binutils-gdb/gdb/fr30-tdep.c

602 lines
26 KiB
C

// OBSOLETE /* Target-dependent code for the Fujitsu FR30.
// OBSOLETE Copyright 1999, 2000, 2001 Free Software Foundation, Inc.
// OBSOLETE
// OBSOLETE This file is part of GDB.
// OBSOLETE
// OBSOLETE This program is free software; you can redistribute it and/or modify
// OBSOLETE it under the terms of the GNU General Public License as published by
// OBSOLETE the Free Software Foundation; either version 2 of the License, or
// OBSOLETE (at your option) any later version.
// OBSOLETE
// OBSOLETE This program is distributed in the hope that it will be useful,
// OBSOLETE but WITHOUT ANY WARRANTY; without even the implied warranty of
// OBSOLETE MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// OBSOLETE GNU General Public License for more details.
// OBSOLETE
// OBSOLETE You should have received a copy of the GNU General Public License
// OBSOLETE along with this program; if not, write to the Free Software
// OBSOLETE Foundation, Inc., 59 Temple Place - Suite 330,
// OBSOLETE Boston, MA 02111-1307, USA. */
// OBSOLETE
// OBSOLETE #include "defs.h"
// OBSOLETE #include "frame.h"
// OBSOLETE #include "inferior.h"
// OBSOLETE #include "obstack.h"
// OBSOLETE #include "target.h"
// OBSOLETE #include "value.h"
// OBSOLETE #include "bfd.h"
// OBSOLETE #include "gdb_string.h"
// OBSOLETE #include "gdbcore.h"
// OBSOLETE #include "symfile.h"
// OBSOLETE #include "regcache.h"
// OBSOLETE
// OBSOLETE /* An expression that tells us whether the function invocation represented
// OBSOLETE by FI does not have a frame on the stack associated with it. */
// OBSOLETE int
// OBSOLETE fr30_frameless_function_invocation (struct frame_info *fi)
// OBSOLETE {
// OBSOLETE int frameless;
// OBSOLETE CORE_ADDR func_start, after_prologue;
// OBSOLETE func_start = (get_pc_function_start ((fi)->pc) +
// OBSOLETE FUNCTION_START_OFFSET);
// OBSOLETE after_prologue = func_start;
// OBSOLETE after_prologue = SKIP_PROLOGUE (after_prologue);
// OBSOLETE frameless = (after_prologue == func_start);
// OBSOLETE return frameless;
// OBSOLETE }
// OBSOLETE
// OBSOLETE /* Function: pop_frame
// OBSOLETE This routine gets called when either the user uses the `return'
// OBSOLETE command, or the call dummy breakpoint gets hit. */
// OBSOLETE
// OBSOLETE void
// OBSOLETE fr30_pop_frame (void)
// OBSOLETE {
// OBSOLETE struct frame_info *frame = get_current_frame ();
// OBSOLETE int regnum;
// OBSOLETE CORE_ADDR sp = read_register (SP_REGNUM);
// OBSOLETE
// OBSOLETE if (PC_IN_CALL_DUMMY (frame->pc, frame->frame, frame->frame))
// OBSOLETE generic_pop_dummy_frame ();
// OBSOLETE else
// OBSOLETE {
// OBSOLETE write_register (PC_REGNUM, FRAME_SAVED_PC (frame));
// OBSOLETE
// OBSOLETE for (regnum = 0; regnum < NUM_REGS; regnum++)
// OBSOLETE if (frame->fsr.regs[regnum] != 0)
// OBSOLETE {
// OBSOLETE write_register (regnum,
// OBSOLETE read_memory_unsigned_integer (frame->fsr.regs[regnum],
// OBSOLETE REGISTER_RAW_SIZE (regnum)));
// OBSOLETE }
// OBSOLETE write_register (SP_REGNUM, sp + frame->framesize);
// OBSOLETE }
// OBSOLETE flush_cached_frames ();
// OBSOLETE }
// OBSOLETE
// OBSOLETE
// OBSOLETE /* Function: fr30_store_return_value
// OBSOLETE Put a value where a caller expects to see it. Used by the 'return'
// OBSOLETE command. */
// OBSOLETE void
// OBSOLETE fr30_store_return_value (struct type *type,
// OBSOLETE char *valbuf)
// OBSOLETE {
// OBSOLETE /* Here's how the FR30 returns values (gleaned from gcc/config/
// OBSOLETE fr30/fr30.h):
// OBSOLETE
// OBSOLETE If the return value is 32 bits long or less, it goes in r4.
