PATCH [C}: tree.h decls for bounded pointers

Greg McGary gkm@eng.ascend.com
Thu Mar 16 15:28:00 GMT 2000


OK to commit?

2000-03-16  Greg McGary  <gkm@gnu.org>

	* tree.h (tree_common): Add bounded_flag member.  Remove
	inaccurate comment about number of remaining bits.
	(BOUNDED_INDIRECT_TYPE_P, BOUNDED_POINTER_TYPE_P,
	BOUNDED_REFERENCE_TYPE_P, MAYBE_BOUNDED_INDIRECT_TYPE_P,
	MAYBE_BOUNDED_POINTER_TYPE_P, MAYBE_BOUNDED_REFERENCE_TYPE_P,
	TREE_BOUNDED, TYPE_MAIN_VARIANTS_PHYSICALLY_EQUAL_P,
	TYPE_MAIN_PHYSICAL_VARIANT, TYPE_BOUNDED): New macros.
	(TYPE_QUAL_BOUNDED): New constant.
	(TYPE_QUALS): Handle bounded qualifier.
	(TREE_EXPR_QUALS, TREE_FUNC_QUALS): New macros.
	(TYPE_BOUNDED_VALUE, TYPE_BOUNDED_BASE, TYPE_BOUNDED_EXTENT,
	TYPE_BOUNDED_SUBTYPE, TYPE_UNBOUNDED_VARIANT, TYPE_POINTER_DEPTH,
	TYPE_AMBIENT_BOUNDEDNESS): New macros.
	(MAX_POINTER_DEPTH, VA_LIST_POINTER_DEPTH): New constants.
	(tree_type): Add pointer_depth member.  Remove
	inaccurate comment about number of remaining bits.
	(DECL_POINTER_DEPTH): Add macro.
	(tree_decl): Add pointer_depth member.

Index: tree.h
===================================================================
RCS file: /cvs/gcc/egcs/gcc/tree.h,v
retrieving revision 1.142
diff -u -p -c -r1.142 tree.h
*** tree.h	2000/03/13 22:54:03	1.142
--- tree.h	2000/03/16 23:23:20
*************** struct tree_common
*** 211,216 ****
--- 211,217 ----
    unsigned public_flag : 1;
    unsigned private_flag : 1;
    unsigned protected_flag : 1;
+   unsigned bounded_flag : 1;
  
    unsigned lang_flag_0 : 1;
    unsigned lang_flag_1 : 1;
*************** struct tree_common
*** 219,226 ****
    unsigned lang_flag_4 : 1;
    unsigned lang_flag_5 : 1;
    unsigned lang_flag_6 : 1;
- 
-   /* There is room for three more flags.  */
  };
  
  /* The following table lists the uses of each of the above flags and
--- 220,225 ----
*************** struct tree_common
*** 326,333 ****
  
         TREE_NOTHROW in
             CALL_EXPR, FUNCTION_DECL
  
- 							  */
  /* Define accessors for the fields that all tree nodes have
     (though some fields are not used for all kinds of nodes).  */
  
--- 325,339 ----
  
         TREE_NOTHROW in
             CALL_EXPR, FUNCTION_DECL
+ 
+    bounded_flag:
+ 
+        TREE_BOUNDED in
+ 	   expressions, VAR_DECL, PARM_DECL, FIELD_DECL, FUNCTION_DECL
+        TYPE_BOUNDED in
+ 	   ..._TYPE
+ */
  
  /* Define accessors for the fields that all tree nodes have
     (though some fields are not used for all kinds of nodes).  */
  
*************** extern void tree_class_check_failed PARA
*** 463,473 ****
     || TREE_CODE (TYPE) == UNION_TYPE || TREE_CODE (TYPE) == QUAL_UNION_TYPE \
     || TREE_CODE (TYPE) == SET_TYPE)
  
! /* Nonzero if TYPE represents a pointer type.  */
  
  #define POINTER_TYPE_P(TYPE) \
    (TREE_CODE (TYPE) == POINTER_TYPE || TREE_CODE (TYPE) == REFERENCE_TYPE)
  
