From c1a398a320f46905eaf6f520dddc441791861dcb Mon Sep 17 00:00:00 2001 From: Carl Love Date: Thu, 23 Mar 2023 18:23:05 -0400 Subject: PowerPC: fix _Float128 type output string PowerPC supports two 128-bit floating point formats, the IBM long double and IEEE 128-bit float. The issue is the DWARF information does not distinguish between the two. There have been proposals of how to extend the DWARF information as discussed in https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104194 but has not been fully implemented. GCC introduced the _Float128 internal type as a work around for the issue. The workaround is not transparent to GDB. The internal _Float128 type name is printed rather then the user specified long double type. This patch adds a new gdbarch method to allow PowerPC to detect the GCC workaround. The workaround checks for "_Float128" name when reading the base typedef from the die_info. If the workaround is detected, the type and format fields from the _Float128 typedef are copied to the long double typedef. The same is done for the complex long double typedef. This patch fixes 74 regression test failures in gdb.base/whatis-ptype-typedefs.exp on PowerPC with IEEE float 128 as the default on GCC. It fixes one regression test failure in gdb.base/complex-parts.exp. The patch has been tested on Power 10 where GCC defaults to IEEE Float 128-bit and on Power 10 where GCC defaults to the IBM 128-bit float. The patch as also been tested on X86-64 with no new regression failures. --- gdb/arch-utils.c | 7 +++++++ gdb/arch-utils.h | 5 +++++ gdb/dwarf2/read.c | 23 +++++++++++++++++++---- gdb/gdbarch-gen.h | 8 ++++++++ gdb/gdbarch.c | 22 ++++++++++++++++++++++ gdb/gdbarch_components.py | 23 +++++++++++++++++++++++ gdb/ppc-linux-tdep.c | 36 ++++++++++++++++++++++++++++++++++++ 7 files changed, 120 insertions(+), 4 deletions(-) diff --git a/gdb/arch-utils.c b/gdb/arch-utils.c index e3af9ce2dbc..997a292e9ef 100644 --- a/gdb/arch-utils.c +++ b/gdb/arch-utils.c @@ -1098,6 +1098,13 @@ default_get_return_buf_addr (struct type *val_type, frame_info_ptr cur_frame) return 0; } +bool +default_dwarf2_omit_typedef_p (struct type *target_type, const char *producer, + const char *name) +{ + return false; +} + /* Non-zero if we want to trace architecture code. */ #ifndef GDBARCH_DEBUG diff --git a/gdb/arch-utils.h b/gdb/arch-utils.h index 56690f0fd43..fc0c0b16793 100644 --- a/gdb/arch-utils.h +++ b/gdb/arch-utils.h @@ -309,6 +309,11 @@ extern void default_read_core_file_mappings extern CORE_ADDR default_get_return_buf_addr (struct type *val_typegdbarch, frame_info_ptr cur_frame); +/* Default implementation of gdbaarch default_dwarf2_omit_typedef_p method. */ +extern bool default_dwarf2_omit_typedef_p (struct type *target_type, + const char *producer, + const char *name); + extern enum return_value_convention default_gdbarch_return_value (struct gdbarch *gdbarch, struct value *function, struct type *valtype, struct regcache *regcache, struct value **read_value, diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c index 8f35b973f3e..29a95cb8b2f 100644 --- a/gdb/dwarf2/read.c +++ b/gdb/dwarf2/read.c @@ -14721,14 +14721,29 @@ static struct type * read_typedef (struct die_info *die, struct dwarf2_cu *cu) { struct objfile *objfile = cu->per_objfile->objfile; - const char *name = NULL; - struct type *this_type, *target_type; + const char *name = dwarf2_full_name (NULL, die, cu); + struct type *this_type; + struct gdbarch *gdbarch = objfile->arch (); + struct type *target_type = die_type (die, cu); + + if (gdbarch_dwarf2_omit_typedef_p (gdbarch, target_type, cu->producer, name)) + { + /* The long double is defined as a base type in C. GCC creates a long + double typedef with target-type _Float128 for the long double to + identify it as the IEEE Float128 value. This is a GCC hack since the + DWARF doesn't distinquish between