 1 (+2 if 3-byte PC).
    This is return address of function.  */
 
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 1d7b1f0d1b28a7a9368391cef42fae7b6e7fd160..80f92d684ba705de48f3fafa5f4ccb7b937546c2 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -11108,17 +11108,6 @@ ix86_initial_elimination_offset (int from, int to)
     }
 }
 
-/* In a dynamically-aligned function, we can't know the offset from
-   stack pointer to frame pointer, so we must ensure that setjmp
-   eliminates fp against the hard fp (%ebp) rather than trying to
-   index from %esp up to the top of the frame across a gap that is
-   of unknown (at compile-time) size.  */
-static rtx
-ix86_builtin_setjmp_frame_value (void)
-{
-  return stack_realign_fp ? hard_frame_pointer_rtx : virtual_stack_vars_rtx;
-}
-
 /* Emits a warning for unsupported msabi to sysv pro/epilogues.  */
 static void warn_once_call_ms2sysv_xlogues (const char *feature)
 {
@@ -50934,9 +50923,6 @@ ix86_run_selftests (void)
 #undef TARGET_MACHINE_DEPENDENT_REORG
 #define TARGET_MACHINE_DEPENDENT_REORG ix86_reorg
 
-#undef TARGET_BUILTIN_SETJMP_FRAME_VALUE
-#define TARGET_BUILTIN_SETJMP_FRAME_VALUE ix86_builtin_setjmp_frame_value
-
 #undef TARGET_BUILD_BUILTIN_VA_LIST
 #define TARGET_BUILD_BUILTIN_VA_LIST ix86_build_builtin_va_list
 
diff --git a/gcc/config/pa/pa.md b/gcc/config/pa/pa.md
index 77611503c67732fb71114e7f1d8e7c1a8883ef41..2fcd597d572117f928c618082d9a61a1463ea6c2 100644
--- a/gcc/config/pa/pa.md
+++ b/gcc/config/pa/pa.md
@@ -6909,13 +6909,7 @@ (define_expand "nonlocal_goto"
   emit_clobber (gen_rtx_MEM (BLKmode, gen_rtx_SCRATCH (VOIDmode)));
   emit_clobber (gen_rtx_MEM (BLKmode, hard_frame_pointer_rtx));
 
-  /* Restore the frame pointer.  The virtual_stack_vars_rtx is saved
-     instead of the hard_frame_pointer_rtx in the save area.  As a
-     result, an extra instruction is needed to adjust for the offset
-     of the virtual stack variables and the hard frame pointer.  */
-  if (GET_CODE (fp) != REG)
-    fp = force_reg (Pmode, fp);
-  emit_move_insn (hard_frame_pointer_rtx, plus_constant (Pmode, fp, -8));
+  emit_move_insn (hard_frame_pointer_rtx, fp);
 
   emit_stack_restore (SAVE_NONLOCAL, stack);
 
diff --git a/gcc/config/sparc/sparc.c b/gcc/config/sparc/sparc.c
index adbef1ab18f532739cf3c0ba1ac80ae5ee288076..093807a8c851024d60d4b96fbb942a9a02e19e8e 100644
--- a/gcc/config/sparc/sparc.c
+++ b/gcc/config/sparc/sparc.c
@@ -679,7 +679,6 @@ static void sparc_output_dwarf_dtprel (FILE *, int, rtx) ATTRIBUTE_UNUSED;
 static void sparc_file_end (void);
 static bool sparc_frame_pointer_required (void);
 static bool sparc_can_eliminate (const int, const int);
-static rtx sparc_builtin_setjmp_frame_value (void);
 static void sparc_conditional_register_usage (void);
 static bool sparc_use_pseudo_pic_reg (void);
 static void sparc_init_pic_reg (void);
@@ -883,9 +882,6 @@ char sparc_hard_reg_printed[8];
 #undef TARGET_FRAME_POINTER_REQUIRED
 #define TARGET_FRAME_POINTER_REQUIRED sparc_frame_pointer_required
 
-#undef TARGET_BUILTIN_SETJMP_FRAME_VALUE
-#define TARGET_BUILTIN_SETJMP_FRAME_VALUE sparc_builtin_setjmp_frame_value
-
 #undef TARGET_CAN_ELIMINATE
 #define TARGET_CAN_ELIMINATE sparc_can_eliminate
 