// OBSOLETE
// OBSOLETE If the return value is 64 bits long or less, it goes in r4 (most
// OBSOLETE significant word) and r5 (least significant word.
// OBSOLETE
// OBSOLETE If the function returns a structure, of any size, the caller
// OBSOLETE passes the function an invisible first argument where the callee
// OBSOLETE should store the value. But GDB doesn't let you do that anyway.
// OBSOLETE
// OBSOLETE If you're returning a value smaller than a word, it's not really
// OBSOLETE necessary to zero the upper bytes of the register; the caller is
// OBSOLETE supposed to ignore them. However, the FR30 typically keeps its
// OBSOLETE values extended to the full register width, so we should emulate
// OBSOLETE that. */
// OBSOLETE
// OBSOLETE /* The FR30 is big-endian, so if we return a small value (like a
// OBSOLETE short or a char), we need to position it correctly within the
// OBSOLETE register. We round the size up to a register boundary, and then
// OBSOLETE adjust the offset so as to place the value at the right end. */
// OBSOLETE int value_size = TYPE_LENGTH (type);
// OBSOLETE int returned_size = (value_size + FR30_REGSIZE - 1) & ~(FR30_REGSIZE - 1);
// OBSOLETE int offset = (REGISTER_BYTE (RETVAL_REG)
// OBSOLETE + (returned_size - value_size));
// OBSOLETE char *zeros = alloca (returned_size);
// OBSOLETE memset (zeros, 0, returned_size);
// OBSOLETE
// OBSOLETE write_register_bytes (REGISTER_BYTE (RETVAL_REG), zeros, returned_size);
// OBSOLETE write_register_bytes (offset, valbuf, value_size);
// OBSOLETE }
// OBSOLETE
// OBSOLETE
// OBSOLETE /* Function: skip_prologue
// OBSOLETE Return the address of the first code past the prologue of the function. */
// OBSOLETE
// OBSOLETE CORE_ADDR
// OBSOLETE fr30_skip_prologue (CORE_ADDR pc)
// OBSOLETE {
// OBSOLETE CORE_ADDR func_addr, func_end;
// OBSOLETE
// OBSOLETE /* See what the symbol table says */
// OBSOLETE
// OBSOLETE if (find_pc_partial_function (pc, NULL, &func_addr, &func_end))
// OBSOLETE {
// OBSOLETE struct symtab_and_line sal;
// OBSOLETE
// OBSOLETE sal = find_pc_line (func_addr, 0);
// OBSOLETE
// OBSOLETE if (sal.line != 0 && sal.end < func_end)
// OBSOLETE {
// OBSOLETE return sal.end;
// OBSOLETE }
// OBSOLETE }
// OBSOLETE
// OBSOLETE /* Either we didn't find the start of this function (nothing we can do),
// OBSOLETE or there's no line info, or the line after the prologue is after
// OBSOLETE the end of the function (there probably isn't a prologue). */
// OBSOLETE
// OBSOLETE return pc;
// OBSOLETE }
// OBSOLETE
// OBSOLETE
// OBSOLETE /* Function: push_arguments
// OBSOLETE Setup arguments and RP for a call to the target. First four args
// OBSOLETE go in FIRST_ARGREG -> LAST_ARGREG, subsequent args go on stack...
// OBSOLETE Structs are passed by reference. XXX not right now Z.R.
// OBSOLETE 64 bit quantities (doubles and long longs) may be split between
// OBSOLETE the regs and the stack.
