rtl.h (MEM_ALIAS_SET): Update documentation.

        * rtl.h (MEM_ALIAS_SET): Update documentation.
        * doc/rtl.texi (Special Accessors): New node.
        (SYMBOL_REF_FLAG): Note relationship with SYMBOL_REF_FLAGS.

From-SVN: r65714

gcc/ChangeLog

+2003-04-16  Richard Henderson  <rth@redhat.com>
+
+	* rtl.h (MEM_ALIAS_SET): Update documentation.
+	* doc/rtl.texi (Special Accessors): New node.
+	(SYMBOL_REF_FLAG): Note relationship with SYMBOL_REF_FLAGS.
+
 2003-04-16  Alexandre Oliva  <aoliva@redhat.com>
 
 	* reload1.c (reload_cse_noop_set_p): Return false if mode of

gcc/doc/rtl.texi

@@ -23,6 +23,7 @@ form uses nested parentheses to indicate the pointers in the internal form.
 * RTL Objects::       Expressions vs vectors vs strings vs integers.
 * RTL Classes::       Categories of RTL expression objects, and their structure.
 * Accessors::         Macros to access expression operands or vector elts.
+* Special Accessors:: Macros to access specific annotations on RTL.
 * Flags::             Other flags in an RTL expression.
 * Machine Modes::     Describing the size and format of a datum.
 * Constants::         Expressions with constant values.
@@ -368,6 +369,120 @@ All the macros defined in this section expand into lvalues and therefore
 can be used to assign the operands, lengths and vector elements as well as
 to access them.
 
+@node Special Accessors
+@section Access to Special Operands
+@cindex access to special operands
+
+Some RTL nodes have special annotations associated with them.
+
+@table @code
+@item MEM
+@table @code
+@findex MEM_ALIAS_SET
+@item MEM_ALIAS_SET (@var{x})
+If 0, @var{x} is not in any alias set, and may alias anything.  Otherwise,
+@var{x} can only alias @code{MEM}s in a conflicting alias set.  This value
+is set in a language-dependent manner in the front-end, and should not be
+altered in the back-end.  In some front-ends, these numbers may correspond
+in some way to types, or other language-level entities, but they need not,
+and the back-end makes no such assumptions.
+These set numbers are tested with @code{alias_sets_conflict_p}.
+
+@findex MEM_EXPR
+@item MEM_EXPR (@var{x})
+If this register is known to hold the value of some user-level
+declaration, this is that tree node.  It may also be a
+@code{COMPONENT_REF}, in which case this is some field reference,
+and @code{TREE_OPERAND (@var{x}, 0)} contains the declaration,
+or another @code{COMPONENT_REF}, or null if there is no compile-time
+object associated with the reference.
+
+@findex MEM_OFFSET
+@item MEM_OFFSET (@var{x})
+The offset from the start of @code{MEM_EXPR} as a @code{CONST_INT} rtx.
+
+@findex MEM_SIZE
+@item MEM_SIZE (@var{x})
+The size in bytes of the memory reference as a @code{CONST_INT} rtx.
+This is mostly relevant for @code{BLKmode} references as otherwise
+the size is implied by the mode.
+
+@findex MEM_ALIGN
+@item MEM_ALIGN (@var{x})
+The known alignment in bits of the memory reference.
+@end table
+
+@item REG
+@table @code
+@findex ORIGINAL_REGNO
+@item ORIGINAL_REGNO (@var{x})
+This field holds the number the register ``originally'' had; for a
+pseudo register turned into a hard reg this will hold the old pseudo
+register number.
+
+@findex REG_EXPR
+@item REG_EXPR (@var{x})
+If this register is known to hold the value of some user-level
+declaration, this is that tree node.
+
+@findex REG_OFFSET
+@item REG_OFFSET (@var{x})
+If this register is known to hold the value of some user-level
+declaration, this is the offset into that logical storage.
+@end table
+
+@item SYMBOL_REF
+@table @code
+@findex SYMBOL_REF_DECL
+@item SYMBOL_REF_DECL (@var{x})
+If the @code{symbol_ref} @var{x} was created for a @code{VAR_DECL} or
+a @code{FUNCTION_DECL}, that tree is recorded here.  If this value is
+null, then @var{x} was created by back end code generation routines,
+and so there is no associated front end symbol table entry.
+
+@findex SYMBOL_REF_FLAGS
+@item SYMBOL_REF_FLAGS (@var{x})
+In a @code{symbol_ref}, this is used to communicate various predicates
+about the symbol.  Some of these are common enough to be computed by
+common code, some are specific to the target.  The common bits are:
+
+@table @code
+@findex SYMBOL_REF_FUNCTION_P
+@findex SYMBOL_FLAG_FUNCTION
+@item SYMBOL_FLAG_FUNCTION
+Set if the symbol refers to a function.
+
+@findex SYMBOL_REF_LOCAL_P
+@findex SYMBOL_FLAG_LOCAL
+@item SYMBOL_FLAG_LOCAL
+Set if the symbol is local to this ``module''.
+See @code{TARGET_BINDS_LOCAL_P}.
+
+@findex SYMBOL_REF_EXTERNAL_P
+@findex SYMBOL_FLAG_EXTERNAL
+@item SYMBOL_FLAG_EXTERNAL
+Set if this symbol is not defined in this translation unit.
+Note that this is not the inverse of @code{SYMBOL_FLAG_LOCAL}.
+
+@findex SYMBOL_REF_SMALL_P
+@findex SYMBOL_FLAG_SMALL
+@item SYMBOL_FLAG_SMALL
+Set if the symbol is located in the small data section.
+See @code{TARGET_IN_SMALL_DATA_P}.
+
+@findex SYMBOL_FLAG_TLS_SHIFT
+@findex SYMBOL_REF_TLS_MODEL
+@item SYMBOL_REF_TLS_MODEL (@var{x})
+This is a multi-bit field accessor that returns the @code{tls_model}
+to be used for a thread-local storage symbol.  It returns zero for
+non-thread-local symbols.
+@end table
+
+Bits beginning with @code{SYMBOL_FLAG_MACH_DEP} are available for
+the target's use.
+@end table
+@end table
+
 @node Flags
 @section Flags in an RTL Expression
 @cindex flags in RTL expression
@@ -687,13 +802,6 @@ Promoted variables are always either sign- or zero-extended to the wider
 mode on every assignment.  Stored in the @code{in_struct} field and
 printed as @samp{/s}.
 
