6a069e5719
* mn10300-prologue.c (fix_frame_pointer): Delete. (set_movm_offsets) Don't return just because movm_args is zero -- still need to save pc and sp in saved_regs. (mn10300_analyze_prologue): Don't return prematurely without calling set_movm_offsets (for pc and sp at minimum).
485 lines
15 KiB
C
485 lines
15 KiB
C
/* Target-dependent code for the Matsushita MN10300 for GDB, the GNU debugger.
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Prologue analysis module, extracted from mn10300-tdep.c, Oct. 1, 2004.
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Copyright 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004 Free
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Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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#include "defs.h"
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#include "symtab.h"
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#include "inferior.h"
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#include "gdbcore.h"
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#include "gdb_string.h"
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#include "trad-frame.h"
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#include "mn10300-tdep.h"
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enum movm_register_bits {
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movm_exother_bit = 0x01,
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movm_exreg1_bit = 0x02,
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movm_exreg0_bit = 0x04,
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movm_other_bit = 0x08,
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movm_a3_bit = 0x10,
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movm_a2_bit = 0x20,
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movm_d3_bit = 0x40,
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movm_d2_bit = 0x80
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};
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/* Values for frame_info.status */
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enum frame_kind {
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MY_FRAME_IN_SP = 0x1,
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MY_FRAME_IN_FP = 0x2,
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NO_MORE_FRAMES = 0x4
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};
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/*
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* Frame Extra Info:
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*
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* status -- actually frame type (SP, FP, or last frame)
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* stack size -- offset to the next frame
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*
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* The former might ultimately be stored in the frame_base.
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* Seems like there'd be a way to store the later too.
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*
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* Temporarily supply empty stub functions as place holders.
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*/
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static void
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my_frame_is_in_sp (struct frame_info *fi, void **this_cache)
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{
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struct trad_frame_cache *cache = mn10300_frame_unwind_cache (fi, this_cache);
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trad_frame_set_this_base (cache,
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frame_unwind_register_unsigned (fi,
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E_SP_REGNUM));
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}
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static void
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my_frame_is_in_fp (struct frame_info *fi, void **this_cache)
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{
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struct trad_frame_cache *cache = mn10300_frame_unwind_cache (fi, this_cache);
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trad_frame_set_this_base (cache,
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frame_unwind_register_unsigned (fi,
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E_A3_REGNUM));
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}
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static void
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my_frame_is_last (struct frame_info *fi)
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{
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}
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static int
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is_my_frame_in_sp (struct frame_info *fi)
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{
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return 0;
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}
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static int
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is_my_frame_in_fp (struct frame_info *fi)
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{
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return 0;
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}
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static int
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is_my_frame_last (struct frame_info *fi)
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{
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return 0;
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}
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static void
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set_my_stack_size (struct frame_info *fi, CORE_ADDR size)
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{
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}
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/* Set offsets of registers saved by movm instruction.