@@ -12985,14 +12981,6 @@ sparc_can_eliminate (const int from ATTRIBUTE_UNUSED, const int to)
   return to == HARD_FRAME_POINTER_REGNUM || !sparc_frame_pointer_required ();
 }
 
-/* Return the hard frame pointer directly to bypass the stack bias.  */
-
-static rtx
-sparc_builtin_setjmp_frame_value (void)
-{
-  return hard_frame_pointer_rtx;
-}
-
 /* If !TARGET_FPU, then make the fp registers and fp cc regs fixed so that
    they won't be allocated.  */
 
diff --git a/gcc/config/vax/vax.c b/gcc/config/vax/vax.c
index 631c598d3b2f26f250d83b370e3e5ddc7ade0919..d0594f023002a2cd7a01e99690eda1d0f7a5b160 100644
--- a/gcc/config/vax/vax.c
+++ b/gcc/config/vax/vax.c
@@ -59,7 +59,6 @@ static rtx vax_function_arg (cumulative_args_t, machine_mode,
 static void vax_function_arg_advance (cumulative_args_t, machine_mode,
 				      const_tree, bool);
 static rtx vax_struct_value_rtx (tree, int);
-static rtx vax_builtin_setjmp_frame_value (void);
 static void vax_asm_trampoline_template (FILE *);
 static void vax_trampoline_init (rtx, tree, rtx);
 static poly_int64 vax_return_pops_args (tree, tree, poly_int64);
@@ -99,9 +98,6 @@ static HOST_WIDE_INT vax_starting_frame_offset (void);
 #undef TARGET_STRUCT_VALUE_RTX
 #define TARGET_STRUCT_VALUE_RTX vax_struct_value_rtx
 
-#undef TARGET_BUILTIN_SETJMP_FRAME_VALUE
-#define TARGET_BUILTIN_SETJMP_FRAME_VALUE vax_builtin_setjmp_frame_value
-
 #undef TARGET_LRA_P
 #define TARGET_LRA_P hook_bool_void_false
 
@@ -1063,12 +1059,6 @@ vax_struct_value_rtx (tree fntype ATTRIBUTE_UNUSED,
   return gen_rtx_REG (Pmode, VAX_STRUCT_VALUE_REGNUM);
 }
 
-static rtx
-vax_builtin_setjmp_frame_value (void)
-{
-  return hard_frame_pointer_rtx;
-}
-
 /* Worker function for NOTICE_UPDATE_CC.  */
 
 void
diff --git a/gcc/function.c b/gcc/function.c
index 69523c1d72309b7ba0e7a0e6ccfadcd3974dac75..1013d727cc877cdb39ecda73e2b72b5c29dd4e78 100644
--- a/gcc/function.c
+++ b/gcc/function.c
@@ -5170,7 +5170,7 @@ expand_function_start (tree subr)
       r_save = expand_expr (t_save, NULL_RTX, VOIDmode, EXPAND_WRITE);
       gcc_assert (GET_MODE (r_save) == Pmode);
 
-      emit_move_insn (r_save, targetm.builtin_setjmp_frame_value ());
+      emit_move_insn (r_save, hard_frame_pointer_rtx);
       update_nonlocal_goto_save_area ();
     }
 
diff --git a/gcc/lra-eliminations.c b/gcc/lra-eliminations.c
index d0cfaa8714a8400a6db5da1ffef58b6225f743bd..df8fa9017fa8f9fffbd2e7c4af969609cf8a5266 100644
--- a/gcc/lra-eliminations.c
+++ b/gcc/lra-eliminations.c
@@ -876,32 +876,6 @@ mark_not_eliminable (rtx x, machine_mode mem_mode)
 
 
 
-#ifdef HARD_FRAME_POINTER_REGNUM
-
-/* Search INSN's reg notes to see whether the destination is equal to
-   WHAT + C for some constant C.  Return true if so, storing C in
-   *OFFSET_OUT and removing the reg note.  */
-static bool
-remove_reg_equal_offset_note (rtx_insn *insn, rtx what, poly_int64 *offset_out)
-{
-  rtx link, *link_loc;
-
-  for (link_loc = &REG_NOTES (insn);
-       (link = *link_loc) != NULL_RTX;
-       link_loc = &XEXP (link, 1))
-    if (REG_NOTE_KIND (link) == REG_EQUAL
-	&& GET_CODE (XEXP (link, 0)) == PLUS
-	&& XEXP (XEXP (link, 0), 0) == what
-	&& poly_int_rtx_p (XEXP (XEXP (link, 0), 1), offset_out))
-      {
-	*link_loc = XEXP (link, 1);
-	return true;
-      }
-  return false;
-}
-
-#endif
-
 /* Scan INSN and eliminate all eliminable hard registers in it.
 
