[commit 1/4] Reimplement function calls on amd64-windows

Joel Brobecker
2013-09-24T16:33:38Z

This patch provides a standalone implementation of function calls
on amd64-windows, instead of providing some bits and pieces hooking
into the function call implementation meant for sysV (in amd64-tdep).
It makes better sense to do it this way, because the two ABIs are
actually very different; for instance, the concept of argument
classification, which is so central in the sysV ABI and drove the
the implementation in amd64-tdep, makes no sense for Windows. It
is therefore better for the Windows implementation to be completely
separate, rather than rely on adaptations of the sysV implementation.

gdb/ChangeLog:

* amd64-tdep.c: #include "value.h"
(amd64_windows_classify): Delete.
(amd64_windows_passed_by_integer_register)
(amd64_windows_passed_by_xmm_register)
(amd64_windows_passed_by_pointer)
(amd64_windows_adjust_args_passed_by_pointer)
(amd64_windows_store_arg_in_reg, amd64_windows_push_arguments)
(amd64_windows_push_dummy_call): New functions.
(amd64_windows_init_abi): Remove setting of
tdep->call_dummy_num_integer_regs, tdep->call_dummy_integer_regs,
tdep->classify, tdep->memory_args_by_pointer and
tdep->integer_param_regs_saved_in_caller_frame.
Add call to set_gdbarch_push_dummy_call.

Tested on amd64-windows. Checked in.

---
gdb/ChangeLog | 16 +++
gdb/amd64-windows-tdep.c | 264 +++++++++++++++++++++++++++++++++++++++++------
2 files changed, 248 insertions(+), 32 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 872baed..71602a0 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,19 @@
+2013-09-24 Joel Brobecker <brobecker@adacore.com>
+
+ * amd64-tdep.c: #include "value.h"
+ (amd64_windows_classify): Delete.
+ (amd64_windows_passed_by_integer_register)
+ (amd64_windows_passed_by_xmm_register)
+ (amd64_windows_passed_by_pointer)
+ (amd64_windows_adjust_args_passed_by_pointer)
+ (amd64_windows_store_arg_in_reg, amd64_windows_push_arguments)
+ (amd64_windows_push_dummy_call): New functions.
+ (amd64_windows_init_abi): Remove setting of
+ tdep->call_dummy_num_integer_regs, tdep->call_dummy_integer_regs,
+ tdep->classify, tdep->memory_args_by_pointer and
+ tdep->integer_param_regs_saved_in_caller_frame.
+ Add call to set_gdbarch_push_dummy_call.
+
2013-09-24 Jan Kratochvil <jan.kratochvil@redhat.com>

* dwarf2read.c (open_and_init_dwp_file): Try open_dwp_file also with
diff --git a/gdb/amd64-windows-tdep.c b/gdb/amd64-windows-tdep.c
index 4e750a1..c09262a 100644
--- a/gdb/amd64-windows-tdep.c
+++ b/gdb/amd64-windows-tdep.c
@@ -31,6 +31,7 @@
#include "coff/i386.h"
#include "coff/pe.h"
#include "libcoff.h"
+#include "value.h"

/* The registers used to pass integer arguments during a function call. */
static int amd64_windows_dummy_call_integer_regs[] =
@@ -41,43 +42,247 @@ static int amd64_windows_dummy_call_integer_regs[] =
9 /* %r9 */
};

-/* Implement the "classify" method in the gdbarch_tdep structure
- for amd64-windows. */
+/* Return nonzero if an argument of type TYPE should be passed
+ via one of the integer registers. */

-static void
-amd64_windows_classify (struct type *type, enum amd64_reg_class class[2])
+static int
+amd64_windows_passed_by_integer_register (struct type *type)
{
switch (TYPE_CODE (type))
{
- case TYPE_CODE_ARRAY:
- /* Arrays are always passed by memory. */
- class[0] = class[1] = AMD64_MEMORY;
- break;
-
+ case TYPE_CODE_INT:
+ case TYPE_CODE_ENUM:
+ case TYPE_CODE_BOOL:
+ case TYPE_CODE_RANGE:
+ case TYPE_CODE_CHAR:
+ case TYPE_CODE_PTR:
+ case TYPE_CODE_REF:
case TYPE_CODE_STRUCT:
case TYPE_CODE_UNION:
- /* Struct/Union types whose size is 1, 2, 4, or 8 bytes
- are passed as if they were integers of the same size.
- Types of different sizes are passed by memory. */
- if (TYPE_LENGTH (type) == 1
- || TYPE_LENGTH (type) == 2
- || TYPE_LENGTH (type) == 4
- || TYPE_LENGTH (type) == 8)
- {
- class[0] = AMD64_INTEGER;
- class[1] = AMD64_NO_CLASS;
- }
- else
- class[0] = class[1] = AMD64_MEMORY;
- break;
+ return (TYPE_LENGTH (type) == 1
+ || TYPE_LENGTH (type) == 2
+ || TYPE_LENGTH (type) == 4
+ || TYPE_LENGTH (type) == 8);

default:
- /* For all the other types, the conventions are the same as
- with the System V ABI. */
- amd64_classify (type, class);
+ return 0;
}
}

