Re: [RFA] arm_scan_prologue: accept strh and strb as well as str

Michael Snyder
2002-05-08T22:36:41Z

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Richard Earnshaw wrote:
>
> > [sorry for the empty reply]
> > OK -- I'd be glad to do that. Could you possibly
> > provide me an example to work from?
>
> Below.
>
> >
> > arm_scan_prologue is easy, since it accepts prologue instructions
> > in any order, but arm_skip_prologue imposes an ordering on them.
> > I would REALLY like to merge these two functions. In fact I started
> > to, but then got busy with other things.
>
> Go for it...

OK, how do you like the attached?

Also, Andrew and I have been discussing whether the saved arg regs
should actually be added to the frame-saved-regs. If we decide that
they should, may I have your pre-approval to make that change?

Thanks,
Michael

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2002-04-25 Michael Snyder <msnyder@redhat.com>

* arm-tdep.c (arm_scan_prologue): Accept strb r(0123),[r11,#-nn],
strh r(0123),[r11,#-nn], str r(0123),[r11,#-nn], as well as
strb r(0123),[sp,#nn], strh r(0123),[sp,#nn] and
str r(0123),[sp,#nn].
(arm_skip_prologue): Ditto. Also make disassembly
order-independent by placing it in a loop.

Index: arm-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/arm-tdep.c,v
retrieving revision 1.57
diff -p -r1.57 arm-tdep.c
*** arm-tdep.c 1 May 2002 00:57:51 -0000 1.57
--- arm-tdep.c 8 May 2002 22:31:53 -0000
*************** arm_skip_prologue (CORE_ADDR pc)
*** 417,423 ****
{
unsigned long inst;
CORE_ADDR skip_pc;
! CORE_ADDR func_addr, func_end;
char *func_name;
struct symtab_and_line sal;

--- 417,423 ----
{
unsigned long inst;
CORE_ADDR skip_pc;
! CORE_ADDR func_addr, func_end = 0;
char *func_name;
struct symtab_and_line sal;

*************** arm_skip_prologue (CORE_ADDR pc)
*** 444,517 ****

/* Can't find the prologue end in the symbol table, try it the hard way
by disassembling the instructions. */
- skip_pc = pc;
- inst = read_memory_integer (skip_pc, 4);
- /* "mov ip, sp" is no longer a required part of the prologue. */
- if (inst == 0xe1a0c00d) /* mov ip, sp */
- {
- skip_pc += 4;
- inst = read_memory_integer (skip_pc, 4);
- }

! /* Some prologues begin with "str lr, [sp, #-4]!". */
! if (inst == 0xe52de004) /* str lr, [sp, #-4]! */
! {
! skip_pc += 4;
! inst = read_memory_integer (skip_pc, 4);
! }

! if ((inst & 0xfffffff0) == 0xe92d0000) /* stmfd sp!,{a1,a2,a3,a4} */
{
- skip_pc += 4;
inst = read_memory_integer (skip_pc, 4);
- }

! if ((inst & 0xfffff800) == 0xe92dd800) /* stmfd sp!,{fp,ip,lr,pc} */
! {
! skip_pc += 4;
! inst = read_memory_integer (skip_pc, 4);
! }

! /* Any insns after this point may float into the code, if it makes
! for better instruction scheduling, so we skip them only if we
! find them, but still consider the function to be frame-ful. */
!
! /* We may have either one sfmfd instruction here, or several stfe
! insns, depending on the version of floating point code we
! support. */
! if ((inst & 0xffbf0fff) == 0xec2d0200) /* sfmfd fn, <cnt>, [sp]! */
! {
! skip_pc += 4;
! inst = read_memory_integer (skip_pc, 4);
! }
! else
! {
! while ((inst & 0xffff8fff) == 0xed6d0103) /* stfe fn, [sp, #-12]! */
! {
! skip_pc += 4;
! inst = read_memory_integer (skip_pc, 4);
! }
! }

! if ((inst & 0xfffff000) == 0xe24cb000) /* sub fp, ip, #nn */
! {
! skip_pc += 4;
! inst = read_memory_integer (skip_pc, 4);
! }

