Re: [RFA] More tweaks to arm_skip_prologue

Michael Snyder
2002-04-23T23:00:54Z

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Richard Earnshaw wrote:
[...]
> This should only ever be "str lr, [sp, #-4]!" (note the writeback).

Richard, how's this revised patch?

Do you think that, if we detect the str lr, [sp, -4]!
we should just return pc + 4 immediately?

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2002-04-22 Michael Snyder <msnyder@redhat.com>

* arm-tdep.c (arm_skip_prologue): Better handling for frameless
functions. Treat "mov ip, sp" as optional. Recognize
"str lr, [sp, #-4]".

Index: arm-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/arm-tdep.c,v
retrieving revision 1.51
diff -p -r1.51 arm-tdep.c
*** arm-tdep.c 22 Apr 2002 23:22:04 -0000 1.51
--- arm-tdep.c 23 Apr 2002 00:00:30 -0000
*************** arm_skip_prologue (CORE_ADDR pc)
*** 446,467 ****
by disassembling the instructions. */
skip_pc = pc;
inst = read_memory_integer (skip_pc, 4);
! if (inst != 0xe1a0c00d) /* mov ip, sp */
! return pc;

! 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} */
! return 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
--- 446,475 ----
by disassembling the instructions. */
skip_pc = pc;
inst = read_memory_integer (skip_pc, 4);
! 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, #-nn]! */
{
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