re PR c++/11326 (C++ IA64 ABI: 3.1.4: sometimes pointer to temporary return value is implicit first parameter preceding "this")

	PR c++/11326
	* c-common.c (flag_abi_version): Remove.
	* c-common.h (flag_abi_version): Likewise.
	* c-opts.c (c_common_handle_option): Remove OPT_fabi_version case.
	* c.opt (fabi-version): Remove.
	* calls.c (expand_call): Always pass a function type to
	struct_value_rtx.  Use convert_memory_address.
	* common.opt (fabi-version): Add it.
	* flags.h (flag_abi_version): Likewise.
	(abi_version_at_least): New macro.
	* opts.c (common_handle_option): Add OPT_fabi_version.
	* toplev.c (flag_abi_version): Define it.
	* config/ia64/ia64.c (ia64_struct_retval_addr_is_first_parm_p):
	New function.
	(ia64_output_mi_thunk): Use it.
	(ia64_struct_value_rtx): Likewise.

	PR c++/11326
	* cp-tree.h (abi_version_at_least): Remove.
	* mangle.c: Include flags.h.

	PR c++/11326
	* g++.dg/abi/structret1.C: New test.

From-SVN: r77968

1 files changed, 38 insertions, 6 deletions

diff --git a/gcc/config/ia64/ia64.c b/gcc/config/ia64/ia64.c
index 8dcee21..ffbb349 100644
--- a/gcc/config/ia64/ia64.c
+++ b/gcc/config/ia64/ia64.c
@@ -8802,6 +8802,27 @@ ia64_rwreloc_section_type_flags (tree decl, const char *name, int reloc)
   return default_section_type_flags_1 (decl, name, reloc, true);
 }
 
+/* Returns true if FNTYPE (a FUNCTION_TYPE or a METHOD_TYPE) returns a
+   structure type and that the address of that type should be passed
+   in out0, rather than in r8.  */
+
+static bool
+ia64_struct_retval_addr_is_first_parm_p (tree fntype)
+{
+  tree ret_type = TREE_TYPE (fntype);
+
+  /* The Itanium C++ ABI requires that out0, rather than r8, be used
+     as the structure return address parameter, if the return value
+     type has a non-trivial copy constructor or destructor.  It is not
+     clear if this same convention should be used for other
+     programming languages.  Until G++ 3.4, we incorrectly used r8 for
+     these return values.  */
+  return (abi_version_at_least (2)
+	  && ret_type
+	  && TYPE_MODE (ret_type) == BLKmode 
+	  && TREE_ADDRESSABLE (ret_type)
+	  && strcmp (lang_hooks.name, "GNU C++") == 0);
+}
 
 /* Output the assembler code for a thunk function.  THUNK_DECL is the
    declaration for the thunk function itself, FUNCTION is the decl for
@@ -8815,6 +8836,8 @@ ia64_output_mi_thunk (FILE *file, tree thunk ATTRIBUTE_UNUSED,
 		      tree function)
 {
   rtx this, insn, funexp;
+  unsigned int this_parmno;
+  unsigned int this_regno;
 
   reload_completed = 1;
   epilogue_completed = 1;
@@ -8828,16 +8851,23 @@ ia64_output_mi_thunk (FILE *file, tree thunk ATTRIBUTE_UNUSED,
   current_frame_info.n_input_regs = 1;
   current_frame_info.need_regstk = (TARGET_REG_NAMES != 0);
 
-  if (!TARGET_REG_NAMES)
-    reg_names[IN_REG (0)] = ia64_reg_numbers[0];
-
   /* Mark the end of the (empty) prologue.  */
   emit_note (NOTE_INSN_PROLOGUE_END);
 
-  this = gen_rtx_REG (Pmode, IN_REG (0));
+  /* Figure out whether "this" will be the first parameter (the
+     typical case) or the second parameter (as happens when the
+     virtual function returns certain class objects).  */
+  this_parmno
+    = (ia64_struct_retval_addr_is_first_parm_p (TREE_TYPE (thunk))
+       ? 1 : 0);
+  this_regno = IN_REG (this_parmno);
+  if (!TARGET_REG_NAMES)
+    reg_names[this_regno] = ia64_reg_numbers[this_parmno];
+
+  this = gen_rtx_REG (Pmode, this_regno);
   if (TARGET_ILP32)
     {
-      rtx tmp = gen_rtx_REG (ptr_mode, IN_REG (0));
+      rtx tmp = gen_rtx_REG (ptr_mode, this_regno);
       REG_POINTER (tmp) = 1;
       if (delta && CONST_OK_FOR_I (delta))
 	{
@@ -8945,9 +8975,11 @@ ia64_output_mi_thunk (FILE *file, tree thunk ATTRIBUTE_UNUSED,
 /* Worker function for TARGET_STRUCT_VALUE_RTX.  */
 
 static rtx
-ia64_struct_value_rtx (tree fntype ATTRIBUTE_UNUSED,
+ia64_struct_value_rtx (tree fntype,
 		       int incoming ATTRIBUTE_UNUSED)
 {
+  if (ia64_struct_retval_addr_is_first_parm_p (fntype))
+    return NULL_RTX;
   return gen_rtx_REG (Pmode, GR_REG (8));
 }