[RFA/commit] Implement return values on amd64-windows.
Joel Brobecker
brobecker@adacore.com
Mon Jan 25 06:20:00 GMT 2010
From: brobecke <brobecke@f8352e7e-cb20-0410-8ce7-b5d9e71c585c>
I forgot to post this patch in the previous amd64-windows funcall series
(although it's not just about function calls, more about the return value).
For instance, we have an test where we do a "finish" from a function
returning a small array:
(gdb) fin
Run till exit from #0 pck.create_small () at pck.adb:5
0x000000000040198d in p () at p.adb:8
8 Small := Create_Small;
Cannot access memory at address 0x100000001
where Create_Small returns a Data_Small defined as follow:
type Data_Small is array (1 .. 2) of Integer;
The way returned values are implemented on Windows64 is quite different
from what is described in the SysV ABI, so I had to implement a windows-
specific version of gdbarch_return_value. But in the end, it wasn't so
bad, since the convention is actually very simple.
gdb/ChangeLog:
* amd64-windows-tdep.c: #include gdbcore.h and regcache.h.
(amd64_windows_return_value): New function.
(amd64_windows_init_abi): Call set_gdbarch_return_value with
amd64_windows_return_value.
Tested on x86_64-windows with AdaCore's testsuite. I would like to commit
in a couple of days if there are no objections.
--
Joel
---
gdb/amd64-windows-tdep.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 55 insertions(+), 0 deletions(-)
diff --git a/gdb/amd64-windows-tdep.c b/gdb/amd64-windows-tdep.c
index 05c4c1e..05d0824 100644
--- a/gdb/amd64-windows-tdep.c
+++ b/gdb/amd64-windows-tdep.c
@@ -21,6 +21,8 @@
#include "solib.h"
#include "solib-target.h"
#include "gdbtypes.h"
+#include "gdbcore.h"
+#include "regcache.h"
/* The registers used to pass integer arguments during a function call. */
static int amd64_windows_dummy_call_integer_regs[] =
@@ -68,6 +70,58 @@ amd64_windows_classify (struct type *type, enum amd64_reg_class class[2])
}
}
+/* Implement the "return_value" gdbarch method for amd64-windows. */
+
+static enum return_value_convention
+amd64_windows_return_value (struct gdbarch *gdbarch, struct type *func_type,
+ struct type *type, struct regcache *regcache,
+ gdb_byte *readbuf, const gdb_byte *writebuf)
+{
+ int len = TYPE_LENGTH (type);
+ int regnum = -1;
+
+ /* See if our value is returned through a register. If it is, then
+ store the associated register number in REGNUM. */
+ switch (TYPE_CODE (type))
+ {
+ case TYPE_CODE_FLT:
+ case TYPE_CODE_DECFLOAT:
+ /* __m128, __m128i, __m128d, floats, and doubles are returned
+ via XMM0. */
+ if (len == 4 || len == 8 || len == 16)
+ regnum = AMD64_XMM0_REGNUM;
+ break;
+ default:
+ /* All other values that are 1, 2, 4 or 8 bytes long are returned
+ via RAX. */
+ if (len == 1 || len == 2 || len == 4 || len == 8)
+ regnum = AMD64_RAX_REGNUM;
+ break;
+ }
+
+ if (regnum < 0)
+ {
+ /* RAX contains the address where the return value has been stored. */
+ if (readbuf)
+ {
+ ULONGEST addr;
+
+ regcache_raw_read_unsigned (regcache, AMD64_RAX_REGNUM, &addr);
+ read_memory (addr, readbuf, TYPE_LENGTH (type));
+ }
+ return RETURN_VALUE_ABI_RETURNS_ADDRESS;
+ }
+ else
+ {
+ /* Extract the return value from the register where it was stored. */
+ if (readbuf)
+ regcache_raw_read_part (regcache, regnum, 0, len, readbuf);
+ if (writebuf)
+ regcache_raw_write_part (regcache, regnum, 0, len, writebuf);
+ return RETURN_VALUE_REGISTER_CONVENTION;
+ }
+}
+
static void
amd64_windows_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
{
@@ -85,6 +139,7 @@ amd64_windows_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
tdep->classify = amd64_windows_classify;
tdep->memory_args_by_pointer = 1;
tdep->integer_param_regs_saved_in_caller_frame = 1;
+ set_gdbarch_return_value (gdbarch, amd64_windows_return_value);
set_solib_ops (gdbarch, &solib_target_so_ops);
}
--
1.6.3.3
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