* gdbarch.sh (gdbarch_skip_main_prologue): New.

	* gdbarch.h, gdbarch.c: Regenerate.
	* i386-tdep.h (i386_skip_main_prologue): Declare.
	* i386-tdep.c (i386_skip_main_prologue): New.
	* i386-cygwin-tdep.c (i386_cygwin_init_abi): Register
	i386_skip_main_prologue as gdbarch_skip_main_prologue gdbarch callback.
	* symtab.c (find_function_start_sal): When pc points at the "main"
	function, call gdbarch_skip_main_prologue.

8 files changed, 102 insertions, 0 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 80160aa44ef..a207f3493b5 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,15 @@
+2008-06-12  Pedro Alves  <pedro_alves@portugalmail.pt>
+	    Pierre Muller  <muller@ics.u-strasbg.fr>
+
+	* gdbarch.sh (gdbarch_skip_main_prologue): New.
+	* gdbarch.h, gdbarch.c: Regenerate.
+	* i386-tdep.h (i386_skip_main_prologue): Declare.
+	* i386-tdep.c (i386_skip_main_prologue): New.
+	* i386-cygwin-tdep.c (i386_cygwin_init_abi): Register 
+	i386_skip_main_prologue as gdbarch_skip_main_prologue gdbarch callback.
+	* symtab.c (find_function_start_sal): When pc points at the "main"
+	function, call gdbarch_skip_main_prologue.
+
 2008-06-11  Daniel Jacobowitz  <dan@codesourcery.com>
 
 	* value.c (value_primitive_field): Fetch lazy register values.
diff --git a/gdb/gdbarch.c b/gdb/gdbarch.c
index 6594b35436e..3a967a9b77c 100644
--- a/gdb/gdbarch.c
+++ b/gdb/gdbarch.c
@@ -183,6 +183,7 @@ struct gdbarch
   gdbarch_integer_to_address_ftype *integer_to_address;
   gdbarch_return_value_ftype *return_value;
   gdbarch_skip_prologue_ftype *skip_prologue;
+  gdbarch_skip_main_prologue_ftype *skip_main_prologue;
   gdbarch_inner_than_ftype *inner_than;
   gdbarch_breakpoint_from_pc_ftype *breakpoint_from_pc;
   gdbarch_adjust_breakpoint_address_ftype *adjust_breakpoint_address;
@@ -313,6 +314,7 @@ struct gdbarch startup_gdbarch =
   0,  /* integer_to_address */
   0,  /* return_value */
   0,  /* skip_prologue */
+  0,  /* skip_main_prologue */
   0,  /* inner_than */
   0,  /* breakpoint_from_pc */
   0,  /* adjust_breakpoint_address */
@@ -561,6 +563,7 @@ verify_gdbarch (struct gdbarch *gdbarch)
   /* Skip verify of return_value, has predicate */
   if (gdbarch->skip_prologue == 0)
     fprintf_unfiltered (log, "\n\tskip_prologue");
+  /* Skip verify of skip_main_prologue, has predicate */
   if (gdbarch->inner_than == 0)
     fprintf_unfiltered (log, "\n\tinner_than");
   if (gdbarch->breakpoint_from_pc == 0)
@@ -999,6 +1002,12 @@ gdbarch_dump (struct gdbarch *gdbarch, struct ui_file *file)
                       "gdbarch_dump: single_step_through_delay = <0x%lx>\n",
                       (long) gdbarch->single_step_through_delay);
   fprintf_unfiltered (file,
+                      "gdbarch_dump: gdbarch_skip_main_prologue_p() = %d\n",
+                      gdbarch_skip_main_prologue_p (gdbarch));
+  fprintf_unfiltered (file,
+                      "gdbarch_dump: skip_main_prologue = <0x%lx>\n",
+                      (long) gdbarch->skip_main_prologue);
+  fprintf_unfiltered (file,
                       "gdbarch_dump: gdbarch_skip_permanent_breakpoint_p() = %d\n",
                       gdbarch_skip_permanent_breakpoint_p (gdbarch));
   fprintf_unfiltered (file,
@@ -2123,6 +2132,30 @@ set_gdbarch_skip_prologue (struct gdbarch *gdbarch,
 }
 