// OBSOLETE When calling a function that returns a struct, a pointer to the struct
// OBSOLETE is passed in as a secret first argument (always in FIRST_ARGREG).
// OBSOLETE
// OBSOLETE Stack space for the args has NOT been allocated: that job is up to us.
// OBSOLETE */
// OBSOLETE
// OBSOLETE CORE_ADDR
// OBSOLETE fr30_push_arguments (int nargs, struct value **args, CORE_ADDR sp,
// OBSOLETE int struct_return, CORE_ADDR struct_addr)
// OBSOLETE {
// OBSOLETE int argreg;
// OBSOLETE int argnum;
// OBSOLETE int stack_offset;
// OBSOLETE struct stack_arg
// OBSOLETE {
// OBSOLETE char *val;
// OBSOLETE int len;
// OBSOLETE int offset;
// OBSOLETE };
// OBSOLETE struct stack_arg *stack_args =
// OBSOLETE (struct stack_arg *) alloca (nargs * sizeof (struct stack_arg));
// OBSOLETE int nstack_args = 0;
// OBSOLETE
// OBSOLETE argreg = FIRST_ARGREG;
// OBSOLETE
// OBSOLETE /* the struct_return pointer occupies the first parameter-passing reg */
// OBSOLETE if (struct_return)
// OBSOLETE write_register (argreg++, struct_addr);
// OBSOLETE
// OBSOLETE stack_offset = 0;
// OBSOLETE
// OBSOLETE /* Process args from left to right. Store as many as allowed in
// OBSOLETE registers, save the rest to be pushed on the stack */
// OBSOLETE for (argnum = 0; argnum < nargs; argnum++)
// OBSOLETE {
// OBSOLETE char *val;
// OBSOLETE struct value *arg = args[argnum];
// OBSOLETE struct type *arg_type = check_typedef (VALUE_TYPE (arg));
// OBSOLETE struct type *target_type = TYPE_TARGET_TYPE (arg_type);
// OBSOLETE int len = TYPE_LENGTH (arg_type);
// OBSOLETE enum type_code typecode = TYPE_CODE (arg_type);
// OBSOLETE CORE_ADDR regval;
// OBSOLETE int newarg;
// OBSOLETE
// OBSOLETE val = (char *) VALUE_CONTENTS (arg);
// OBSOLETE
// OBSOLETE {
// OBSOLETE /* Copy the argument to general registers or the stack in
// OBSOLETE register-sized pieces. Large arguments are split between
// OBSOLETE registers and stack. */
// OBSOLETE while (len > 0)
// OBSOLETE {
// OBSOLETE if (argreg <= LAST_ARGREG)
// OBSOLETE {
// OBSOLETE int partial_len = len < REGISTER_SIZE ? len : REGISTER_SIZE;
// OBSOLETE regval = extract_address (val, partial_len);
// OBSOLETE
// OBSOLETE /* It's a simple argument being passed in a general
// OBSOLETE register. */
// OBSOLETE write_register (argreg, regval);
// OBSOLETE argreg++;
// OBSOLETE len -= partial_len;
// OBSOLETE val += partial_len;
// OBSOLETE }
// OBSOLETE else
// OBSOLETE {
// OBSOLETE /* keep for later pushing */
// OBSOLETE stack_args[nstack_args].val = val;
// OBSOLETE stack_args[nstack_args++].len = len;
// OBSOLETE break;
// OBSOLETE }
// OBSOLETE }
// OBSOLETE }
// OBSOLETE }
// OBSOLETE /* now do the real stack pushing, process args right to left */
// OBSOLETE while (nstack_args--)
// OBSOLETE {
// OBSOLETE sp -= stack_args[nstack_args].len;
// OBSOLETE write_memory (sp, stack_args[nstack_args].val,
// OBSOLETE stack_args[nstack_args].len);
// OBSOLETE }
// OBSOLETE
// OBSOLETE /* Return adjusted stack pointer. */
// OBSOLETE return sp;
// OBSOLETE }
// OBSOLETE
// OBSOLETE void _initialize_fr30_tdep (void);
// OBSOLETE
// OBSOLETE void
// OBSOLETE _initialize_fr30_tdep (void)
// OBSOLETE {
// OBSOLETE extern int print_insn_fr30 (bfd_vma, disassemble_info *);
// OBSOLETE tm_print_insn = print_insn_fr30;
// OBSOLETE }
// OBSOLETE
// OBSOLETE /* Function: check_prologue_cache
// OBSOLETE Check if prologue for this frame's PC has already been scanned.
