Persistent IA64 (and others?) exception failure
Richard Henderson
rth@redhat.com
Sun Mar 17 12:32:00 GMT 2002
On Thu, Mar 14, 2002 at 09:55:14AM -0800, Boehm, Hans wrote:
> The gcc back end still occasionally optimizes away saving of the return
> address at function calls that are known not to return, e.g. because they
> always raise an exception. This was first pointed out a long time ago
> (http://gcc.gnu.org/ml/gcc/2001-11/msg00960.html). Richard Henderson
> suggested a better approach
> (http://gcc.gnu.org/ml/gcc/2001-11/msg01290.html). But at least as of a
> couple of days ago, this was still broken in 3.1.
Try this.
r~
* flow.c (EH_USES): Provide default.
(calculate_global_regs_live): Use it for EH edges and noreturn calls.
* doc/tm.texi (EH_USES): New.
* config/ia64/ia64.c (ia64_eh_uses): New.
* config/ia64/ia64-protos.h: Update.
* config/ia64/ia64.h (EH_USES): New.
Index: flow.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/flow.c,v
retrieving revision 1.505
diff -c -p -d -r1.505 flow.c
*** flow.c 2002/02/19 02:53:17 1.505
--- flow.c 2002/03/17 20:30:59
*************** Software Foundation, 59 Temple Place - S
*** 167,172 ****
--- 167,175 ----
#ifndef EPILOGUE_USES
#define EPILOGUE_USES(REGNO) 0
#endif
+ #ifndef EH_USES
+ #define EH_USES(REGNO) 0
+ #endif
#ifdef HAVE_conditional_execution
#ifndef REVERSE_CONDEXEC_PREDICATES_P
*************** calculate_global_regs_live (blocks_in, b
*** 1111,1131 ****
/* Begin by propagating live_at_start from the successor blocks. */
CLEAR_REG_SET (new_live_at_end);
- for (e = bb->succ; e; e = e->succ_next)
- {
- basic_block sb = e->dest;
! /* Call-clobbered registers die across exception and call edges. */
! /* ??? Abnormal call edges ignored for the moment, as this gets
! confused by sibling call edges, which crashes reg-stack. */
! if (e->flags & EDGE_EH)
! {
! bitmap_operation (tmp, sb->global_live_at_start,
! call_used, BITMAP_AND_COMPL);
! IOR_REG_SET (new_live_at_end, tmp);
! }
! else
! IOR_REG_SET (new_live_at_end, sb->global_live_at_start);
}
/* The all-important stack pointer must always be live. */
--- 1114,1153 ----
/* Begin by propagating live_at_start from the successor blocks. */
CLEAR_REG_SET (new_live_at_end);
! if (bb->succ)
! for (e = bb->succ; e; e = e->succ_next)
! {
! basic_block sb = e->dest;
!
! /* Call-clobbered registers die across exception and
! call edges. */
! /* ??? Abnormal call edges ignored for the moment, as this gets
! confused by sibling call edges, which crashes reg-stack. */
! if (e->flags & EDGE_EH)
! {
! bitmap_operation (tmp, sb->global_live_at_start,
! call_used, BITMAP_AND_COMPL);
! IOR_REG_SET (new_live_at_end, tmp);
! }
! else
! IOR_REG_SET (new_live_at_end, sb->global_live_at_start);
!
! /* If a target saves one register in another (instead of on
! the stack) the save register will need to be live for EH. */
! if (e->flags & EDGE_EH)
! for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
! if (EH_USES (i))
! SET_REGNO_REG_SET (new_live_at_end, i);
! }
! else
! {
! /* This might be a noreturn function that throws. And
! even if it isn't, getting the unwind info right helps
! debugging. */
! for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
! if (EH_USES (i))
! SET_REGNO_REG_SET (new_live_at_end, i);
}
/* The all-important stack pointer must always be live. */
Index: doc/tm.texi
===================================================================
RCS file: /cvs/gcc/gcc/gcc/doc/tm.texi,v
retrieving revision 1.102
diff -c -p -d -r1.102 tm.texi
*** tm.texi 2002/02/23 12:59:09 1.102
--- tm.texi 2002/03/17 20:30:59
*************** Define this macro as a C expression that
*** 3956,3961 ****
--- 3956,3967 ----
used by the epilogue or the @samp{return} pattern. The stack and frame
pointer registers are already be assumed to be used as needed.
+ @findex EH_USES
+ @item EH_USES (@var{regno})
+ Define this macro as a C expression that is nonzero for registers that are
+ used by the exception handling mechanism, and so should be considered live
+ on entry to an exception edge.