  /* Nonzero if TYPE represents a type.  */
  
  #define TYPE_P(TYPE)	(TREE_CODE_CLASS (TREE_CODE (TYPE)) == 't')
--- 469,522 ----
     || TREE_CODE (TYPE) == UNION_TYPE || TREE_CODE (TYPE) == QUAL_UNION_TYPE \
     || TREE_CODE (TYPE) == SET_TYPE)
  
! /* Nonzero if TYPE represents an unbounded pointer or unbounded
!    reference type.  (It should be renamed to INDIRECT_TYPE_P.)  */
  
  #define POINTER_TYPE_P(TYPE) \
    (TREE_CODE (TYPE) == POINTER_TYPE || TREE_CODE (TYPE) == REFERENCE_TYPE)
  
+ /* Nonzero if TYPE represents a bounded pointer or bounded reference type.  */
+ 
+ #define BOUNDED_INDIRECT_TYPE_P(TYPE) \
+   (TREE_CODE (TYPE) == RECORD_TYPE && TREE_TYPE (TYPE))
+ 
+ /* Nonzero if TYPE represents a bounded pointer type.  */
+ 
+ #define BOUNDED_POINTER_TYPE_P(TYPE) \
+   (BOUNDED_INDIRECT_TYPE_P (TYPE) \
+    && TREE_CODE (TYPE_BOUNDED_SUBTYPE (TYPE)) == POINTER_TYPE)
+ 
+ /* Nonzero if TYPE represents a bounded reference type.  Bounded
+    reference types have two specific uses: (1) When a reference is
+    seated to a variable-length RECORD_TYPE that has an array of
+    indeterminate length as its final field.  For all other objects, it
+    is sufficient to check bounds at the time the reference is seated,
+    and assume that all future uses of the reference are safe, since
+    the address of references cannot change.  (2) When a reference
+    supertype is seated to an subtype object.  The bounds "remember"
+    the true size of the complete object, so that subsequent upcasts of
+    the address of the reference will be checked properly (is such a
+    thing valid C++?).  */
+ 
+ #define BOUNDED_REFERENCE_TYPE_P(TYPE) \
+   (BOUNDED_INDIRECT_TYPE_P (TYPE) \
+    && TREE_CODE (TYPE_BOUNDED_SUBTYPE (TYPE)) == REFERENCE_TYPE)
+ 
+ /* Nonzero if TYPE represents a pointer type, either bounded or unbounded.  */
+ 
+ /* Nonzero if TYPE represents a pointer or reference type, either
+    bounded or unbounded.  */
+ 
+ #define MAYBE_BOUNDED_INDIRECT_TYPE_P(TYPE) \
+   (INDIRECT_TYPE_P (TYPE) || BOUNDED_INDIRECT_TYPE_P (TYPE))
+ 
+ #define MAYBE_BOUNDED_POINTER_TYPE_P(TYPE) \
+   (TREE_CODE (TYPE) == POINTER_TYPE || BOUNDED_POINTER_TYPE_P (TYPE))
+ 
+ /* Nonzero if TYPE represents a reference type, either bounded or unbounded.  */
+ 
+ #define MAYBE_BOUNDED_REFERENCE_TYPE_P(TYPE) \
+   (TREE_CODE (TYPE) == REFERENCE_TYPE || BOUNDED_REFERENCE_TYPE_P (TYPE))
  /* Nonzero if TYPE represents a type.  */
  
  #define TYPE_P(TYPE)	(TREE_CODE_CLASS (TREE_CODE (TYPE)) == 't')
*************** extern void tree_class_check_failed PARA
*** 609,614 ****
--- 658,697 ----
     In a BLOCK node, this is BLOCK_HANDLER_BLOCK.  */
  #define TREE_PROTECTED(NODE) ((NODE)->common.protected_flag)
  
