-@c Copyright (C) 1988,89,92,93,94,96 Free Software Foundation, Inc.
+@c Copyright (C) 1988,89,92,93,94,96,97,1998 Free Software Foundation, Inc.
@c This is part of the GCC manual.
@c For copying conditions, see the file gcc.texi.
should call @code{DEFAULT_WORD_SWITCH_TAKES_ARG} and then check for
additional options.
+@findex SWITCH_CURTAILS_COMPILATION
+@item SWITCH_CURTAILS_COMPILATION (@var{char})
+A C expression which determines whether the option @samp{-@var{char}}
+stops compilation before the generation of an executable. The value is
+boolean, non-zero if the option does stop an executable from being
+generated, zero otherwise.
+
+By default, this macro is defined as
+@code{DEFAULT_SWITCH_CURTAILS_COMPILATION}, which handles the standard
+options properly. You need not define
+@code{SWITCH_CURTAILS_COMPILATION} unless you wish to add additional
+options which affect the generation of an executable. Any redefinition
+should call @code{DEFAULT_SWITCH_CURTAILS_COMPILATION} and then check
+for additional options.
+
@findex SWITCHES_NEED_SPACES
@item SWITCHES_NEED_SPACES
A string-valued C expression which enumerates the options for which
This macro is similar to @code{LINK_LIBGCC_SPECIAL}, except that it does
not affect @samp{-L} options.
+@findex LINK_COMMAND_SPEC
+@item LINK_COMMAND_SPEC
+A C string constant giving the complete command line need to execute the
+linker. When you do this, you will need to update your port each time a
+change is made to the link command line within @file{gcc.c}. Therefore,
+define this macro only if you need to completely redefine the command
+line for invoking the linker and there is no other way to accomplish
+the effect you need.
+
@findex MULTILIB_DEFAULTS
@item MULTILIB_DEFAULTS
Define this macro as a C expression for the initializer of an array of
@findex INIT_ENVIRONMENT
@item INIT_ENVIRONMENT
-Define this macro as a C string constant if you with to set environment
+Define this macro as a C string constant if you wish to set environment
variables for programs called by the driver, such as the assembler and
loader. The driver passes the value of this macro to @code{putenv} to
initialize the necessary environment variables.
Cross compilers do not use this macro and do not search either
@file{/usr/include} or its replacement.
+@findex STANDARD_INCLUDE_COMPONENT
+@item STANDARD_INCLUDE_COMPONENT
+The ``component'' corresponding to @code{STANDARD_INCLUDE_DIR}.
+See @code{INCLUDE_DEFAULTS}, below, for the description of components.
+If you do not define this macro, no component is used.
+
@findex INCLUDE_DEFAULTS
@item INCLUDE_DEFAULTS
Define this macro if you wish to override the entire default search path
-for include files. The default search path includes
-@code{GCC_INCLUDE_DIR}, @code{LOCAL_INCLUDE_DIR},
+for include files. For a native compiler, the default search path
+usually consists of @code{GCC_INCLUDE_DIR}, @code{LOCAL_INCLUDE_DIR},
@code{SYSTEM_INCLUDE_DIR}, @code{GPLUSPLUS_INCLUDE_DIR}, and
@code{STANDARD_INCLUDE_DIR}. In addition, @code{GPLUSPLUS_INCLUDE_DIR}
and @code{GCC_INCLUDE_DIR} are defined automatically by @file{Makefile},
@code{GPLUSPLUS_INCLUDE_DIR} is used only for C++ programs.
The definition should be an initializer for an array of structures.
-Each array element should have two elements: the directory name (a
-string constant) and a flag for C++-only directories. Mark the end of
-the array with a null element. For example, here is the definition used
-for VMS:
+Each array element should have four elements: the directory name (a
+string constant), the component name, and flag for C++-only directories,
+and a flag showing that the includes in the directory don't need to be
+wrapped in @code{extern @samp{C}} when compiling C++. Mark the end of
+the array with a null element.
+
+The component name denotes what GNU package the include file is part of,
+if any, in all upper-case letters. For example, it might be @samp{GCC}
+or @samp{BINUTILS}. If the package is part of the a vendor-supplied
+operating system, code the component name as @samp{0}.
+
+
+For example, here is the definition used for VAX/VMS:
@example
#define INCLUDE_DEFAULTS \
@{ \
- @{ "GNU_GXX_INCLUDE:", 1@}, \
- @{ "GNU_CC_INCLUDE:", 0@}, \
- @{ "SYS$SYSROOT:[SYSLIB.]", 0@}, \
- @{ ".", 0@}, \
- @{ 0, 0@} \
+ @{ "GNU_GXX_INCLUDE:", "G++", 1, 1@}, \
+ @{ "GNU_CC_INCLUDE:", "GCC", 0, 0@}, \
+ @{ "SYS$SYSROOT:[SYSLIB.]", 0, 0, 0@}, \
+ @{ ".", 0, 0, 0@}, \
+ @{ 0, 0, 0, 0@} \
@}
@end example
@end table
with a subgrouping for each command option.
Each subgrouping contains a string constant, that defines the option
-name, and a number, which contains the bits to set in
-@code{target_flags}. A negative number says to clear bits instead;
-the negative of the number is which bits to clear. The actual option
-name is made by appending @samp{-m} to the specified name.
+name, a number, which contains the bits to set in
+@code{target_flags}, and a second string which is the description
+displayed by --help. If the number is negative then the bits specified
+by the number are cleared instead of being set. If the description
+string is present but empty, then no help information will be displayed
+for that option, but it will not count as an undocumented option. The
+actual option name is made by appending @samp{-m} to the specified name.
One of the subgroupings should have a null string. The number in
this grouping is the default value for @code{target_flags}. Any
@smallexample
#define TARGET_SWITCHES \
- @{ @{ "68020", 1@}, \
- @{ "68000", -1@}, \
- @{ "", 1@}@}
+ @{ @{ "68020", 1, "" @}, \
+ @{ "68000", -1, "Compile for the 68000" @}, \
+ @{ "", 1, "" @}@}
@end smallexample
@findex TARGET_OPTIONS
subgrouping for each command option.
Each subgrouping contains a string constant, that defines the fixed part
-of the option name, and the address of a variable. The variable, type
-@code{char *}, is set to the variable part of the given option if the fixed
-part matches. The actual option name is made by appending @samp{-m} to the
-specified name.
+of the option name, the address of a variable, and a description string.
+The variable, type @code{char *}, is set to the variable part of the
+given option if the fixed part matches. The actual option name is made
+by appending @samp{-m} to the specified name.
Here is an example which defines @samp{-mshort-data-@var{number}}. If the
given option is @samp{-mshort-data-512}, the variable @code{m88k_short_data}
@smallexample
extern char *m88k_short_data;
#define TARGET_OPTIONS \
- @{ @{ "short-data-", &m88k_short_data @} @}
+ @{ @{ "short-data-", &m88k_short_data, "Specify the size of the short data section" @} @}
@end smallexample
@findex TARGET_VERSION
@samp{-O}. That is what @code{OPTIMIZATION_OPTIONS} is for.
