From 977adac5db461a0f8e7d7a5b2a82c6b81f015433 Mon Sep 17 00:00:00 2001 From: Nicholas Duffek Date: Tue, 1 May 2001 19:36:11 +0000 Subject: [PATCH] * config/rs6000/tm-rs6000.h (IN_SOLIB_RETURN_TRAMPOLINE): Define. (rs6000_in_solib_return_trampoline): Declare. * rs6000-tdep.c (rs6000_in_solib_return_trampoline): New function. (rs6000_skip_trampoline_code): Skip bigtoc fixup code. * xcoffread.c (read_xcoff_symtab): Perform the ISFCN function check after the CSECT check rather than before it. Allocate separate symtabs for CSECTs whose names begin with '@'. (scan_xcoff_symtab): Don't ignore symbols beginning with '@'. Activate the misc_func_recorded mechanism for whose names begin with '@'. --- gdb/ChangeLog | 14 ++++++++ gdb/config/rs6000/tm-rs6000.h | 7 ++++ gdb/rs6000-tdep.c | 61 ++++++++++++++++++++++++++++++++--- gdb/xcoffread.c | 37 ++++++++++----------- 4 files changed, 96 insertions(+), 23 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 7b9a4f8525..30c6acbc5f 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,17 @@ +2001-05-01 Nicholas Duffek + + * config/rs6000/tm-rs6000.h (IN_SOLIB_RETURN_TRAMPOLINE): Define. + (rs6000_in_solib_return_trampoline): Declare. + * rs6000-tdep.c (rs6000_in_solib_return_trampoline): New + function. + (rs6000_skip_trampoline_code): Skip bigtoc fixup code. + * xcoffread.c (read_xcoff_symtab): Perform the ISFCN function + check after the CSECT check rather than before it. Allocate + separate symtabs for CSECTs whose names begin with '@'. + (scan_xcoff_symtab): Don't ignore symbols beginning with '@'. + Activate the misc_func_recorded mechanism for whose names begin + with '@'. + 2001-04-30 J.T. Conklin * ppcnbsd-nat.c (fetch_inferior_registers) diff --git a/gdb/config/rs6000/tm-rs6000.h b/gdb/config/rs6000/tm-rs6000.h index d16ca9a43a..96eb16337f 100644 --- a/gdb/config/rs6000/tm-rs6000.h +++ b/gdb/config/rs6000/tm-rs6000.h @@ -32,6 +32,13 @@ #undef CPLUS_MARKER #define CPLUS_MARKER '.' +/* Return whether PC in function NAME is in code that should be skipped when + single-stepping. */ + +#define IN_SOLIB_RETURN_TRAMPOLINE(pc, name) \ + rs6000_in_solib_return_trampoline (pc, name) +extern int rs6000_in_solib_return_trampoline (CORE_ADDR, char *); + /* If PC is in some function-call trampoline code, return the PC where the function itself actually starts. If not, return NULL. */ diff --git a/gdb/rs6000-tdep.c b/gdb/rs6000-tdep.c index 3b4aeb95f6..3c0a7b9ad5 100644 --- a/gdb/rs6000-tdep.c +++ b/gdb/rs6000-tdep.c @@ -1132,19 +1132,55 @@ rs6000_extract_return_value (struct type *valtype, char *regbuf, char *valbuf) static CORE_ADDR rs6000_struct_return_address; -/* Indirect function calls use a piece of trampoline code to do context - switching, i.e. to set the new TOC table. Skip such code if we are on - its first instruction (as when we have single-stepped to here). - Also skip shared library trampoline code (which is different from +/* Return whether handle_inferior_event() should proceed through code + starting at PC in function NAME when stepping. + + The AIX -bbigtoc linker option generates functions @FIX0, @FIX1, etc. to + handle memory references that are too distant to fit in instructions + generated by the compiler. For example, if 'foo' in the following + instruction: + + lwz r9,foo(r2) + + is greater than 32767, the linker might replace the lwz with a branch to + somewhere in @FIX1 that does the load in 2 instructions and then branches + back to where execution should continue. + + GDB should silently step over @FIX code, just like AIX dbx does. + Unfortunately, the linker uses the "b" instruction for the branches, + meaning that the link register doesn't get set. Therefore, GDB's usual + step_over_function() mechanism won't work. + + Instead, use the IN_SOLIB_RETURN_TRAMPOLINE and SKIP_TRAMPOLINE_CODE hooks + in handle_inferior_event() to skip past @FIX code. */ + +int +rs6000_in_solib_return_trampoline (CORE_ADDR pc, char *name) +{ + return name && !strncmp (name, "@FIX", 4); +} + +/* Skip code that the user doesn't want to see when stepping: + + 1. Indirect function calls use a piece of trampoline code to do context + switching, i.e. to set the new TOC table. Skip such code if we are on + its first instruction (as when we have single-stepped to here). + + 2. Skip shared library trampoline code (which is different from indirect function call trampolines). + + 3. Skip bigtoc fixup code. + Result is desired PC to step until, or NULL if we are not in - trampoline code. */ + code that should be skipped. */ CORE_ADDR rs6000_skip_trampoline_code (CORE_ADDR pc) { register unsigned int ii, op; + int rel; CORE_ADDR solib_target_pc; + struct minimal_symbol *msymbol; static unsigned trampoline_code[] = { @@ -1158,6 +1194,21 @@ rs6000_skip_trampoline_code (CORE_ADDR pc) 0 }; + /* Check for bigtoc fixup code. */ + msymbol = lookup_minimal_symbol_by_pc (pc); + if (msymbol && rs6000_in_solib_return_trampoline (pc, SYMBOL_NAME (msymbol))) + { + /* Double-check that the third instruction from PC is relative "b". */ + op = read_memory_integer (pc + 8, 4); + if ((op & 0xfc000003) == 0x48000000) + { + /* Extract bits 6-29 as a signed 24-bit relative word address and + add it to the containing PC. */ + rel = ((int)(op << 6) >> 6); + return pc + 8 + rel; + } + } + /* If pc is in a shared library trampoline, return its target. */ solib_target_pc = find_solib_trampoline_target (pc); if (solib_target_pc) diff --git a/gdb/xcoffread.c b/gdb/xcoffread.c index 586f258d90..6e52710d47 100644 --- a/gdb/xcoffread.c +++ b/gdb/xcoffread.c @@ -1081,14 +1081,6 @@ read_xcoff_symtab (struct partial_symtab *pst) /* done with all files, everything from here on is globals */ } - /* if explicitly specified as a function, treat is as one. */ - if (ISFCN (cs->c_type) && cs->c_sclass != C_TPDEF) - { - bfd_coff_swap_aux_in (abfd, raw_auxptr, cs->c_type, cs->c_sclass, - 0, cs->c_naux, &main_aux); - goto function_entry_point; - } - if ((cs->c_sclass == C_EXT || cs->c_sclass == C_HIDEXT) && cs->c_naux == 1) { @@ -1158,7 +1150,8 @@ read_xcoff_symtab (struct partial_symtab *pst) SECT_OFF_TEXT (objfile)); file_end_addr = file_start_addr + CSECT_LEN (&main_aux); - if (cs->c_name && cs->c_name[0] == '.') + if (cs->c_name && (cs->c_name[0] == '.' + || cs->c_name[0] == '@')) { last_csect_name = cs->c_name; last_csect_val = cs->c_value; @@ -1232,6 +1225,16 @@ read_xcoff_symtab (struct partial_symtab *pst) } } + /* If explicitly specified as a function, treat is as one. This check + evaluates to true for @FIX* bigtoc CSECT symbols, so it must occur + after the above CSECT check. */ + if (ISFCN (cs->c_type) && cs->c_sclass != C_TPDEF) + { + bfd_coff_swap_aux_in (abfd, raw_auxptr, cs->c_type, cs->c_sclass, + 0, cs->c_naux, &main_aux); + goto function_entry_point; + } + switch (cs->c_sclass) { @@ -2243,14 +2246,8 @@ scan_xcoff_symtab (struct objfile *objfile) else csect_aux = main_aux[0]; - /* If symbol name starts with ".$" or "$", ignore it. - - A symbol like "@FIX1" introduces a section for -bbigtoc jump - tables, which contain anonymous linker-generated code. - Ignore those sections to avoid "pc 0x... in read in psymtab, - but not in symtab" warnings from find_pc_sect_symtab. */ - - if (namestring[0] == '$' || namestring[0] == '@' + /* If symbol name starts with ".$" or "$", ignore it. */ + if (namestring[0] == '$' || (namestring[0] == '.' && namestring[1] == '$')) break; @@ -2296,7 +2293,11 @@ scan_xcoff_symtab (struct objfile *objfile) objfile->static_psymbols.next); } } - if (namestring && namestring[0] == '.') + /* Activate the misc_func_recorded mechanism for + compiler- and linker-generated CSECTs like ".strcmp" + and "@FIX1". */ + if (namestring && (namestring[0] == '.' + || namestring[0] == '@')) { last_csect_name = namestring; last_csect_val = symbol.n_value; -- 2.34.1