PowerPC64 little-endian fixes: 128-bit DFP parameters / registers

The powerpc64le-linux ABI specifies that when a 128-bit DFP value is
passed in a pair of floating-point registers, the first register holds
the most-significant part of the value.  This is as opposed to the
usual rule on little-endian systems, where the first register would
hold the least-significant part.

This affects two places in GDB, the read/write routines for the
128-bit DFP pseudo-registers, and the function call / return
sequence.  For the former, current code already distinguishes
between big- and little-endian targets, but gets the latter
wrong.  This is presumably because *GCC* also got it wrong,
and GDB matches the old GCC behavior.  But GCC is now fixed:
http://gcc.gnu.org/ml/gcc-patches/2013-11/msg02145.html
so GDB needs to be fixed too.  (Old code shouldn't really be
an issue since there is no code "out there" so far that uses
dfp128 on little-endian ...)

gdb/ChangeLog:

	* ppc-sysv-tdep.c (ppc64_sysv_abi_push_freg): Use correct order
	within a register pair holding a DFP 128-bit value on little-endian.
	(ppc64_sysv_abi_return_value_base): Likewise.
	* rs6000-tdep.c (dfp_pseudo_register_read): Likewise.
	(dfp_pseudo_register_write): Likewise.

gdb/testsuite/ChangeLog:

	* gdb.arch/powerpc-d128-regs.exp: Enable on powerpc64*-*.
This commit is contained in:
Ulrich Weigand 2014-02-04 18:34:19 +01:00
parent 5b757e5ddb
commit 0ff3e01fdc
5 changed files with 27 additions and 11 deletions

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@ -1,3 +1,11 @@
2014-02-04 Ulrich Weigand  <uweigand@de.ibm.com>
* ppc-sysv-tdep.c (ppc64_sysv_abi_push_freg): Use correct order
within a register pair holding a DFP 128-bit value on little-endian.
(ppc64_sysv_abi_return_value_base): Likewise.
* rs6000-tdep.c (dfp_pseudo_register_read): Likewise.
(dfp_pseudo_register_write): Likewise.
2014-02-04 Ulrich Weigand  <uweigand@de.ibm.com>
* ppc-sysv-tdep.c (ppc64_sysv_abi_push_freg): Use correct

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@ -1270,9 +1270,11 @@ ppc64_sysv_abi_push_freg (struct gdbarch *gdbarch,
if (argpos->regcache && argpos->freg <= 12)
{
int regnum = tdep->ppc_fp0_regnum + argpos->freg;
int lopart = gdbarch_byte_order (gdbarch) == BFD_ENDIAN_BIG ? 8 : 0;
int hipart = gdbarch_byte_order (gdbarch) == BFD_ENDIAN_BIG ? 0 : 8;
regcache_cooked_write (argpos->regcache, regnum, val);
regcache_cooked_write (argpos->regcache, regnum + 1, val + 8);
regcache_cooked_write (argpos->regcache, regnum, val + hipart);
regcache_cooked_write (argpos->regcache, regnum + 1, val + lopart);
}
argpos->freg += 2;
@ -1685,16 +1687,18 @@ ppc64_sysv_abi_return_value_base (struct gdbarch *gdbarch, struct type *valtype,
&& TYPE_CODE (valtype) == TYPE_CODE_DECFLOAT)
{
int regnum = tdep->ppc_fp0_regnum + 2 + 2 * index;
int lopart = gdbarch_byte_order (gdbarch) == BFD_ENDIAN_BIG ? 8 : 0;
int hipart = gdbarch_byte_order (gdbarch) == BFD_ENDIAN_BIG ? 0 : 8;
if (writebuf != NULL)
{
regcache_cooked_write (regcache, regnum, writebuf);
regcache_cooked_write (regcache, regnum + 1, writebuf + 8);
regcache_cooked_write (regcache, regnum, writebuf + hipart);
regcache_cooked_write (regcache, regnum + 1, writebuf + lopart);
}
if (readbuf != NULL)
{
regcache_cooked_read (regcache, regnum, readbuf);
regcache_cooked_read (regcache, regnum + 1, readbuf + 8);
regcache_cooked_read (regcache, regnum, readbuf + hipart);
regcache_cooked_read (regcache, regnum + 1, readbuf + lopart);
}
return 1;
}

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@ -2672,10 +2672,10 @@ dfp_pseudo_register_read (struct gdbarch *gdbarch, struct regcache *regcache,
else
{
status = regcache_raw_read (regcache, tdep->ppc_fp0_regnum +
2 * reg_index + 1, buffer + 8);
2 * reg_index + 1, buffer);
if (status == REG_VALID)
status = regcache_raw_read (regcache, tdep->ppc_fp0_regnum +
2 * reg_index, buffer);
2 * reg_index, buffer + 8);
}
return status;
@ -2701,9 +2701,9 @@ dfp_pseudo_register_write (struct gdbarch *gdbarch, struct regcache *regcache,
else
{
regcache_raw_write (regcache, tdep->ppc_fp0_regnum +
2 * reg_index + 1, buffer + 8);
2 * reg_index + 1, buffer);
regcache_raw_write (regcache, tdep->ppc_fp0_regnum +
2 * reg_index, buffer);
2 * reg_index, buffer + 8);
}
}

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@ -1,3 +1,7 @@
2014-02-04 Ulrich Weigand <uweigand@de.ibm.com>
* gdb.arch/powerpc-d128-regs.exp: Enable on powerpc64*-*.
2014-02-04 Ulrich Weigand <uweigand@de.ibm.com>
* gdb.arch/vsx-regs.exp: Check target endianness. Provide variants

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@ -20,7 +20,7 @@
# Testcase for ppc decimal128 pseudo-registers.
if ![istarget "powerpc64-*"] then {
if ![istarget "powerpc64*-*"] then {
verbose "Skipping powerpc Decimal128 pseudo-registers testcase."
return
}