@findex OPTIMIZATION_OPTIONS
-@item OPTIMIZATION_OPTIONS (@var{level})
+@item OPTIMIZATION_OPTIONS (@var{level}, @var{size})
Some machines may desire to change what optimizations are performed for
various optimization levels. This macro, if defined, is executed once
just after the optimization level is determined and before the remainder
@var{level} is the optimization level specified; 2 if @samp{-O2} is
specified, 1 if @samp{-O} is specified, and 0 if neither is specified.
+@var{size} is non-zero if @samp{-Os} is specified and zero otherwise.
+
You should not use this macro to change options that are not
machine-specific. These should uniformly selected by the same
optimization level on all supported machines. Use this macro to enable
@findex POINTERS_EXTEND_UNSIGNED
@item POINTERS_EXTEND_UNSIGNED
A C expression whose value is nonzero if pointers that need to be
-extended from being @code{POINTER_SIZE} bits wide to @code{Pmode}
-are sign-extended and zero if they are zero-extended.
+extended from being @code{POINTER_SIZE} bits wide to @code{Pmode} are to
+be zero-extended and zero if they are to be sign-extended.
You need not define this macro if the @code{POINTER_SIZE} is equal
to the width of @code{Pmode}.
@item BIGGEST_ALIGNMENT
Biggest alignment that any data type can require on this machine, in bits.
+@findex MINIMUM_ATOMIC_ALIGNMENT
+@item MINIMUM_ATOMIC_ALIGNMENT
+If defined, the smallest alignment, in bits, that can be given to an
+object that can be referenced in one operation, without disturbing any
+nearby object. Normally, this is @code{BITS_PER_UNIT}, but may be larger
+on machines that don't have byte or half-word store operations.
+
@findex BIGGEST_FIELD_ALIGNMENT
@item BIGGEST_FIELD_ALIGNMENT
Biggest alignment that any structure field can require on this machine,
@findex DATA_ALIGNMENT
@item DATA_ALIGNMENT (@var{type}, @var{basic-align})
-If defined, a C expression to compute the alignment for a static
-variable. @var{type} is the data type, and @var{basic-align} is the
-alignment that the object would ordinarily have. The value of this
+If defined, a C expression to compute the alignment for a variables in
+the static store. @var{type} is the data type, and @var{basic-align} is
+the alignment that the object would ordinarily have. The value of this
macro is used instead of that alignment to align the object.
If this macro is not defined, then @var{basic-align} is used.
appropriate sizes. If this macro is undefined, @code{GET_MODE_BITSIZE
(DImode)} is assumed.
+@findex STACK_SAVEAREA_MODE
+@item STACK_SAVEAREA_MODE (@var{save_level})
+If defined, an expression of type @code{enum machine_mode} that
+specifies the mode of the save area operand of a
+@code{save_stack_@var{level}} named pattern (@pxref{Standard Names}).
+@var{save_level} is one of @code{SAVE_BLOCK}, @code{SAVE_FUNCTION}, or
+@code{SAVE_NONLOCAL} and selects which of the three named patterns is
+having its mode specified.
+
+You need not define this macro if it always returns @code{Pmode}. You
+would most commonly define this macro if the
+@code{save_stack_@var{level}} patterns need to support both a 32- and a
+64-bit mode.
+
+@findex STACK_SIZE_MODE
+@item STACK_SIZE_MODE
+If defined, an expression of type @code{enum machine_mode} that
+specifies the mode of the size increment operand of an
+@code{allocate_stack} named pattern (@pxref{Standard Names}).
+
+You need not define this macro if it always returns @code{word_mode}.
+You would most commonly define this macro if the @code{allocate_stack}
+pattern needs to support both a 32- and a 64-bit mode.
+
@findex CHECK_FLOAT_VALUE
@item CHECK_FLOAT_VALUE (@var{mode}, @var{value}, @var{overflow})
A C statement to validate the value @var{value} (of type
The ordering of the component words of floating point values stored in
memory is controlled by @code{FLOAT_WORDS_BIG_ENDIAN} for the target
machine and @code{HOST_FLOAT_WORDS_BIG_ENDIAN} for the host.
+
+@findex DEFAULT_VTABLE_THUNKS
+@item DEFAULT_VTABLE_THUNKS
+GNU CC supports two ways of implementing C++ vtables: traditional or with
+so-called ``thunks''. The flag @samp{-fvtable-thunk} chooses between them.
+Define this macro to be a C expression for the default value of that flag.
+If @code{DEFAULT_VTABLE_THUNKS} is 0, GNU CC uses the traditional
+implementation by default. The ``thunk'' implementation is more efficient
+(especially if you have provided an implementation of
+@code{ASM_OUTPUT_MI_THUNK}, see @ref{Function Entry}), but is not binary
+compatible with code compiled using the traditional implementation.
+If you are writing a new ports, define @code{DEFAULT_VTABLE_THUNKS} to 1.
+
+If you do not define this macro, the default for @samp{-fvtable-thunk} is 0.
@end table
@node Type Layout
the target machine. If you don't define this, the default is two
words.
+@findex WIDEST_HARDWARE_FP_SIZE
+@item WIDEST_HARDWARE_FP_SIZE
+A C expression for the size in bits of the widest floating-point format
+supported by the hardware. If you define this macro, you must specify a
+value less than or equal to the value of @code{LONG_DOUBLE_TYPE_SIZE}.
+If you do not define this macro, the value of @code{LONG_DOUBLE_TYPE_SIZE}
+is the default.
+
@findex DEFAULT_SIGNED_CHAR
@item DEFAULT_SIGNED_CHAR
An expression whose value is 1 or 0, according to whether the type
registers must always be saved and the save-multiple-registers
instruction supports only sequences of consecutive registers. On such
machines, define @code{REG_ALLOC_ORDER} to be an initializer that lists
-the highest numbered allocatable register first.
+the highest numbered allocable register first.
@findex ORDER_REGS_FOR_LOCAL_ALLOC
@item ORDER_REGS_FOR_LOCAL_ALLOC
/ UNITS_PER_WORD))
@end smallexample
+@findex ALTER_HARD_SUBREG
+@item ALTER_HARD_SUBREG (@var{tgt_mode}, @var{word}, @var{src_mode}, @var{regno})
+A C expression that returns an adjusted hard register number for
+
+@smallexample
+(subreg:@var{tgt_mode} (reg:@var{src_mode} @var{regno}) @var{word})
+@end smallexample
+
+This may be needed if the target machine has mixed sized big-endian
+registers, like Sparc v9.
+
@findex HARD_REGNO_MODE_OK
@item HARD_REGNO_MODE_OK (@var{regno}, @var{mode})
A C expression that is nonzero if it is permissible to store a value
#define HARD_REGNO_MODE_OK(REGNO, MODE) 1
@end smallexample
-It is not necessary for this macro to check for the numbers of fixed
-registers, because the allocation mechanism considers them to be always
-occupied.
