-@c Copyright (c) 1999, 2000, 2001 Free Software Foundation, Inc.
+@c Copyright (c) 1999, 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
@c Free Software Foundation, Inc.
@c This is part of the GCC manual.
@c For copying conditions, see the file gcc.texi.
font}, except when talking about the actual C type @code{tree}.
You can tell what kind of node a particular tree is by using the
-@code{TREE_CODE} macro. Many, many macros take a trees as input and
-return trees as output. However, most macros require a certain kinds of
+@code{TREE_CODE} macro. Many, many macros take trees as input and
+return trees as output. However, most macros require a certain kind of
tree node as input. In other words, there is a type-system for trees,
but it is not reflected in the C type-system.
predicates end in @samp{_P}. Do not rely on the result type of these
macros being of any particular type. You may, however, rely on the fact
that the type can be compared to @code{0}, so that statements like
-@example
+@smallexample
if (TEST_P (t) && !TEST_P (y))
x = 1;
-@end example
+@end smallexample
@noindent
and
-@example
+@smallexample
int i = (TEST_P (t) != 0);
-@end example
+@end smallexample
@noindent
are legal. Macros that return @code{int} values now may be changed to
return @code{tree} values, or other pointers in the future. Even those
that continue to return @code{int} may return multiple nonzero codes
where previously they returned only zero and one. Therefore, you should
not write code like
-@example
+@smallexample
if (TEST_P (t) == 1)
-@end example
+@end smallexample
@noindent
as this code is not guaranteed to work correctly in the future.
values are lvalues.
In general, the names of macros are all in uppercase, while the names of
-functions are entirely in lower case. There are rare exceptions to this
+functions are entirely in lowercase. There are rare exceptions to this
rule. You should assume that any macro or function whose name is made
up entirely of uppercase letters may evaluate its arguments more than
once. You may assume that a macro or function whose name is made up
requirements for the ABI required 32-bit alignment. Then,
@code{TYPE_SIZE} would be an @code{INTEGER_CST} for 32, while
@code{TYPE_PRECISION} would be 24.) The integer type is unsigned if
-@code{TREE_UNSIGNED} holds; otherwise, it is signed.
+@code{TYPE_UNSIGNED} holds; otherwise, it is signed.
The @code{TYPE_MIN_VALUE} is an @code{INTEGER_CST} for the smallest
integer that may be represented by this type. Similarly, the
@item ENUMERAL_TYPE
Used to represent an enumeration type. The @code{TYPE_PRECISION} gives
(as an @code{int}), the number of bits used to represent the type. If
-there are no negative enumeration constants, @code{TREE_UNSIGNED} will
+there are no negative enumeration constants, @code{TYPE_UNSIGNED} will
hold. The minimum and maximum enumeration constants may be obtained
with @code{TYPE_MIN_VALUE} and @code{TYPE_MAX_VALUE}, respectively; each
of these macros returns an @code{INTEGER_CST}.
insufficient for a sound processing.
@item OFFSET_TYPE
-This node is used to represent a data member; for example a
-pointer-to-data-member is represented by a @code{POINTER_TYPE} whose
-@code{TREE_TYPE} is an @code{OFFSET_TYPE}. For a data member @code{X::m}
-the @code{TYPE_OFFSET_BASETYPE} is @code{X} and the @code{TREE_TYPE} is
-the type of @code{m}.
+This node is used to represent a pointer-to-data member. For a data
+member @code{X::m} the @code{TYPE_OFFSET_BASETYPE} is @code{X} and the
+@code{TREE_TYPE} is the type of @code{m}.
@item TYPENAME_TYPE
Used to represent a construct of the form @code{typename T::A}. The
The name of the global namespace is @samp{::}, even though in C++ the
global namespace is unnamed. However, you should use comparison with
@code{global_namespace}, rather than @code{DECL_NAME} to determine
-whether or not a namespaces is the global one. An unnamed namespace
+whether or not a namespace is the global one. An unnamed namespace
will have a @code{DECL_NAME} equal to @code{anonymous_namespace_name}.
Within a single translation unit, all unnamed namespaces will have the
same name.
@findex CLASSTYPE_DECLARED_CLASS
@findex TYPE_BINFO
@findex BINFO_TYPE
-@findex TREE_VIA_PUBLIC
-@findex TREE_VIA_PROTECTED
-@findex TREE_VIA_PRIVATE
@findex TYPE_FIELDS
@findex TYPE_VFIELD
@findex TYPE_METHODS
Every class has an associated @dfn{binfo}, which can be obtained with
@code{TYPE_BINFO}. Binfos are used to represent base-classes. The
binfo given by @code{TYPE_BINFO} is the degenerate case, whereby every
-class is considered to be its own base-class. The base classes for a
-particular binfo can be obtained with @code{BINFO_BASETYPES}. These
-base-classes are themselves binfos. The class type associated with a
-binfo is given by @code{BINFO_TYPE}. It is always the case that
-@code{BINFO_TYPE (TYPE_BINFO (x))} is the same type as @code{x}, up to
-qualifiers. However, it is not always the case that @code{TYPE_BINFO
-(BINFO_TYPE (y))} is always the same binfo as @code{y}. The reason is
-that if @code{y} is a binfo representing a base-class @code{B} of a
-derived class @code{D}, then @code{BINFO_TYPE (y)} will be @code{B},
-and @code{TYPE_BINFO (BINFO_TYPE (y))} will be @code{B} as its own
-base-class, rather than as a base-class of @code{D}.
