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/ppc-linux-tdep.c | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) (limited to 'gdb/ppc-linux-tdep.c') diff --git a/gdb/ppc-linux-tdep.c b/gdb/ppc-linux-tdep.c index fcddb20..784dafa 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 v1.1