+You need not include code to check for the numbers of fixed registers,
+because the allocation mechanism considers them to be always occupied.
@cindex register pairs
On some machines, double-precision values must be kept in even/odd
-register pairs. The way to implement that is to define this macro
-to reject odd register numbers for such modes.
-
-@ignore
-@c I think this is not true now
-GNU CC assumes that it can always move values between registers and
-(suitably addressed) memory locations. If it is impossible to move a
-value of a certain mode between memory and certain registers, then
-@code{HARD_REGNO_MODE_OK} must not allow this mode in those registers.
-@end ignore
+register pairs. You can implement that by defining this macro to reject
+odd register numbers for such modes.
The minimum requirement for a mode to be OK in a register is that the
@samp{mov@var{mode}} instruction pattern support moves between the
-register and any other hard register for which the mode is OK; and that
-moving a value into the register and back out not alter it.
+register and other hard register in the same class and that moving a
+value into the register and back out not alter it.
-Since the same instruction used to move @code{SImode} will work for all
-narrower integer modes, it is not necessary on any machine for
+Since the same instruction used to move @code{word_mode} will work for
+all narrower integer modes, it is not necessary on any machine for
@code{HARD_REGNO_MODE_OK} to distinguish between these modes, provided
you define patterns @samp{movhi}, etc., to take advantage of this. This
is useful because of the interaction between @code{HARD_REGNO_MODE_OK}
@findex MODES_TIEABLE_P
@item MODES_TIEABLE_P (@var{mode1}, @var{mode2})
-A C expression that is nonzero if it is desirable to choose register
-allocation so as to avoid move instructions between a value of mode
-@var{mode1} and a value of mode @var{mode2}.
+A C expression that is nonzero if a value of mode
+@var{mode1} is accessible in mode @var{mode2} without copying.
If @code{HARD_REGNO_MODE_OK (@var{r}, @var{mode1})} and
-@code{HARD_REGNO_MODE_OK (@var{r}, @var{mode2})} are ever different
-for any @var{r}, then @code{MODES_TIEABLE_P (@var{mode1},
-@var{mode2})} must be zero.
+@code{HARD_REGNO_MODE_OK (@var{r}, @var{mode2})} are always the same for
+any @var{r}, then @code{MODES_TIEABLE_P (@var{mode1}, @var{mode2})}
+should be nonzero. If they differ for any @var{r}, you should define
+this macro to return zero unless some other mechanism ensures the
+accessibility of the value in a narrower mode.
+
+You should define this macro to return nonzero in as many cases as
+possible since doing so will allow GNU CC to perform better register
+allocation.
+
+@findex AVOID_CCMODE_COPIES
+@item AVOID_CCMODE_COPIES
+Define this macro if the compiler should avoid copies to/from @code{CCmode}
+registers. You should only define this macro if support fo copying to/from
+@code{CCmode} is incomplete.
@end table
@node Leaf Functions
either a suitable hard register or a pseudo register that has been
allocated such a hard register.
+@findex REGNO_MODE_OK_FOR_BASE_P
+@item REGNO_MODE_OK_FOR_BASE_P (@var{num}, @var{mode})
+A C expression that is just like @code{REGNO_OK_FOR_BASE_P}, except that
+that expression may examine the mode of the memory reference in
+@var{mode}. You should define this macro if the mode of the memory
+reference affects whether a register may be used as a base register. If
+you define this macro, the compiler will use it instead of
+@code{REGNO_OK_FOR_BASE_P}.
+
@findex REGNO_OK_FOR_INDEX_P
@item REGNO_OK_FOR_INDEX_P (@var{num})
A C expression which is nonzero if register number @var{num} is
would not be enough registers to use as spill registers if this were
done.
-Define @code{SMALL_REGISTER_CLASSES} on these machines. When it is
-defined, the compiler allows registers explicitly used in the rtl to be
-used as spill registers but avoids extending the lifetime of these
-registers.
+Define @code{SMALL_REGISTER_CLASSES} to be an expression with a non-zero
+value on these machines. When this macro has a non-zero value, the
+compiler allows registers explicitly used in the rtl to be used as spill
+registers but avoids extending the lifetime of these registers.
-It is always safe to define this macro, but if you unnecessarily define
-it, you will reduce the amount of optimizations that can be performed in
-some cases. If you do not define this macro when it is required, the
-compiler will run out of spill registers and print a fatal error
-message. For most machines, you should not define this macro.
+It is always safe to define this macro with a non-zero value, but if you
+unnecessarily define it, you will reduce the amount of optimizations
+that can be performed in some cases. If you do not define this macro
+with a non-zero value when it is required, the compiler will run out of
+spill registers and print a fatal error message. For most machines, you
+should not define this macro at all.
@findex CLASS_LIKELY_SPILLED_P
@item CLASS_LIKELY_SPILLED_P (@var{class})
The default value of this macro returns 1 if @var{class} has exactly one
register and zero otherwise. On most machines, this default should be
-used. Only define this macro to some other expression if pseudo
+used. Only define this macro to some other expression if pseudos
allocated by @file{local-alloc.c} end up in memory because their hard
registers were needed for spill registers. If this macro returns nonzero
for those classes, those pseudos will only be allocated by
@table @code
@findex CONST_OK_FOR_LETTER_P
@item CONST_OK_FOR_LETTER_P (@var{value}, @var{c})
-A C expression that defines the machine-dependent operand constraint letters
-that specify particular ranges of integer values. If @var{c} is one
-of those letters, the expression should check that @var{value}, an integer,
-is in the appropriate range and return 1 if so, 0 otherwise. If @var{c} is
-not one of those letters, the value should be 0 regardless of @var{value}.
+A C expression that defines the machine-dependent operand constraint
+letters (@samp{I}, @samp{J}, @samp{K}, @dots{} @samp{P}) that specify
+particular ranges of integer values. If @var{c} is one of those
+letters, the expression should check that @var{value}, an integer, is in
+the appropriate range and return 1 if so, 0 otherwise. If @var{c} is
+not one of those letters, the value should be 0 regardless of
+@var{value}.
@findex CONST_DOUBLE_OK_FOR_LETTER_P
@item CONST_DOUBLE_OK_FOR_LETTER_P (@var{value}, @var{c})
A C expression that defines the machine-dependent operand constraint
-letters that specify particular ranges of @code{const_double} values.
+letters that specify particular ranges of @code{const_double} values
+(@samp{G} or @samp{H}).
If @var{c} is one of those letters, the expression should check that
@var{value}, an RTX of code @code{const_double}, is in the appropriate
@findex EXTRA_CONSTRAINT
@item EXTRA_CONSTRAINT (@var{value}, @var{c})
A C expression that defines the optional machine-dependent constraint
-letters that can be used to segregate specific types of operands,
-usually memory references, for the target machine. Normally this macro
-will not be defined. If it is required for a particular target machine,
-it should return 1 if @var{value} corresponds to the operand type
-represented by the constraint letter @var{c}. If @var{c} is not defined
-as an extra constraint, the value returned should be 0 regardless of
-@var{value}.
