[PATCH] ARM half-precision floating point, 3/8 (target hooks)

[Sandra Loosemore <sandra at codesourcery dot com>]

This patch adds the target hooks that are required to get the C and
C++ language-level support for HFmode, specifically including the
implicit promotion and restrictions on function argument/return types.
The included documentation patch should be sufficient to explain the
details.

-Sandra


2009-04-15  Sandra Loosemore  <sandra@codesourcery.com>

	gcc/
	* doc/tm.texi (Misc): Document TARGET_INVALID_PARAMETER_TYPE,
	TARGET_INVALID_RETURN_TYPE, TARGET_PROMOTED_TYPE, and
	TARGET_CONVERT_TO_TYPE.
	* hooks.c (hook_tree_const_tree_null): Define.
	* hooks.h (hook_tree_const_tree_null): Declare.
	* target.h (struct gcc_target):  Add invalid_parameter_type,
	invalid_return_type, promoted_type, and convert_to_type fields.
	* target-def.h: (TARGET_INVALID_PARAMETER_TYPE): Define.
	(TARGET_INVALID_RETURN_TYPE): Define.
	(TARGET_PROMOTED_TYPE): Define.
	(TARGET_CONVERT_TO_TYPE): Define.
	(TARGET_INITIALIZER): Update for new fields.
	* c-decl.c (grokdeclarator): Check targetm.invalid_return_type.
	(grokparms): Check targetm.invalid_parameter_type.
	* c-typeck.c (default_conversion): Check targetm.promoted_type.
	* c-convert.c (convert): Check targetm.convert_to_type.
	* cp/typeck.c (default_conversion): Check targetm.promoted_type.
	* cp/decl.c (grokdeclarator): Check targetm.invalid_return_type.
	(grokparms): Check targetm.invalid_parameter_type.
	* cp/cvt.c (ocp_convert): Check targetm.convert_to_type.
	(build_expr_type_conversion): Check targetm.promoted_type.

Index: gcc/doc/tm.texi
===================================================================
--- gcc/doc/tm.texi	(revision 146010)
+++ gcc/doc/tm.texi	(working copy)
@@ -10684,6 +10684,36 @@ and @var{type2}, or @code{NULL} if valid
 the front end.
 @end deftypefn
 
+@deftypefn {Target Hook} {const char *} TARGET_INVALID_PARAMETER_TYPE (tree @var{type})
+If defined, this macro returns the diagnostic message when it is
+invalid for functions to include parameters of type @var{type}, 
+or @code{NULL} if validity should be determined by
+the front end.
+@end deftypefn
+
+@deftypefn {Target Hook} {const char *} TARGET_INVALID_RETURN_TYPE (tree @var{type})
+If defined, this macro returns the diagnostic message when it is
+invalid for functions to have return type @var{type}, 
+or @code{NULL} if validity should be determined by
+the front end.
+@end deftypefn
+
+@deftypefn {Target Hook} {tree} TARGET_PROMOTED_TYPE (tree @var{type})
+If defined, this target hook returns the type to which values of 
+@var{type} should be promoted when they appear in expressions, 
+analogous to the integer promotions, or @code{NULL_TREE} to use the
+front end's normal promotion rules.  This hook is useful when there are
+target-specific types with special promotion rules.
+@end deftypefn
+
+@deftypefn {Target Hook} {tree} TARGET_CONVERT_TO_TYPE (tree @var{type}, tree @var{expr})
+If defined, this hook returns the result of converting @var{expr} to 
+@var{type}.  It should return the converted expression, 
+or @code{NULL_TREE} to apply the front end's normal conversion rules.
+This hook is useful when there are target-specific types with special 
+conversion rules.
+@end deftypefn
+
 @defmac TARGET_USE_JCR_SECTION
 This macro determines whether to use the JCR section to register Java
 classes. By default, TARGET_USE_JCR_SECTION is defined to 1 if both
Index: gcc/hooks.c
===================================================================
--- gcc/hooks.c	(revision 146010)
+++ gcc/hooks.c	(working copy)
@@ -335,3 +335,10 @@ hook_constcharptr_int_const_tree_const_t
 {
   return NULL;
 }
+
+/* Generic hook that takes a const_tree and returns NULL_TREE.  */
+tree
+hook_tree_const_tree_null (const_tree t ATTRIBUTE_UNUSED)
+{
+  return NULL;
+}
Index: gcc/hooks.h
===================================================================
--- gcc/hooks.h	(revision 146010)
+++ gcc/hooks.h	(working copy)
@@ -64,6 +64,8 @@ extern int hook_int_rtx_bool_0 (rtx, boo
 extern int hook_int_size_t_constcharptr_int_0 (size_t, const char *, int);
 extern int hook_int_void_no_regs (void);
 
