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[commit] Add SINGLE_STEP_THROUGH_DELAY
- From: Andrew Cagney <cagney at gnu dot org>
- To: gdb-patches at sources dot redhat dot com, organ dot friberg at axis dot com
- Date: Sun, 31 Oct 2004 12:36:49 -0500
- Subject: [commit] Add SINGLE_STEP_THROUGH_DELAY
Hello,
Ref: gdb-patches: STEP_SKIPS_DELAY question, sort of
http://sources.redhat.com/ml/gdb-patches/2004-10/msg00015.html
I've taken Organ's infrun.c patch and implemented it for the MIPS.
There are going to be teething problems I'm sure.
Andrew
2004-10-31 Orjan Friberg <organ.friberg@axis.com>
Andrew Cagney <cagney@gnu.org>
* gdbarch.sh (single_step_through_delay): Add.
* gdbarch.h, gdbarch.c: Re-generate.
* config/mips/tm-mips.h (STEP_SKIPS_DELAY_P, STEP_SKIPS_DELAY)
(mips_step_skips_delay): Delete.
* mips-tdep.c (mips_single_step_through_delay): Replace
mips_step_skips_delay.
(mips_gdbarch_init): Set single_step_through_delay.
(mips_dump_tdep): Do not print STEP_SKIPS_DELAY.
Index: gdbarch.sh
===================================================================
RCS file: /cvs/src/src/gdb/gdbarch.sh,v
retrieving revision 1.348
diff -p -u -r1.348 gdbarch.sh
--- gdbarch.sh 2 Sep 2004 17:22:08 -0000 1.348
+++ gdbarch.sh 31 Oct 2004 17:28:10 -0000
@@ -611,6 +611,9 @@ f:=:CORE_ADDR:smash_text_address:CORE_AD
# FIXME/cagney/2001-01-18: The logic is backwards. It should be asking if the target can
# single step. If not, then implement single step using breakpoints.
F:=:void:software_single_step:enum target_signal sig, int insert_breakpoints_p:sig, insert_breakpoints_p
+# Return non-zero if the processor is executing a delay slot and a
+# further single-step is needed before the instruction finishes.
+M::int:single_step_through_delay:struct frame_info *frame:frame
# FIXME: cagney/2003-08-28: Need to find a better way of selecting the
# disassembler. Perhaps objdump can handle it?
f:TARGET_PRINT_INSN:int:print_insn:bfd_vma vma, struct disassemble_info *info:vma, info::0:
Index: infrun.c
===================================================================
RCS file: /cvs/src/src/gdb/infrun.c,v
retrieving revision 1.180
diff -p -u -r1.180 infrun.c
--- infrun.c 31 Oct 2004 16:14:00 -0000 1.180
+++ infrun.c 31 Oct 2004 17:28:11 -0000
@@ -714,24 +714,17 @@ proceed (CORE_ADDR addr, enum target_sig
if (addr == (CORE_ADDR) -1)
{
- /* If there is a breakpoint at the address we will resume at,
- step one instruction before inserting breakpoints
- so that we do not stop right away (and report a second
- hit at this breakpoint). */
-
if (read_pc () == stop_pc && breakpoint_here_p (read_pc ()))
+ /* There is a breakpoint at the address we will resume at,
+ step one instruction before inserting breakpoints so that
+ we do not stop right away (and report a second hit at this
+ breakpoint). */
oneproc = 1;
-
-#ifndef STEP_SKIPS_DELAY
-#define STEP_SKIPS_DELAY(pc) (0)
-#define STEP_SKIPS_DELAY_P (0)
-#endif
- /* Check breakpoint_here_p first, because breakpoint_here_p is fast
- (it just checks internal GDB data structures) and STEP_SKIPS_DELAY
- is slow (it needs to read memory from the target). */
- if (STEP_SKIPS_DELAY_P
- && breakpoint_here_p (read_pc () + 4)
- && STEP_SKIPS_DELAY (read_pc ()))
+ else if (gdbarch_single_step_through_delay_p (current_gdbarch)
+ && gdbarch_single_step_through_delay (current_gdbarch,
+ get_current_frame ()))
+ /* We stepped onto an instruction that needs to be stepped
+ again before re-inserting the breakpoint, do so. */
oneproc = 1;
}
else
@@ -1781,6 +1774,39 @@ handle_inferior_event (struct execution_
stopped_by_random_signal = 0;
breakpoints_failed = 0;
+ if (stop_signal == TARGET_SIGNAL_TRAP
+ && trap_expected
+ && gdbarch_single_step_through_delay_p (current_gdbarch)
+ && currently_stepping (ecs))
+ {
+ /* We're trying to step of a breakpoint. Turns out that we're
+ also on an instruction that needs to be stepped multiple
+ times before it's been fully executing. E.g., architectures
+ with a delay slot. It needs to be stepped twice, once for
+ the instruction and once for the delay slot. */
+ int step_through_delay
+ = gdbarch_single_step_through_delay (current_gdbarch,
+ get_current_frame ());
+ if (step_range_end == 0 && step_through_delay)
+ {
+ /* The user issued a continue when stopped at a breakpoint.
