arm software watchpoint: return to epilogue

Hi,
This patch is to handle a software watchpoint case that program returns
to caller's epilogue, and it causes the fail in thumb mode,

finish^M
Run till exit from #0  func () at gdb/testsuite/gdb.base/watchpoint-cond-gone.c:26^M
0x000001f6 in jumper ()^M
(gdb) FAIL: gdb.base/watchpoint-cond-gone.exp: Catch the no longer valid watchpoint

In the test, jumper calls func, and programs returns from func to
jumper's epilogue, IOW, the branch instruction is the last instruction
of jumper's function body.

    jumper:
    .....
    0x000001f2 <+10>:    bl      0x200   [1] <---- indirect call to func
    0x000001f6 <+14>:    mov     sp, r7  [2] <---- start of the epilogue
    0x000001f8 <+16>:    add     sp, #8
    0x000001fa <+18>:    pop     {r7}
    0x000001fc <+20>:    pop     {r0}
    0x000001fe <+22>:    bx      r0

When the inferior returns from func back to jumper, it is expected
that an expression of a software watchpoint becomes out-of-scope.
GDB validates the expression by checking the corresponding frame,
but this check is guarded by gdbarch_in_function_epilogue_p.  See
breakpoint.c:watchpoint_check.

It doesn't work in this case, because program returns from func's
epilogue back to jumper's epilogue [2], GDB thinks the program is
still within the epilogue, but in fact it goes to a different one.
When PC points at [2], the sp-restore instruction is to be
executed, so the stack frame isn't destroyed yet and we can still
use the frame mechanism reliably.

Note that when PC points to the first instruction of restoring SP,
it is part of epilogue, but we still return zero.  When goes to
the next instruction, the backward scan will still match the
epilogue sequence correctly.  The reason for doing this is to
handle the "return-to-epilogue" case.

What this patch does is to restrict the epilogue matching that let
GDB think the first SP restore instruction isn't part of the epilogue,
and fall back to use frame mechanism.  We set 'found_stack_adjust'
zero before backward scan, and we've done this for arm mode
counterpart (arm_in_function_epilogue_p) too.

The patch is tested in arm-none-eabi and arm-none-linux-gnueabi with
various multilibs.  OK to apply?

gdb:

2014-08-28  Yao Qi  <yao@codesourcery.com>

	* arm-tdep.c (thumb_in_function_epilogue_p): Don't set
	found_stack_adjust in forward scan.  Remove condition check
	on found_stack_adjust which is always true.  Indent the code.
Shadow SIM's debug_printf function

GDB and SIM both have functions called "debug_printf", which conflicts
at link time.  This commit shadows SIM's debug_printf with a macro so
that SIM's symbol ends up being called "sim_debug_printf".

sim/common/ChangeLog:

	* sim-trace.h (debug_printf): New define.
Straightforward fatal to internal_error conversions

This commit replaces most of the calls to fatal that represent
internal errors with calls to internal_error, either directly
or via gdb_assert and gdb_assert_not_reached.

gdb/gdbserver/ChangeLog:

	* inferiors.c (get_thread_process): Replace check with gdb_assert.
	* linux-low.c (linux_wait_for_event_filtered): Replace fatal with
	internal_error.
	(linux_resume_one_lwp): Likewise.
	* linux-x86-low.c (x86_siginfo_fixup): Replace checks with
	gdb_assert.
	* mem-break.c (raw_bkpt_type_to_target_hw_bp_type): Replace fatal
	with internal_error.
	* regcache.c (get_thread_regcache): Replace check with gdb_assert.
	(init_register_cache): Replace fatal with gdb_assert_not_reached.
	(find_register_by_name): Replace fatal with internal_error.
	(find_regno): Likewise.
	* tdesc.c (init_target_desc): Replace check with gdb_assert.
	* thread-db.c (thread_db_create_event): Likewise.
	(thread_db_load_search): Likewise.
	(try_thread_db_load_1): Likewise.
	* tracepoint.c (get_jump_space_head): Replace fatal with
	internal_error.
	(claim_trampoline_space): Likewise.
	(have_fast_tracepoint_trampoline_buffer): Likewise.
	(cmd_qtstart): Likewise.
	(stop_tracing): Likewise.
	(fast_tracepoint_collecting): Likewise.
	(target_malloc): Likewise.
	(download_tracepoint): Likewise.
	(download_trace_state_variables): Replace check with gdb_assert.
	(upload_fast_traceframes): Replace fatal with internal_error.
Convert fatal to gdb_assert in both i386_dr_low_set_addr