-
-The @code{BINFO_BASETYPES} is a @code{TREE_VEC} (@pxref{Containers}).
-Base types appear in left-to-right order in this vector. You can tell
-whether or @code{public}, @code{protected}, or @code{private}
-inheritance was used by using the @code{TREE_VIA_PUBLIC},
-@code{TREE_VIA_PROTECTED}, and @code{TREE_VIA_PRIVATE} macros. Each of
-these macros takes a @code{BINFO} and is true if and only if the
-indicated kind of inheritance was used. If @code{TREE_VIA_VIRTUAL}
-holds of a binfo, then its @code{BINFO_TYPE} was inherited from
-virtually.
+class is considered to be its own base-class. The base binfos for a
+particular binfo are held in a vector, whose length is obtained with
+@code{BINFO_N_BASE_BINFOS}. The base binfos themselves are obtained
+with @code{BINFO_BASE_BINFO} and @code{BINFO_BASE_ITERATE}. To add a
+new binfo, use @code{BINFO_BASE_APPEND}. The vector of base binfos can
+be obtained with @code{BINFO_BASE_BINFOS}, but normally you do not need
+to use that. The class type associated with a binfo is given by
+@code{BINFO_TYPE}. It is not always the case that @code{BINFO_TYPE
+(TYPE_BINFO (x))}, because of typedefs and qualified types. Neither is
+it the case that @code{TYPE_BINFO (BINFO_TYPE (y))} is the same binfo as
+@code{y}. The reason is that if @code{y} is a binfo representing a
+base-class @code{B} of a derived class @code{D}, then @code{BINFO_TYPE
+(y)} will be @code{B}, and @code{TYPE_BINFO (BINFO_TYPE (y))} will be
+@code{B} as its own base-class, rather than as a base-class of @code{D}.
+
+The access to a base type can be found with @code{BINFO_BASE_ACCESS}.
+This will produce @code{access_public_node}, @code{access_private_node}
+or @code{access_protected_node}. If bases are always public,
+@code{BINFO_BASE_ACCESSES} may be @code{NULL}.
+
+@code{BINFO_VIRTUAL_P} is used to specify whether the binfo is inherited
+virtually or not. The other flags, @code{BINFO_MARKED_P} and
+@code{BINFO_FLAG_1} to @code{BINFO_FLAG_6} can be used for language
+specific use.
The following macros can be used on a tree node representing a class-type.
default constructor.
@item CLASSTYPE_HAS_MUTABLE
-@item TYPE_HAS_MUTABLE_P
+@itemx TYPE_HAS_MUTABLE_P
These predicates hold for a class-type having a mutable data member.
@item CLASSTYPE_NON_POD_P
@item TREE_TYPE
This macro returns the type of the entity declared.
-@item DECL_SOURCE_FILE
+@item TREE_FILENAME
This macro returns the name of the file in which the entity was
declared, as a @code{char*}. For an entity declared implicitly by the
compiler (like @code{__builtin_memcpy}), this will be the string
@code{"<internal>"}.
-@item DECL_SOURCE_LINE
+@item TREE_LINENO
This macro returns the line number at which the entity was declared, as
an @code{int}.
compiler. For example, this predicate will hold of an implicitly
declared member function, or of the @code{TYPE_DECL} implicitly
generated for a class type. Recall that in C++ code like:
-@example
+@smallexample
struct S @{@};
-@end example
+@end smallexample
@noindent
is roughly equivalent to C code like:
-@example
+@smallexample
struct S @{@};
typedef struct S S;
-@end example
+@end smallexample
The implicitly generated @code{typedef} declaration is represented by a
@code{TYPE_DECL} for which @code{DECL_ARTIFICIAL} holds.
be @code{NULL_TREE}.
To determine the scope of a function, you can use the
-@code{DECL_REAL_CONTEXT} macro. This macro will return the class
+@code{DECL_CONTEXT} macro. This macro will return the class
(either a @code{RECORD_TYPE} or a @code{UNION_TYPE}) or namespace (a
@code{NAMESPACE_DECL}) of which the function is a member. For a virtual
function, this macro returns the class in which the function was
actually defined, not the base class in which the virtual declaration
-occurred. If a friend function is defined in a class scope, the
-@code{DECL_CLASS_CONTEXT} macro can be used to determine the class in
+occurred.
+
+If a friend function is defined in a class scope, the
+@code{DECL_FRIEND_CONTEXT} macro can be used to determine the class in
which it was defined. For example, in
-@example
+@smallexample
class C @{ friend void f() @{@} @};
-@end example
-the @code{DECL_REAL_CONTEXT} for @code{f} will be the
-@code{global_namespace}, but the @code{DECL_CLASS_CONTEXT} will be the
+@end smallexample
+@noindent
+the @code{DECL_CONTEXT} for @code{f} will be the
+@code{global_namespace}, but the @code{DECL_FRIEND_CONTEXT} will be the
@code{RECORD_TYPE} for @code{C}.
-The @code{DECL_REAL_CONTEXT} and @code{DECL_CLASS_CONTEXT} are not
-available in C; instead you should simply use @code{DECL_CONTEXT}. In C,
-the @code{DECL_CONTEXT} for a function maybe another function. This
-representation indicates that the GNU nested function extension is in
-use. For details on the semantics of nested functions, see the GCC
-Manual. The nested function can refer to local variables in its
+In C, the @code{DECL_CONTEXT} for a function maybe another function.