+letters (@samp{Q}, @samp{R}, @samp{S}, @samp{T}, @samp{U}) that can
+be used to segregate specific types of operands, usually memory
+references, for the target machine. Normally this macro will not be
+defined. If it is required for a particular target machine, it should
+return 1 if @var{value} corresponds to the operand type represented by
+the constraint letter @var{c}. If @var{c} is not defined as an extra
+constraint, the value returned should be 0 regardless of @var{value}.
For example, on the ROMP, load instructions cannot have their output in r0 if
the memory reference contains a symbolic address. Constraint letter
@menu
* Frame Layout::
+* Stack Checking::
* Frame Registers::
* Elimination::
* Stack Arguments::
address of the stack word that points to the previous frame.
@findex SETUP_FRAME_ADDRESSES
-@item SETUP_FRAME_ADDRESSES ()
+@item SETUP_FRAME_ADDRESSES
If defined, a C expression that produces the machine-specific code to
setup the stack so that arbitrary frames can be accessed. For example,
on the Sparc, we must flush all of the register windows to the stack
-before we can access arbitrary stack frames.
-This macro will seldom need to be defined.
+before we can access arbitrary stack frames. You will seldom need to
+define this macro.
+
+@findex BUILTIN_SETJMP_FRAME_VALUE
+@item BUILTIN_SETJMP_FRAME_VALUE
+If defined, a C expression that contains an rtx that is used to store
+the address of the current frame into the built in @code{setjmp} buffer.
+The default value, @code{virtual_stack_vars_rtx}, is correct for most
+machines. One reason you may need to define this macro is if
+@code{hard_frame_pointer_rtx} is the appropriate value on your machine.
@findex RETURN_ADDR_RTX
@item RETURN_ADDR_RTX (@var{count}, @var{frameaddr})
A C expression whose value is RTL representing the value of the return
-address for the frame @var{count} steps up from the current frame.
-@var{frameaddr} is the frame pointer of the @var{count} frame, or
-the frame pointer of the @var{count} @minus{} 1 frame if
+address for the frame @var{count} steps up from the current frame, after
+the prologue. @var{frameaddr} is the frame pointer of the @var{count}
+frame, or the frame pointer of the @var{count} @minus{} 1 frame if
@code{RETURN_ADDR_IN_PREVIOUS_FRAME} is defined.
+The value of the expression must always be the correct address when
+@var{count} is zero, but may be @code{NULL_RTX} if there is not way to
+determine the return address of other frames.
+
@findex RETURN_ADDR_IN_PREVIOUS_FRAME
@item RETURN_ADDR_IN_PREVIOUS_FRAME
Define this if the return address of a particular stack frame is accessed
from the frame pointer of the previous stack frame.
+
+@findex INCOMING_RETURN_ADDR_RTX
+@item INCOMING_RETURN_ADDR_RTX
+A C expression whose value is RTL representing the location of the
+incoming return address at the beginning of any function, before the
+prologue. This RTL is either a @code{REG}, indicating that the return
+value is saved in @samp{REG}, or a @code{MEM} representing a location in
+the stack.
+
+You only need to define this macro if you want to support call frame
+debugging information like that provided by DWARF 2.
+
+@findex INCOMING_FRAME_SP_OFFSET
+@item INCOMING_FRAME_SP_OFFSET
+A C expression whose value is an integer giving the offset, in bytes,
+from the value of the stack pointer register to the top of the stack
+frame at the beginning of any function, before the prologue. The top of
+the frame is defined to be the value of the stack pointer in the
+previous frame, just before the call instruction.
+
+You only need to define this macro if you want to support call frame
+debugging information like that provided by DWARF 2.
+@end table
+
+@node Stack Checking
+@subsection Specifying How Stack Checking is Done
+
+GNU CC will check that stack references are within the boundaries of
+the stack, if the @samp{-fstack-check} is specified, in one of three ways:
+
+@enumerate
+@item
+If the value of the @code{STACK_CHECK_BUILTIN} macro is nonzero, GNU CC
+will assume that you have arranged for stack checking to be done at
+appropriate places in the configuration files, e.g., in
+@code{FUNCTION_PROLOGUE}. GNU CC will do not other special processing.
+
+@item
+If @code{STACK_CHECK_BUILTIN} is zero and you defined a named pattern
+called @code{check_stack} in your @file{md} file, GNU CC will call that
+pattern with one argument which is the address to compare the stack
+value against. You must arrange for this pattern to report an error if
+the stack pointer is out of range.
+
+@item
+If neither of the above are true, GNU CC will generate code to periodically
+``probe'' the stack pointer using the values of the macros defined below.
+@end enumerate
+
+Normally, you will use the default values of these macros, so GNU CC
+will use the third approach.
+
+@table @code
+@findex STACK_CHECK_BUILTIN
+@item STACK_CHECK_BUILTIN
+A nonzero value if stack checking is done by the configuration files in a
+machine-dependent manner. You should define this macro if stack checking
+is require by the ABI of your machine or if you would like to have to stack
+checking in some more efficient way than GNU CC's portable approach.
+The default value of this macro is zero.
+
+@findex STACK_CHECK_PROBE_INTERVAL
+@item STACK_CHECK_PROBE_INTERVAL
+An integer representing the interval at which GNU CC must generate stack
+probe instructions. You will normally define this macro to be no larger
+than the size of the ``guard pages'' at the end of a stack area. The
+default value of 4096 is suitable for most systems.
+
+@findex STACK_CHECK_PROBE_LOAD
+@item STACK_CHECK_PROBE_LOAD
+A integer which is nonzero if GNU CC should perform the stack probe
+as a load instruction and zero if GNU CC should use a store instruction.
+The default is zero, which is the most efficient choice on most systems.
+
+@findex STACK_CHECK_PROTECT
+@item STACK_CHECK_PROTECT
+The number of bytes of stack needed to recover from a stack overflow,
+for languages where such a recovery is supported. The default value of
+75 words should be adequate for most machines.
+
+@findex STACK_CHECK_MAX_FRAME_SIZE
+@item STACK_CHECK_MAX_FRAME_SIZE
+The maximum size of a stack frame, in bytes. GNU CC will generate probe
+instructions in non-leaf functions to ensure at least this many bytes of
+stack are available. If a stack frame is larger than this size, stack
+checking will not be reliable and GNU CC will issue a warning. The
+default is chosen so that GNU CC only generates one instruction on most
+systems. You should normally not change the default value of this macro.
+
+@findex STACK_CHECK_FIXED_FRAME_SIZE
+@item STACK_CHECK_FIXED_FRAME_SIZE
+GNU CC uses this value to generate the above warning message. It
+represents the amount of fixed frame used by a function, not including
+space for any callee-saved registers, temporaries and user variables.
+You need only specify an upper bound for this amount and will normally
+use the default of four words.