+/* Return nonzero if an argument of type TYPE should be passed
+ via one of the XMM registers. */
+
+static int
+amd64_windows_passed_by_xmm_register (struct type *type)
+{
+ return ((TYPE_CODE (type) == TYPE_CODE_FLT
+ || TYPE_CODE (type) == TYPE_CODE_DECFLOAT)
+ && (TYPE_LENGTH (type) == 4 || TYPE_LENGTH (type) == 8));
+}
+
+/* Return non-zero iff an argument of the given TYPE should be passed
+ by pointer. */
+
+static int
+amd64_windows_passed_by_pointer (struct type *type)
+{
+ if (amd64_windows_passed_by_integer_register (type))
+ return 0;
+
+ if (amd64_windows_passed_by_xmm_register (type))
+ return 0;
+
+ return 1;
+}
+
+/* For each argument that should be passed by pointer, reserve some
+ stack space, store a copy of the argument on the stack, and replace
+ the argument by its address. Return the new Stack Pointer value.
+
+ NARGS is the number of arguments. ARGS is the array containing
+ the value of each argument. SP is value of the Stack Pointer. */
+
+static CORE_ADDR
+amd64_windows_adjust_args_passed_by_pointer (struct value **args,
+ int nargs, CORE_ADDR sp)
+{
+ int i;
+
+ for (i = 0; i < nargs; i++)
+ if (amd64_windows_passed_by_pointer (value_type (args[i])))
+ {
+ struct type *type = value_type (args[i]);
+ const gdb_byte *valbuf = value_contents (args[i]);
+ const int len = TYPE_LENGTH (type);
+
+ /* Store a copy of that argument on the stack, aligned to
+ a 16 bytes boundary, and then use the copy's address as
+ the argument. */
+
+ sp -= len;
+ sp &= ~0xf;
+ write_memory (sp, valbuf, len);
+
+ args[i]
+ = value_addr (value_from_contents_and_address (type, valbuf, sp));
+ }
+
+ return sp;
+}
+
+/* Store the value of ARG in register REGNO (right-justified).
+ REGCACHE is the register cache. */
+
+static void
+amd64_windows_store_arg_in_reg (struct regcache *regcache,
+ struct value *arg, int regno)
+{
+ struct type *type = value_type (arg);
+ const gdb_byte *valbuf = value_contents (arg);
+ gdb_byte buf[8];
+
+ gdb_assert (TYPE_LENGTH (type) <= 8);
+ memset (buf, 0, sizeof buf);
+ memcpy (buf, valbuf, min (TYPE_LENGTH (type), 8));
+ regcache_cooked_write (regcache, regno, buf);
+}
+
+/* Push the arguments for an inferior function call, and return
+ the updated value of the SP (Stack Pointer).
+
+ All arguments are identical to the arguments used in
+ amd64_windows_push_dummy_call. */
+
+static CORE_ADDR
+amd64_windows_push_arguments (struct regcache *regcache, int nargs,
+ struct value **args, CORE_ADDR sp,
+ int struct_return)
+{
+ int reg_idx = 0;
+ int i;
+ struct value **stack_args = alloca (nargs * sizeof (struct value *));
+ int num_stack_args = 0;
+ int num_elements = 0;
+ int element = 0;
+
+ /* First, handle the arguments passed by pointer.
+
+ These arguments are replaced by pointers to a copy we are making
+ in inferior memory. So use a copy of the ARGS table, to avoid
+ modifying the original one. */
+ {
+ struct value **args1 = alloca (nargs * sizeof (struct value *));
+
+ memcpy (args1, args, nargs * sizeof (struct value *));
+ sp = amd64_windows_adjust_args_passed_by_pointer (args1, nargs, sp);
+ args = args1;
+ }
+
+ /* Reserve a register for the "hidden" argument. */
+ if (struct_return)
+ reg_idx++;
+
+ for (i = 0; i < nargs; i++)
+ {
+ struct type *type = value_type (args[i]);
+ int len = TYPE_LENGTH (type);
+ int on_stack_p = 1;
+
+ if (reg_idx < ARRAY_SIZE (amd64_windows_dummy_call_integer_regs))