This commit converts if..fatal checks in both i386_dr_low_set_addr
implementations to gdb_asserts.  It's not obvious from the context,
but the conditional in both cases is changed to match the equivalent
conditional in the i386_dr_low_get_addr implementations.  Nothing
fundamental has changed because DR_FIRSTADDR is zero.  This commit
also removes a vague comment in Linux i386_dr_low_get_addr.  I could
have reworded the comment (and replicated it three times for the other
identical assertions) but I think the existence of specific functions
for the status and control registers makes it fairly obvious what is
going on.

gdb/gdbserver/ChangeLog:

	* linux-x86-low.c (i386_dr_low_set_addr): Replace check with
	gdb_assert.
	(i386_dr_low_get_addr): Remove vague comment.
	* win32-i386-low.c (i386_dr_low_set_addr): Replace check with
	gdb_assert.
Downgrade fatal to warning in linux_async

This commit downgrades a fatal error to a warning in linux_async.
linux_async is called from two different places in gdbserver:

 Via target_async from handle_accept_event.  The argument
   is always zero, so the warning will never be printed here.

 Via start_non_stop from handle_general_set.  This prints
   its own error message to stderr on failure, which will
   be preceded by the warning if it is emitted.

gdb/gdbserver/ChangeLog:

	* linux-low.c (linux_async): Replace fatal with warning.
	Tidy up and return.
	(linux_start_non_stop): Return -1 if linux_async failed.
Convert fatal to error in remote_prepare

This commit converts a call to fatal in remote_prepare with a call to
error.  remote_prepare is called precisely once, from main, at a point
where jumping to toplevel will call exit (1), so error and fatal are
functionally equivalent at this point.  Note that remote_prepare calls
perror_with_name (which calls error) so callers of remote_prepare must
already handle the fact that it may exit via longjmp.

gdb/gdbserver/ChangeLog:

	* remote-utils.c (remote_prepare): Replace fatal with error.
Convert fatal to perror_with_name in IPA code

This commit converts four calls to fatal into calls to
perror_with_name.  perror_with_name calls error, which
in IPA terminates with exit (1) rather than longjmp, so
there is no functional change here.

gdb/gdbserver/ChangeLog:

	* tracepoint.c (gdb_agent_init): Replace fatal with
	perror_with_name.
	(initialize_tracepoint): Likewise.
Remove fatal function and prototype

This commit removes the now-unused fatal function and prototype.

gdb/gdbserver/ChangeLog:

	* utils.h (fatal): Remove declaration.
	* utils.c (fatal): Remove function.
Check S-record with 0 size

	* srec.c (srec_scan): Return error for 0 size.
Rewrite {amd64,i386}-pseudo.c to better specify register liveness.

clang was using eax to construct %0 here:

  asm ("mov %%eax, 0(%0)\n\t"
       "mov %%ebx, 4(%0)\n\t"
       "mov %%ecx, 8(%0)\n\t"
       "mov %%edx, 12(%0)\n\t"
       "mov %%esi, 16(%0)\n\t"
       "mov %%edi, 20(%0)\n\t"
       : /* no output operands */
       : "r" (data)
       : "eax", "ebx", "ecx", "edx", "esi", "edi");

which caused amd64-word.exp (and others similarly) to fail.
It's a perfectly legit thing for clang to do given the available data.
The patch fixes this by marking the registers as live from the
time of the preceding breakpoint.

gdb/testsuite/ChangeLog:

	* gdb.arch/amd64-pseudo.c (main): Rewrite to better specify when
	eax,etc. are live with values set by gdb and thus the compiler can't
	use them.
	* gdb.arch/i386-pseudo.c (main): Ditto.
symtab.c (find_function_start_sal): Move definition to better spot.

gdb/ChangeLog:

	* symtab.c (find_function_start_sal): Move definition to better spot.
Move definition of some prologue-related functions to a better location.

gdb/ChangeLog:

	* symtab.c (in_prologue): Move definition to better spot.
	(skip_prologue_using_sal): Ditto.
daily update
Fix testsuite ld_simple_link_defsyms for windows targets

	* lib/ld-lib.exp (ld_simple_link_defsyms): Provide both __main
	and ___main for windows targets.
Report an error for S-records with less than the miniumum size

	* srec.c (srec_scan): Revert last change.  Report an error for
	S-records with less than the miniumum byte count.
Prevent alpha_vms_object_p stopping bfd_check_format_matches scan

Any error other than bfd_error_wrong_format returned from object_p()
is effectively a fatal error.

	* vms-alpha.c (alpha_vma_object_p): Don't return file_truncated
	error.  Remove redundant bfd_set_error.
PowerPC64 call lacks nop error

	* elf64-ppc.c (ppc64_elf_relocate_section): Report a different
	error for calls via a toc adjusting stub without a nop.