+ /* In a ..._TYPE node, nonzero means that the type's size and layout,
+    (or the size and layout of its arguments and/or return value in the
+    case of a FUNCTION_TYPE or METHOD_TYPE) was changed by the presence
+    of pointer bounds.  Use TYPE_BOUNDED instead of this macro when the
+    node is a type, because eventually we may make that a different
+    bit.  TYPE_BOUNDED doesn't mean that this type is a bounded indirect
+    type--use BOUNDED_POINTER_TYPE_P, BOUNDED_REFERENCE_TYPE_P,
+    BOUNDED_INDIRECT_TYPE_P to test for that.
+ 
+    In a FUNCTION_DECL, nonzero means that the size and layout of one
+    of its arguments and/or return value was changed by the presence of
+    pointer bounds.  This value can differ from the value of
+    TYPE_BOUNDED (TREE_TYPE (fundecl)) if the function was implicitly
+    declared, then later called with pointer args, or was declared with
+    a variable argument list and is later called with pointer values in
+    the variable argument list.
+ 
+    In a VAR_DECL, PARM_DECL or FIELD_DECL, TREE_BOUNDED matches the value
+    of the decl's type's BOUNDED_POINTER_TYPE_P.
+ 
+    In a CONSTRUCTOR or other expression, nonzero means the value is a
+    bounded pointer.  It is insufficient to determine the boundedness
+    of an expression EXP with BOUNDED_POINTER_TYPE_P (TREE_TYPE (EXP)),
+    since we allow pointer to be temporarily cast to integer for
+    rounding up to an alignment boudary in a way that preserves the
+    pointer's bounds.
+ 
+    In an IDENTIFIER_NODE, nonzero means that the name is prefixed with
+    BP_PREFIX (see varasm.c).  This occurs for the DECL_ASSEMBLER_NAME
+    of a function that has bounded pointer(s) for its return type and/or
+    argument type(s).  */
+ 
+ #define TREE_BOUNDED(NODE) ((NODE)->common.bounded_flag)
+ 
  /* These flags are available for each language front end to use internally.  */
  #define TREE_LANG_FLAG_0(NODE) ((NODE)->common.lang_flag_0)
  #define TREE_LANG_FLAG_1(NODE) ((NODE)->common.lang_flag_1)
*************** struct tree_block
*** 853,858 ****
--- 936,961 ----
  #define TYPE_OBSTACK(NODE) (TYPE_CHECK (NODE)->type.obstack)
  #define TYPE_LANG_SPECIFIC(NODE) (TYPE_CHECK (NODE)->type.lang_specific)
  
+ /* Indirect types present difficulties because they may be represented
+    as either POINTER_TYPE/REFERENCE_TYPE nodes (unbounded) or as
+    RECORD_TYPE nodes (bounded).  Bounded and unbounded pointers might
+    be logically equivalent, but physically different.  Simple
+    comparison of the main variant only tells if the types are
+    logically equivalent.  Use this predicate to compare for physical
+    equivalency.  */
+ 
+ /* Types have the same main variant, and have the same boundedness.  */
+ #define TYPE_MAIN_VARIANTS_PHYSICALLY_EQUAL_P(TYPE1, TYPE2)	\
+   (TYPE_MAIN_VARIANT (TYPE1) == TYPE_MAIN_VARIANT (TYPE2)	\
+    && TREE_CODE (TYPE1) == TREE_CODE (TYPE2))
+ 
+ /* Return the type variant that has no qualifiers (i.e., the main variant),
+    except that the boundedness qualifier is preserved.  */
+ #define TYPE_MAIN_PHYSICAL_VARIANT(TYPE)		\
+   (BOUNDED_POINTER_TYPE_P (TYPE)			\
+    ? build_qualified_type (TYPE, TYPE_QUAL_BOUNDED)	\
+    : TYPE_MAIN_VARIANT (TYPE))
+ 
  /* For aggregate types, information about this type, as a base type
     for itself.  Used in a language-dependent way for types that are
     neither a RECORD_TYPE, QUAL_UNION_TYPE, nor a UNION_TYPE.  */
*************** struct tree_block
*** 904,909 ****
--- 1007,1017 ----
     the term.  */
  #define TYPE_RESTRICT(NODE) (TYPE_CHECK (NODE)->type.restrict_flag)
  
