This is the mail archive of the
gdb-patches@sources.redhat.com
mailing list for the GDB project.
Re: [PATCH] Proper _to_regnum for DWARF on Cygwin
The attached is what I actually checked in. I changed some of the
comments to better reflect my own view on the matter.
Thanks anyway,
Mark
Index: ChangeLog
from Mark Kettenis <kettenis@gnu.org>
Based on a patch from Brian Ford <ford@vss.fsi.com>:
* i386-tdep.c: Correct register numbering scheme comments
throughout.
(i386_stab_reg_to_regnum): Rename to i386_dbx_reg_to_regnum.
(i386_dwarf_reg_to_regnum): Rename to i386_svr4_reg_to_regnum.
(i386_coff_init_abi, i386_elf_init_abi): Accomodate renames above.
(i386_gdb_arch_init): Likewise.
Index: i386-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/i386-tdep.c,v
retrieving revision 1.186
diff -u -p -r1.186 i386-tdep.c
--- i386-tdep.c 16 Apr 2004 16:49:55 -0000 1.186
+++ i386-tdep.c 18 Apr 2004 18:33:06 -0000
@@ -51,8 +51,7 @@
#include "i386-tdep.h"
#include "i387-tdep.h"
-/* Names of the registers. The first 10 registers match the register
- numbering scheme used by GCC for stabs and DWARF. */
+/* Register names. */
static char *i386_register_names[] =
{
@@ -71,7 +70,7 @@ static char *i386_register_names[] =
static const int i386_num_register_names = ARRAY_SIZE (i386_register_names);
-/* MMX registers. */
+/* Register names for MMX pseudo-registers. */
static char *i386_mmx_names[] =
{
@@ -166,49 +165,15 @@ i386_register_name (int reg)
return NULL;
}
-
-/* FIXME: jimb/2004-04-01: I don't think these functions are right.
- For a given platform, GCC always uses the same register numbering
- in both STABS and Dwarf2: gcc/dbxout.c and gcc/dwarf2out.c both use
- the DBX_REGISTER_NUMBER macro, as defined by the config headers.
- If you compile a program so that its variables are allocated to
- floating-point registers, first with STABS and again with Dwarf 2,
- you'll see that the variable's register numbers are the same in
- each case.
-
- GCC does use (at least) two different register numberings on the
- i386; they differ in how they number %ebp, %esp, %eflags, and the
- floating-point registers. And it has a third numbering for "64bit
- mode", which I assume is x86_64. But it always uses a given
- numbering in both STABS and Dwarf.
-
- This does not match the arrangement we have below, which presumes
- that STABS and Dwarf numberings are different, and does some
- strange mixing and matching (e.g., registering the Dwarf 2 function
- as the STABS function for "Generic i386 ELF") to get close enough
- to the right effect on the platforms we care about.
-
- If we wanted to match GCC, we should have two separate register
- number translation functions (we handle x86_64 in a separate tdep
- file altogether), one corresponding to each of GCC's i386 register
- maps. And for a given platform, we would register one of them as
- both the STABS and Dwarf 2 functions.
-
- However, we don't aspire to match GCC; we aspire to match the
- native system's tools. I don't have access to lots of different
- native compilers and debuggers to verify that GCC is matching their
- behavior in this regard. Is it sufficient to argue that we at
- least want to match GNU's compiler, and say we'll fix bugs relative
- to native tools as they're reported? */
-
-
-/* Convert stabs register number REG to the appropriate register
+/* Convert a dbx register number REG to the appropriate register
number used by GDB. */
static int
-i386_stab_reg_to_regnum (int reg)
+i386_dbx_reg_to_regnum (int reg)
{
- /* This implements what GCC calls the "default" register map. */
+ /* This implements what GCC calls the "default" register map
+ (dbx_register_map[]). */
+
if (reg >= 0 && reg <= 7)
{
/* General-purpose registers. The debug info calls %ebp
@@ -239,13 +204,16 @@ i386_stab_reg_to_regnum (int reg)
return NUM_REGS + NUM_PSEUDO_REGS;
}
-/* Convert DWARF register number REG to the appropriate register
- number used by GDB. */
+/* Convert SVR4 register number REG to the appropriate register number
+ used by GDB. */
static int
-i386_dwarf_reg_to_regnum (int reg)
+i386_svr4_reg_to_regnum (int reg)
{
- /* The DWARF register numbering includes %eip and %eflags, and
+ /* This implements the GCC register map that tries to be compatible
+ with the SVR4 C compiler for DWARF (svr4_dbx_register_map[]). */