+This representation indicates that the GNU nested function extension
+is in use. For details on the semantics of nested functions, see the
+GCC Manual. The nested function can refer to local variables in its
containing function. Such references are not explicitly marked in the
tree structure; back ends must look at the @code{DECL_CONTEXT} for the
referenced @code{VAR_DECL}. If the @code{DECL_CONTEXT} for the
referenced @code{VAR_DECL} is not the same as the function currently
-being processed, and neither @code{DECL_EXTERNAL} nor @code{DECL_STATIC}
-hold, then the reference is to a local variable in a containing
-function, and the back end must take appropriate action.
+being processed, and neither @code{DECL_EXTERNAL} nor
+@code{DECL_STATIC} hold, then the reference is to a local variable in
+a containing function, and the back end must take appropriate action.
@menu
* Function Basics:: Function names, linkage, and so forth.
modifications. (Of course, the back end should not modify
@code{DECL_ASSEMBLER_NAME} itself.)
+Using @code{DECL_ASSEMBLER_NAME} will cause additional memory to be
+allocated (for the mangled name of the entity) so it should be used
+only when emitting assembly code. It should not be used within the
+optimizers to determine whether or not two declarations are the same,
+even though some of the existing optimizers do use it in that way.
+These uses will be removed over time.
+
@item DECL_EXTERNAL
This predicate holds if the function is undefined.
the adjusted @code{this} pointer must be adjusted again. The complete
calculation is given by the following pseudo-code:
-@example
+@smallexample
this += THUNK_DELTA
if (THUNK_VCALL_OFFSET)
this += (*((ptrdiff_t **) this))[THUNK_VCALL_OFFSET]
-@end example
+@end smallexample
Finally, the thunk should jump to the location given
by @code{DECL_INITIAL}; this will always be an expression for the
@subsection Function Bodies
@cindex function body
@cindex statements
-@tindex ASM_STMT
-@findex ASM_STRING
-@findex ASM_CV_QUAL
-@findex ASM_INPUTS
-@findex ASM_OUTPUTS
-@findex ASM_CLOBBERS
@tindex BREAK_STMT
@tindex CLEANUP_STMT
@findex CLEANUP_DECL
@findex CLEANUP_EXPR
-@tindex COMPOUND_STMT
-@findex COMPOUND_BODY
@tindex CONTINUE_STMT
@tindex DECL_STMT
@findex DECL_STMT_DECL
@findex FOR_COND
@findex FOR_EXPR
@findex FOR_BODY
-@tindex FILE_STMT
-@findex FILE_STMT_FILENAME
-@tindex GOTO_STMT
-@findex GOTO_DESTINATION
-@findex GOTO_FAKE_P
@tindex HANDLER
@tindex IF_STMT
@findex IF_COND
@findex THEN_CLAUSE
@findex ELSE_CLAUSE
-@tindex LABEL_STMT
-@tindex LABEL_STMT_LABEL
@tindex RETURN_INIT
@tindex RETURN_STMT
@findex RETURN_EXPR
-@tindex SCOPE_STMT
-@findex SCOPE_BEGIN_P
-@findex SCOPE_END_P
-@findex SCOPE_NULLIFIED_P
@tindex SUBOBJECT
@findex SUBOBJECT_CLEANUP
@tindex SWITCH_STMT
use of the particular value given by @code{DECL_INITIAL}.
The @code{DECL_SAVED_TREE} macro will give the complete body of the
-function. This node will usually be a @code{COMPOUND_STMT} representing
-the outermost block of the function, but it may also be a
-@code{TRY_BLOCK}, a @code{RETURN_INIT}, or any other valid statement.
+function.
@subsubsection Statements
-There are tree nodes corresponding to all of the source-level statement
-constructs. These are enumerated here, together with a list of the
-various macros that can be used to obtain information about them. There
-are a few macros that can be used with all statements:
+There are tree nodes corresponding to all of the source-level
+statement constructs, used within the C and C++ frontends. These are
+enumerated here, together with a list of the various macros that can
+be used to obtain information about them. There are a few macros that
+can be used with all statements:
@ftable @code
-@item STMT_LINENO
-This macro returns the line number for the statement. If the statement
-spans multiple lines, this value will be the number of the first line on
-which the statement occurs. Although we mention @code{CASE_LABEL} below
-as if it were a statement, they do not allow the use of
-@code{STMT_LINENO}. There is no way to obtain the line number for a
-@code{CASE_LABEL}.
-
-Statements do not contain information about
-the file from which they came; that information is implicit in the
-@code{FUNCTION_DECL} from which the statements originate.
-
@item STMT_IS_FULL_EXPR_P
In C++, statements normally constitute ``full expressions''; temporaries
created during a statement are destroyed when the statement is complete.
of statements, connected via their @code{TREE_CHAIN}s. So, you should
always process the statement tree by looping over substatements, like
this:
-@example
+@smallexample
void process_stmt (stmt)
tree stmt;
@{
stmt = TREE_CHAIN (stmt);
@}
@}
-@end example
+@end smallexample
In other words, while the @code{then} clause of an @code{if} statement
in C++ can be only one statement (although that one statement may be a
compound statement), the intermediate representation will sometimes use
several statements chained together.