+ Set up for another trap and get out of here. */
+ ecs->another_trap = 1;
+ keep_going (ecs);
+ return;
+ }
+ else if (step_through_delay)
+ {
+ /* The user issued a step when stopped at a breakpoint.
+ Maybe we should stop, maybe we should not - the delay
+ slot *might* correspond to a line of source. In any
+ case, don't decide that here, just set ecs->another_trap,
+ making sure we single-step again before breakpoints are
+ re-inserted. */
+ ecs->another_trap = 1;
+ }
+ }
+
/* Look at the cause of the stop, and decide what to do.
The alternatives are:
1) break; to really stop and return to the debugger,
Index: mips-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/mips-tdep.c,v
retrieving revision 1.358
diff -p -u -r1.358 mips-tdep.c
--- mips-tdep.c 31 Oct 2004 16:14:00 -0000 1.358
+++ mips-tdep.c 31 Oct 2004 17:28:11 -0000
@@ -4142,16 +4142,19 @@ is_delayed (unsigned long insn)
}
int
-mips_step_skips_delay (CORE_ADDR pc)
+mips_single_step_through_delay (struct gdbarch *gdbarch,
+ struct frame_info *frame)
{
+ CORE_ADDR pc = get_frame_pc (frame);
char buf[MIPS_INSN32_SIZE];
/* There is no branch delay slot on MIPS16. */
if (mips_pc_is_mips16 (pc))
return 0;
- if (target_read_memory (pc, buf, sizeof buf) != 0)
- /* If error reading memory, guess that it is not a delayed branch. */
+ if (!safe_frame_unwind_memory (frame, pc, buf, sizeof buf))
+ /* If error reading memory, guess that it is not a delayed
+ branch. */
return 0;
return is_delayed (extract_unsigned_integer (buf, sizeof buf));
}
@@ -5097,6 +5100,8 @@ mips_gdbarch_init (struct gdbarch_info i
set_gdbarch_in_solib_return_trampoline (gdbarch, mips_in_solib_return_trampoline);
}
+ set_gdbarch_single_step_through_delay (gdbarch, mips_single_step_through_delay);
+
/* Hook in OS ABI-specific overrides, if they have been registered. */
gdbarch_init_osabi (info, gdbarch);
@@ -5305,9 +5310,6 @@ mips_dump_tdep (struct gdbarch *current_
"mips_dump_tdep: STEP_SKIPS_DELAY # %s\n",
XSTRING (STEP_SKIPS_DELAY (PC)));
fprintf_unfiltered (file,
- "mips_dump_tdep: STEP_SKIPS_DELAY_P = %d\n",
- STEP_SKIPS_DELAY_P);
- fprintf_unfiltered (file,
"mips_dump_tdep: STOPPED_BY_WATCHPOINT # %s\n",
XSTRING (STOPPED_BY_WATCHPOINT (WS)));
fprintf_unfiltered (file,
Index: config/mips/tm-mips.h
===================================================================
RCS file: /cvs/src/src/gdb/config/mips/tm-mips.h,v
retrieving revision 1.76
diff -p -u -r1.76 tm-mips.h
--- config/mips/tm-mips.h 31 Oct 2004 16:14:01 -0000 1.76
+++ config/mips/tm-mips.h 31 Oct 2004 17:28:11 -0000
@@ -33,12 +33,6 @@ struct symbol;
struct type;
struct value;
-/* Return non-zero if PC points to an instruction which will cause a step
- to execute both the instruction at PC and an instruction at PC+4. */
-extern int mips_step_skips_delay (CORE_ADDR);
-#define STEP_SKIPS_DELAY_P (1)
-#define STEP_SKIPS_DELAY(pc) (mips_step_skips_delay (pc))
-
/* Special symbol found in blocks associated with routines. We can
hang mdebug_extra_func_info's off of this. */