! if ((inst & 0xfffff000) == 0xe24dd000) /* sub sp, sp, #nn */
! {
! skip_pc += 4;
! inst = read_memory_integer (skip_pc, 4);
! }

! while ((inst & 0xffffcfc0) == 0xe50b0000) /* str r(0123), [r11, #-nn] */
! {
! skip_pc += 4;
! inst = read_memory_integer (skip_pc, 4);
}

! return skip_pc;
}

/* *INDENT-OFF* */
--- 444,506 ----

/* Can't find the prologue end in the symbol table, try it the hard way
by disassembling the instructions. */

! /* Like arm_scan_prologue, stop no later than pc + 64. */
! if (func_end == 0 || func_end > pc + 64)
! func_end = pc + 64;

! for (skip_pc = pc; skip_pc < func_end; skip_pc += 4)
{
inst = read_memory_integer (skip_pc, 4);

! /* "mov ip, sp" is no longer a required part of the prologue. */
! if (inst == 0xe1a0c00d) /* mov ip, sp */
! continue;

! /* Some prologues begin with "str lr, [sp, #-4]!". */
! if (inst == 0xe52de004) /* str lr, [sp, #-4]! */
! continue;

! if ((inst & 0xfffffff0) == 0xe92d0000) /* stmfd sp!,{a1,a2,a3,a4} */
! continue;

! if ((inst & 0xfffff800) == 0xe92dd800) /* stmfd sp!,{fp,ip,lr,pc} */
! continue;

! /* Any insns after this point may float into the code, if it makes
! for better instruction scheduling, so we skip them only if we
! find them, but still consider the function to be frame-ful. */
!
! /* We may have either one sfmfd instruction here, or several stfe
! insns, depending on the version of floating point code we
! support. */
! if ((inst & 0xffbf0fff) == 0xec2d0200) /* sfmfd fn, <cnt>, [sp]! */
! continue;
!
! if ((inst & 0xffff8fff) == 0xed6d0103) /* stfe fn, [sp, #-12]! */
! continue;
!
! if ((inst & 0xfffff000) == 0xe24cb000) /* sub fp, ip, #nn */
! continue;
!
! if ((inst & 0xfffff000) == 0xe24dd000) /* sub sp, sp, #nn */
! continue;
!
! if ((inst & 0xffffc000) == 0xe54b0000 || /* strb r(0123),[r11,#-nn] */
! (inst & 0xffffc0f0) == 0xe14b00b0 || /* strh r(0123),[r11,#-nn] */
! (inst & 0xffffc000) == 0xe50b0000) /* str r(0123),[r11,#-nn] */
! continue;
!
! if ((inst & 0xffffc000) == 0xe5cd0000 || /* strb r(0123),[sp,#nn] */
! (inst & 0xffffc0f0) == 0xe1cd00b0 || /* strh r(0123),[sp,#nn] */
! (inst & 0xffffc000) == 0xe58d0000) /* str r(0123),[sp,#nn] */
! continue;
!
! /* Un-recognized instruction; stop scanning. */
! break;
}

! return skip_pc; /* End of prologue */
}

/* *INDENT-OFF* */
*************** thumb_scan_prologue (struct frame_info *
*** 597,603 ****
whether to save LR (R14). */
mask = (insn & 0xff) | ((insn & 0x100) << 6);

! /* Calculate offsets of saved R0-R7 and LR. */
for (regno = ARM_LR_REGNUM; regno >= 0; regno--)
if (mask & (1 << regno))
{
--- 586,592 ----
whether to save LR (R14). */
mask = (insn & 0xff) | ((insn & 0x100) << 6);

! /* Calculate offsets of saved R0-R7 and LR. */
for (regno = ARM_LR_REGNUM; regno >= 0; regno--)
if (mask & (1 << regno))
{
*************** thumb_scan_prologue (struct frame_info *
*** 611,617 ****
else if ((insn & 0xff00) == 0xb000) /* add sp, #simm OR
sub sp, #simm */
{
! if ((findmask & 1) == 0) /* before push? */
continue;
else
findmask |= 4; /* add/sub sp found */
--- 600,606 ----
else if ((insn & 0xff00) == 0xb000) /* add sp, #simm OR
sub sp, #simm */
{
! if ((findmask & 1) == 0) /* before push? */
continue;
else
findmask |= 4; /* add/sub sp found */
*************** arm_scan_prologue (struct frame_info *fi
*** 857,863 ****
Be careful, however, and if it doesn't look like a prologue,
don't try to scan it. If, for instance, a frameless function
begins with stmfd sp!, then we will tell ourselves there is
! a frame, which will confuse stack traceback, as well ad"finish"
and other operations that rely on a knowledge of the stack
traceback.