@table @code
-@item ASM_STMT
+@item ASM_EXPR
Used to represent an inline assembly statement. For an inline assembly
statement like:
-@example
+@smallexample
asm ("mov x, y");
-@end example
+@end smallexample
The @code{ASM_STRING} macro will return a @code{STRING_CST} node for
@code{"mov x, y"}. If the original statement made use of the
extended-assembly syntax, then @code{ASM_OUTPUTS},
@code{ASM_INPUTS}, and @code{ASM_CLOBBERS} will be the outputs, inputs,
and clobbers for the statement, represented as @code{STRING_CST} nodes.
The extended-assembly syntax looks like:
-@example
+@smallexample
asm ("fsinx %1,%0" : "=f" (result) : "f" (angle));
-@end example
+@end smallexample
The first string is the @code{ASM_STRING}, containing the instruction
template. The next two strings are the output and inputs, respectively;
this statement has no clobbers. As this example indicates, ``plain''
If the assembly statement is declared @code{volatile}, or if the
statement was not an extended assembly statement, and is therefore
implicitly volatile, then the predicate @code{ASM_VOLATILE_P} will hold
-of the @code{ASM_STMT}.
+of the @code{ASM_EXPR}.
@item BREAK_STMT
Used to represent a @code{break} statement. There are no additional
fields.
-@item CASE_LABEL
+@item CASE_LABEL_EXPR
Use to represent a @code{case} label, range of @code{case} labels, or a
@code{default} label. If @code{CASE_LOW} is @code{NULL_TREE}, then this is a
Otherwise, if both @code{CASE_LOW} and @code{CASE_HIGH} are defined, the
statement is a range of case labels. Such statements originate with the
extension that allows users to write things of the form:
-@example
+@smallexample
case 2 ... 5:
-@end example
+@end smallexample
The first value will be @code{CASE_LOW}, while the second will be
@code{CASE_HIGH}.
should be run in the reverse order of the order in which the associated
@code{CLEANUP_STMT}s were encountered.
-@item COMPOUND_STMT
-
-Used to represent a brace-enclosed block. The first substatement is
-given by @code{COMPOUND_BODY}. Subsequent substatements are found by
-following the @code{TREE_CHAIN} link from one substatement to the next.
-The @code{COMPOUND_BODY} will be @code{NULL_TREE} if there are no
-substatements.
-
@item CONTINUE_STMT
Used to represent a @code{continue} statement. There are no additional
Used to represent an expression statement. Use @code{EXPR_STMT_EXPR} to
obtain the expression.
-@item FILE_STMT
-
-Used to record a change in filename within the body of a function.
-Use @code{FILE_STMT_FILENAME} to obtain the new filename.
-
@item FOR_STMT
Used to represent a @code{for} statement. The @code{FOR_INIT_STMT} is
return statements, while @code{FOR_COND} and @code{FOR_EXPR} return
expressions.
-@item GOTO_STMT
+@item GOTO_EXPR
Used to represent a @code{goto} statement. The @code{GOTO_DESTINATION} will
usually be a @code{LABEL_DECL}. However, if the ``computed goto'' extension
has been used, the @code{GOTO_DESTINATION} will be an arbitrary expression
indicating the destination. This expression will always have pointer type.
-Additionally the @code{GOTO_FAKE_P} flag is set whenever the goto statement
-does not come from source code, but it is generated implicitly by the compiler.
-This is used for branch prediction.
@item HANDLER
Used to represent a C++ @code{catch} block. The @code{HANDLER_TYPE}
is the type of exception that will be caught by this handler; it is
-equal (by pointer equality) to @code{CATCH_ALL_TYPE} if this handler
-is for all types. @code{HANDLER_PARMS} is the @code{DECL_STMT} for
-the catch parameter, and @code{HANDLER_BODY} is the
-@code{COMPOUND_STMT} for the block itself.
+equal (by pointer equality) to @code{NULL} if this handler is for all
+types. @code{HANDLER_PARMS} is the @code{DECL_STMT} for the catch
+parameter, and @code{HANDLER_BODY} is the code for the block itself.
@item IF_STMT
@code{TREE_VALUE} should be used as the conditional expression itself.
This representation is used to handle C++ code like this:
-@example
+@smallexample
if (int i = 7) @dots{}
-@end example
+@end smallexample
where there is a new local variable (or variables) declared within the
condition.
condition, while the @code{ELSE_CLAUSE} represents the statement given
by the @code{else} condition.
-@item LABEL_STMT
+@item LABEL_EXPR
Used to represent a label. The @code{LABEL_DECL} declared by this
-statement can be obtained with the @code{LABEL_STMT_LABEL} macro. The
+statement can be obtained with the @code{LABEL_EXPR_LABEL} macro. The
@code{IDENTIFIER_NODE} giving the name of the label can be obtained from
the @code{LABEL_DECL} with @code{DECL_NAME}.