 int
+gdbarch_skip_main_prologue_p (struct gdbarch *gdbarch)
+{
+  gdb_assert (gdbarch != NULL);
+  return gdbarch->skip_main_prologue != NULL;
+}
+
+CORE_ADDR
+gdbarch_skip_main_prologue (struct gdbarch *gdbarch, CORE_ADDR ip)
+{
+  gdb_assert (gdbarch != NULL);
+  gdb_assert (gdbarch->skip_main_prologue != NULL);
+  if (gdbarch_debug >= 2)
+    fprintf_unfiltered (gdb_stdlog, "gdbarch_skip_main_prologue called\n");
+  return gdbarch->skip_main_prologue (gdbarch, ip);
+}
+
+void
+set_gdbarch_skip_main_prologue (struct gdbarch *gdbarch,
+                              gdbarch_skip_main_prologue_ftype skip_main_prologue)
+{
+  gdbarch->skip_main_prologue = skip_main_prologue;
+}
+
+int
 gdbarch_inner_than (struct gdbarch *gdbarch, CORE_ADDR lhs, CORE_ADDR rhs)
 {
   gdb_assert (gdbarch != NULL);
diff --git a/gdb/gdbarch.h b/gdb/gdbarch.h
index 44d1f2dbba6..cede82693ae 100644
--- a/gdb/gdbarch.h
+++ b/gdb/gdbarch.h
@@ -379,6 +379,12 @@ typedef CORE_ADDR (gdbarch_skip_prologue_ftype) (struct gdbarch *gdbarch, CORE_A
 extern CORE_ADDR gdbarch_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR ip);
 extern void set_gdbarch_skip_prologue (struct gdbarch *gdbarch, gdbarch_skip_prologue_ftype *skip_prologue);
 
+extern int gdbarch_skip_main_prologue_p (struct gdbarch *gdbarch);
+
+typedef CORE_ADDR (gdbarch_skip_main_prologue_ftype) (struct gdbarch *gdbarch, CORE_ADDR ip);
+extern CORE_ADDR gdbarch_skip_main_prologue (struct gdbarch *gdbarch, CORE_ADDR ip);
+extern void set_gdbarch_skip_main_prologue (struct gdbarch *gdbarch, gdbarch_skip_main_prologue_ftype *skip_main_prologue);
+
 typedef int (gdbarch_inner_than_ftype) (CORE_ADDR lhs, CORE_ADDR rhs);
 extern int gdbarch_inner_than (struct gdbarch *gdbarch, CORE_ADDR lhs, CORE_ADDR rhs);
 extern void set_gdbarch_inner_than (struct gdbarch *gdbarch, gdbarch_inner_than_ftype *inner_than);
diff --git a/gdb/gdbarch.sh b/gdb/gdbarch.sh
index a38ba033c67..d33fd7d4214 100755
--- a/gdb/gdbarch.sh
+++ b/gdb/gdbarch.sh
@@ -482,6 +482,7 @@ M:CORE_ADDR:integer_to_address:struct type *type, const gdb_byte *buf:type, buf
 M:enum return_value_convention:return_value:struct type *functype, struct type *valtype, struct regcache *regcache, gdb_byte *readbuf, const gdb_byte *writebuf:functype, valtype, regcache, readbuf, writebuf
 
 m:CORE_ADDR:skip_prologue:CORE_ADDR ip:ip:0:0
+M:CORE_ADDR:skip_main_prologue:CORE_ADDR ip:ip
 f:int:inner_than:CORE_ADDR lhs, CORE_ADDR rhs:lhs, rhs:0:0
 m:const gdb_byte *:breakpoint_from_pc:CORE_ADDR *pcptr, int *lenptr:pcptr, lenptr::0:
 M:CORE_ADDR:adjust_breakpoint_address:CORE_ADDR bpaddr:bpaddr
diff --git a/gdb/i386-cygwin-tdep.c b/gdb/i386-cygwin-tdep.c
index 3a8d6eeac36..1e4205d54b0 100644
--- a/gdb/i386-cygwin-tdep.c
+++ b/gdb/i386-cygwin-tdep.c
@@ -227,6 +227,8 @@ i386_cygwin_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 
   set_gdbarch_skip_trampoline_code (gdbarch, i386_cygwin_skip_trampoline_code);
 