// OBSOLETE If it has, copy the relevant information about that prologue and
// OBSOLETE return non-zero. Otherwise do not copy anything and return zero.
// OBSOLETE
// OBSOLETE The information saved in the cache includes:
// OBSOLETE * the frame register number;
// OBSOLETE * the size of the stack frame;
// OBSOLETE * the offsets of saved regs (relative to the old SP); and
// OBSOLETE * the offset from the stack pointer to the frame pointer
// OBSOLETE
// OBSOLETE The cache contains only one entry, since this is adequate
// OBSOLETE for the typical sequence of prologue scan requests we get.
// OBSOLETE When performing a backtrace, GDB will usually ask to scan
// OBSOLETE the same function twice in a row (once to get the frame chain,
// OBSOLETE and once to fill in the extra frame information).
// OBSOLETE */
// OBSOLETE
// OBSOLETE static struct frame_info prologue_cache;
// OBSOLETE
// OBSOLETE static int
// OBSOLETE check_prologue_cache (struct frame_info *fi)
// OBSOLETE {
// OBSOLETE int i;
// OBSOLETE
// OBSOLETE if (fi->pc == prologue_cache.pc)
// OBSOLETE {
// OBSOLETE fi->framereg = prologue_cache.framereg;
// OBSOLETE fi->framesize = prologue_cache.framesize;
// OBSOLETE fi->frameoffset = prologue_cache.frameoffset;
// OBSOLETE for (i = 0; i <= NUM_REGS; i++)
// OBSOLETE fi->fsr.regs[i] = prologue_cache.fsr.regs[i];
// OBSOLETE return 1;
// OBSOLETE }
// OBSOLETE else
// OBSOLETE return 0;
// OBSOLETE }
// OBSOLETE
// OBSOLETE
// OBSOLETE /* Function: save_prologue_cache
// OBSOLETE Copy the prologue information from fi to the prologue cache.
// OBSOLETE */
// OBSOLETE
// OBSOLETE static void
// OBSOLETE save_prologue_cache (struct frame_info *fi)
// OBSOLETE {
// OBSOLETE int i;
// OBSOLETE
// OBSOLETE prologue_cache.pc = fi->pc;
// OBSOLETE prologue_cache.framereg = fi->framereg;
// OBSOLETE prologue_cache.framesize = fi->framesize;
// OBSOLETE prologue_cache.frameoffset = fi->frameoffset;
// OBSOLETE
// OBSOLETE for (i = 0; i <= NUM_REGS; i++)
// OBSOLETE {
// OBSOLETE prologue_cache.fsr.regs[i] = fi->fsr.regs[i];
// OBSOLETE }
// OBSOLETE }
// OBSOLETE
// OBSOLETE
// OBSOLETE /* Function: scan_prologue
// OBSOLETE Scan the prologue of the function that contains PC, and record what
// OBSOLETE we find in PI. PI->fsr must be zeroed by the called. Returns the
// OBSOLETE pc after the prologue. Note that the addresses saved in pi->fsr
// OBSOLETE are actually just frame relative (negative offsets from the frame
// OBSOLETE pointer). This is because we don't know the actual value of the
// OBSOLETE frame pointer yet. In some circumstances, the frame pointer can't
// OBSOLETE be determined till after we have scanned the prologue. */
// OBSOLETE
// OBSOLETE static void