If the function uses the G++ ``named return value'' extension, meaning
that the function has been defined like:
-@example
+@smallexample
S f(int) return s @{@dots{}@}
-@end example
+@end smallexample
then there will be a @code{RETURN_INIT}. There is never a named
returned value for a constructor. The first argument to the
@code{RETURN_INIT} is the name of the object returned; the second
Used to represent a @code{return} statement. The @code{RETURN_EXPR} is
the expression returned; it will be @code{NULL_TREE} if the statement
was just
-@example
+@smallexample
return;
-@end example
-
-@item SCOPE_STMT
-
-A scope-statement represents the beginning or end of a scope. If
-@code{SCOPE_BEGIN_P} holds, this statement represents the beginning of a
-scope; if @code{SCOPE_END_P} holds this statement represents the end of
-a scope. On exit from a scope, all cleanups from @code{CLEANUP_STMT}s
-occurring in the scope must be run, in reverse order to the order in
-which they were encountered. If @code{SCOPE_NULLIFIED_P} or
-@code{SCOPE_NO_CLEANUPS_P} holds of the scope, back ends should behave
-as if the @code{SCOPE_STMT} were not present at all.
+@end smallexample
@item SUBOBJECT
@node Expression trees
@section Expressions
@cindex expression
+@findex TREE_TYPE
@findex TREE_OPERAND
@tindex INTEGER_CST
@findex TREE_INT_CST_HIGH
@findex PTRMEM_CST_MEMBER
@tindex VAR_DECL
@tindex NEGATE_EXPR
+@tindex ABS_EXPR
@tindex BIT_NOT_EXPR
@tindex TRUTH_NOT_EXPR
+@tindex PREDECREMENT_EXPR
+@tindex PREINCREMENT_EXPR
+@tindex POSTDECREMENT_EXPR
+@tindex POSTINCREMENT_EXPR
@tindex ADDR_EXPR
@tindex INDIRECT_REF
@tindex FIX_TRUNC_EXPR
@tindex CONJ_EXPR
@tindex REALPART_EXPR
@tindex IMAGPART_EXPR
+@tindex NON_LVALUE_EXPR
@tindex NOP_EXPR
@tindex CONVERT_EXPR
@tindex THROW_EXPR
@tindex PLUS_EXPR
@tindex MINUS_EXPR
@tindex MULT_EXPR
+@tindex RDIV_EXPR
@tindex TRUNC_DIV_EXPR
+@tindex FLOOR_DIV_EXPR
+@tindex CEIL_DIV_EXPR
+@tindex ROUND_DIV_EXPR
@tindex TRUNC_MOD_EXPR
-@tindex RDIV_EXPR
+@tindex FLOOR_MOD_EXPR
+@tindex CEIL_MOD_EXPR
+@tindex ROUND_MOD_EXPR
+@tindex EXACT_DIV_EXPR
+@tindex ARRAY_REF
+@tindex ARRAY_RANGE_REF
@tindex LT_EXPR
@tindex LE_EXPR
@tindex GT_EXPR
@tindex GE_EXPR
@tindex EQ_EXPR
@tindex NE_EXPR
-@tindex INIT_EXPR
+@tindex ORDERED_EXPR
+@tindex UNORDERED_EXPR
+@tindex UNLT_EXPR
+@tindex UNLE_EXPR
+@tindex UNGT_EXPR
+@tindex UNGE_EXPR
+@tindex UNEQ_EXPR
+@tindex LTGT_EXPR
@tindex MODIFY_EXPR
+@tindex INIT_EXPR
@tindex COMPONENT_REF
@tindex COMPOUND_EXPR
@tindex COND_EXPR
@tindex CALL_EXPR
-@tindex CONSTRUCTOR
-@tindex COMPOUND_LITERAL_EXPR
@tindex STMT_EXPR
@tindex BIND_EXPR
@tindex LOOP_EXPR
@tindex EXIT_EXPR
@tindex CLEANUP_POINT_EXPR
-@tindex ARRAY_REF
-@tindex VTABLE_REF
+@tindex CONSTRUCTOR
+@tindex COMPOUND_LITERAL_EXPR
+@tindex SAVE_EXPR
+@tindex TARGET_EXPR
+@tindex AGGR_INIT_EXPR
@tindex VA_ARG_EXPR
The internal representation for expressions is for the most part quite
@code{TREE_OPERAND} macro. For example, to access the first operand to
a binary plus expression @code{expr}, use:
-@example
+@smallexample
TREE_OPERAND (expr, 0)
-@end example
+@end smallexample
@noindent
As this example indicates, the operands are zero-indexed.
constants is obtained with @code{TREE_TYPE}; they are not always of type
@code{int}. In particular, @code{char} constants are represented with
@code{INTEGER_CST} nodes. The value of the integer constant @code{e} is
-given by @example
+given by
+@smallexample
((TREE_INT_CST_HIGH (e) << HOST_BITS_PER_WIDE_INT)
+ TREE_INST_CST_LOW (e))
-@end example
+@end smallexample
@noindent
HOST_BITS_PER_WIDE_INT is at least thirty-two on all platforms. Both
@code{TREE_INT_CST_HIGH} and @code{TREE_INT_CST_LOW} return a
Note that the @code{DECL_CONTEXT} for the @code{PTRMEM_CST_MEMBER} is in
general different from the @code{PTRMEM_CST_CLASS}. For example,
given:
-@example
+@smallexample
struct B @{ int i; @};
struct D : public B @{@};
int D::*dp = &D::i;
-@end example
+@end smallexample
@noindent
The @code{PTRMEM_CST_CLASS} for @code{&D::i} is @code{D}, even though
the @code{DECL_CONTEXT} for the @code{PTRMEM_CST_MEMBER} is @code{B},
integer and floating-point types. The type of negation can be
determined by looking at the type of the expression.