+
+@findex STACK_CHECK_MAX_VAR_SIZE
+@item STACK_CHECK_MAX_VAR_SIZE
+The maximum size, in bytes, of an object that GNU CC will place in the
+fixed area of the stack frame when the user specifies
+@samp{-fstack-check}.
+GNU CC computed the default from the values of the above macros and you will
+normally not need to override that default.
@end table
@need 2000
between these two locations). On those machines, define
@code{FRAME_POINTER_REGNUM} the number of a special, fixed register to
be used internally until the offset is known, and define
-@code{HARD_FRAME_POINTER_REGNUM} to be actual the hard register number
+@code{HARD_FRAME_POINTER_REGNUM} to be the actual hard register number
used for the frame pointer.
You should define this macro only in the very rare circumstances when it
From this it is possible to obtain the data types of the value and
arguments (if known).
-When a call to a library function is being considered, @var{funtype}
+When a call to a library function is being considered, @var{fundecl}
will contain an identifier node for the library function. Thus, if
you need to distinguish among various library functions, you can do so
by their names. Note that ``library function'' in this context means
defined, the argument will be computed in the stack and then loaded into
a register.
+@findex MUST_PASS_IN_STACK
+@item MUST_PASS_IN_STACK (@var{mode}, @var{type})
+Define as a C expression that evaluates to nonzero if we do not know how
+to pass TYPE solely in registers. The file @file{expr.h} defines a
+definition that is usually appropriate, refer to @file{expr.h} for additional
+documentation.
+
@findex FUNCTION_INCOMING_ARG
@item FUNCTION_INCOMING_ARG (@var{cum}, @var{mode}, @var{type}, @var{named})
Define this macro if the target machine has ``register windows'', so
the structure-value address. On many machines, no registers can be
used for this purpose since all function arguments are pushed on the
stack.
+
+@findex LOAD_ARGS_REVERSED
+@item LOAD_ARGS_REVERSED
+If defined, the order in which arguments are loaded into their
+respective argument registers is reversed so that the last
+argument is loaded first. This macro only effects arguments
+passed in registers.
+
@end table
@node Scalar Return
have already been extracted from it.) It might possibly be useful on
some targets, but probably not.
-For many targets, the target-independent code in the C++ frontend will
-be sufficient and you can leave this macro undefined. You need to
-define this macro if the code generated by default would clobber any of
-the incoming arguments; this is only likely if parameters can be passed
-in registers. You should also define this macro if the default code is
-sub-optimal.
+If you do not define this macro, the target-independent code in the C++
+frontend will generate a less efficient heavyweight thunk that calls
+@var{function} instead of jumping to it. The generic approach does
+not support varargs.
@end table
@node Profiling
A C statement or compound statement to output to @var{file} some
assembler code to initialize basic-block profiling for the current
object module. The global compile flag @code{profile_block_flag}
-distingishes two profile modes.
+distinguishes two profile modes.
@table @code
@findex __bb_init_func
A C statement or compound statement to output to @var{file} some
assembler code to increment the count associated with the basic
block number @var{blockno}. The global compile flag
-@code{profile_block_flag} distingishes two profile modes.
+@code{profile_block_flag} distinguishes two profile modes.
@table @code
@item profile_block_flag != 2
@findex STRICT_ARGUMENT_NAMING
@item STRICT_ARGUMENT_NAMING
-Define this macro if the location where a function argument is passed
-depends on whether or not it is a named argument.
+Define this macro to be a nonzero value if the location where a function
+argument is passed depends on whether or not it is a named argument.
This macro controls how the @var{named} argument to @code{FUNCTION_ARG}
-is set for varargs and stdarg functions. With this macro defined,
-the @var{named} argument is always true for named arguments, and false for
-unnamed arguments. If this is not defined, but @code{SETUP_INCOMING_VARARGS}
-is defined, then all arguments are treated as named. Otherwise, all named
-arguments except the last are treated as named.
+is set for varargs and stdarg functions. If this macro returns a
+nonzero value, the @var{named} argument is always true for named
+arguments, and false for unnamed arguments. If it returns a value of
+zero, but @code{SETUP_INCOMING_VARARGS} is defined, then all arguments
+are treated as named. Otherwise, all named arguments except the last
+are treated as named.
+
+You need not define this macro if it always returns zero.
@end table
@node Trampolines
requires two variant definitions, of which @code{REG_OK_STRICT}
controls the one actually used.
+@findex REG_MODE_OK_FOR_BASE_P
+@item REG_MODE_OK_FOR_BASE_P (@var{x}, @var{mode})
+A C expression that is just like @code{REG_OK_FOR_BASE_P}, except that
+that expression may examine the mode of the memory reference in
+@var{mode}. You should define this macro if the mode of the memory
+reference affects whether a register may be used as a base register. If
+you define this macro, the compiler will use it instead of
+@code{REG_OK_FOR_BASE_P}.
+
@findex REG_OK_FOR_INDEX_P
@item REG_OK_FOR_INDEX_P (@var{x})
A C expression that is nonzero if @var{x} (assumed to be a @code{reg}
fact, it is safe for this macro to do nothing. But often a
machine-dependent strategy can generate better code.
+@findex LEGITIMIZE_RELOAD_ADDRESS
+@item LEGITIMIZE_RELOAD_ADDRESS (@var{x}, @var{mode}, @var{opnum}, @var{type}, @var{ind_levels}, @var{win})
+A C compound statement that attempts to replace @var{x}, which is an address
+that needs reloading, with a valid memory address for an operand of mode
+@var{mode}. @var{win} will be a C statement label elsewhere in the code.
+It is not necessary to define this macro, but it might be useful for
+performance reasons.
+
+For example, on the i386, it is sometimes possible to use a single
+reload register instead of two by reloading a sum of two pseudo
+registers into a register. On the other hand, for number of RISC
+processors offsets are limited so that often an intermediate address
+needs to be generated in order to address a stack slot. By defining
+LEGITIMIZE_RELOAD_ADDRESS appropriately, the intermediate addresses
+generated for adjacent some stack slots can be made identical, and thus
+be shared.
+
+@emph{Note}: This macro should be used with caution. It is necessary
+to know something of how reload works in order to effectively use this,
+and it is quite easy to produce macros that build in too much knowledge
+of reload internals.
+
+@emph{Note}: This macro must be able to reload an address created by a
+previous invocation of this macro. If it fails to handle such addresses
+then the compiler may generate incorrect code or abort.
+
+@findex push_reload
+The macro definition should use @code{push_reload} to indicate parts that
+need reloading; @var{opnum}, @var{type} and @var{ind_levels} are usually
+suitable to be passed unaltered to @code{push_reload}.
+
+The code generated by this macro must not alter the substructure of
+@var{x}. If it transforms @var{x} into a more legitimate form, it
+should assign @var{x} (which will always be a C variable) a new value.
+This also applies to parts that you change indirectly by calling
+@code{push_reload}.
+
+@findex strict_memory_address_p
+The macro definition may use @code{strict_memory_address_p} to test if
+the address has become legitimate.
