Simplify setjmp and non-local goto implementation (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).
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 + x86-64 bootstrap OK, new test passes on AArch64, x86-64 and Arm.

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 = hfp 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.
	* config/xtensa/xtensa.c (xtensa_frame_pointer_required): Force frame
	pointer	if has_nonlocal_label.

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

From-SVN: r272473

7 files changed, 3 insertions, 82 deletions

diff --git a/gcc/config/arc/arc.c b/gcc/config/arc/arc.c
index 2a530de..89f69c79 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
@@ -10960,28 +10958,6 @@ 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, HARD_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 a9f72b3..f3896f7 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 76ac5bb..649a7e4 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -5788,17 +5788,6 @@ 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.  */
 void warn_once_call_ms2sysv_xlogues (const char *feature)
 {
@@ -22767,9 +22756,6 @@ 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 84630ad..a568e79 100644
--- a/gcc/config/pa/pa.md
+++ b/gcc/config/pa/pa.md
@@ -6909,10 +6909,7 @@
 
   lab = copy_to_reg (lab);
 
-  /* Restore the stack and frame pointers.  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.  */
+  /* Restore the stack and frame pointers.  */
   fp = copy_to_reg (fp);
   emit_stack_restore (SAVE_NONLOCAL, stack);
 
@@ -6920,7 +6917,7 @@
   emit_insn (gen_blockage ());
   emit_clobber (hard_frame_pointer_rtx);
   emit_clobber (frame_pointer_rtx);
-  emit_move_insn (hard_frame_pointer_rtx, plus_constant (Pmode, fp, -8));
+  emit_move_insn (hard_frame_pointer_rtx, fp);
 
   emit_use (hard_frame_pointer_rtx);
   emit_use (stack_pointer_rtx);
diff --git a/gcc/config/sparc/sparc.c b/gcc/config/sparc/sparc.c
index 6d52f83..0227a53 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);
@@ -878,9 +877,6 @@ 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
 
@@ -13003,14 +12999,6 @@ 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 547a7e0..9559ffb 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
 
@@ -1067,12 +1063,6 @@ 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/config/xtensa/xtensa.c b/gcc/config/xtensa/xtensa.c
index ee56124..2b97fa2 100644
--- a/gcc/config/xtensa/xtensa.c
+++ b/gcc/config/xtensa/xtensa.c
@@ -2739,7 +2739,7 @@ xtensa_frame_pointer_required (void)
      This seems wrong but maybe it's necessary for other architectures.
      This function is derived from the i386 code.  */
 
-  if (cfun->machine->accesses_prev_frame)
+  if (cfun->machine->accesses_prev_frame || cfun->has_nonlocal_label)
     return true;
 
   return false;