+extern tree hook_tree_const_tree_null (const_tree);
+
 extern tree hook_tree_tree_tree_null (tree, tree);
 extern tree hook_tree_tree_tree_tree_null (tree, tree, tree);
 extern tree hook_tree_tree_tree_tree_3rd_identity (tree, tree, tree);
Index: gcc/target.h
===================================================================
--- gcc/target.h	(revision 146010)
+++ gcc/target.h	(working copy)
@@ -901,6 +901,24 @@ struct gcc_target
      is not permitted on TYPE1 and TYPE2, NULL otherwise.  */
   const char *(*invalid_binary_op) (int op, const_tree type1, const_tree type2);
 
+  /* Return the diagnostic message string if TYPE is not valid as a
+     function parameter type, NULL otherwise.  */
+  const char *(*invalid_parameter_type) (const_tree type);
+
+  /* Return the diagnostic message string if TYPE is not valid as a
+     function return type, NULL otherwise.  */
+  const char *(*invalid_return_type) (const_tree type);
+
+  /* If values of TYPE are promoted to some other type when used in
+     expressions (analogous to the integer promotions), return that type,
+     or NULL_TREE otherwise.  */
+  tree (*promoted_type) (const_tree type);
+
+  /* Convert EXPR to TYPE, if target-specific types with special conversion
+     rules are involved.  Return the converted expression, or NULL to apply
+     the standard conversion rules.  */
+  tree (*convert_to_type) (tree type, tree expr);
+
   /* Return the array of IRA cover classes for the current target.  */
   const enum reg_class *(*ira_cover_classes) (void);
 
Index: gcc/cp/typeck.c
===================================================================
--- gcc/cp/typeck.c	(revision 146010)
+++ gcc/cp/typeck.c	(working copy)
@@ -1699,10 +1699,14 @@ decay_conversion (tree exp)
 tree
 default_conversion (tree exp)
 {
+  /* Check for target-specific promotions.  */
+  tree promoted_type = targetm.promoted_type (TREE_TYPE (exp));
+  if (promoted_type)
+    exp = cp_convert (promoted_type, exp);
   /* Perform the integral promotions first so that bitfield
      expressions (which may promote to "int", even if the bitfield is
      declared "unsigned") are promoted correctly.  */
-  if (INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (TREE_TYPE (exp)))
+  else if (INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (TREE_TYPE (exp)))
     exp = perform_integral_promotions (exp);
   /* Perform the other conversions.  */
   exp = decay_conversion (exp);
Index: gcc/cp/decl.c
===================================================================
--- gcc/cp/decl.c	(revision 146010)
+++ gcc/cp/decl.c	(working copy)
@@ -7607,6 +7607,7 @@ grokdeclarator (const cp_declarator *dec
   bool parameter_pack_p = declarator? declarator->parameter_pack_p : false;
   bool set_no_warning = false;
   bool template_type_arg = false;
+  const char *errmsg;
 
   signed_p = declspecs->specs[(int)ds_signed];
   unsigned_p = declspecs->specs[(int)ds_unsigned];
@@ -8286,6 +8287,12 @@ grokdeclarator (const cp_declarator *dec
 		type_quals = TYPE_UNQUALIFIED;
 		set_no_warning = true;
 	      }
+	    errmsg = targetm.invalid_return_type (type);
+	    if (errmsg)
+	      {
+		error (errmsg);
+		type = integer_type_node;
+	      }
 
 	    /* Error about some types functions can't return.  */
 
@@ -9665,6 +9672,7 @@ grokparms (tree parmlist, tree *parms)
       tree type = NULL_TREE;
       tree init = TREE_PURPOSE (parm);
       tree decl = TREE_VALUE (parm);
+      const char *errmsg;
 
       if (parm == void_list_node)
 	break;
@@ -9698,6 +9706,14 @@ grokparms (tree parmlist, tree *parms)
 	  init = NULL_TREE;
 	}
 
+      if (type != error_mark_node
+	  && (errmsg = targetm.invalid_parameter_type (type)))
+	{
+	  error (errmsg);
+	  type = error_mark_node;
+	  TREE_TYPE (decl) = error_mark_node;
+	}
+
       if (type != error_mark_node)
 	{
 	  if (deprecated_state != DEPRECATED_SUPPRESS)
Index: gcc/cp/cvt.c
===================================================================
--- gcc/cp/cvt.c	(revision 146010)
+++ gcc/cp/cvt.c	(working copy)
@@ -581,6 +581,7 @@ ocp_convert (tree type, tree expr, int c
   tree e = expr;
   enum tree_code code = TREE_CODE (type);
   const char *invalid_conv_diag;
+  tree e1;
 
   if (error_operand_p (e) || type == error_mark_node)
     return error_mark_node;
@@ -629,6 +630,9 @@ ocp_convert (tree type, tree expr, int c
 	}
     }
 
+  if ((e1 = targetm.convert_to_type (type, e)))
+    return e1;
+
   if (code == VOID_TYPE && (convtype & CONV_STATIC))
     {
       e = convert_to_void (e, /*implicit=*/NULL, tf_warning_or_error);
@@ -1224,11 +1228,18 @@ build_expr_type_conversion (int desires,
 tree
 type_promotes_to (tree type)
 {
+  tree promoted_type;
+
   if (type == error_mark_node)
     return error_mark_node;
 
   type = TYPE_MAIN_VARIANT (type);
 