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This is a helper function for mn10300_analyze_prologue. */
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static void
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set_movm_offsets (struct frame_info *fi,
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void **this_cache,
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int movm_args)
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{
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struct trad_frame_cache *cache;
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int offset = 0;
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CORE_ADDR base;
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if (cache == NULL || fi == NULL)
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return;
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cache = mn10300_frame_unwind_cache (fi, this_cache);
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base = trad_frame_get_this_base (cache);
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if (movm_args & movm_other_bit)
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{
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/* The `other' bit leaves a blank area of four bytes at the
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beginning of its block of saved registers, making it 32 bytes
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long in total. */
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trad_frame_set_reg_addr (cache, E_LAR_REGNUM, base + offset + 4);
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trad_frame_set_reg_addr (cache, E_LIR_REGNUM, base + offset + 8);
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trad_frame_set_reg_addr (cache, E_MDR_REGNUM, base + offset + 12);
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trad_frame_set_reg_addr (cache, E_A0_REGNUM + 1, base + offset + 16);
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trad_frame_set_reg_addr (cache, E_A0_REGNUM, base + offset + 20);
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trad_frame_set_reg_addr (cache, E_D0_REGNUM + 1, base + offset + 24);
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trad_frame_set_reg_addr (cache, E_D0_REGNUM, base + offset + 28);
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offset += 32;
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}
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if (movm_args & movm_a3_bit)
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{
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trad_frame_set_reg_addr (cache, E_A3_REGNUM, base + offset);
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offset += 4;
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}
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if (movm_args & movm_a2_bit)
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{
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trad_frame_set_reg_addr (cache, E_A2_REGNUM, base + offset);
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offset += 4;
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}
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if (movm_args & movm_d3_bit)
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{
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trad_frame_set_reg_addr (cache, E_D3_REGNUM, base + offset);
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offset += 4;
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}
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if (movm_args & movm_d2_bit)
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{
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trad_frame_set_reg_addr (cache, E_D2_REGNUM, base + offset);
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offset += 4;
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}
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if (AM33_MODE)
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{
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if (movm_args & movm_exother_bit)
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{
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trad_frame_set_reg_addr (cache, E_MCVF_REGNUM, base + offset);
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trad_frame_set_reg_addr (cache, E_MCRL_REGNUM, base + offset + 4);
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trad_frame_set_reg_addr (cache, E_MCRH_REGNUM, base + offset + 8);
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trad_frame_set_reg_addr (cache, E_MDRQ_REGNUM, base + offset + 12);
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trad_frame_set_reg_addr (cache, E_E1_REGNUM, base + offset + 16);
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trad_frame_set_reg_addr (cache, E_E0_REGNUM, base + offset + 20);
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offset += 24;
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}
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if (movm_args & movm_exreg1_bit)
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{
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trad_frame_set_reg_addr (cache, E_E7_REGNUM, base + offset);
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trad_frame_set_reg_addr (cache, E_E6_REGNUM, base + offset + 4);
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trad_frame_set_reg_addr (cache, E_E5_REGNUM, base + offset + 8);
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trad_frame_set_reg_addr (cache, E_E4_REGNUM, base + offset + 12);
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offset += 16;
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}
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if (movm_args & movm_exreg0_bit)
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{
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trad_frame_set_reg_addr (cache, E_E3_REGNUM, base + offset);
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trad_frame_set_reg_addr (cache, E_E2_REGNUM, base + offset + 4);
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offset += 8;
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}
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}
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/* The last (or first) thing on the stack will be the PC. */
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trad_frame_set_reg_addr (cache, E_PC_REGNUM, base + offset);
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/* Save the SP in the 'traditional' way.
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This will be the same location where the PC is saved. */
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trad_frame_set_reg_value (cache, E_SP_REGNUM, base + offset);
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}
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/* The main purpose of this file is dealing with prologues to extract
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information about stack frames and saved registers.
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In gcc/config/mn13000/mn10300.c, the expand_prologue prologue
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function is pretty readable, and has a nice explanation of how the
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prologue is generated. The prologues generated by that code will
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have the following form (NOTE: the current code doesn't handle all
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this!):
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+ If this is an old-style varargs function, then its arguments
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need to be flushed back to the stack:
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mov d0,(4,sp)
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mov d1,(4,sp)
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+ If we use any of the callee-saved registers, save them now.
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movm [some callee-saved registers],(sp)
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+ If we have any floating-point registers to save:
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- Decrement the stack pointer to reserve space for the registers.
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If the function doesn't need a frame pointer, we may combine
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this with the adjustment that reserves space for the frame.
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add -SIZE, sp
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- Save the floating-point registers. We have two possible
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strategies:
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. Save them at fixed offset from the SP:
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fmov fsN,(OFFSETN,sp)
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fmov fsM,(OFFSETM,sp)
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...
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Note that, if OFFSETN happens to be zero, you'll get the
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different opcode: fmov fsN,(sp)
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. Or, set a0 to the start of the save area, and then use
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post-increment addressing to save the FP registers.