+The behavior of this operation on signed arithmetic overflow is
+controlled by the @code{flag_wrapv} and @code{flag_trapv} variables.
+
+@item ABS_EXPR
+These nodes represent the absolute value of the single operand, for
+both integer and floating-point types. This is typically used to
+implement the @code{abs}, @code{labs} and @code{llabs} builtins for
+integer types, and the @code{fabs}, @code{fabsf} and @code{fabsl}
+builtins for floating point types. The type of abs operation can
+be determined by looking at the type of the expression.
+
+This node is not used for complex types. To represent the modulus
+or complex abs of a complex value, use the @code{BUILT_IN_CABS},
+@code{BUILT_IN_CABSF} or @code{BUILT_IN_CABSL} builtins, as used
+to implement the C99 @code{cabs}, @code{cabsf} and @code{cabsl}
+built-in functions.
+
@item BIT_NOT_EXPR
These nodes represent bitwise complement, and will always have integral
type. The only operand is the value to be complemented.
@item TRUTH_NOT_EXPR
These nodes represent logical negation, and will always have integral
-(or boolean) type. The operand is the value being negated.
+(or boolean) type. The operand is the value being negated. The type
+of the operand and that of the result are always of @code{BOOLEAN_TYPE}
+or @code{INTEGER_TYPE}.
@item PREDECREMENT_EXPR
@itemx PREINCREMENT_EXPR
These nodes represent the conjugate of their operand.
@item REALPART_EXPR
-@item IMAGPART_EXPR
+@itemx IMAGPART_EXPR
These nodes represent respectively the real and the imaginary parts
of complex numbers (their sole argument).
These nodes represent logical and and logical or, respectively. These
operators are not strict; i.e., the second operand is evaluated only if
the value of the expression is not determined by evaluation of the first
-operand. The type of the operands, and the result type, is always of
-boolean or integral type.
+operand. The type of the operands and that of the result are always of
+@code{BOOLEAN_TYPE} or @code{INTEGER_TYPE}.
@item TRUTH_AND_EXPR
@itemx TRUTH_OR_EXPR
They are strict; both arguments are always evaluated. There are no
corresponding operators in C or C++, but the front end will sometimes
generate these expressions anyhow, if it can tell that strictness does
-not matter.
+not matter. The type of the operands and that of the result are
+always of @code{BOOLEAN_TYPE} or @code{INTEGER_TYPE}.
@itemx PLUS_EXPR
@itemx MINUS_EXPR
@itemx MULT_EXPR
-@itemx TRUNC_DIV_EXPR
-@itemx TRUNC_MOD_EXPR
-@itemx RDIV_EXPR
These nodes represent various binary arithmetic operations.
Respectively, these operations are addition, subtraction (of the second
-operand from the first), multiplication, integer division, integer
-remainder, and floating-point division. The operands to the first three
-of these may have either integral or floating type, but there will never
-be case in which one operand is of floating type and the other is of
-integral type.
+operand from the first) and multiplication. Their operands may have
+either integral or floating type, but there will never be case in which
+one operand is of floating type and the other is of integral type.
+
+The behavior of these operations on signed arithmetic overflow is
+controlled by the @code{flag_wrapv} and @code{flag_trapv} variables.
+
+@item RDIV_EXPR
+This node represents a floating point division operation.
+
+@item TRUNC_DIV_EXPR
+@itemx FLOOR_DIV_EXPR
+@itemx CEIL_DIV_EXPR
+@itemx ROUND_DIV_EXPR
+These nodes represent integer division operations that return an integer
+result. @code{TRUNC_DIV_EXPR} rounds towards zero, @code{FLOOR_DIV_EXPR}
+rounds towards negative infinity, @code{CEIL_DIV_EXPR} rounds towards
+positive infinity and @code{ROUND_DIV_EXPR} rounds to the closest integer.
+Integer division in C and C++ is truncating, i.e@. @code{TRUNC_DIV_EXPR}.
+
+The behavior of these operations on signed arithmetic overflow, when
+dividing the minimum signed integer by minus one, is controlled by the
+@code{flag_wrapv} and @code{flag_trapv} variables.
+
+@item TRUNC_MOD_EXPR
+@itemx FLOOR_MOD_EXPR
+@itemx CEIL_MOD_EXPR
+@itemx ROUND_MOD_EXPR
+These nodes represent the integer remainder or modulus operation.
+The integer modulus of two operands @code{a} and @code{b} is
+defined as @code{a - (a/b)*b} where the division calculated using
+the corresponding division operator. Hence for @code{TRUNC_MOD_EXPR}
+this definition assumes division using truncation towards zero, i.e@.
+@code{TRUNC_DIV_EXPR}. Integer remainder in C and C++ uses truncating
+division, i.e@. @code{TRUNC_MOD_EXPR}.
-The result of a @code{TRUNC_DIV_EXPR} is always rounded towards zero.
-The @code{TRUNC_MOD_EXPR} of two operands @code{a} and @code{b} is
-always @code{a - a/b} where the division is as if computed by a
-@code{TRUNC_DIV_EXPR}.
+@item EXACT_DIV_EXPR
+The @code{EXACT_DIV_EXPR} code is used to represent integer divisions where
+the numerator is known to be an exact multiple of the denominator. This
+allows the backend to choose between the faster of @code{TRUNC_DIV_EXPR},
+@code{CEIL_DIV_EXPR} and @code{FLOOR_DIV_EXPR} for the current target.