+
+@findex copy_rtx
+If you want to change only a part of @var{x}, one standard way of doing
+this is to use @code{copy_rtx}. Note, however, that is unshares only a
+single level of rtl. Thus, if the part to be changed is not at the
+top level, you'll need to replace first the top leve
+It is not necessary for this macro to come up with a legitimate
+address; but often a machine-dependent strategy can generate better code.
+
@findex GO_IF_MODE_DEPENDENT_ADDRESS
@item GO_IF_MODE_DEPENDENT_ADDRESS (@var{addr}, @var{label})
A C statement or compound statement with a conditional @code{goto
@var{x} satisfies @code{CONSTANT_P}, so you need not check this. In fact,
@samp{1} is a suitable definition for this macro on machines where
anything @code{CONSTANT_P} is valid.@refill
+
+@findex DONT_RECORD_EQUIVALENCE
+@item DONT_RECORD_EQUIVALENCE (@var{note})
+A C expression that is nonzero if the @code{REG_EQUAL} note @var{x} should not
+be promoted to a @code{REG_EQUIV} note.
+
+Define this macro if @var{note} refers to a constant that must be accepted
+by @code{LEGITIMATE_CONSTANT_P}, but must not appear as an immediate operand.
+
+Most machine descriptions do not need to define this macro.
@end table
@node Condition Code
This macro is optional; do not define it if the default cost assumptions
are adequate for the target machine.
+@findex DEFAULT_RTX_COSTS
+@item DEFAULT_RTX_COSTS (@var{x}, @var{code}, @var{outer_code})
+This macro, if defined, is called for any case not handled by the
+@code{RTX_COSTS} or @code{CONST_COSTS} macros. This eliminates the need
+to put case labels into the macro, but the code, or any functions it
+calls, must assume that the RTL in @var{x} could be of any type that has
+not already been handled. The arguments are the same as for
+@code{RTX_COSTS}, and the macro should execute a return statement giving
+the cost of any RTL expressions that it can handle. The default cost
+calculation is used for any RTL for which this macro does not return a
+value.
+
+This macro is optional; do not define it if the default cost assumptions
+are adequate for the target machine.
+
@findex ADDRESS_COST
@item ADDRESS_COST (@var{address})
An expression giving the cost of an addressing mode that contains
if the @samp{mov@var{m}} pattern's constraints do not allow such copying.
@findex MEMORY_MOVE_COST
-@item MEMORY_MOVE_COST (@var{m})
-A C expression for the cost of moving data of mode @var{m} between a
-register and memory. A value of 4 is the default; this cost is relative
-to those in @code{REGISTER_MOVE_COST}.
-
-If moving between registers and memory is more expensive than between
-two registers, you should define this macro to express the relative cost.
+@item MEMORY_MOVE_COST (@var{mode}, @var{class}, @var{in})
+A C expression for the cost of moving data of mode @var{mode} between a
+register of class @var{class} and memory; @var{in} is zero if the value
+is to be written to memory, non-zero if it is to be read in. This cost
+is relative to those in @code{REGISTER_MOVE_COST}. If moving between
+registers and memory is more expensive than between two registers, you
+should define this macro to express the relative cost.
+
+If you do not define this macro, GNU CC uses a default cost of 4 plus
+the cost of copying via a secondary reload register, if one is
+needed. If your machine requires a secondary reload register to copy
+between memory and a register of @var{class} but the reload mechanism is
+more complex than copying via an intermediate, define this macro to
+reflect the actual cost of the move.
+
+GNU CC defines the function @code{memory_move_secondary_cost} if
+secondary reloads are needed. It computes the costs due to copying via
+a secondary register. If your machine copies from memory using a
+secondary register in the conventional way but the default base value of
+4 is not correct for your machine, define this macro to add some other
+value to the result of that function. The arguments to that function
+are the same as to this macro.
@findex BRANCH_COST
@item BRANCH_COST
@findex JUMP_TABLES_IN_TEXT_SECTION
@item JUMP_TABLES_IN_TEXT_SECTION
-Define this macro if jump tables (for @code{tablejump} insns) should be
-output in the text section, along with the assembler instructions.
-Otherwise, the readonly data section is used.
+Define this macro to be an expression with a non-zero value if jump
+tables (for @code{tablejump} insns) should be output in the text
+section, along with the assembler instructions. Otherwise, the
+readonly data section is used.
This macro is irrelevant if there is no separate readonly data section.
the characters that encode section info. Define this macro if
@code{ENCODE_SECTION_INFO} alters the symbol's name string.
+@findex UNIQUE_SECTION_P
+@item UNIQUE_SECTION_P (@var{decl})
+A C expression which evaluates to true if @var{decl} should be placed
+into a unique section for some target-specific reason. If you do not
+define this macro, the default is @samp{0}. Note that the flag
+@samp{-ffunction-sections} will also cause functions to be placed into
+unique sections.
+
@findex UNIQUE_SECTION
-@item UNIQUE_SECTION (@var{decl})
-For objects going into their own sections, a C expression of the name of the
-section, expressed as a STRING_CST node, to put @var{decl} into. The
-STRING_CST node must be allocated in the saveable obstack. Function
-@code{build_string} can be used to do this. If you do not define this macro,
-GNU CC will use the symbol name as the section name.
+@item UNIQUE_SECTION (@var{decl}, @var{reloc})
+A C statement to build up a unique section name, expressed as a
+STRING_CST node, and assign it to @samp{DECL_SECTION_NAME (@var{decl})}.
+@var{reloc} indicates whether the initial value of @var{exp} requires
+link-time relocations. If you do not define this macro, GNU CC will use
+the symbol name prefixed by @samp{.} as the section name.
@end table
@node PIC
This macro need not be defined if the standard form of output
for the file format in use is appropriate.
+@findex OUTPUT_QUOTED_STRING
+@item OUTPUT_QUOTED_STRING (@var{stream}, @var{name})
+A C statement to output the string @var{string} to the stdio stream
+@var{stream}. If you do not call the function @code{output_quoted_string}
+in your config files, GNU CC will only call it to output filenames to
+the assembler source. So you can use it to canonicalize the format
+of the filename using this macro.
+
@findex ASM_OUTPUT_SOURCE_LINE
@item ASM_OUTPUT_SOURCE_LINE (@var{stream}, @var{line})
A C statement to output DBX or SDB debugging information before code
macro is not defined, nothing is output for a @samp{#ident} directive.
@findex ASM_OUTPUT_SECTION_NAME
-@item ASM_OUTPUT_SECTION_NAME (@var{stream}, @var{decl}, @var{name})
+@item ASM_OUTPUT_SECTION_NAME (@var{stream}, @var{decl}, @var{name}, @var{reloc})
A C statement to output something to the assembler file to switch to section
@var{name} for object @var{decl} which is either a @code{FUNCTION_DECL}, a
-@code{VAR_DECL} or @code{NULL_TREE}. Some target formats do not support
+@code{VAR_DECL} or @code{NULL_TREE}. @var{reloc}
+indicates whether the initial value of @var{exp} requires link-time
+relocations. Some target formats do not support
arbitrary sections. Do not define this macro in such cases.