the IBM long double and IEEE + 128-bit float. Replace the GCC workaround for the long double + typedef with the actual type information copied from the target-type + with the correct long double base type name. */ + this_type = copy_type (target_type); + this_type->set_name (name); + set_die_type (die, this_type, cu); + return this_type; + } - name = dwarf2_full_name (NULL, die, cu); this_type = type_allocator (objfile).new_type (TYPE_CODE_TYPEDEF, 0, name); this_type->set_target_is_stub (true); set_die_type (die, this_type, cu); - target_type = die_type (die, cu); if (target_type != this_type) this_type->set_target_type (target_type); else diff --git a/gdb/gdbarch-gen.h b/gdb/gdbarch-gen.h index a2bd08b8315..56b0a917168 100644 --- a/gdb/gdbarch-gen.h +++ b/gdb/gdbarch-gen.h @@ -468,6 +468,14 @@ typedef CORE_ADDR (gdbarch_get_return_buf_addr_ftype) (struct type *val_type, fr extern CORE_ADDR gdbarch_get_return_buf_addr (struct gdbarch *gdbarch, struct type *val_type, frame_info_ptr cur_frame); extern void set_gdbarch_get_return_buf_addr (struct gdbarch *gdbarch, gdbarch_get_return_buf_addr_ftype *get_return_buf_addr); +/* Return true if the typedef record needs to be replaced.". + + Return 0 by default */ + +typedef bool (gdbarch_dwarf2_omit_typedef_p_ftype) (struct type *target_type, const char *producer, const char *name); +extern bool gdbarch_dwarf2_omit_typedef_p (struct gdbarch *gdbarch, struct type *target_type, const char *producer, const char *name); +extern void set_gdbarch_dwarf2_omit_typedef_p (struct gdbarch *gdbarch, gdbarch_dwarf2_omit_typedef_p_ftype *dwarf2_omit_typedef_p); + /* Return true if the return value of function is stored in the first hidden parameter. In theory, this feature should be language-dependent, specified by language and its ABI, such as C++. Unfortunately, compiler may diff --git a/gdb/gdbarch.c b/gdb/gdbarch.c index 995f49e525f..9406458189f 100644 --- a/gdb/gdbarch.c +++ b/gdb/gdbarch.c @@ -114,6 +114,7 @@ struct gdbarch gdbarch_return_value_ftype *return_value = nullptr; gdbarch_return_value_as_value_ftype *return_value_as_value = default_gdbarch_return_value; gdbarch_get_return_buf_addr_ftype *get_return_buf_addr = default_get_return_buf_addr; + gdbarch_dwarf2_omit_typedef_p_ftype *dwarf2_omit_typedef_p = default_dwarf2_omit_typedef_p; gdbarch_return_in_first_hidden_param_p_ftype *return_in_first_hidden_param_p = default_return_in_first_hidden_param_p; gdbarch_skip_prologue_ftype *skip_prologue = nullptr; gdbarch_skip_main_prologue_ftype *skip_main_prologue = nullptr; @@ -370,6 +371,7 @@ verify_gdbarch (struct gdbarch *gdbarch) if ((gdbarch->return_value_as_value == default_gdbarch_return_value) == (gdbarch->return_value == nullptr)) log.puts ("\n\treturn_value_as_value"); /* Skip verify of get_return_buf_addr, invalid_p == 0 */ + /* Skip verify of dwarf2_omit_typedef_p, invalid_p == 0 */ /* Skip verify of return_in_first_hidden_param_p, invalid_p == 0 */ if (gdbarch->skip_prologue == 0) log.puts ("\n\tskip_prologue"); @@ -788,6 +790,9 @@ gdbarch_dump (struct gdbarch *gdbarch, struct ui_file *file) gdb_printf (file, "gdbarch_dump: get_return_buf_addr = <%s>\n", host_address_to_string (gdbarch->get_return_buf_addr)); + gdb_printf (file, + "gdbarch_dump: dwarf2_omit_typedef_p = <%s>\n", + host_address_to_string (gdbarch->dwarf2_omit_typedef_p)); gdb_printf (file, "gdbarch_dump: return_in_first_hidden_param_p = <%s>\n", host_address_to_string (gdbarch->return_in_first_hidden_param_p)); @@ -2617,6 +2622,23 @@ set_gdbarch_get_return_buf_addr (struct gdbarch *gdbarch, gdbarch->get_return_buf_addr = get_return_buf_addr; } +bool +gdbarch_dwarf2_omit_typedef_p (struct gdbarch *gdbarch, struct type *target_type, const char *producer, const char *name) +{ + gdb_assert (gdbarch != NULL); + gdb_assert (gdbarch->dwarf2_omit_typedef_p != NULL); + if (gdbarch_debug >= 2) + gdb_printf (gdb_stdlog, "gdbarch_dwarf2_omit_typedef_p called\n"); + return gdbarch->dwarf2_omit_typedef_p (target_type, producer, name); +} + +void +set_gdbarch_dwarf2_omit_typedef_p (struct gdbarch *gdbarch, + gdbarch_dwarf2_omit_typedef_p_ftype dwarf2_omit_typedef_p) +{ + gdbarch->dwarf2_omit_typedef_p = dwarf2_omit_typedef_p; +} + int gdbarch_return_in_first_hidden_param_p (struct gdbarch *gdbarch, struct type *type) { diff --git a/gdb/gdbarch_components.py b/gdb/gdbarch_components.py index 9f0430c7770..a0e35b8b5e8 100644 --- a/gdb/gdbarch_components.py +++ b/gdb/gdbarch_components.py @@ -901,6 +901,29 @@ May return 0 when unable to determine that address.""", invalid=False, ) + +# The DWARF info currently does not distinquish between IEEE 128-bit floating +# point values and the IBM 128-bit floating point format. GCC has an internal +# hack to identify the IEEE 128-bit floating point value. The long double is a +# defined base type in C. The GCC hack uses a typedef for long double to +# reference_Float128 base to identify the long double as and IEEE 128-bit +# value. The following method is used to "fix" the long double type to be a +# base type with the IEEE float format info from the _Float128 basetype and +# the long double name. With the fix, the proper name is printed for the +# GDB typedef command. +Function( + comment=""" +Return true if the typedef record needs to be replaced.". + +Return 0 by default""", + type="bool", + name="dwarf2_omit_typedef_p", + params=[("struct type *", "target_type"), ("const char *", "producer"), + ("const char *", "name")], + predefault="default_dwarf2_omit_typedef_p", + invalid=False, +) + Method( comment=""" Return true if the return value of function is stored in the first hidden diff --git a/gdb/ppc-linux-tdep.c b/gdb/ppc-linux-tdep.c index fcddb2008a0..784dafa59db 100644 --- a/gdb/ppc-linux-tdep.c +++ b/gdb/ppc-linux-tdep.c @@ -62,6 +62,7 @@ #include "user-regs.h" #include #include "elf-bfd.h" +#include "producer.h" #include "features/rs6000/powerpc-32l.c" #include "features/rs6000/powerpc-altivec32l.c" @@ -2006,6 +2007,38 @@ ppc_floatformat_for_type (struct gdbarch *gdbarch, return default_floatformat_for_type (gdbarch, name, len); } +static bool +linux_dwarf2_omit_typedef_p (struct type *target_type, + const char *producer, const char *name) +{ + int gcc_major, gcc_minor; + + if (producer_is_gcc (producer, &gcc_major, &gcc_minor)) + { + if ((target_type->code () == TYPE_CODE_FLT + || target_type->code () == TYPE_CODE_COMPLEX) + && (strcmp (name, "long double") == 0 + || strcmp (name, "complex long double") == 0)) + { + /* IEEE 128-bit floating point and IBM long double are two + encodings for 128-bit values. The DWARF debug data can't + distinguish between them. See bugzilla: + https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104194 + + A GCC hack was introduced to still allow the debugger to identify + the case where "long double" uses the IEEE 128-bit floating point + format: GCC will emit a bogus DWARF type record pretending that + "long double" is a typedef alias for the _Float128 type. + + This hack should not be visible to the GDB user, so we replace + this bogus typedef by a normal floating-point type, copying the + format information from the target type of the bogus typedef. */ + return true; + } + } + return false; +} + /* Specify the powerpc64le target triplet. This can be variations of ppc64le-{distro}-linux-gcc @@ -2083,6 +2116,9 @@ ppc_linux_init_abi (struct gdbarch_info info, /* Support for floating-point data type variants. */ set_gdbarch_floatformat_for_type (gdbarch, ppc_floatformat_for_type); + /* Support for replacing typedef record. */ + set_gdbarch_dwarf2_omit_typedef_p (gdbarch, linux_dwarf2_omit_typedef_p); + /* Handle inferior calls during interrupted system calls. */ set_gdbarch_write_pc (gdbarch, ppc_linux_write_pc); -- cgit v1.2.1