// OBSOLETE fr30_scan_prologue (struct frame_info *fi)
// OBSOLETE {
// OBSOLETE int sp_offset, fp_offset;
// OBSOLETE CORE_ADDR prologue_start, prologue_end, current_pc;
// OBSOLETE
// OBSOLETE /* Check if this function is already in the cache of frame information. */
// OBSOLETE if (check_prologue_cache (fi))
// OBSOLETE return;
// OBSOLETE
// OBSOLETE /* Assume there is no frame until proven otherwise. */
// OBSOLETE fi->framereg = SP_REGNUM;
// OBSOLETE fi->framesize = 0;
// OBSOLETE fi->frameoffset = 0;
// OBSOLETE
// OBSOLETE /* Find the function prologue. If we can't find the function in
// OBSOLETE the symbol table, peek in the stack frame to find the PC. */
// OBSOLETE if (find_pc_partial_function (fi->pc, NULL, &prologue_start, &prologue_end))
// OBSOLETE {
// OBSOLETE /* Assume the prologue is everything between the first instruction
// OBSOLETE in the function and the first source line. */
// OBSOLETE struct symtab_and_line sal = find_pc_line (prologue_start, 0);
// OBSOLETE
// OBSOLETE if (sal.line == 0) /* no line info, use current PC */
// OBSOLETE prologue_end = fi->pc;
// OBSOLETE else if (sal.end < prologue_end) /* next line begins after fn end */
// OBSOLETE prologue_end = sal.end; /* (probably means no prologue) */
// OBSOLETE }
// OBSOLETE else
// OBSOLETE {
// OBSOLETE /* XXX Z.R. What now??? The following is entirely bogus */
// OBSOLETE prologue_start = (read_memory_integer (fi->frame, 4) & 0x03fffffc) - 12;
// OBSOLETE prologue_end = prologue_start + 40;
// OBSOLETE }
// OBSOLETE
// OBSOLETE /* Now search the prologue looking for instructions that set up the
// OBSOLETE frame pointer, adjust the stack pointer, and save registers. */
// OBSOLETE
// OBSOLETE sp_offset = fp_offset = 0;
// OBSOLETE for (current_pc = prologue_start; current_pc < prologue_end; current_pc += 2)
// OBSOLETE {
// OBSOLETE unsigned int insn;
// OBSOLETE
// OBSOLETE insn = read_memory_unsigned_integer (current_pc, 2);
// OBSOLETE
// OBSOLETE if ((insn & 0xfe00) == 0x8e00) /* stm0 or stm1 */
// OBSOLETE {
// OBSOLETE int reg, mask = insn & 0xff;
// OBSOLETE
// OBSOLETE /* scan in one sweep - create virtual 16-bit mask from either insn's mask */
// OBSOLETE if ((insn & 0x0100) == 0)
// OBSOLETE {
// OBSOLETE mask <<= 8; /* stm0 - move to upper byte in virtual mask */
// OBSOLETE }
// OBSOLETE
// OBSOLETE /* Calculate offsets of saved registers (to be turned later into addresses). */
// OBSOLETE for (reg = R4_REGNUM; reg <= R11_REGNUM; reg++)
// OBSOLETE if (mask & (1 << (15 - reg)))
// OBSOLETE {
// OBSOLETE sp_offset -= 4;
// OBSOLETE fi->fsr.regs[reg] = sp_offset;
// OBSOLETE }
// OBSOLETE }
// OBSOLETE else if ((insn & 0xfff0) == 0x1700) /* st rx,@-r15 */
// OBSOLETE {
// OBSOLETE int reg = insn & 0xf;