+ /* If nonzero, this type's size and layout, (or the size and layout of
+    its arguments and/or return value in the case of a FUNCTION_TYPE or
+    METHOD_TYPE) was changed by the presence of pointer bounds.  */
+ #define TYPE_BOUNDED(NODE) (TYPE_CHECK (NODE)->common.bounded_flag)
+ 
  /* There is a TYPE_QUAL value for each type qualifier.  They can be
     combined by bitwise-or to form the complete set of qualifiers for a
     type.  */
*************** struct tree_block
*** 912,923 ****
  #define TYPE_QUAL_CONST    0x1
  #define TYPE_QUAL_VOLATILE 0x2
  #define TYPE_QUAL_RESTRICT 0x4
  
  /* The set of type qualifiers for this type.  */
! #define TYPE_QUALS(NODE)			\
!   ((TYPE_READONLY(NODE) * TYPE_QUAL_CONST)	\
!    | (TYPE_VOLATILE(NODE) * TYPE_QUAL_VOLATILE)	\
!    | (TYPE_RESTRICT(NODE) * TYPE_QUAL_RESTRICT))
  
  /* These flags are available for each language front end to use internally.  */
  #define TYPE_LANG_FLAG_0(NODE) (TYPE_CHECK (NODE)->type.lang_flag_0)
--- 1020,1044 ----
  #define TYPE_QUAL_CONST    0x1
  #define TYPE_QUAL_VOLATILE 0x2
  #define TYPE_QUAL_RESTRICT 0x4
+ #define TYPE_QUAL_BOUNDED  0x8
  
  /* The set of type qualifiers for this type.  */
! #define TYPE_QUALS(NODE)					\
!   ((TYPE_READONLY (NODE) * TYPE_QUAL_CONST)			\
!    | (TYPE_VOLATILE (NODE) * TYPE_QUAL_VOLATILE)		\
!    | (TYPE_RESTRICT (NODE) * TYPE_QUAL_RESTRICT)		\
!    | (BOUNDED_INDIRECT_TYPE_P (NODE) * TYPE_QUAL_BOUNDED))
! 
! /* The set of qualifiers pertinent to an expression node.  */
! #define TREE_EXPR_QUALS(NODE)				\
!   ((TREE_READONLY (NODE) * TYPE_QUAL_CONST)		\
!    | (TREE_THIS_VOLATILE (NODE) * TYPE_QUAL_VOLATILE)	\
!    | (TREE_BOUNDED (NODE) * TYPE_QUAL_BOUNDED))
! 
! /* The set of qualifiers pertinent to a FUNCTION_DECL node.  */
! #define TREE_FUNC_QUALS(NODE)				\
!   ((TREE_READONLY (NODE) * TYPE_QUAL_CONST)		\
!    | (TREE_THIS_VOLATILE (NODE) * TYPE_QUAL_VOLATILE))
  
  /* These flags are available for each language front end to use internally.  */
  #define TYPE_LANG_FLAG_0(NODE) (TYPE_CHECK (NODE)->type.lang_flag_0)
*************** struct tree_block
*** 949,954 ****
--- 1070,1134 ----
     compact a way as possible.  */
  #define TYPE_PACKED(NODE) (TYPE_CHECK (NODE)->type.packed_flag)
  
