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3eba3a011a
Recently I tried the m68k port of gdb. It had some issues, which are
fixed in this patch.
* Various types of return values were not being handled properly. In
particular:
* arrays are returned by following the same convention as
structures. This matters in languages like Ada, where an array
can in fact be returned as a value.
* "long double" was not being handled correctly in
m68k_svr4_return_value.
* GCC's m68k back end does not return vector types in registers, so
change gdb to follow.
* GCC's m68k back end doesn't faithfully implement the ABI, and so
some objects with unusual size (not possible in C, but possible in
Ada) are not returned correctly.
* gcc implements an m68k ABI variant that it simply describes as
"embedded". This ABI is similar to the SVR4 ABI, but rather than
returning pointer-typed values in %a0, such values are returned in
%d0. To support this, an ELF osabi sniffer is added.
* Commit 85f7484a ("m68k: tag floating-point ABI used") adds an
attribute that can be used to recognize when hard- or soft-float is
in use. gdb can now read this tag and choose the ABI accordingly.
I was unable to run the gdb test suite with this patch. Instead, I
tested it using qemu and the internal AdaCore test suite.
gdb/ChangeLog
2020-09-14 Tom Tromey <tromey@adacore.com>
* m68k-tdep.c (m68k_extract_return_value): Use
pointer_result_regnum.
(m68k_store_return_value): Likewise.
(m68k_reg_struct_return_p): Handle vectors and arrays.
(m68k_return_value): Handle arrays.
(m68k_svr4_return_value): Fix single-element aggregate handling.
Handle long double. Adjust for embedded ABI.
(m68k_svr4_init_abi): Set pointer_result_regnum.
(m68k_embedded_init_abi): New function.
(m68k_gdbarch_init): Handle Tag_GNU_M68K_ABI_FP.
(m68k_osabi_sniffer): New function.
(_initialize_m68k_tdep): Register osabi sniffer.
* m68k-tdep.h (struct gdbarch_tdep) <pointer_result_regnum>: New
member.
113 lines
3.2 KiB
C
113 lines
3.2 KiB
C
/* Target-dependent code for the Motorola 68000 series.
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Copyright (C) 1990-2020 Free 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 3 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, see <http://www.gnu.org/licenses/>. */
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#ifndef M68K_TDEP_H
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#define M68K_TDEP_H
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struct frame_info;
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/* Register numbers of various important registers. */
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enum m68k_regnum
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{
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M68K_D0_REGNUM = 0,
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M68K_D1_REGNUM = 1,
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M68K_D2_REGNUM = 2,
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M68K_D7_REGNUM = 7,
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M68K_A0_REGNUM = 8,
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M68K_A1_REGNUM = 9,
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M68K_A2_REGNUM = 10,
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M68K_FP_REGNUM = 14, /* Address of executing stack frame. */
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M68K_SP_REGNUM = 15, /* Address of top of stack. */
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M68K_PS_REGNUM = 16, /* Processor status. */
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M68K_PC_REGNUM = 17, /* Program counter. */
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M68K_FP0_REGNUM = 18, /* Floating point register 0. */
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M68K_FPC_REGNUM = 26, /* 68881 control register. */
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M68K_FPS_REGNUM = 27, /* 68881 status register. */
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M68K_FPI_REGNUM = 28
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};
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/* Number of machine registers. */
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#define M68K_NUM_REGS (M68K_FPI_REGNUM + 1)
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/* Size of the largest register. */
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#define M68K_MAX_REGISTER_SIZE 12
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/* Convention for returning structures. */
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enum struct_return
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{
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pcc_struct_return, /* Return "short" structures in memory. */
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reg_struct_return /* Return "short" structures in registers. */
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};
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/* Particular flavour of m68k. */
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enum m68k_flavour
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{
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m68k_no_flavour,
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m68k_coldfire_flavour,
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m68k_fido_flavour
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};
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/* Target-dependent structure in gdbarch. */
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struct gdbarch_tdep
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{
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/* Offset to PC value in the jump buffer. If this is negative,
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longjmp support will be disabled. */
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int jb_pc;
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/* The size of each entry in the jump buffer. */
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size_t jb_elt_size;
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/* Register in which the address to store a structure value is
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passed to a function. */
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int struct_value_regnum;
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/* Register in which a pointer value is returned. In the SVR4 ABI,
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this is %a0, but in GCC's "embedded" ABI, this is %d0. */
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int pointer_result_regnum;
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/* Convention for returning structures. */
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enum struct_return struct_return;
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/* Convention for returning floats. zero in int regs, non-zero in float. */
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int float_return;
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/* The particular flavour of m68k. */
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enum m68k_flavour flavour;
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/* Flag set if the floating point registers are present, or assumed
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to be present. */
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int fpregs_present;
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/* ISA-specific data types. */
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struct type *m68k_ps_type;
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struct type *m68881_ext_type;
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};
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/* Initialize a SVR4 architecture variant. */
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extern void m68k_svr4_init_abi (struct gdbarch_info, struct gdbarch *);
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/* Functions exported from m68k-bsd-tdep.c. */
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extern int m68kbsd_fpreg_offset (struct gdbarch *gdbarch, int regnum);
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#endif /* m68k-tdep.h */
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