+  /* Check for promotions of target-defined types first.  */
+  promoted_type = targetm.promoted_type (type);
+  if (promoted_type)
+    return promoted_type;
+
   /* bool always promotes to int (not unsigned), even if it's the same
      size.  */
   if (type == boolean_type_node)
Index: gcc/c-decl.c
===================================================================
--- gcc/c-decl.c	(revision 146010)
+++ gcc/c-decl.c	(working copy)
@@ -4000,6 +4000,7 @@ grokdeclarator (const struct c_declarato
   bool bitfield = width != NULL;
   tree element_type;
   struct c_arg_info *arg_info = 0;
+  const char *errmsg;
   tree expr_dummy;
   bool expr_const_operands_dummy;
 
@@ -4583,6 +4584,12 @@ grokdeclarator (const struct c_declarato
 		error ("%qs declared as function returning an array", name);
 		type = integer_type_node;
 	      }
+	    errmsg = targetm.invalid_return_type (type);
+	    if (errmsg)
+	      {
+		error (errmsg);
+		type = integer_type_node;
+	      }
 
 	    /* Construct the function type and go to the next
 	       inner layer of declarator.  */
@@ -5096,6 +5103,7 @@ grokparms (struct c_arg_info *arg_info, 
     {
       tree parm, type, typelt;
       unsigned int parmno;
+      const char *errmsg;
 
       /* If there is a parameter of incomplete type in a definition,
 	 this is an error.  In a declaration this is valid, and a
@@ -5139,6 +5147,14 @@ grokparms (struct c_arg_info *arg_info, 
 		}
 	    }
 
+	  errmsg = targetm.invalid_parameter_type (type);
+	  if (errmsg)
+	    {
+	      error (errmsg);
+	      TREE_VALUE (typelt) = error_mark_node;
+	      TREE_TYPE (parm) = error_mark_node;
+	    }
+
 	  if (DECL_NAME (parm) && TREE_USED (parm))
 	    warn_if_shadowing (parm);
 	}
Index: gcc/c-typeck.c
===================================================================
--- gcc/c-typeck.c	(revision 146010)
+++ gcc/c-typeck.c	(working copy)
@@ -1780,6 +1780,7 @@ default_conversion (tree exp)
   tree orig_exp;
   tree type = TREE_TYPE (exp);
   enum tree_code code = TREE_CODE (type);
+  tree promoted_type;
 
   /* Functions and arrays have been converted during parsing.  */
   gcc_assert (code != FUNCTION_TYPE);
@@ -1807,6 +1808,10 @@ default_conversion (tree exp)
   if (exp == error_mark_node)
     return error_mark_node;
 
+  promoted_type = targetm.promoted_type (type);
+  if (promoted_type)
+    return convert (promoted_type, exp);
+
   if (INTEGRAL_TYPE_P (type))
     return perform_integral_promotions (exp);
 
Index: gcc/c-convert.c
===================================================================
--- gcc/c-convert.c	(revision 146010)
+++ gcc/c-convert.c	(working copy)
@@ -86,6 +86,8 @@ convert (tree type, tree expr)
 
   if (type == TREE_TYPE (expr))
     return expr;
+  if ((ret =  targetm.convert_to_type (type, expr)))
+      return ret;
 
   STRIP_TYPE_NOPS (e);
 
Index: gcc/target-def.h
===================================================================
--- gcc/target-def.h	(revision 146010)
+++ gcc/target-def.h	(working copy)
@@ -537,6 +537,10 @@
 #define TARGET_INVALID_CONVERSION hook_constcharptr_const_tree_const_tree_null
 #define TARGET_INVALID_UNARY_OP hook_constcharptr_int_const_tree_null
 #define TARGET_INVALID_BINARY_OP hook_constcharptr_int_const_tree_const_tree_null
+#define TARGET_INVALID_PARAMETER_TYPE hook_constcharptr_const_tree_null
+#define TARGET_INVALID_RETURN_TYPE hook_constcharptr_const_tree_null
+#define TARGET_PROMOTED_TYPE hook_tree_const_tree_null
+#define TARGET_CONVERT_TO_TYPE hook_tree_tree_tree_null
 
 #define TARGET_FIXED_CONDITION_CODE_REGS hook_bool_uintp_uintp_false
 
@@ -918,6 +922,10 @@
   TARGET_INVALID_CONVERSION,			\
   TARGET_INVALID_UNARY_OP,			\
   TARGET_INVALID_BINARY_OP,			\
+  TARGET_INVALID_PARAMETER_TYPE,		\
+  TARGET_INVALID_RETURN_TYPE,			\
+  TARGET_PROMOTED_TYPE,				\
+  TARGET_CONVERT_TO_TYPE,			\
   TARGET_IRA_COVER_CLASSES,			\
   TARGET_SECONDARY_RELOAD,			\
   TARGET_EXPAND_TO_RTL_HOOK,			\