+  set_gdbarch_skip_main_prologue (gdbarch, i386_skip_main_prologue);
+
   tdep->struct_return = reg_struct_return;
 
   tdep->gregset_reg_offset = i386_win32_gregset_reg_offset;
diff --git a/gdb/i386-tdep.c b/gdb/i386-tdep.c
index be4f4f38dfe..91bd7d040b2 100644
--- a/gdb/i386-tdep.c
+++ b/gdb/i386-tdep.c
@@ -1160,6 +1160,38 @@ i386_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR start_pc)
   return pc;
 }
 
+/* Check that the code pointed to by PC corresponds to a call to
+   __main, skip it if so.  Return PC otherwise.  */
+
+CORE_ADDR
+i386_skip_main_prologue (struct gdbarch *gdbarch, CORE_ADDR pc)
+{
+  gdb_byte op;
+
+  target_read_memory (pc, &op, 1);
+  if (op == 0xe8)
+    {
+      gdb_byte buf[4];
+
+      if (target_read_memory (pc + 1, buf, sizeof buf) == 0)
+ 	{
+	  /* Make sure address is computed correctly as a 32bit
+	     integer even if CORE_ADDR is 64 bit wide.  */
+ 	  struct minimal_symbol *s;
+ 	  CORE_ADDR call_dest = pc + 5 + extract_signed_integer (buf, 4);
+
+	  call_dest = call_dest & 0xffffffffU;
+ 	  s = lookup_minimal_symbol_by_pc (call_dest);
+ 	  if (s != NULL
+ 	      && SYMBOL_LINKAGE_NAME (s) != NULL
+ 	      && strcmp (SYMBOL_LINKAGE_NAME (s), "__main") == 0)
+ 	    pc += 5;
+ 	}
+    }
+
+  return pc;
+}
+
 /* This function is 64-bit safe.  */
 
 static CORE_ADDR
diff --git a/gdb/i386-tdep.h b/gdb/i386-tdep.h
index 227ac66c295..d1366b68b25 100644
--- a/gdb/i386-tdep.h
+++ b/gdb/i386-tdep.h
@@ -170,6 +170,7 @@ extern struct type *i386_sse_type (struct gdbarch *gdbarch);
 
 /* Functions exported from i386-tdep.c.  */
 extern CORE_ADDR i386_pe_skip_trampoline_code (CORE_ADDR pc, char *name);
+extern CORE_ADDR i386_skip_main_prologue (struct gdbarch *gdbarch, CORE_ADDR pc);
 
 /* Return the name of register REGNUM.  */
 extern char const *i386_register_name (struct gdbarch * gdbarch, int regnum);
diff --git a/gdb/symtab.c b/gdb/symtab.c
index 6adecbf4252..0466490edd9 100644
--- a/gdb/symtab.c
+++ b/gdb/symtab.c
@@ -2617,6 +2617,21 @@ find_function_start_sal (struct symbol *sym, int funfirstline)
       /* Recalculate the line number (might not be N+1).  */
       sal = find_pc_sect_line (pc, SYMBOL_BFD_SECTION (sym), 0);
     }
+
+  /* On targets with executable formats that don't have a concept of
+     constructors (ELF with .init has, PE doesn't), gcc emits a call
+     to `__main' in `main' between the prologue and before user
+     code.  */
+  if (funfirstline
+      && gdbarch_skip_main_prologue_p (current_gdbarch)
+      && SYMBOL_LINKAGE_NAME (sym)
+      && strcmp (SYMBOL_LINKAGE_NAME (sym), "main") == 0)
+    {
+      pc = gdbarch_skip_main_prologue (current_gdbarch, pc);
+      /* Recalculate the line number (might not be N+1).  */
+      sal = find_pc_sect_line (pc, SYMBOL_BFD_SECTION (sym), 0);
+    }
+
   sal.pc = pc;
 
   return sal;