From f595cb1909c318d0baf767a2a70c37caf56a111c Mon Sep 17 00:00:00 2001 From: Mark Kettenis Date: Mon, 3 May 2004 21:56:09 +0000 Subject: * m68k-tdep.h (struct gdbarch_tdep): Add member struct_value_regnum. (m68k_svr4_init_abi): New prototype. * m68k-tdep.c: Include "floatformat.h". Add comment about all the different calling conventions. (m68k_extract_return_value): Remove code dealing with single-field structs. (m68k_store_return_value): Remove code dealing with single-field structs. Correctly store return values of 5, 6, 7 or 8 bytes. (m68k_extract_struct_value_address): Remove function. (m68k_svr4_extract_return_value,m68k_svr4_store_return_value) (m68k_reg_struct_return_p, m68k_return_value) (m68k_svr4_return_value): New functions. (m68k_use_struct_convention): Remove function. (m68k_push_dummy_call): Use new struct_value_regnum member of `struct gdbarch_tdep' instead of hardcoded register number to store STRUCT_ADDR. (m68k_svr4_init_abi): New function. (m68k_gdbarch_init): Don't set extract_return_value, store_return_values, deprecated_extract_struct_value_address and use_struct_convention. Set return_value instead. Initialize new struct_value_regnum member of `struct gdbarch_tdep'. * m68klinux-tdep.c: Update copyright year. (m68k_linux_extract_return_value, m68k_linux_store_return_value) (m68k_linux_extract_struct_value_address): Remove function. (m68k_linux_init_abi): Don't set extract_return_value, store_return_values, deprecated_extract_struct_value_address and use_struct_convention. Call m68k_svr4_init_abi but override the new struct_value_regnum member of `struct gdbarch_tdep'. * Makefile.in (m68k-tdep.o): Update dependencies. --- gdb/m68k-tdep.c | 205 +++++++++++++++++++++++++++++++++++++++++++++----------- 1 file changed, 165 insertions(+), 40 deletions(-) (limited to 'gdb/m68k-tdep.c') diff --git a/gdb/m68k-tdep.c b/gdb/m68k-tdep.c index 66f21fe2bca..d0c4f0e15ee 100644 --- a/gdb/m68k-tdep.c +++ b/gdb/m68k-tdep.c @@ -25,6 +25,7 @@ #include "frame.h" #include "frame-base.h" #include "frame-unwind.h" +#include "floatformat.h" #include "symtab.h" #include "gdbcore.h" #include "value.h" @@ -129,8 +130,36 @@ m68k_register_name (int regnum) return register_names[regnum]; } -/* Extract from an array REGBUF containing the (raw) register state, a - function return value of TYPE, and copy that, in virtual format, +/* There is a fair number of calling conventions that are in somewhat + wide use. The 68000/08/10 don't support an FPU, not even as a + coprocessor. All function return values are stored in %d0/%d1. + Structures are returned in a static buffer, a pointer to which is + returned in %d0. This means that functions returning a structure + are not re-entrant. To avoid this problem some systems use a + convention where the caller passes a pointer to a buffer in %a1 + where the return values is to be stored. This convention is the + default, and is implemented in the function m68k_return_value. + + The 68020/030/040/060 do support an FPU, either as a coprocessor + (68881/2) or built-in (68040/68060). That's why System V release 4 + (SVR4) instroduces a new calling convention specified by the SVR4 + psABI. Integer values are returned in %d0/%d1, pointer return + values in %a0 and floating values in %fp0. When calling functions + returning a structure the caller should pass a pointer to a buffer + for the return value in %a0. This convention is implemented in the + function m68k_svr4_return_value, and by appropriately setting the + struct_value_regnum member of `struct gdbarch_tdep'. + + GNU/Linux returns values in the same way as SVR4 does, but uses %a1 + for passing the structure return value buffer. + + GCC can also generate code where small structures are returned in + %d0/%d1 instead of in memory by using -freg-struct-return. This is + the default on NetBSD a.out, OpenBSD and GNU/Linux and several + embedded systems. This convention is implemented by setting the + struct_return member of `struct gdbarch_tdep' to reg_struct_return. */ + +/* Read a function return value of TYPE from REGCACHE, and copy that into VALBUF. */ static void @@ -140,13 +169,6 @@ m68k_extract_return_value (struct type *type, struct regcache *regcache, int len = TYPE_LENGTH (type); char buf[M68K_MAX_REGISTER_SIZE]; - if (TYPE_CODE (type) == TYPE_CODE_STRUCT - && TYPE_NFIELDS (type) == 1) - { - m68k_extract_return_value (TYPE_FIELD_TYPE (type, 0), regcache, valbuf); - return; - } - if (len <= 4) { regcache_raw_read (regcache, M68K_D0_REGNUM, buf); @@ -164,29 +186,39 @@ m68k_extract_return_value (struct type *type, struct regcache *regcache, "Cannot extract return value of %d bytes long.", len); } -/* Write into the appropriate registers a function return value stored - in VALBUF of type TYPE, given in virtual format. */ - static void -m68k_store_return_value (struct type *type, struct regcache *regcache, - const void *valbuf) +m68k_svr4_extract_return_value (struct type *type, struct regcache *regcache, + void *valbuf) { int len = TYPE_LENGTH (type); + char buf[M68K_MAX_REGISTER_SIZE]; - if (TYPE_CODE (type) == TYPE_CODE_STRUCT - && TYPE_NFIELDS (type) == 1) + if (TYPE_CODE (type) == TYPE_CODE_FLT) { - m68k_store_return_value (TYPE_FIELD_TYPE (type, 0), regcache, valbuf); - return; + regcache_raw_read (regcache, M68K_FP0_REGNUM, buf); + convert_typed_floating (buf, builtin_type_m68881_ext, valbuf, type); } + else if (TYPE_CODE (type) == TYPE_CODE_PTR && len == 4) + regcache_raw_read (regcache, M68K_A0_REGNUM, valbuf); + else + m68k_extract_return_value (type, regcache, valbuf); +} + +/* Write a function return value of TYPE from VALBUF into REGCACHE. */ + +static void +m68k_store_return_value (struct type *type, struct regcache *regcache, + const void *valbuf) +{ + int len = TYPE_LENGTH (type); if (len <= 4) regcache_raw_write_part (regcache, M68K_D0_REGNUM, 4 - len, len, valbuf); else if (len <= 8) { - regcache_raw_write_part (regcache, M68K_D1_REGNUM, 8 - len, + regcache_raw_write_part (regcache, M68K_D0_REGNUM, 8 - len, len - 4, valbuf); - regcache_raw_write (regcache, M68K_D0_REGNUM, + regcache_raw_write (regcache, M68K_D1_REGNUM, (char *) valbuf + (len - 4)); } else @@ -194,29 +226,108 @@ m68k_store_return_value (struct type *type, struct regcache *regcache, "Cannot store return value of %d bytes long.", len); } -/* Extract from REGCACHE, which contains the (raw) register state, the - address in which a function should return its structure value, as a - CORE_ADDR. */ - -static CORE_ADDR -m68k_extract_struct_value_address (struct regcache *regcache) +static void +m68k_svr4_store_return_value (struct type *type, struct regcache *regcache, + const void *valbuf) { - char buf[4]; + int len = TYPE_LENGTH (type); - regcache_cooked_read (regcache, M68K_D0_REGNUM, buf); - return extract_unsigned_integer (buf, 4); + if (TYPE_CODE (type) == TYPE_CODE_FLT) + { + char buf[M68K_MAX_REGISTER_SIZE]; + convert_typed_floating (valbuf, type, buf, builtin_type_m68881_ext); + regcache_raw_write (regcache, M68K_FP0_REGNUM, buf); + } + else if (TYPE_CODE (type) == TYPE_CODE_PTR && len == 4) + { + regcache_raw_write (regcache, M68K_A0_REGNUM, valbuf); + regcache_raw_write (regcache, M68K_D0_REGNUM, valbuf); + } + else + m68k_store_return_value (type, regcache, valbuf); } +/* Return non-zero if TYPE, which is assumed to be a structure or + union type, should be returned in registers for architecture + GDBARCH. */ + static int -m68k_use_struct_convention (int gcc_p, struct type *type) +m68k_reg_struct_return_p (struct gdbarch *gdbarch, struct type *type) { - enum struct_return struct_return; + struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); + enum type_code code = TYPE_CODE (type); + int len = TYPE_LENGTH (type); - struct_return = gdbarch_tdep (current_gdbarch)->struct_return; - return generic_use_struct_convention (struct_return == reg_struct_return, - type); + gdb_assert (code == TYPE_CODE_STRUCT || code == TYPE_CODE_UNION); + + if (tdep->struct_return == pcc_struct_return) + return 0; + + return (len == 1 || len == 2 || len == 4 || len == 8); } +/* Determine, for architecture GDBARCH, how a return value of TYPE + should be returned. If it is supposed to be returned in registers, + and READBUF is non-zero, read the appropriate value from REGCACHE, + and copy it into READBUF. If WRITEBUF is non-zero, write the value + from WRITEBUF into REGCACHE. */ + +static enum return_value_convention +m68k_return_value (struct gdbarch *gdbarch, struct type *type, + struct regcache *regcache, void *readbuf, + const