+
+ /* The SVR4 register numbering includes %eip and %eflags, and
numbers the floating point registers differently. */
if (reg >= 0 && reg <= 9)
{
@@ -259,8 +227,8 @@ i386_dwarf_reg_to_regnum (int reg)
}
else if (reg >= 21)
{
- /* The SSE and MMX registers have identical numbers as in stabs. */
- return i386_stab_reg_to_regnum (reg);
+ /* The SSE and MMX registers have the same numbers as with dbx. */
+ return i386_dbx_reg_to_regnum (reg);
}
/* This will hopefully provoke a warning. */
@@ -1819,9 +1787,9 @@ i386_svr4_sigcontext_addr (struct frame_
void
i386_coff_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
{
- /* We typically use DWARF-in-COFF with the stabs register numbering. */
- set_gdbarch_dwarf_reg_to_regnum (gdbarch, i386_stab_reg_to_regnum);
- set_gdbarch_dwarf2_reg_to_regnum (gdbarch, i386_stab_reg_to_regnum);
+ /* We typically use DWARF-in-COFF with the dbx register numbering. */
+ set_gdbarch_dwarf_reg_to_regnum (gdbarch, i386_dbx_reg_to_regnum);
+ set_gdbarch_dwarf2_reg_to_regnum (gdbarch, i386_dbx_reg_to_regnum);
}
/* Generic ELF. */
@@ -1829,8 +1797,8 @@ i386_coff_init_abi (struct gdbarch_info
void
i386_elf_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
{
- /* We typically use stabs-in-ELF with the DWARF register numbering. */
- set_gdbarch_stab_reg_to_regnum (gdbarch, i386_dwarf_reg_to_regnum);
+ /* We typically use stabs-in-ELF with the SVR4 register numbering. */
+ set_gdbarch_stab_reg_to_regnum (gdbarch, i386_svr4_reg_to_regnum);
}
/* System V Release 4 (SVR4). */
@@ -2024,13 +1992,43 @@ i386_gdbarch_init (struct gdbarch_info i
set_gdbarch_ps_regnum (gdbarch, I386_EFLAGS_REGNUM); /* %eflags */
set_gdbarch_fp0_regnum (gdbarch, I386_ST0_REGNUM); /* %st(0) */
- /* Use the "default" register numbering scheme for stabs and COFF. */
- set_gdbarch_stab_reg_to_regnum (gdbarch, i386_stab_reg_to_regnum);
- set_gdbarch_sdb_reg_to_regnum (gdbarch, i386_stab_reg_to_regnum);
-
- /* Use the DWARF register numbering scheme for DWARF and DWARF 2. */
- set_gdbarch_dwarf_reg_to_regnum (gdbarch, i386_dwarf_reg_to_regnum);
- set_gdbarch_dwarf2_reg_to_regnum (gdbarch, i386_dwarf_reg_to_regnum);
+ /* NOTE: kettenis/20040418: GCC does have two possible register
+ numbering schemes on the i386: dbx and SVR4. These schemes
+ differ in how they number %ebp, %esp, %eflags, and the
+ floating-point registers, and are implemented by the attays
+ dbx_register_map[] and svr4_dbx_register_map in
+ gcc/config/i386.c. GCC also defines a third numbering scheme in
+ gcc/config/i386.c, which it designates as the "default" register
+ map used in 64bit mode. This last register numbering scheme is
+ implemented in dbx64_register_map, and us used for AMD64; see
+ amd64-tdep.c.
+
+ Currently, each GCC i386 target always uses the same register
+ numbering scheme across all its supported debugging formats
+ i.e. SDB (COFF), stabs and DWARF 2. This is because
+ gcc/sdbout.c, gcc/dbxout.c and gcc/dwarf2out.c all use the
+ DBX_REGISTER_NUMBER macro which is defined by each target's
+ respective config header in a manner independent of the requested
+ output debugging format.
+
+ This does not match the arrangement below, which presumes that
+ the SDB and stabs numbering schemes differ from the DWARF and
+ DWARF 2 ones. The reason for this arrangement is that it is
+ likely to get the numbering scheme for the target's
+ default/native debug format right. For targets where GCC is the
+ native compiler (FreeBSD, NetBSD, OpenBSD, GNU/Linux) or for
+ targets where the native toolchain uses a different numbering
+ scheme for a particular debug format (stabs-in-ELF on Solaris)
+ the defaults below will have to be overridden, like the functions
+ i386_coff_init_abi() and i386_elf_init_abi() do. */
+
+ /* Use the dbx register numbering scheme for stabs and COFF. */
+ set_gdbarch_stab_reg_to_regnum (gdbarch, i386_dbx_reg_to_regnum);
+ set_gdbarch_sdb_reg_to_regnum (gdbarch, i386_dbx_reg_to_regnum);
+
+ /* Use the SVR4 register numbering scheme for DWARF and DWARF 2. */
+ set_gdbarch_dwarf_reg_to_regnum (gdbarch, i386_svr4_reg_to_regnum);
+ set_gdbarch_dwarf2_reg_to_regnum (gdbarch, i386_svr4_reg_to_regnum);
/* We don't define ECOFF_REG_TO_REGNUM, since ECOFF doesn't seem to
be in use on any of the supported i386 targets. */