From 1525a46258c3653a3a085d212ea4ca0aef7ce2ec Mon Sep 17 00:00:00 2001
From: Hannes Domani <ssbssa@yahoo.de>
Date: Tue, 25 Feb 2014 20:51:45 +0100
Subject: [PATCH] use thiscall calling convention for class members

---
 gdb/i386-tdep.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 52 insertions(+), 1 deletion(-)

diff --git a/gdb/i386-tdep.c b/gdb/i386-tdep.c
index bb414b6..bead16e 100644
--- a/gdb/i386-tdep.c
+++ b/gdb/i386-tdep.c
@@ -45,6 +45,8 @@
 #include "remote.h"
 #include "exceptions.h"
 #include "gdb_assert.h"
+#include "infcall.h"
+#include "dwarf2.h"
 #include <string.h>
 
 #include "i386-tdep.h"
@@ -2529,6 +2531,50 @@ i386_push_dummy_call (struct gdbarch *gdbarch, struct value *function,
   int i;
   int write_pass;
   int args_space = 0;
+  struct type *func_type = value_type (function);
+  int i386_windows_thiscall = 0;
+
+  if (func_type)
+    {
+      func_type = check_typedef (func_type);
+
+      if (TYPE_CODE (func_type) == TYPE_CODE_PTR)
+	func_type = check_typedef (TYPE_TARGET_TYPE (func_type));
+
+      if ((TYPE_CODE (func_type) == TYPE_CODE_METHOD)
+	  && nargs > 0)
+	{
+	  CORE_ADDR funaddr = find_function_addr (function, NULL);
+	  struct symbol *funsym = find_pc_function (funaddr);
+	  if (funsym != NULL
+	      && SYMBOL_BLOCK_OPS (funsym))
+	    {
+	      struct symbol *thissym;
+	      thissym = lookup_block_symbol (funsym->ginfo.value.block,
+					     "this", VAR_DOMAIN);
+	      if (thissym != NULL)
+		{
+		  const gdb_byte *start;
+		  size_t length;
+		  const struct symbol_block_ops *ops_block =
+		    SYMBOL_BLOCK_OPS (funsym);
+		  ops_block->find_frame_base_location (thissym, 0,
+						       &start, &length);
+		  if (length == 1
+		      && start[0] == DW_OP_reg1)
+		    /* 'this' pointer is stored in register ECX.  */
+		    i386_windows_thiscall = 1;
+		  else if (length == 2
+		      && start[0] == DW_OP_fbreg
+		      && start[1] == 0x74)
+		    /* 'this' pointer is copied from ECX to
+		       stack-relative -12 (0x74), happens when
+		       comiled with -O0.  */
+		    i386_windows_thiscall = 1;
+		}
+	    }
+	}
+    }
 
   /* Determine the total space required for arguments and struct
      return address in a first pass (allowing for 16-byte-aligned
@@ -2551,7 +2597,7 @@ i386_push_dummy_call (struct gdbarch *gdbarch, struct value *function,
 	    args_space += 4;
 	}
 
-      for (i = 0; i < nargs; i++)
+      for (i = i386_windows_thiscall; i < nargs; i++)
 	{
 	  int len = TYPE_LENGTH (value_enclosing_type (args[i]));
 
@@ -2603,6 +2649,11 @@ i386_push_dummy_call (struct gdbarch *gdbarch, struct value *function,
   /* ...and fake a frame pointer.  */
   regcache_cooked_write (regcache, I386_EBP_REGNUM, buf);
 
+  /* 'this' pointer needs to be in ECX.  */
+  if (i386_windows_thiscall)
+    regcache_cooked_write (regcache, I386_ECX_REGNUM,
+			   value_contents_all (args[0]));
+
   /* MarkK wrote: This "+ 8" is all over the place:
      (i386_frame_this_id, i386_sigtramp_frame_this_id,
      i386_dummy_id).  It's there, since all frame unwinders for
-- 
1.8.4.msysgit.0