@item ARRAY_REF
These nodes represent array accesses. The first operand is the array;
the second is the index. To calculate the address of the memory
accessed, you must scale the index by the size of the type of the array
elements. The type of these expressions must be the type of a component of
-the array.
+the array. The third and fourth operands are used after gimplification
+to represent the lower bound and component size but should not be used
+directly; call @code{array_ref_low_bound} and @code{array_ref_element_size}
+instead.
@item ARRAY_RANGE_REF
These nodes represent access to a range (or ``slice'') of an array. The
type is the same as that of the first operand. The range of that array
type determines the amount of data these expressions access.
-@item EXACT_DIV_EXPR
-Document.
-
@item LT_EXPR
@itemx LE_EXPR
@itemx GT_EXPR
@itemx GE_EXPR
@itemx EQ_EXPR
@itemx NE_EXPR
-
These nodes represent the less than, less than or equal to, greater
than, greater than or equal to, equal, and not equal comparison
operators. The first and second operand with either be both of integral
type or both of floating type. The result type of these expressions
-will always be of integral or boolean type.
+will always be of integral or boolean type. These operations return
+the result type's zero value for false, and the result type's one value
+for true.
+
+For floating point comparisons, if we honor IEEE NaNs and either operand
+is NaN, then @code{NE_EXPR} always returns true and the remaining operators
+always return false. On some targets, comparisons against an IEEE NaN,
+other than equality and inequality, may generate a floating point exception.
+
+@item ORDERED_EXPR
+@itemx UNORDERED_EXPR
+These nodes represent non-trapping ordered and unordered comparison
+operators. These operations take two floating point operands and
+determine whether they are ordered or unordered relative to each other.
+If either operand is an IEEE NaN, their comparison is defined to be
+unordered, otherwise the comparison is defined to be ordered. The
+result type of these expressions will always be of integral or boolean
+type. These operations return the result type's zero value for false,
+and the result type's one value for true.
+
+@item UNLT_EXPR
+@itemx UNLE_EXPR
+@itemx UNGT_EXPR
+@itemx UNGE_EXPR
+@itemx UNEQ_EXPR
+@itemx LTGT_EXPR
+These nodes represent the unordered comparison operators.
+These operations take two floating point operands and determine whether
+the operands are unordered or are less than, less than or equal to,
+greater than, greater than or equal to, or equal respectively. For
+example, @code{UNLT_EXPR} returns true if either operand is an IEEE
+NaN or the first operand is less than the second. With the possible
+exception of @code{LTGT_EXPR}, all of these operations are guaranteed
+not to generate a floating point exception. The result
+type of these expressions will always be of integral or boolean type.
+These operations return the result type's zero value for false,
+and the result type's one value for true.
@item MODIFY_EXPR
These nodes represent assignment. The left-hand side is the first
@item COMPONENT_REF
These nodes represent non-static data member accesses. The first
operand is the object (rather than a pointer to it); the second operand
-is the @code{FIELD_DECL} for the data member.
+is the @code{FIELD_DECL} for the data member. The third operand represents
+the byte offset of the field, but should not be used directly; call
+@code{component_ref_field_offset} instead.
@item COMPOUND_EXPR
These nodes represent comma-expressions. The first operand is an
is of boolean or integral type. If it evaluates to a nonzero value,
the second operand should be evaluated, and returned as the value of the
expression. Otherwise, the third operand is evaluated, and returned as
-the value of the expression. As a GNU extension, the middle operand of
-the @code{?:} operator may be omitted in the source, like this:
-
-@example
-x ? : 3
-@end example
-@noindent
-which is equivalent to
-
-@example
-x ? x : 3
-@end example
-
-@noindent
-assuming that @code{x} is an expression without side-effects. However,
-in the case that the first operation causes side effects, the
-side-effects occur only once. Consumers of the internal representation
-do not need to worry about this oddity; the second operand will be
-always be present in the internal representation.
+the value of the expression.
+
+The second operand must have the same type as the entire expression,
+unless it unconditionally throws an exception or calls a noreturn
+function, in which case it should have void type. The same constraints
+apply to the third operand. This allows array bounds checks to be
+represented conveniently as @code{(i >= 0 && i < 10) ? i : abort()}.
+
+As a GNU extension, the C language front-ends allow the second
+operand of the @code{?:} operator may be omitted in the source.
+For example, @code{x ? : 3} is equivalent to @code{x ? x : 3},
+assuming that @code{x} is an expression without side-effects.
+In the tree representation, however, the second operand is always
+present, possibly protected by @code{SAVE_EXPR} if the first
+argument does cause side-effects.
@item CALL_EXPR
These nodes are used to represent calls to functions, including
@item STMT_EXPR
These nodes are used to represent GCC's statement-expression extension.