// OBSOLETE
// OBSOLETE sp_offset -= 4;
// OBSOLETE fi->fsr.regs[reg] = sp_offset;
// OBSOLETE }
// OBSOLETE else if ((insn & 0xff00) == 0x0f00) /* enter */
// OBSOLETE {
// OBSOLETE fp_offset = fi->fsr.regs[FP_REGNUM] = sp_offset - 4;
// OBSOLETE sp_offset -= 4 * (insn & 0xff);
// OBSOLETE fi->framereg = FP_REGNUM;
// OBSOLETE }
// OBSOLETE else if (insn == 0x1781) /* st rp,@-sp */
// OBSOLETE {
// OBSOLETE sp_offset -= 4;
// OBSOLETE fi->fsr.regs[RP_REGNUM] = sp_offset;
// OBSOLETE }
// OBSOLETE else if (insn == 0x170e) /* st fp,@-sp */
// OBSOLETE {
// OBSOLETE sp_offset -= 4;
// OBSOLETE fi->fsr.regs[FP_REGNUM] = sp_offset;
// OBSOLETE }
// OBSOLETE else if (insn == 0x8bfe) /* mov sp,fp */
// OBSOLETE {
// OBSOLETE fi->framereg = FP_REGNUM;
// OBSOLETE }
// OBSOLETE else if ((insn & 0xff00) == 0xa300) /* addsp xx */
// OBSOLETE {
// OBSOLETE sp_offset += 4 * (signed char) (insn & 0xff);
// OBSOLETE }
// OBSOLETE else if ((insn & 0xff0f) == 0x9b00 && /* ldi:20 xx,r0 */
// OBSOLETE read_memory_unsigned_integer (current_pc + 4, 2)
// OBSOLETE == 0xac0f) /* sub r0,sp */
// OBSOLETE {
// OBSOLETE /* large stack adjustment */
// OBSOLETE sp_offset -= (((insn & 0xf0) << 12) | read_memory_unsigned_integer (current_pc + 2, 2));
// OBSOLETE current_pc += 4;
// OBSOLETE }
// OBSOLETE else if (insn == 0x9f80 && /* ldi:32 xx,r0 */
// OBSOLETE read_memory_unsigned_integer (current_pc + 6, 2)
// OBSOLETE == 0xac0f) /* sub r0,sp */
// OBSOLETE {
// OBSOLETE /* large stack adjustment */
// OBSOLETE sp_offset -=
// OBSOLETE (read_memory_unsigned_integer (current_pc + 2, 2) << 16 |
// OBSOLETE read_memory_unsigned_integer (current_pc + 4, 2));
// OBSOLETE current_pc += 6;
// OBSOLETE }
// OBSOLETE }
// OBSOLETE
// OBSOLETE /* The frame size is just the negative of the offset (from the original SP)
// OBSOLETE of the last thing thing we pushed on the stack. The frame offset is
// OBSOLETE [new FP] - [new SP]. */
// OBSOLETE fi->framesize = -sp_offset;
// OBSOLETE fi->frameoffset = fp_offset - sp_offset;
// OBSOLETE
// OBSOLETE save_prologue_cache (fi);
// OBSOLETE }
// OBSOLETE
// OBSOLETE /* Function: init_extra_frame_info
// OBSOLETE Setup the frame's frame pointer, pc, and frame addresses for saved
// OBSOLETE registers. Most of the work is done in scan_prologue().
// OBSOLETE
// OBSOLETE Note that when we are called for the last frame (currently active frame),
// OBSOLETE that fi->pc and fi->frame will already be setup. However, fi->frame will
// OBSOLETE be valid only if this routine uses FP. For previous frames, fi-frame will
// OBSOLETE always be correct (since that is derived from fr30_frame_chain ()).
// OBSOLETE
// OBSOLETE We can be called with the PC in the call dummy under two circumstances.
