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binutils-gdb/gdb/mips-tdep.h
Simon Marchi 8480a37e14 gdb: pass frames as const frame_info_ptr & 
We currently pass frames to function by value, as `frame_info_ptr`.
This is somewhat expensive:

 - the size of `frame_info_ptr` is 64 bytes, which is a bit big to pass
   by value
 - the constructors and destructor link/unlink the object in the global
   `frame_info_ptr::frame_list` list.  This is an `intrusive_list`, so
   it's not so bad: it's just assigning a few points, there's no memory
   allocation as if it was `std::list`, but still it's useless to do
   that over and over.

As suggested by Tom Tromey, change many function signatures to accept
`const frame_info_ptr &` instead of `frame_info_ptr`.

Some functions reassign their `frame_info_ptr` parameter, like:

  void
  the_func (frame_info_ptr frame)
  {
    for (; frame != nullptr; frame = get_prev_frame (frame))
      {
        ...
      }
  }

I wondered what to do about them, do I leave them as-is or change them
(and need to introduce a separate local variable that can be
re-assigned).  I opted for the later for consistency.  It might not be
clear why some functions take `const frame_info_ptr &` while others take
`frame_info_ptr`.  Also, if a function took a `frame_info_ptr` because
it did re-assign its parameter, I doubt that we would think to change it
to `const frame_info_ptr &` should the implementation change such that
it doesn't need to take `frame_info_ptr` anymore.  It seems better to
have a simple rule and apply it everywhere.

Change-Id: I59d10addef687d157f82ccf4d54f5dde9a963fd0
Approved-By: Andrew Burgess <aburgess@redhat.com>
2024-02-20 10:42:25 -05:00