The statement-expression extension allows code like this:
-@example
+@smallexample
int f() @{ return (@{ int j; j = 3; j + 7; @}); @}
-@end example
+@end smallexample
In other words, an sequence of statements may occur where a single
expression would normally appear. The @code{STMT_EXPR} node represents
such an expression. The @code{STMT_EXPR_STMT} gives the statement
-contained in the expression; this is always a @code{COMPOUND_STMT}. The
-value of the expression is the value of the last sub-statement in the
-@code{COMPOUND_STMT}. More precisely, the value is the value computed
-by the last @code{EXPR_STMT} in the outermost scope of the
-@code{COMPOUND_STMT}. For example, in:
-@example
+contained in the expression. The value of the expression is the value
+of the last sub-statement in the body. More precisely, the value is the
+value computed by the last statement nested inside @code{BIND_EXPR},
+@code{TRY_FINALLY_EXPR}, or @code{TRY_CATCH_EXPR}. For example, in:
+@smallexample
(@{ 3; @})
-@end example
+@end smallexample
the value is @code{3} while in:
-@example
+@smallexample
(@{ if (x) @{ 3; @} @})
-@end example
-(represented by a nested @code{COMPOUND_STMT}), there is no value. If
-the @code{STMT_EXPR} does not yield a value, it's type will be
-@code{void}.
+@end smallexample
+there is no value. If the @code{STMT_EXPR} does not yield a value,
+it's type will be @code{void}.
@item BIND_EXPR
These nodes represent local blocks. The first operand is a list of
-temporary variables, connected via their @code{TREE_CHAIN} field. These
-will never require cleanups. The scope of these variables is just the
-body of the @code{BIND_EXPR}. The body of the @code{BIND_EXPR} is the
+variables, connected via their @code{TREE_CHAIN} field. These will
+never require cleanups. The scope of these variables is just the body
+of the @code{BIND_EXPR}. The body of the @code{BIND_EXPR} is the
second operand.
@item LOOP_EXPR
@code{CONSTRUCTOR} is a @code{RECORD_TYPE} or @code{UNION_TYPE}, then
the @code{TREE_PURPOSE} of each node in the @code{TREE_LIST} will be a
@code{FIELD_DECL} and the @code{TREE_VALUE} of each node will be the
-expression used to initialize that field. You should not depend on the
-fields appearing in any particular order, nor should you assume that all
-fields will be represented. Unrepresented fields may be assigned any
-value.
+expression used to initialize that field.
If the @code{TREE_TYPE} of the @code{CONSTRUCTOR} is an
@code{ARRAY_TYPE}, then the @code{TREE_PURPOSE} of each element in the
@code{TREE_PURPOSE} is @code{NULL_TREE}, then the initializer is for the
next available array element.
-Conceptually, before any initialization is done, the entire area of
-storage is initialized to zero.
+In the front end, you should not depend on the fields appearing in any
+particular order. However, in the middle end, fields must appear in
+declaration order. You should not assume that all fields will be
+represented. Unrepresented fields will be set to zero.
@item COMPOUND_LITERAL_EXPR
@findex COMPOUND_LITERAL_EXPR_DECL_STMT
@item TARGET_EXPR
A @code{TARGET_EXPR} represents a temporary object. The first operand
is a @code{VAR_DECL} for the temporary variable. The second operand is
-the initializer for the temporary. The initializer is evaluated, and
-copied (bitwise) into the temporary.
+the initializer for the temporary. The initializer is evaluated and,
+if non-void, copied (bitwise) into the temporary. If the initializer
+is void, that means that it will perform the initialization itself.
Often, a @code{TARGET_EXPR} occurs on the right-hand side of an
assignment, or as the second operand to a comma-expression which is
@item AGGR_INIT_EXPR
An @code{AGGR_INIT_EXPR} represents the initialization as the return
value of a function call, or as the result of a constructor. An
-@code{AGGR_INIT_EXPR} will only appear as the second operand of a
-@code{TARGET_EXPR}. The first operand to the @code{AGGR_INIT_EXPR} is
-the address of a function to call, just as in a @code{CALL_EXPR}. The
-second operand are the arguments to pass that function, as a
-@code{TREE_LIST}, again in a manner similar to that of a
-@code{CALL_EXPR}. The value of the expression is that returned by the
-function.
+@code{AGGR_INIT_EXPR} will only appear as a full-expression, or as the
+second operand of a @code{TARGET_EXPR}. The first operand to the
+@code{AGGR_INIT_EXPR} is the address of a function to call, just as in
+a @code{CALL_EXPR}. The second operand are the arguments to pass that
+function, as a @code{TREE_LIST}, again in a manner similar to that of
+a @code{CALL_EXPR}.
If @code{AGGR_INIT_VIA_CTOR_P} holds of the @code{AGGR_INIT_EXPR}, then
the initialization is via a constructor call. The address of the third
operand of the @code{AGGR_INIT_EXPR}, which is always a @code{VAR_DECL},
is taken, and this value replaces the first argument in the argument
-list. In this case, the value of the expression is the @code{VAR_DECL}
-given by the third operand to the @code{AGGR_INIT_EXPR}; constructors do
-not return a value.
-
-@item VTABLE_REF
-A @code{VTABLE_REF} indicates that the interior expression computes
-a value that is a vtable entry. It is used with @option{-fvtable-gc}
-to track the reference through to front end to the middle end, at
-which point we transform this to a @code{REG_VTABLE_REF} note, which
-survives the balance of code generation.
-
-The first operand is the expression that computes the vtable reference.
-The second operand is the @code{VAR_DECL} of the vtable. The third
-operand is an @code{INTEGER_CST} of the byte offset into the vtable.
+list.
+
+In either case, the expression is void.
@item VA_ARG_EXPR
This node is used to implement support for the C/C++ variable argument-list
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