[RFA 1/2] Revert "amd64-windows: memory args passed by pointer during function calls."

[Joel Brobecker]

A more correct implementation of parameters passed by pointer will
follow.

gdb/ChangeLog:

	Revert the following change:
	* i386-tdep.h (gdbarch_tdep): Add field memory_args_by_pointer.
	* amd64-tdep.c (amd64_push_arguments): Add handling of architectures
	where tdep->memory_args_by_pointer is non-zero.
	* amd64-windows-tdep.c (amd64_windows_init_abi): Set
	tdep->memory_args_by_pointer to 1.

Tested on both amd64-windows and amd64-linux.
OK to commit?

Thanks,
-- 
Joel

---
 gdb/amd64-tdep.c         |   40 ++++++----------------------------------
 gdb/amd64-windows-tdep.c |    1 -
 gdb/i386-tdep.h          |    9 ---------
 3 files changed, 6 insertions(+), 44 deletions(-)

diff --git a/gdb/amd64-tdep.c b/gdb/amd64-tdep.c
index a4172fc..c6ee493 100644
--- a/gdb/amd64-tdep.c
+++ b/gdb/amd64-tdep.c
@@ -749,8 +749,7 @@ static CORE_ADDR
 amd64_push_arguments (struct regcache *regcache, int nargs,
 		      struct value **args, CORE_ADDR sp, int struct_return)
 {
-  struct gdbarch *gdbarch = get_regcache_arch (regcache);
-  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+  struct gdbarch_tdep *tdep = gdbarch_tdep (get_regcache_arch (regcache));
   int *integer_regs = tdep->call_dummy_integer_regs;
   int num_integer_regs = tdep->call_dummy_num_integer_regs;
 
@@ -763,11 +762,6 @@ amd64_push_arguments (struct regcache *regcache, int nargs,
     AMD64_XMM0_REGNUM + 6, AMD64_XMM0_REGNUM + 7,
   };
   struct value **stack_args = alloca (nargs * sizeof (struct value *));
-  /* An array that mirrors the stack_args array.  For all arguments
-     that are passed by MEMORY, if that argument's address also needs
-     to be stored in a register, the ARG_ADDR_REGNO array will contain
-     that register number (or a negative value otherwise).  */
-  int *arg_addr_regno = alloca (nargs * sizeof (int));
   int num_stack_args = 0;
   int num_elements = 0;
   int element = 0;
@@ -811,19 +805,7 @@ amd64_push_arguments (struct regcache *regcache, int nargs,
 	{
 	  /* The argument will be passed on the stack.  */
 	  num_elements += ((len + 7) / 8);
-	  stack_args[num_stack_args] = args[i];
-          /* If this is an AMD64_MEMORY argument whose address must also
-             be passed in one of the integer registers, reserve that
-             register and associate this value to that register so that
-             we can store the argument address as soon as we know it.  */
-          if (class[0] == AMD64_MEMORY
-              && tdep->memory_args_by_pointer
-              && integer_reg < tdep->call_dummy_num_integer_regs)
-            arg_addr_regno[num_stack_args] =
-              tdep->call_dummy_integer_regs[integer_reg++];
-          else
-            arg_addr_regno[num_stack_args] = -1;
-          num_stack_args++;
+	  stack_args[num_stack_args++] = args[i];
 	}
       else
 	{
@@ -878,20 +860,10 @@ amd64_push_arguments (struct regcache *regcache, int nargs,
     {
       struct type *type = value_type (stack_args[i]);
       const gdb_byte *valbuf = value_contents (stack_args[i]);
-      CORE_ADDR arg_addr = sp + element * 8;
-
-      write_memory (arg_addr, valbuf, TYPE_LENGTH (type));
-      if (arg_addr_regno[i] >= 0)
-        {
-          /* We also need to store the address of that argument in
-             the given register.  */
-          gdb_byte buf[8];
-          enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
-
-          store_unsigned_integer (buf, 8, byte_order, arg_addr);
-          regcache_cooked_write (regcache, arg_addr_regno[i], buf);
-        }
-      element += ((TYPE_LENGTH (type) + 7) / 8);
+      int len = TYPE_LENGTH (type);
+
+      write_memory (sp + element * 8, valbuf, len);
+      element += ((len + 7) / 8);
     }
 
   /* The psABI says that "For calls that may call functions that use
diff --git a/gdb/amd64-windows-tdep.c b/gdb/amd64-windows-tdep.c
index 142e141..3e8a830 100644
--- a/gdb/amd64-windows-tdep.c
+++ b/gdb/amd64-windows-tdep.c
@@ -213,7 +213,6 @@ amd64_windows_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
     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_return_value (gdbarch, amd64_windows_return_value);
   set_gdbarch_skip_main_prologue (gdbarch, amd64_skip_main_prologue);
diff --git a/gdb/i386-tdep.h b/gdb/i386-tdep.h
index 5f233f5..01b0936 100644
--- a/gdb/i386-tdep.h
+++ b/gdb/i386-tdep.h
@@ -85,15 +85,6 @@ struct gdbarch_tdep
      and store the result in CLASS.  */
   void (*classify) (struct type *type, enum amd64_reg_class class[2]);
 
-  /* Used on amd64 only.  Non-zero if the first few MEMORY arguments
-     should be passed by pointer.
-
-     More precisely, MEMORY arguments are passed through the stack.
-     But certain architectures require that their address be passed
-     by register as well, if there are still some integer registers
-     available for argument passing.  */
-  int memory_args_by_pointer;
-
   /* Used on amd64 only.
 
      If non-zero, then the callers of a function are expected to reserve
-- 
1.7.9.5