At present this macro is only used to support section attributes.
Berkeley Unix assembler, do not define the macro
@code{ASM_OUTPUT_ASCII}.
+@findex CONSTANT_POOL_BEFORE_FUNCTION
+@item CONSTANT_POOL_BEFORE_FUNCTION
+You may define this macro as a C expression. You should define the
+expression to have a non-zero value if GNU CC should output the constant
+pool for a function before the code for the function, or a zero value if
+GNU CC should output the constant pool after the function. If you do
+not define this macro, the usual case, GNU CC will output the constant
+pool before the function.
+
@findex ASM_OUTPUT_POOL_PROLOGUE
@item ASM_OUTPUT_POOL_PROLOGUE (@var{file} @var{funname} @var{fundecl} @var{size})
A C statement to output assembler commands to define the start of the
You need not define this macro if it would do nothing.
+@findex CONSTANT_AFTER_FUNCTION_P
+@item CONSTANT_AFTER_FUNCTION_P (@var{exp})
+Define this macro as a C expression which is nonzero if the constant
+@var{exp}, of type @code{tree}, should be output after the code for a
+function. The compiler will normally output all constants before the
+function; you need not define this macro if this is OK.
+
+@findex ASM_OUTPUT_POOL_EPILOGUE
+@item ASM_OUTPUT_POOL_EPILOGUE (@var{file} @var{funname} @var{fundecl} @var{size})
+A C statement to output assembler commands to at the end of the constant
+pool for a function. @var{funname} is a string giving the name of the
+function. Should the return type of the function be required, you can
+obtain it via @var{fundecl}. @var{size} is the size, in bytes, of the
+constant pool that GNU CC wrote immediately before this call.
+
+If no constant-pool epilogue is required, the usual case, you need not
+define this macro.
+
@findex IS_ASM_LOGICAL_LINE_SEPARATOR
@item IS_ASM_LOGICAL_LINE_SEPARATOR (@var{C})
Define this macro as a C expression which is nonzero if @var{C} is
handling the required alignment of the variable. The alignment is specified
as the number of bits.
+@findex ASM_OUTPUT_ALIGNED_DECL_COMMON
+@item ASM_OUTPUT_ALIGNED_DECL_COMMON (@var{stream}, @var{decl}, @var{name}, @var{size}, @var{alignment})
+Like @code{ASM_OUTPUT_ALIGNED_COMMON} except that @var{decl} of the
+variable to be output, if there is one, or @code{NULL_TREE} if there
+is not corresponding variable. If you define this macro, GNU CC wil use it
+in place of both @code{ASM_OUTPUT_COMMON} and
+@code{ASM_OUTPUT_ALIGNED_COMMON}. Define this macro when you need to see
+the variable's decl in order to chose what to output.
+
@findex ASM_OUTPUT_SHARED_COMMON
@item ASM_OUTPUT_SHARED_COMMON (@var{stream}, @var{name}, @var{size}, @var{rounded})
If defined, it is similar to @code{ASM_OUTPUT_COMMON}, except that it
@code{c++} which do not have @code{common} data. However, this macro currently
is not defined for all targets. If this macro and
@code{ASM_OUTPUT_ALIGNED_BSS} are not defined then @code{ASM_OUTPUT_COMMON}
-or @code{ASM_OUTPUT_ALIGNED_COMMON} is used.
+or @code{ASM_OUTPUT_ALIGNED_COMMON} or
+@code{ASM_OUTPUT_ALIGNED_DECL_COMMON} is used.
@findex ASM_OUTPUT_ALIGNED_BSS
@item ASM_OUTPUT_ALIGNED_BSS (@var{stream}, @var{decl}, @var{name}, @var{size}, @var{alignment})
handling the required alignment of the variable. The alignment is specified
as the number of bits.
+@findex ASM_OUTPUT_ALIGNED_DECL_LOCAL
+@item ASM_OUTPUT_ALIGNED_DECL_LOCAL (@var{stream}, @var{decl}, @var{name}, @var{size}, @var{alignment})
+Like @code{ASM_OUTPUT_ALIGNED_DECL} except that @var{decl} of the
+variable to be output, if there is one, or @code{NULL_TREE} if there
+is not corresponding variable. If you define this macro, GNU CC wil use it
+in place of both @code{ASM_OUTPUT_DECL} and
+@code{ASM_OUTPUT_ALIGNED_DECL}. Define this macro when you need to see
+the variable's decl in order to chose what to output.
+
+
@findex ASM_OUTPUT_SHARED_LOCAL
@item ASM_OUTPUT_SHARED_LOCAL (@var{stream}, @var{name}, @var{size}, @var{rounded})
If defined, it is similar to @code{ASM_OUTPUT_LOCAL}, except that it
requires changes to @var{decl}, such as putting it in a separate section.
@findex SUPPORTS_ONE_ONLY
-@item SUPPORTS_WEAK
+@item SUPPORTS_ONE_ONLY
A C expression which evaluates to true if the target supports one-only
semantics.
If you don't define this macro, @file{varasm.c} provides a default
definition. If @code{MAKE_DECL_ONE_ONLY} is defined, the default
definition is @samp{1}; otherwise, it is @samp{0}. Define this macro if
-you want to control weak symbol support with a compiler flag, or if
+you want to control one-only symbol support with a compiler flag, or if
setting the @code{DECL_ONE_ONLY} flag is enough to mark a declaration to
be emitted as one-only.
If SET_ASM_OP is defined, a default definition is provided which is
correct for most systems.
+
+@findex ASM_OUTPUT_DEFINE_LABEL_DIFFERENCE_SYMBOL
+@item ASM_OUTPUT_DEFINE_LABEL_DIFFERENCE_SYMBOL (@var{stream}, @var{symbol}, @var{high}, @var{low})
+A C statement to output to the stdio stream @var{stream} assembler code
+which defines (equates) the symbol @var{symbol} to have a value equal to
+the difference of the two symbols @var{high} and @var{low}, i.e.
+@var{high} minus @var{low}. GNU CC guarantees that the symbols @var{high}
+and @var{low} are already known by the assembler so that the difference
+resolves into a constant.
+
+If SET_ASM_OP is defined, a default definition is provided which is
+correct for most systems.
+
+@findex ASM_OUTPUT_WEAK_ALIAS
+@item ASM_OUTPUT_WEAK_ALIAS (@var{stream}, @var{name}, @var{value})
+A C statement to output to the stdio stream @var{stream} assembler code
+which defines (equates) the weak symbol @var{name} to have the value
+@var{value}.
+
+Define this macro if the target only supports weak aliases; define
+ASM_OUTPUT_DEF instead if possible.