+ {
+ if (amd64_windows_passed_by_integer_register (type))
+ {
+ amd64_windows_store_arg_in_reg
+ (regcache, args[i],
+ amd64_windows_dummy_call_integer_regs[reg_idx]);
+ on_stack_p = 0;
+ reg_idx++;
+ }
+ else if (amd64_windows_passed_by_xmm_register (type))
+ {
+ amd64_windows_store_arg_in_reg
+ (regcache, args[i], AMD64_XMM0_REGNUM + reg_idx);
+ /* In case of varargs, these parameters must also be
+ passed via the integer registers. */
+ amd64_windows_store_arg_in_reg
+ (regcache, args[i],
+ amd64_windows_dummy_call_integer_regs[reg_idx]);
+ on_stack_p = 0;
+ reg_idx++;
+ }
+ }
+
+ if (on_stack_p)
+ {
+ num_elements += ((len + 7) / 8);
+ stack_args[num_stack_args++] = args[i];
+ }
+ }
+
+ /* Allocate space for the arguments on the stack, keeping it
+ aligned on a 16 byte boundary. */
+ sp -= num_elements * 8;
+ sp &= ~0xf;
+
+ /* Write out the arguments to the stack. */
+ for (i = 0; i < num_stack_args; i++)
+ {
+ struct type *type = value_type (stack_args[i]);
+ const gdb_byte *valbuf = value_contents (stack_args[i]);
+
+ write_memory (sp + element * 8, valbuf, TYPE_LENGTH (type));
+ element += ((TYPE_LENGTH (type) + 7) / 8);
+ }
+
+ return sp;
+}
+
+/* Implement the "push_dummy_call" gdbarch method. */
+
+static CORE_ADDR
+amd64_windows_push_dummy_call
+ (struct gdbarch *gdbarch, struct value *function,
+ struct regcache *regcache, CORE_ADDR bp_addr,
+ int nargs, struct value **args,
+ CORE_ADDR sp, int struct_return, CORE_ADDR struct_addr)
+{
+ enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+ gdb_byte buf[8];
+
+ /* Pass arguments. */
+ sp = amd64_windows_push_arguments (regcache, nargs, args, sp,
+ struct_return);
+
+ /* Pass "hidden" argument". */
+ if (struct_return)
+ {
+ /* The "hidden" argument is passed throught the first argument
+ register. */
+ const int arg_regnum = amd64_windows_dummy_call_integer_regs[0];
+
+ store_unsigned_integer (buf, 8, byte_order, struct_addr);
+ regcache_cooked_write (regcache, arg_regnum, buf);
+ }
+
+ /* Reserve some memory on the stack for the integer-parameter
+ registers, as required by the ABI. */
+ sp -= ARRAY_SIZE (amd64_windows_dummy_call_integer_regs) * 8;
+
+ /* Store return address. */
+ sp -= 8;
+ store_unsigned_integer (buf, 8, byte_order, bp_addr);
+ write_memory (sp, buf, 8);
+
+ /* Update the stack pointer... */
+ store_unsigned_integer (buf, 8, byte_order, sp);
+ regcache_cooked_write (regcache, AMD64_RSP_REGNUM, buf);
+
+ /* ...and fake a frame pointer. */
+ regcache_cooked_write (regcache, AMD64_RBP_REGNUM, buf);
+
+ return sp + 16;
+}
+
/* Implement the "return_value" gdbarch method for amd64-windows. */

static enum return_value_convention
@@ -976,12 +1181,7 @@ amd64_windows_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
set_gdbarch_long_bit (gdbarch, 32);

/* Function calls. */
- tdep->call_dummy_num_integer_regs =
- ARRAY_SIZE (amd64_windows_dummy_call_integer_regs);
- tdep->call_dummy_integer_regs = amd64_windows_dummy_call_integer_regs;
- tdep->classify = amd64_windows_classify;
- tdep->memory_args_by_pointer = 1;
- tdep->integer_param_regs_saved_in_caller_frame = 1;
+ set_gdbarch_push_dummy_call (gdbarch, amd64_windows_push_dummy_call);
set_gdbarch_return_value (gdbarch, amd64_windows_return_value);
set_gdbarch_skip_main_prologue (gdbarch, amd64_skip_main_prologue);
set_gdbarch_skip_trampoline_code (gdbarch,
--
1.8.1.2