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*-*.

5 files changed, 27 insertions, 11 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index e4a913b..1d2e30c 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,13 @@
 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
 	offset on little-endian when passing _Decimal32.
 	(ppc64_sysv_abi_return_value_base): Likewise for return values.
diff --git a/gdb/ppc-sysv-tdep.c b/gdb/ppc-sysv-tdep.c
index de5a663..8e460e5 100644
--- a/gdb/ppc-sysv-tdep.c
+++ b/gdb/ppc-sysv-tdep.c
@@ -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;
     }
diff --git a/gdb/rs6000-tdep.c b/gdb/rs6000-tdep.c
index adee085..b407bd6 100644
--- a/gdb/rs6000-tdep.c
+++ b/gdb/rs6000-tdep.c
@@ -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);
     }
 }
 
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 5680bc6..7378bb2 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,5 +1,9 @@
 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
 	of the test patterns for use on little-endian systems.
 
diff --git a/gdb/testsuite/gdb.arch/powerpc-d128-regs.exp b/gdb/testsuite/gdb.arch/powerpc-d128-regs.exp
index 035cf12..622004c 100644
--- a/gdb/testsuite/gdb.arch/powerpc-d128-regs.exp
+++ b/gdb/testsuite/gdb.arch/powerpc-d128-regs.exp
@@ -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
 }