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mov sp, a0
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add SIZE, a0
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fmov fsN,(a0+)
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fmov fsM,(a0+)
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...
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+ If the function needs a frame pointer, we set it here.
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mov sp, a3
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+ Now we reserve space for the stack frame proper. This could be
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merged into the `add -SIZE, sp' instruction for FP saves up
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above, unless we needed to set the frame pointer in the previous
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step, or the frame is so large that allocating the whole thing at
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once would put the FP register save slots out of reach of the
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addressing mode (128 bytes).
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add -SIZE, sp
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One day we might keep the stack pointer constant, that won't
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change the code for prologues, but it will make the frame
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pointerless case much more common. */
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/* Analyze the prologue to determine where registers are saved,
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the end of the prologue, etc etc. Return the end of the prologue
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scanned.
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We store into FI (if non-null) several tidbits of information:
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* stack_size -- size of this stack frame. Note that if we stop in
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certain parts of the prologue/epilogue we may claim the size of the
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current frame is zero. This happens when the current frame has
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not been allocated yet or has already been deallocated.
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* fsr -- Addresses of registers saved in the stack by this frame.
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* status -- A (relatively) generic status indicator. It's a bitmask
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with the following bits:
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MY_FRAME_IN_SP: The base of the current frame is actually in
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the stack pointer. This can happen for frame pointerless
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functions, or cases where we're stopped in the prologue/epilogue
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itself. For these cases mn10300_analyze_prologue will need up
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update fi->frame before returning or analyzing the register
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save instructions.
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MY_FRAME_IN_FP: The base of the current frame is in the
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frame pointer register ($a3).
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NO_MORE_FRAMES: Set this if the current frame is "start" or
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if the first instruction looks like mov <imm>,sp. This tells
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frame chain to not bother trying to unwind past this frame. */
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CORE_ADDR
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mn10300_analyze_prologue (struct frame_info *fi,
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void **this_cache,
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CORE_ADDR pc)
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{
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CORE_ADDR func_addr, func_end, addr, stop;
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long stack_size;
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int imm_size;
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unsigned char buf[4];
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int status, movm_args = 0;
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char *name;
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/* Use the PC in the frame if it's provided to look up the
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start of this function.
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Note: kevinb/2003-07-16: We used to do the following here:
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pc = (fi ? get_frame_pc (fi) : pc);
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But this is (now) badly broken when called from analyze_dummy_frame().
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*/
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if (fi)
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{
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pc = (pc ? pc : get_frame_pc (fi));
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/* At the start of a function our frame is in the stack pointer. */
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my_frame_is_in_sp (fi, this_cache);
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}
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/* Find the start of this function. */
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status = find_pc_partial_function (pc, &name, &func_addr, &func_end);
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/* Do nothing if we couldn't find the start of this function
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MVS: comment went on to say "or if we're stopped at the first
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instruction in the prologue" -- but code doesn't reflect that,
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and I don't want to do that anyway. */
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if (status == 0)
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{
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return pc;
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}
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/* If we're in start, then give up. */
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if (strcmp (name, "start") == 0)
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{
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if (fi != NULL)
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my_frame_is_last (fi);
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return pc;
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}
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#if 0
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/* Get the next two bytes into buf, we need two because rets is a two
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byte insn and the first isn't enough to uniquely identify it. */
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status = deprecated_read_memory_nobpt (pc, buf, 2);
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if (status != 0)
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return pc;
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/* Note: kevinb/2003-07-16: We shouldn't be making these sorts of
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changes to the frame in prologue examination code. */
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/* If we're physically on an "rets" instruction, then our frame has
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already been deallocated. Note this can also be true for retf
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and ret if they specify a size of zero.
