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Re: Initialize default floating-point model on ARM for GNU binaries
> From: Richard Earnshaw <rearnsha@arm.com>
> Date: Tue, 18 Jul 2006 17:31:56 +0100
>
> The problem is that in the most common configuration still using the
> legacy ELF format (arm-unknown-elf) the flags are generated incorrectly
> by the compiler/assembler combination. These tools fail to correctly
> set the softfpa bit in the ELF header and the result is that gdb will
> think they contain FPA instructions when they do not. Thus I think this
> change will cause a large number of new failures on arm-elf.
>
> I guess we could fudge this by making the auto-detect code fold case 0
> on to case EF_ARM_SOFT_FLOAT, but it would need a big comment to explain
> the background.
That doesn't sound like a bad idea. Here's a patch with a variant of
this: leave things set to "auto" if no flag is set. That way the code
path for arm-unknown-elf will be very close to what it is right now,
which will default to "softfpa" in the end.
ok?
Index: ChangeLog
from Mark Kettenis <kettenis@gnu.org>
* arm-tdep.c (arm_gdbarch_init): Get default floating-point model
from ELF flags for binaries produced by the GNU toolchain.
Index: arm-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/arm-tdep.c,v
retrieving revision 1.211
diff -u -p -r1.211 arm-tdep.c
--- arm-tdep.c 16 Jul 2006 10:33:25 -0000 1.211
+++ arm-tdep.c 18 Jul 2006 17:43:47 -0000
@@ -2594,7 +2594,7 @@ arm_gdbarch_init (struct gdbarch_info in
if (arm_abi == ARM_ABI_AUTO && info.abfd != NULL)
{
- int ei_osabi;
+ int ei_osabi, e_flags;
switch (bfd_get_flavour (info.abfd))
{
@@ -2611,19 +2611,18 @@ arm_gdbarch_init (struct gdbarch_info in
case bfd_target_elf_flavour:
ei_osabi = elf_elfheader (info.abfd)->e_ident[EI_OSABI];
+ e_flags = elf_elfheader (info.abfd)->e_flags;
+
if (ei_osabi == ELFOSABI_ARM)
{
/* GNU tools used to use this value, but do not for EABI
- objects. There's nowhere to tag an EABI version anyway,
- so assume APCS. */
+ objects. There's nowhere to tag an EABI version
+ anyway, so assume APCS. */
arm_abi = ARM_ABI_APCS;
}
else if (ei_osabi == ELFOSABI_NONE)
{
- int e_flags, eabi_ver;
-
- e_flags = elf_elfheader (info.abfd)->e_flags;
- eabi_ver = EF_ARM_EABI_VERSION (e_flags);
+ int eabi_ver = EF_ARM_EABI_VERSION (e_flags);
switch (eabi_ver)
{
@@ -2640,8 +2639,32 @@ arm_gdbarch_init (struct gdbarch_info in
break;
default:
+ /* Leave it as "auto". */
warning (_("unknown ARM EABI version 0x%x"), eabi_ver);
- arm_abi = ARM_ABI_APCS;
+ break;
+ }
+ }
+
+ if (fp_model == ARM_FLOAT_AUTO)
+ {
+ int e_flags = elf_elfheader (info.abfd)->e_flags;
+
+ switch (e_flags & (EF_ARM_SOFT_FLOAT | EF_ARM_VFP_FLOAT))
+ {
+ case 0:
+ /* Leave it as "auto". Strictly speaking this case
+ means FPA, but almost nobody uses that now, and
+ many toolchains fail to set the appropriate bits
+ for the floating-point model they use. */
+ break;
+ case EF_ARM_SOFT_FLOAT:
+ fp_model = ARM_FLOAT_SOFT_FPA;
+ break;
+ case EF_ARM_VFP_FLOAT:
+ fp_model = ARM_FLOAT_VFP;
+ break;
+ case EF_ARM_SOFT_FLOAT | EF_ARM_VFP_FLOAT:
+ fp_model = ARM_FLOAT_SOFT_VFP;
break;
}
}