// OBSOLETE First, during normal backtracing, second, while figuring out the frame
// OBSOLETE pointer just prior to calling the target function (see run_stack_dummy). */
// OBSOLETE
// OBSOLETE void
// OBSOLETE fr30_init_extra_frame_info (struct frame_info *fi)
// OBSOLETE {
// OBSOLETE int reg;
// OBSOLETE
// OBSOLETE if (fi->next)
// OBSOLETE fi->pc = FRAME_SAVED_PC (fi->next);
// OBSOLETE
// OBSOLETE memset (fi->fsr.regs, '\000', sizeof fi->fsr.regs);
// OBSOLETE
// OBSOLETE if (PC_IN_CALL_DUMMY (fi->pc, fi->frame, fi->frame))
// OBSOLETE {
// OBSOLETE /* We need to setup fi->frame here because run_stack_dummy gets it wrong
// OBSOLETE by assuming it's always FP. */
// OBSOLETE fi->frame = generic_read_register_dummy (fi->pc, fi->frame, SP_REGNUM);
// OBSOLETE fi->framesize = 0;
// OBSOLETE fi->frameoffset = 0;
// OBSOLETE return;
// OBSOLETE }
// OBSOLETE fr30_scan_prologue (fi);
// OBSOLETE
// OBSOLETE if (!fi->next) /* this is the innermost frame? */
// OBSOLETE fi->frame = read_register (fi->framereg);
// OBSOLETE else
// OBSOLETE /* not the innermost frame */
// OBSOLETE /* If we have an FP, the callee saved it. */
// OBSOLETE if (fi->framereg == FP_REGNUM)
// OBSOLETE if (fi->next->fsr.regs[fi->framereg] != 0)
// OBSOLETE fi->frame = read_memory_integer (fi->next->fsr.regs[fi->framereg], 4);
// OBSOLETE
// OBSOLETE /* Calculate actual addresses of saved registers using offsets determined
// OBSOLETE by fr30_scan_prologue. */
// OBSOLETE for (reg = 0; reg < NUM_REGS; reg++)
// OBSOLETE if (fi->fsr.regs[reg] != 0)
// OBSOLETE {
// OBSOLETE fi->fsr.regs[reg] += fi->frame + fi->framesize - fi->frameoffset;
// OBSOLETE }
// OBSOLETE }
// OBSOLETE
// OBSOLETE /* Function: find_callers_reg
// OBSOLETE Find REGNUM on the stack. Otherwise, it's in an active register.
// OBSOLETE One thing we might want to do here is to check REGNUM against the
// OBSOLETE clobber mask, and somehow flag it as invalid if it isn't saved on
// OBSOLETE the stack somewhere. This would provide a graceful failure mode
// OBSOLETE when trying to get the value of caller-saves registers for an inner
// OBSOLETE frame. */
// OBSOLETE
// OBSOLETE CORE_ADDR
// OBSOLETE fr30_find_callers_reg (struct frame_info *fi, int regnum)
// OBSOLETE {
// OBSOLETE for (; fi; fi = fi->next)
// OBSOLETE if (PC_IN_CALL_DUMMY (fi->pc, fi->frame, fi->frame))
// OBSOLETE return generic_read_register_dummy (fi->pc, fi->frame, regnum);
// OBSOLETE else if (fi->fsr.regs[regnum] != 0)
// OBSOLETE return read_memory_unsigned_integer (fi->fsr.regs[regnum],
// OBSOLETE REGISTER_RAW_SIZE (regnum));
// OBSOLETE
// OBSOLETE return read_register (regnum);
// OBSOLETE }
// OBSOLETE
// OBSOLETE
// OBSOLETE /* Function: frame_chain
// OBSOLETE Figure out the frame prior to FI. Unfortunately, this involves
// OBSOLETE scanning the prologue of the caller, which will also be done
// OBSOLETE shortly by fr30_init_extra_frame_info. For the dummy frame, we
// OBSOLETE just return the stack pointer that was in use at the time the
// OBSOLETE function call was made. */
// OBSOLETE
// OBSOLETE
// OBSOLETE CORE_ADDR
// OBSOLETE fr30_frame_chain (struct frame_info *fi)
// OBSOLETE {