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In this case fi->frame is bogus, we need to fix it. */
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if (fi && buf[0] == 0xf0 && buf[1] == 0xfc)
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{
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if (get_next_frame (fi) == NULL)
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deprecated_update_frame_base_hack (fi, read_sp ());
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return get_frame_pc (fi);
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}
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/* Similarly if we're stopped on the first insn of a prologue as our
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frame hasn't been allocated yet. */
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if (fi && get_frame_pc (fi) == func_addr)
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{
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if (get_next_frame (fi) == NULL)
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deprecated_update_frame_base_hack (fi, read_sp ());
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return get_frame_pc (fi);
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}
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#endif
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/* NOTE: from here on, we don't want to return without jumping to
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finish_prologue. */
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/* Figure out where to stop scanning. */
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stop = fi ? pc : func_end;
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/* Don't walk off the end of the function. */
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stop = stop > func_end ? func_end : stop;
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/* Start scanning on the first instruction of this function. */
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addr = func_addr;
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/* Suck in two bytes. */
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if (addr + 2 >= stop
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|| (status = deprecated_read_memory_nobpt (addr, buf, 2)) != 0)
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goto finish_prologue;
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/* First see if this insn sets the stack pointer from a register; if
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so, it's probably the initialization of the stack pointer in _start,
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so mark this as the bottom-most frame. */
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if (buf[0] == 0xf2 && (buf[1] & 0xf3) == 0xf0)
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{
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if (fi)
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my_frame_is_last (fi);
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goto finish_prologue;
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}
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/* Now look for movm [regs],sp, which saves the callee saved registers.
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At this time we don't know if fi->frame is valid, so we only note
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that we encountered a movm instruction. Later, we'll set the entries
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in fsr.regs as needed. */
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if (buf[0] == 0xcf)
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{
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/* Extract the register list for the movm instruction. */
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movm_args = buf[1];
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addr += 2;
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/* Quit now if we're beyond the stop point. */
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if (addr >= stop)
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goto finish_prologue;
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/* Get the next two bytes so the prologue scan can continue. */
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status = deprecated_read_memory_nobpt (addr, buf, 2);
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if (status != 0)
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goto finish_prologue;
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}
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/* Now see if we set up a frame pointer via "mov sp,a3" */
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if (buf[0] == 0x3f)
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{
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addr += 1;
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/* The frame pointer is now valid. */
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if (fi)
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{
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my_frame_is_in_fp (fi, this_cache);
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}
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/* Quit now if we're beyond the stop point. */
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if (addr >= stop)
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goto finish_prologue;
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/* Get two more bytes so scanning can continue. */
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status = deprecated_read_memory_nobpt (addr, buf, 2);
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if (status != 0)
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goto finish_prologue;
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}
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/* Next we should allocate the local frame. No more prologue insns
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are found after allocating the local frame.
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Search for add imm8,sp (0xf8feXX)
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or add imm16,sp (0xfafeXXXX)
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or add imm32,sp (0xfcfeXXXXXXXX).
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If none of the above was found, then this prologue has no
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additional stack. */
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imm_size = 0;
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if (buf[0] == 0xf8 && buf[1] == 0xfe)
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imm_size = 1;
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else if (buf[0] == 0xfa && buf[1] == 0xfe)
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imm_size = 2;
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else if (buf[0] == 0xfc && buf[1] == 0xfe)
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imm_size = 4;
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if (imm_size != 0)
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{
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/* Suck in imm_size more bytes, they'll hold the size of the
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current frame. */
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status = deprecated_read_memory_nobpt (addr + 2, buf, imm_size);
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if (status != 0)
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goto finish_prologue;
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/* Note the size of the stack in the frame info structure. */
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stack_size = extract_signed_integer (buf, imm_size);
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if (fi)
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set_my_stack_size (fi, stack_size);
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/* We just consumed 2 + imm_size bytes. */
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addr += 2 + imm_size;
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/* No more prologue insns follow, so begin preparation to return. */
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goto finish_prologue;
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}
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/* Do the essentials and get out of here. */
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finish_prologue:
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/* Note if/where callee saved registers were saved. */
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if (fi)
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set_movm_offsets (fi, this_cache, movm_args);
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return addr;
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}
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