    If REPLACE_P is true, do the replacement destructively.  Also
@@ -939,72 +913,6 @@ eliminate_regs_in_insn (rtx_insn *insn, bool replace_p, bool first_p,
       return;
     }
 
-  /* Check for setting an eliminable register.	*/
-  if (old_set != 0 && REG_P (SET_DEST (old_set))
-      && (ep = get_elimination (SET_DEST (old_set))) != NULL)
-    {
-      for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS]; ep++)
-	if (ep->from_rtx == SET_DEST (old_set) && ep->can_eliminate)
-	  {
-	    bool delete_p = replace_p;
-	    
-#ifdef HARD_FRAME_POINTER_REGNUM
-	    if (ep->from == FRAME_POINTER_REGNUM
-		&& ep->to == HARD_FRAME_POINTER_REGNUM)
-	      /* If this is setting the frame pointer register to the
-		 hardware frame pointer register and this is an
-		 elimination that will be done (tested above), this
-		 insn is really adjusting the frame pointer downward
-		 to compensate for the adjustment done before a
-		 nonlocal goto.  */
-	      {
-		rtx src = SET_SRC (old_set);
-		poly_int64 offset = 0;
-
-		/* We should never process such insn with non-zero
-		   UPDATE_SP_OFFSET.  */
-		lra_assert (known_eq (update_sp_offset, 0));
-		
-		if (remove_reg_equal_offset_note (insn, ep->to_rtx, &offset)
-		    || strip_offset (src, &offset) == ep->to_rtx)
-		  {
-		    if (replace_p)
-		      {
-			SET_DEST (old_set) = ep->to_rtx;
-			lra_update_insn_recog_data (insn);
-			return;
-		      }
-		    offset -= (ep->offset - ep->previous_offset);
-		    src = plus_constant (Pmode, ep->to_rtx, offset);
-		    
-		    /* First see if this insn remains valid when we
-		       make the change.  If not, keep the INSN_CODE
-		       the same and let the constraint pass fit it
-		       up.  */
-		    validate_change (insn, &SET_SRC (old_set), src, 1);
-		    validate_change (insn, &SET_DEST (old_set),
-				     ep->from_rtx, 1);
-		    if (! apply_change_group ())
-		      {
-			SET_SRC (old_set) = src;
-			SET_DEST (old_set) = ep->from_rtx;
-		      }
-		    lra_update_insn_recog_data (insn);
-		    /* Add offset note for future updates.  */
-		    add_reg_note (insn, REG_EQUAL, copy_rtx (src));
-		    return;
-		  }
-	      }
-#endif
-	    
-	    /* This insn isn't serving a useful purpose.  We delete it
-	       when REPLACE is set.  */
-	    if (delete_p)
-	      lra_delete_dead_insn (insn);
-	    return;
-	  }
-    }
-
   /* We allow one special case which happens to work on all machines we
      currently support: a single set with the source or a REG_EQUAL
      note being a PLUS of an eliminable register and a constant.  */
diff --git a/gcc/reload1.c b/gcc/reload1.c
index 3c0c9ff982fcbd4daba481c62a486e02b74ffbdd..9117325e5b56146ecaa3da2278c36e5435678c56 100644
--- a/gcc/reload1.c
+++ b/gcc/reload1.c
@@ -3234,96 +3234,6 @@ eliminate_regs_in_insn (rtx_insn *insn, int replace)
       return 0;
     }
 