// OBSOLETE CORE_ADDR fn_start, callers_pc, fp;
// OBSOLETE struct frame_info caller_fi;
// OBSOLETE int framereg;
// OBSOLETE
// OBSOLETE /* is this a dummy frame? */
// OBSOLETE if (PC_IN_CALL_DUMMY (fi->pc, fi->frame, fi->frame))
// OBSOLETE return fi->frame; /* dummy frame same as caller's frame */
// OBSOLETE
// OBSOLETE /* is caller-of-this a dummy frame? */
// OBSOLETE callers_pc = FRAME_SAVED_PC (fi); /* find out who called us: */
// OBSOLETE fp = fr30_find_callers_reg (fi, FP_REGNUM);
// OBSOLETE if (PC_IN_CALL_DUMMY (callers_pc, fp, fp))
// OBSOLETE return fp; /* dummy frame's frame may bear no relation to ours */
// OBSOLETE
// OBSOLETE if (find_pc_partial_function (fi->pc, 0, &fn_start, 0))
// OBSOLETE if (fn_start == entry_point_address ())
// OBSOLETE return 0; /* in _start fn, don't chain further */
// OBSOLETE
// OBSOLETE framereg = fi->framereg;
// OBSOLETE
// OBSOLETE /* If the caller is the startup code, we're at the end of the chain. */
// OBSOLETE if (find_pc_partial_function (callers_pc, 0, &fn_start, 0))
// OBSOLETE if (fn_start == entry_point_address ())
// OBSOLETE return 0;
// OBSOLETE
// OBSOLETE memset (&caller_fi, 0, sizeof (caller_fi));
// OBSOLETE caller_fi.pc = callers_pc;
// OBSOLETE fr30_scan_prologue (&caller_fi);
// OBSOLETE framereg = caller_fi.framereg;
// OBSOLETE
// OBSOLETE /* If the caller used a frame register, return its value.
// OBSOLETE Otherwise, return the caller's stack pointer. */
// OBSOLETE if (framereg == FP_REGNUM)
// OBSOLETE return fr30_find_callers_reg (fi, framereg);
// OBSOLETE else
// OBSOLETE return fi->frame + fi->framesize;
// OBSOLETE }
// OBSOLETE
// OBSOLETE /* Function: frame_saved_pc
// OBSOLETE Find the caller of this frame. We do this by seeing if RP_REGNUM
// OBSOLETE is saved in the stack anywhere, otherwise we get it from the
// OBSOLETE registers. If the inner frame is a dummy frame, return its PC
// OBSOLETE instead of RP, because that's where "caller" of the dummy-frame
// OBSOLETE will be found. */
// OBSOLETE
// OBSOLETE CORE_ADDR
// OBSOLETE fr30_frame_saved_pc (struct frame_info *fi)
// OBSOLETE {
// OBSOLETE if (PC_IN_CALL_DUMMY (fi->pc, fi->frame, fi->frame))
// OBSOLETE return generic_read_register_dummy (fi->pc, fi->frame, PC_REGNUM);
// OBSOLETE else
// OBSOLETE return fr30_find_callers_reg (fi, RP_REGNUM);
// OBSOLETE }
// OBSOLETE
// OBSOLETE /* Function: fix_call_dummy
// OBSOLETE Pokes the callee function's address into the CALL_DUMMY assembly stub.
// OBSOLETE Assumes that the CALL_DUMMY looks like this:
// OBSOLETE jarl <offset24>, r31
// OBSOLETE trap
// OBSOLETE */
// OBSOLETE
// OBSOLETE int
// OBSOLETE fr30_fix_call_dummy (char *dummy, CORE_ADDR sp, CORE_ADDR fun, int nargs,
// OBSOLETE struct value **args, struct type *type, int gcc_p)
// OBSOLETE {
// OBSOLETE long offset24;
// OBSOLETE
// OBSOLETE offset24 = (long) fun - (long) entry_point_address ();
// OBSOLETE offset24 &= 0x3fffff;
// OBSOLETE offset24 |= 0xff800000; /* jarl <offset24>, r31 */
// OBSOLETE
// OBSOLETE store_unsigned_integer ((unsigned int *) &dummy[2], 2, offset24 & 0xffff);
// OBSOLETE store_unsigned_integer ((unsigned int *) &dummy[0], 2, offset24 >> 16);
// OBSOLETE return 0;
// OBSOLETE }