--- 846,852 ----
Be careful, however, and if it doesn't look like a prologue,
don't try to scan it. If, for instance, a frameless function
begins with stmfd sp!, then we will tell ourselves there is
! a frame, which will confuse stack traceback, as well as "finish"
and other operations that rely on a knowledge of the stack
traceback.

*************** arm_scan_prologue (struct frame_info *fi
*** 870,876 ****
[Note further: The "mov ip,sp" only seems to be missing in
frameless functions at optimization level "-O2" or above,
in which case it is often (but not always) replaced by
! "str lr, [sp, #-4]!". - Michael Snyder, 2002-04-23] */

sp_offset = fp_offset = 0;

--- 859,865 ----
[Note further: The "mov ip,sp" only seems to be missing in
frameless functions at optimization level "-O2" or above,
in which case it is often (but not always) replaced by
! "str lr, [sp, #-4]!". - Michael Snyder, 2002-04-23] */

sp_offset = fp_offset = 0;

*************** arm_scan_prologue (struct frame_info *fi
*** 904,910 ****
fi->saved_regs[regno] = sp_offset;
}
}
! else if ((insn & 0xffffcfc0) == 0xe50b0000) /* str rx, [r11, -n] */
{
/* No need to add this to saved_regs -- it's just an arg reg. */
continue;
--- 893,908 ----
fi->saved_regs[regno] = sp_offset;
}
}
! else if ((insn & 0xffffc000) == 0xe54b0000 || /* strb rx,[r11,#-n] */
! (insn & 0xffffc0f0) == 0xe14b00b0 || /* strh rx,[r11,#-n] */
! (insn & 0xffffc000) == 0xe50b0000) /* str rx,[r11,#-n] */
! {
! /* No need to add this to saved_regs -- it's just an arg reg. */
! continue;
! }
! else if ((insn & 0xffffc000) == 0xe5cd0000 || /* strb rx,[sp,#n] */
! (insn & 0xffffc0f0) == 0xe1cd00b0 || /* strh rx,[sp,#n] */
! (insn & 0xffffc000) == 0xe58d0000) /* str rx,[sp,#n] */
{
/* No need to add this to saved_regs -- it's just an arg reg. */
continue;
*************** arm_scan_prologue (struct frame_info *fi
*** 960,966 ****
}
else if ((insn & 0xf0000000) != 0xe0000000)
break; /* Condition not true, exit early */
! else if ((insn & 0xfe200000) == 0xe8200000) /* ldm? */
break; /* Don't scan past a block load */
else
/* The optimizer might shove anything into the prologue,
--- 958,964 ----
}
else if ((insn & 0xf0000000) != 0xe0000000)
break; /* Condition not true, exit early */
! else if ((insn & 0xfe200000) == 0xe8200000) /* ldm? */
break; /* Don't scan past a block load */
else
/* The optimizer might shove anything into the prologue,
*************** arm_get_next_pc (CORE_ADDR pc)
*** 2050,2056 ****
static void
arm_software_single_step (enum target_signal sig, int insert_bpt)
{
! static int next_pc; /* State between setting and unsetting. */
static char break_mem[BREAKPOINT_MAX]; /* Temporary storage for mem@bpt */

if (insert_bpt)
--- 2048,2054 ----
static void
arm_software_single_step (enum target_signal sig, int insert_bpt)
{
! static int next_pc; /* State between setting and unsetting. */
static char break_mem[BREAKPOINT_MAX]; /* Temporary storage for mem@bpt */

if (insert_bpt)