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/* Target-dependent header for the MIPS architecture, for GDB, the GNU Debugger.
Copyright (C) 2002-2024 Free Software Foundation, Inc.
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#ifndef MIPS_TDEP_H
#define MIPS_TDEP_H
#include "objfiles.h"
#include "gdbarch.h"
struct gdbarch;
/* All the possible MIPS ABIs. */
enum mips_abi
{
MIPS_ABI_UNKNOWN = 0,
MIPS_ABI_N32,
MIPS_ABI_O32,
MIPS_ABI_N64,
MIPS_ABI_O64,
MIPS_ABI_EABI32,
MIPS_ABI_EABI64,
MIPS_ABI_LAST
};
/* Return the MIPS ABI associated with GDBARCH. */
enum mips_abi mips_abi (struct gdbarch *gdbarch);
/* Base and compressed MIPS ISA variations. */
enum mips_isa
{
ISA_MIPS = -1, /* mips_compression_string depends on it. */
ISA_MIPS16,
ISA_MICROMIPS
};
/* Corresponding MSYMBOL_TARGET_FLAG aliases. */
#define MSYMBOL_TARGET_FLAG_MIPS16(sym) \
(sym)->target_flag_1 ()
#define SET_MSYMBOL_TARGET_FLAG_MIPS16(sym) \
(sym)->set_target_flag_1 (true)
#define MSYMBOL_TARGET_FLAG_MICROMIPS(sym) \
(sym)->target_flag_2 ()
#define SET_MSYMBOL_TARGET_FLAG_MICROMIPS(sym) \
(sym)->set_target_flag_2 (true)
/* Return the MIPS ISA's register size. Just a short cut to the BFD
architecture's word size. */
extern int mips_isa_regsize (struct gdbarch *gdbarch);
/* Return the current index for various MIPS registers. */
struct mips_regnum
{
int pc;
int fp0;
int fp_implementation_revision;
int fp_control_status;
int badvaddr; /* Bad vaddr for addressing exception. */
int cause; /* Describes last exception. */
int hi; /* Multiply/divide temp. */
int lo; /* ... */
int dspacc; /* SmartMIPS/DSP accumulators. */
int dspctl; /* DSP control. */
};
extern const struct mips_regnum *mips_regnum (struct gdbarch *gdbarch);
/* Some MIPS boards don't support floating point while others only
support single-precision floating-point operations. */
enum mips_fpu_type
{
MIPS_FPU_DOUBLE, /* Full double precision floating point. */
MIPS_FPU_SINGLE, /* Single precision floating point (R4650). */
MIPS_FPU_NONE /* No floating point. */
};
/* MIPS specific per-architecture information. */
struct mips_gdbarch_tdep : gdbarch_tdep_base
{
/* from the elf header */
int elf_flags = 0;
/* mips options */
enum mips_abi mips_abi {};
enum mips_abi found_abi {};
enum mips_isa mips_isa {};
enum mips_fpu_type mips_fpu_type {};
int mips_last_arg_regnum = 0;
int mips_last_fp_arg_regnum = 0;
int default_mask_address_p = 0;
/* Is the target using 64-bit raw integer registers but only
storing a left-aligned 32-bit value in each? */
int mips64_transfers_32bit_regs_p = 0;
/* Indexes for various registers. IRIX and embedded have
different values. This contains the "public" fields. Don't
add any that do not need to be public. */
const struct mips_regnum *regnum = nullptr;
/* Register names table for the current register set. */
const char * const *mips_processor_reg_names = nullptr;
/* The size of register data available from the target, if known.
This doesn't quite obsolete the manual
mips64_transfers_32bit_regs_p, since that is documented to force
left alignment even for big endian (very strange). */
int register_size_valid_p = 0;
int register_size = 0;
/* Return the expected next PC if FRAME is stopped at a syscall
instruction. */
CORE_ADDR (*syscall_next_pc) (const frame_info_ptr &frame) = nullptr;
};
/* Register numbers of various important registers. */
enum
{
MIPS_ZERO_REGNUM = 0, /* Read-only register, always 0. */
MIPS_AT_REGNUM = 1,
MIPS_V0_REGNUM = 2, /* Function integer return value. */
MIPS_A0_REGNUM = 4, /* Loc of first arg during a subr call. */
MIPS_S2_REGNUM = 18, /* Contains return address in MIPS16 thunks. */
MIPS_T9_REGNUM = 25, /* Contains address of callee in PIC. */
MIPS_GP_REGNUM = 28,
MIPS_SP_REGNUM = 29,
MIPS_RA_REGNUM = 31,
MIPS_PS_REGNUM = 32, /* Contains processor status. */
MIPS_EMBED_LO_REGNUM = 33,
MIPS_EMBED_HI_REGNUM = 34,
MIPS_EMBED_BADVADDR_REGNUM = 35,
MIPS_EMBED_CAUSE_REGNUM = 36,
MIPS_EMBED_PC_REGNUM = 37,
MIPS_EMBED_FP0_REGNUM = 38,
MIPS_UNUSED_REGNUM = 73, /* Never used, FIXME. */
MIPS_FIRST_EMBED_REGNUM = 74, /* First CP0 register for embedded use. */
MIPS_PRID_REGNUM = 89, /* Processor ID. */
MIPS_LAST_EMBED_REGNUM = 89 /* Last one. */
};
/* Instruction sizes and other useful constants. */
enum
{
MIPS_INSN16_SIZE = 2,
MIPS_INSN32_SIZE = 4,
/* The number of floating-point or integer registers. */
MIPS_NUMREGS = 32
};
/* Single step based on where the current instruction will take us. */
extern std::vector<CORE_ADDR> mips_software_single_step
(struct regcache *regcache);
/* Strip the ISA (compression) bit off from ADDR. */
extern CORE_ADDR mips_unmake_compact_addr (CORE_ADDR addr);
/* Tell if the program counter value in MEMADDR is in a standard
MIPS function. */
extern int mips_pc_is_mips (CORE_ADDR memaddr);
/* Tell if the program counter value in MEMADDR is in a MIPS16
function. */
extern int mips_pc_is_mips16 (struct gdbarch *gdbarch, CORE_ADDR memaddr);
/* Tell if the program counter value in MEMADDR is in a microMIPS
function. */
extern int mips_pc_is_micromips (struct gdbarch *gdbarch, CORE_ADDR memaddr);
/* Return the currently configured (or set) saved register size. */
extern unsigned int mips_abi_regsize (struct gdbarch *gdbarch);
/* Make PC the address of the next instruction to execute. */
extern void mips_write_pc (struct regcache *regcache, CORE_ADDR pc);
/* Target descriptions which only indicate the size of general
registers. */
extern struct target_desc *mips_tdesc_gp32;
extern struct target_desc *mips_tdesc_gp64;
/* Return non-zero if PC is in a MIPS SVR4 lazy binding stub section. */
static inline int
in_mips_stubs_section (CORE_ADDR pc)
{
return pc_in_section (pc, ".MIPS.stubs");
}
#endif /* MIPS_TDEP_H */
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