+ /* A bounded pointer or bounded reference type (collectively called
+    indirect types) is represented as a RECORD_TYPE node containing
+    three pointer fields whose type is the corresponding unbounded
+    POINTER_TYPE or REFERENCE_TYPE.  A RECORD_TYPE node that represents
+    a bounded indirect type differs from a normal RECORD_TYPE node in
+    that its TREE_TYPE is non-NULL and has the pointed-to type just as
+    a POINTER_TYPE or REFERENCE_TYPE node has.  The bounded RECORD_TYPE
+    nodes are stored on the same type variant chain alongside the
+    variants of the underlaying indirect types nodes.  The main variant
+    of such chains is always the unbounded type.  */
+ 
+ /* Access the field decls of a bounded-pointer type.  */
+ #define TYPE_BOUNDED_VALUE(TYPE) TYPE_FIELDS (TYPE)
+ #define TYPE_BOUNDED_BASE(TYPE) TREE_CHAIN (TYPE_BOUNDED_VALUE (TYPE))
+ #define TYPE_BOUNDED_EXTENT(TYPE) TREE_CHAIN (TYPE_BOUNDED_BASE (TYPE))
+ 
+ /* Access the simple-pointer subtype of a bounded-pointer type.  */
+ #define TYPE_BOUNDED_SUBTYPE(TYPE) TREE_TYPE (TYPE_BOUNDED_VALUE (TYPE))
+ 
+ /* Find the unbounded counterpart to a type, or return TYPE if it is
+    already unbounded.  */
+ #define TYPE_UNBOUNDED_VARIANT(TYPE) \
+   (BOUNDED_POINTER_TYPE_P (TYPE) ? TYPE_BOUNDED_SUBTYPE (TYPE) : (TYPE))
+ 
+ /* This field comprises two bits, for values in the range 0..3:
+ 
+    depth=0 means that type is a scalar, or an aggregate that contains
+    only depth=0 types, or a function that has only depth=0 types for
+    its return value and argument types.
+ 
+    depth=1 means that type is a pointer to a depth=0 type, or an
+    aggregate that contains only depth=0 and depth=1 types, or a
+    function that has only depth=0 and depth=1 types for its return
+    value and argument types.
+ 
+    The meanings of depth=2 and depth=3 are obvious by induction.
+    Varargs functions are depth=3.  The type `va_list' is depth=3.
+ 
+    The purpose of measuring pointer depth of a type is to determine
+    the eligibility of a function for an automatically-generated
+    bounded-pointer thunk.  A depth=0 functions needs no thunk.  A
+    depth=1 function is eligible for an automatic thunk.  Functions
+    with depth 2 or more are too complex to get automatic thunks.
+ 
+    Function decls also have a pointer_depth field, since we also
+    consider the actual argument types for functions.  */
+ 
+ #define TYPE_POINTER_DEPTH(TYPE) (TYPE_CHECK (TYPE)->type.pointer_depth)
+ 
+ /* In a FUNCTION_TYPE node, this bit stores the value of
+    default_pointer_boundedness at the time TYPE was created.  It is
+    useful for choosing default boundedness of function arguments for
+    non-prototype function decls and for varargs/stdarg lists.  */
+ 
+ #define TYPE_AMBIENT_BOUNDEDNESS(TYPE) (TYPE_CHECK (TYPE)->type.transparent_union_flag)
+ 
+ #define MAX_POINTER_DEPTH 2
+ #define VA_LIST_POINTER_DEPTH 3
+ 
  struct tree_type
  {
    char common[sizeof (struct tree_common)];
*************** struct tree_type
*** 971,976 ****
--- 1151,1157 ----
    unsigned transparent_union_flag : 1;
    unsigned packed_flag : 1;
    unsigned restrict_flag : 1;
+   unsigned pointer_depth : 2;
  
    unsigned lang_flag_0 : 1;
    unsigned lang_flag_1 : 1;
*************** struct tree_type
*** 979,985 ****
    unsigned lang_flag_4 : 1;
    unsigned lang_flag_5 : 1;
    unsigned lang_flag_6 : 1;
-   /* room for 3 more bits */
  
    unsigned int align;
    union tree_node *pointer_to;
--- 1160,1165 ----
*************** struct tree_type
*** 1387,1392 ****
--- 1567,1582 ----
  #define DECL_POINTER_ALIAS_SET_KNOWN_P(NODE) \
    (DECL_POINTER_ALIAS_SET (NODE) != - 1)
  
+ /* The pointer_depth field comprises two bits for values in the range
+    0..3.  The value is normally equal to TYPE_POINTER_DEPTH of decl's
+    type node, but for functions it migth be greater.  For example,
+    this can happen when the function is declared to accept a parameter
+    of type void* (depth=1), but is actually called with an argument of
+    type foo** (depth=2).  The function type will get the formal
+    parameter's depth, but the function decl will get the actual
+    argument's depth.  */
+ #define DECL_POINTER_DEPTH(DECL) (DECL_CHECK (DECL)->decl.pointer_depth)
+ 
  struct tree_decl
  {
    char common[sizeof (struct tree_common)];
*************** struct tree_decl
*** 1429,1434 ****
--- 1619,1625 ----
  #else
    enum built_in_class built_in_class : 2;
  #endif
+   unsigned pointer_depth : 2;
  
    unsigned lang_flag_0 : 1;
    unsigned lang_flag_1 : 1;


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