void *writebuf) +{ + enum type_code code = TYPE_CODE (type); + + if ((code == TYPE_CODE_STRUCT || code == TYPE_CODE_UNION) + && !m68k_reg_struct_return_p (gdbarch, type)) + return RETURN_VALUE_STRUCT_CONVENTION; + + /* GCC returns a `long double' in memory. */ + if (code == TYPE_CODE_FLT && TYPE_LENGTH (type) == 12) + return RETURN_VALUE_STRUCT_CONVENTION; + + if (readbuf) + m68k_extract_return_value (type, regcache, readbuf); + if (writebuf) + m68k_store_return_value (type, regcache, writebuf); + + return RETURN_VALUE_REGISTER_CONVENTION; +} + +static enum return_value_convention +m68k_svr4_return_value (struct gdbarch *gdbarch, struct type *type, + struct regcache *regcache, void *readbuf, + const void *writebuf) +{ + enum type_code code = TYPE_CODE (type); + + if ((code == TYPE_CODE_STRUCT || code == TYPE_CODE_UNION) + && !m68k_reg_struct_return_p (gdbarch, type)) + return RETURN_VALUE_STRUCT_CONVENTION; + + /* This special case is for structures consisting of a single + `float' or `double' member. These structures are returned in + %fp0. For these structures, we call ourselves recursively, + changing TYPE into the type of the first member of the structure. + Since that should work for all structures that have only one + member, we don't bother to check the member's type here. */ + if (code == TYPE_CODE_STRUCT && TYPE_NFIELDS (type) == 1) + { + type = check_typedef (TYPE_FIELD_TYPE (type, 0)); + return m68k_svr4_return_value (gdbarch, type, regcache, + readbuf, writebuf); + } + + if (readbuf) + m68k_svr4_extract_return_value (type, regcache, readbuf); + if (writebuf) + m68k_svr4_store_return_value (type, regcache, writebuf); + + return RETURN_VALUE_REGISTER_CONVENTION; +} + + /* A function that tells us whether the function invocation represented by fi does not have a frame on the stack associated with it. If it does not, FRAMELESS is set to 1, else 0. */ @@ -293,6 +404,7 @@ m68k_push_dummy_call (struct gdbarch *gdbarch, CORE_ADDR func_addr, struct value **args, CORE_ADDR sp, int struct_return, CORE_ADDR struct_addr) { + struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); char buf[4]; int i; @@ -321,7 +433,7 @@ m68k_push_dummy_call (struct gdbarch *gdbarch, CORE_ADDR func_addr, if (struct_return) { store_unsigned_integer (buf, 4, struct_addr); - regcache_cooked_write (regcache, M68K_A1_REGNUM, buf); + regcache_cooked_write (regcache, tdep->struct_value_regnum, buf); } /* Store return address. */ @@ -952,6 +1064,22 @@ m68k_get_longjmp_target (CORE_ADDR *pc) *pc = extract_unsigned_integer (buf, TARGET_PTR_BIT / TARGET_CHAR_BIT); return 1; } + + +/* System V Release 4 (SVR4). */ + +void +m68k_svr4_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) +{ + struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); + + /* SVR4 uses a different calling convention. */ + set_gdbarch_return_value (gdbarch, m68k_svr4_return_value); + + /* SVR4 uses %a0 instead of %a1. */ + tdep->struct_value_regnum = M68K_A0_REGNUM; +} + /* Function: m68k_gdbarch_init Initializer function for the m68k gdbarch vector. @@ -984,11 +1112,6 @@ m68k_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches) set_gdbarch_believe_pcc_promotion (gdbarch, 1); set_gdbarch_decr_pc_after_break (gdbarch, 2); - set_gdbarch_extract_return_value (gdbarch, m68k_extract_return_value); - set_gdbarch_store_return_value (gdbarch, m68k_store_return_value); - set_gdbarch_deprecated_extract_struct_value_address (gdbarch, m68k_extract_struct_value_address); - set_gdbarch_use_struct_convention (gdbarch, m68k_use_struct_convention); - set_gdbarch_deprecated_frameless_function_invocation (gdbarch, m68k_frameless_function_invocation); set_gdbarch_frame_args_skip (gdbarch, 8); @@ -1002,6 +1125,7 @@ m68k_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches) set_gdbarch_fp0_regnum (gdbarch, M68K_FP0_REGNUM); set_gdbarch_push_dummy_call (gdbarch, m68k_push_dummy_call); + set_gdbarch_return_value (gdbarch, m68k_return_value); /* Disassembler. */ set_gdbarch_print_insn (gdbarch, print_insn_m68k); @@ -1012,6 +1136,7 @@ m68k_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches) #else tdep->jb_pc = -1; #endif + tdep->struct_value_regnum = M68K_A1_REGNUM; tdep->struct_return = pcc_struct_return; /* Frame unwinder. */ -- cgit v1.2.1