-  if (old_set != 0 && REG_P (SET_DEST (old_set))
-      && REGNO (SET_DEST (old_set)) < FIRST_PSEUDO_REGISTER)
-    {
-      /* Check for setting an eliminable register.  */
-      for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS]; ep++)
-	if (ep->from_rtx == SET_DEST (old_set) && ep->can_eliminate)
-	  {
-	    /* If this is setting the frame pointer register to the
-	       hardware frame pointer register and this is an elimination
-	       that will be done (tested above), this insn is really
-	       adjusting the frame pointer downward to compensate for
-	       the adjustment done before a nonlocal goto.  */
-	    if (!HARD_FRAME_POINTER_IS_FRAME_POINTER
-		&& ep->from == FRAME_POINTER_REGNUM
-		&& ep->to == HARD_FRAME_POINTER_REGNUM)
-	      {
-		rtx base = SET_SRC (old_set);
-		rtx_insn *base_insn = insn;
-		HOST_WIDE_INT offset = 0;
-
-		while (base != ep->to_rtx)
-		  {
-		    rtx_insn *prev_insn;
-		    rtx prev_set;
-
-		    if (GET_CODE (base) == PLUS
-		        && CONST_INT_P (XEXP (base, 1)))
-		      {
-		        offset += INTVAL (XEXP (base, 1));
-		        base = XEXP (base, 0);
-		      }
-		    else if ((prev_insn = prev_nonnote_insn (base_insn)) != 0
-			     && (prev_set = single_set (prev_insn)) != 0
-			     && rtx_equal_p (SET_DEST (prev_set), base))
-		      {
-		        base = SET_SRC (prev_set);
-		        base_insn = prev_insn;
-		      }
-		    else
-		      break;
-		  }
-
-		if (base == ep->to_rtx)
-		  {
-		    rtx src = plus_constant (Pmode, ep->to_rtx,
-					     offset - ep->offset);
-
-		    new_body = old_body;
-		    if (! replace)
-		      {
-			new_body = copy_insn (old_body);
-			if (REG_NOTES (insn))
-			  REG_NOTES (insn) = copy_insn_1 (REG_NOTES (insn));
-		      }
-		    PATTERN (insn) = new_body;
-		    old_set = single_set (insn);
-
-		    /* First see if this insn remains valid when we
-		       make the change.  If not, keep the INSN_CODE
-		       the same and let reload fit it up.  */
-		    validate_change (insn, &SET_SRC (old_set), src, 1);
-		    validate_change (insn, &SET_DEST (old_set),
-				     ep->to_rtx, 1);
-		    if (! apply_change_group ())
-		      {
-			SET_SRC (old_set) = src;
-			SET_DEST (old_set) = ep->to_rtx;
-		      }
-
-		    val = 1;
-		    goto done;
-		  }
-	      }
-
-	    /* In this case this insn isn't serving a useful purpose.  We
-	       will delete it in reload_as_needed once we know that this
-	       elimination is, in fact, being done.
-
-	       If REPLACE isn't set, we can't delete this insn, but needn't
-	       process it since it won't be used unless something changes.  */
-	    if (replace)
-	      {
-		delete_dead_insn (insn);
-		return 1;
-	      }
-	    val = 1;
-	    goto done;
-	  }
-    }
-
   /* We allow one special case which happens to work on all machines we
      currently support: a single set with the source or a REG_EQUAL
      note being a PLUS of an eliminable register and a constant.  */
diff --git a/gcc/testsuite/gcc.c-torture/execute/pr84521.c b/gcc/testsuite/gcc.c-torture/execute/pr84521.c
new file mode 100644
index 0000000000000000000000000000000000000000..995a30223afd1401186c7eaf541f27606aed59b5
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/pr84521.c
@@ -0,0 +1,54 @@
+/* { dg-require-effective-target indirect_jumps } */
+/* { dg-additional-options "-fomit-frame-pointer -fno-inline" }  */
+
+extern void abort (void);
+
+void
+broken_longjmp (void *p)
+{
+  __builtin_longjmp (p, 1);
+}
+
+volatile int x = 256;
+void *volatile p = (void*)&x;
+void *volatile p1;
+
+void
+test (void)
+{
+  void *buf[5];
+  void *volatile q = p;
+  
+  if (!__builtin_setjmp (buf))
+    broken_longjmp (buf);
+
+  /* Fails if stack pointer corrupted.  */
+  if (p != q)
+    abort ();
+}
+
+void
+test2 (void)
+{
+  void *volatile q = p;
+  p1 = __builtin_alloca (x);
+  test ();
+
+  /* Fails if frame pointer corrupted.  */
+  if (p != q)
+    abort ();
+}
+
+int
+main (void)
+{
+  void *volatile q = p;
+  test ();
+  test2 ();
+  /* Fails if stack pointer corrupted.  */
+  if (p != q)
+    abort ();
+
+  return 0;
+}
+

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