+
@findex DELAY_SLOTS_FOR_EPILOGUE
@item DELAY_SLOTS_FOR_EPILOGUE
Define this macro if the function epilogue contains delay slots to which
Index: config/ia64/ia64-protos.h
===================================================================
RCS file: /cvs/gcc/gcc/gcc/config/ia64/ia64-protos.h,v
retrieving revision 1.36
diff -c -p -d -r1.36 ia64-protos.h
*** ia64-protos.h 2002/01/21 02:24:02 1.36
--- ia64-protos.h 2002/03/17 20:30:59
*************** extern void ia64_encode_section_info PAR
*** 122,127 ****
--- 122,128 ----
extern int ia64_register_move_cost PARAMS((enum machine_mode, enum reg_class,
enum reg_class));
extern int ia64_epilogue_uses PARAMS((int));
+ extern int ia64_eh_uses PARAMS((int));
extern void emit_safe_across_calls PARAMS((FILE *));
extern void ia64_init_builtins PARAMS((void));
extern void ia64_override_options PARAMS((void));
Index: config/ia64/ia64.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/config/ia64/ia64.c,v
retrieving revision 1.139.2.6
diff -c -p -d -r1.139.2.6 ia64.c
*** ia64.c 2002/03/15 06:43:17 1.139.2.6
--- ia64.c 2002/03/17 20:30:59
*************** static rtx ia64_expand_compare_and_swap
*** 138,144 ****
static rtx ia64_expand_lock_test_and_set PARAMS ((enum machine_mode,
tree, rtx));
static rtx ia64_expand_lock_release PARAMS ((enum machine_mode, tree, rtx));
- const struct attribute_spec ia64_attribute_table[];
static bool ia64_assemble_integer PARAMS ((rtx, unsigned int, int));
static void ia64_output_function_prologue PARAMS ((FILE *, HOST_WIDE_INT));
static void ia64_output_function_epilogue PARAMS ((FILE *, HOST_WIDE_INT));
--- 138,143 ----
*************** static int ia64_variable_issue PARAMS ((
*** 156,161 ****
--- 155,168 ----
static rtx ia64_cycle_display PARAMS ((int, rtx));
+ /* Table of valid machine attributes. */
+ static const struct attribute_spec ia64_attribute_table[] =
+ {
+ /* { name, min_len, max_len, decl_req, type_req, fn_type_req, handler } */
+ { "syscall_linkage", 0, 0, false, true, true, NULL },
+ { NULL, 0, 0, false, false, false, NULL }
+ };
+
/* Initialize the GCC target structure. */
#undef TARGET_ATTRIBUTE_TABLE
#define TARGET_ATTRIBUTE_TABLE ia64_attribute_table
*************** ia64_epilogue_uses (regno)
*** 6808,6820 ****
}
}
! /* Table of valid machine attributes. */
! const struct attribute_spec ia64_attribute_table[] =
{
! /* { name, min_len, max_len, decl_req, type_req, fn_type_req, handler } */
! { "syscall_linkage", 0, 0, false, true, true, NULL },
! { NULL, 0, 0, false, false, false, NULL }
! };
/* For ia64, SYMBOL_REF_FLAG set means that it is a function.
--- 6815,6847 ----
}
}
! /* Return true if REGNO is used by the frame unwinder. */
!
! int
! ia64_eh_uses (regno)
! int regno;
{
! if (! reload_completed)
! return 0;
!
! if (current_frame_info.reg_save_b0
! && regno == current_frame_info.reg_save_b0)
! return 1;
! if (current_frame_info.reg_save_pr
! && regno == current_frame_info.reg_save_pr)
! return 1;
! if (current_frame_info.reg_save_ar_pfs
! && regno == current_frame_info.reg_save_ar_pfs)
! return 1;
! if (current_frame_info.reg_save_ar_unat
! && regno == current_frame_info.reg_save_ar_unat)
! return 1;
! if (current_frame_info.reg_save_ar_lc
! && regno == current_frame_info.reg_save_ar_lc)
! return 1;
!
! return 0;
! }
/* For ia64, SYMBOL_REF_FLAG set means that it is a function.
Index: config/ia64/ia64.h
===================================================================
RCS file: /cvs/gcc/gcc/gcc/config/ia64/ia64.h,v
retrieving revision 1.99
diff -c -p -d -r1.99 ia64.h
*** ia64.h 2002/01/21 06:22:12 1.99
--- ia64.h 2002/03/17 20:31:00
*************** do { \
*** 1404,1409 ****
--- 1404,1413 ----
#define EPILOGUE_USES(REGNO) ia64_epilogue_uses (REGNO)
+ /* Nonzero for registers used by the exception handling mechanism. */
+
+ #define EH_USES(REGNO) ia64_eh_uses (REGNO)
+
/* Output at beginning of assembler file. */
#define ASM_FILE_START(FILE) \
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