-@findex SYMBOL_REF_FLAG
-@cindex @code{symbol_ref} and @samp{/v}
-@cindex @code{volatil}, in @code{symbol_ref}
-@item SYMBOL_REF_FLAG (@var{x})
-In a @code{symbol_ref}, this is used as a flag for machine-specific purposes.
-Stored in the @code{volatil} field and printed as @samp{/v}.
-
 @findex SYMBOL_REF_USED
 @cindex @code{used}, in @code{symbol_ref}
 @item SYMBOL_REF_USED (@var{x})
@@ -707,6 +815,17 @@ once.  Stored in the @code{used} field.
 @item SYMBOL_REF_WEAK (@var{x})
 In a @code{symbol_ref}, indicates that @var{x} has been declared weak.
 Stored in the @code{integrated} field and printed as @samp{/i}.
+
+@findex SYMBOL_REF_FLAG
+@cindex @code{symbol_ref} and @samp{/v}
+@cindex @code{volatil}, in @code{symbol_ref}
+@item SYMBOL_REF_FLAG (@var{x})
+In a @code{symbol_ref}, this is used as a flag for machine-specific purposes.
+Stored in the @code{volatil} field and printed as @samp{/v}.
+
+Most uses of @code{SYMBOL_REF_FLAG} are historic and may be subsumed
+by @code{SYMBOL_REF_FLAGS}.  Certainly use of @code{SYMBOL_REF_FLAGS}
+is mandatory if the target requires more than one bit of storage.
 @end table
 
 These are the fields to which the above macros refer:

gcc/rtl.h

@@ -1133,13 +1133,10 @@ do {						\
 
 /* For a MEM rtx, the alias set.  If 0, this MEM is not in any alias
    set, and may alias anything.  Otherwise, the MEM can only alias
-   MEMs in the same alias set.  This value is set in a
+   MEMs in a conflicting alias set.  This value is set in a
    language-dependent manner in the front-end, and should not be
-   altered in the back-end.  These set numbers are tested for zero,
-   and compared for equality; they have no other significance.  In
-   some front-ends, these numbers may correspond in some way to types,
-   or other language-level entities, but they need not, and the
-   back-end makes no such assumptions.  */
+   altered in the back-end.  These set numbers are tested with
+   alias_sets_conflict_p.  */
 #define MEM_ALIAS_SET(RTX) (MEM_ATTRS (RTX) == 0 ? 0 : MEM_ATTRS (RTX)->alias)
 
 /* For a MEM rtx, the decl it is known to refer to, if it is known to