+
@findex OBJC_GEN_METHOD_LABEL
@item OBJC_GEN_METHOD_LABEL (@var{buf}, @var{is_inst}, @var{class_name}, @var{cat_name}, @var{sel_name})
Define this macro to override the default assembler names used for
Define the macros @code{REGISTER_PREFIX}, @code{LOCAL_LABEL_PREFIX},
@code{USER_LABEL_PREFIX} and @code{IMMEDIATE_PREFIX} if you can express
-the variations in assemble language syntax with that mechanism. Define
+the variations in assembler language syntax with that mechanism. Define
@code{ASSEMBLER_DIALECT} and use the @samp{@{option0|option1@}} syntax
if the syntax variant are larger and involve such things as different
opcodes or operand order.
@table @code
@cindex dispatch table
@findex ASM_OUTPUT_ADDR_DIFF_ELT
-@item ASM_OUTPUT_ADDR_DIFF_ELT (@var{stream}, @var{value}, @var{rel})
+@item ASM_OUTPUT_ADDR_DIFF_ELT (@var{stream}, @var{body}, @var{value}, @var{rel})
A C statement to output to the stdio stream @var{stream} an assembler
pseudo-instruction to generate a difference between two labels.
@var{value} and @var{rel} are the numbers of two internal labels. The
You must provide this macro on machines where the addresses in a
dispatch table are relative to the table's own address. If defined, GNU
CC will also use this macro on all machines when producing PIC.
+@var{body} is the body of the ADDR_DIFF_VEC; it is provided so that the
+mode and flags can be read.
@findex ASM_OUTPUT_ADDR_VEC_ELT
@item ASM_OUTPUT_ADDR_VEC_ELT (@var{stream}, @var{value})
This macro need not be defined on most platforms.
+@findex EXCEPTION_SECTION
+@item EXCEPTION_SECTION ()
+A C expression to switch to the section in which the main
+exception table is to be placed (@pxref{Sections}). The default is a
+section named @code{.gcc_except_table} on machines that support named
+sections via @code{ASM_OUTPUT_SECTION_NAME}, otherwise if @samp{-fpic}
+or @samp{-fPIC} is in effect, the @code{data_section}, otherwise the
+@code{readonly_data_section}.
+
+@findex EH_FRAME_SECTION_ASM_OP
+@item EH_FRAME_SECTION_ASM_OP
+If defined, a C string constant for the assembler operation to switch to
+the section for exception handling frame unwind information. If not
+defined, GNU CC will provide a default definition if the target supports
+named sections. @file{crtstuff.c} uses this macro to switch to the
+appropriate section.
+
+You should define this symbol if your target supports DWARF 2 frame
+unwind information and the default definition does not work.
+
@findex OMIT_EH_TABLE
@item OMIT_EH_TABLE ()
A C expression that is nonzero if the normal exception table output
@item MASK_RETURN_ADDR
An rtx used to mask the return address found via RETURN_ADDR_RTX, so
that it does not contain any extraneous set bits in it.
+
+@findex DWARF2_UNWIND_INFO
+@item DWARF2_UNWIND_INFO
+Define this macro to 0 if your target supports DWARF 2 frame unwind
+information, but it does not yet work with exception handling.
+Otherwise, if your target supports this information (if it defines
+@samp{INCOMING_RETURN_ADDR_RTX} and either @samp{UNALIGNED_INT_ASM_OP}
+or @samp{OBJECT_FORMAT_ELF}), GCC will provide a default definition of
+1.
+
+If this macro is defined to 1, the DWARF 2 unwinder will be the default
+exception handling mechanism; otherwise, setjmp/longjmp will be used by
+default.
+
+If this macro is defined to anything, the DWARF 2 unwinder will be used
+instead of inline unwinders and __unwind_function in the non-setjmp case.
+
@end table
@node Alignment Output
This describes commands for alignment.
@table @code
-@findex ASM_OUTPUT_ALIGN_CODE
-@item ASM_OUTPUT_ALIGN_CODE (@var{file})
-A C expression to output text to align the location counter in the way
-that is desirable at a point in the code that is reached only by
-jumping.
+@findex LABEL_ALIGN_AFTER_BARRIER
+@item LABEL_ALIGN_AFTER_BARRIER (@var{label})
+The alignment (log base 2) to put in front of @var{label}, which follows
+a BARRIER.
This macro need not be defined if you don't want any special alignment
to be done at such a time. Most machine descriptions do not currently
define the macro.
-@findex ASM_OUTPUT_LOOP_ALIGN
-@item ASM_OUTPUT_LOOP_ALIGN (@var{file})
-A C expression to output text to align the location counter in the way
-that is desirable at the beginning of a loop.
+@findex LOOP_ALIGN
+@item LOOP_ALIGN (@var{label})
+The alignment (log base 2) to put in front of @var{label}, which follows
+a NOTE_INSN_LOOP_BEG note.
This macro need not be defined if you don't want any special alignment
to be done at such a time. Most machine descriptions do not currently
define the macro.
+@findex LABEL_ALIGN
+@item LABEL_ALIGN (@var{label})
+The alignment (log base 2) to put in front of @var{label}.
+If LABEL_ALIGN_AFTER_BARRIER / LOOP_ALIGN specify a different alignment,
+the maximum of the specified values is used.
+
@findex ASM_OUTPUT_SKIP
@item ASM_OUTPUT_SKIP (@var{stream}, @var{nbytes})
A C statement to output to the stdio stream @var{stream} an assembler
@findex ASM_NO_SKIP_IN_TEXT
@item ASM_NO_SKIP_IN_TEXT
Define this macro if @code{ASM_OUTPUT_SKIP} should not be used in the
-text section because it fails put zeros in the bytes that are skipped.
+text section because it fails to put zeros in the bytes that are skipped.
This is true on many Unix systems, where the pseudo--op to skip bytes
produces no-op instructions rather than zeros when used in the text
section.
@findex PREFERRED_DEBUGGING_TYPE
@item PREFERRED_DEBUGGING_TYPE
-A C expression that returns the type of debugging output GNU CC produces
-when the user specifies @samp{-g} or @samp{-ggdb}. Define this if you
-have arranged for GNU CC to support more than one format of debugging
-output. Currently, the allowable values are @code{DBX_DEBUG},
-@code{SDB_DEBUG}, @code{DWARF_DEBUG}, and @code{XCOFF_DEBUG}.
+A C expression that returns the type of debugging output GNU CC should
+produce when the user specifies just @samp{-g}. Define
+this if you have arranged for GNU CC to support more than one format of
+debugging output. Currently, the allowable values are @code{DBX_DEBUG},
+@code{SDB_DEBUG}, @code{DWARF_DEBUG}, @code{DWARF2_DEBUG}, and
+@code{XCOFF_DEBUG}.
+
+When the user specifies @samp{-ggdb}, GNU CC normally also uses the
+value of this macro to select the debugging output format, but with two
+exceptions. If @code{DWARF2_DEBUGGING_INFO} is defined and
+@code{LINKER_DOES_NOT_WORK_WITH_DWARF2} is not defined, GNU CC uses the
+value @code{DWARF2_DEBUG}. Otherwise, if @code{DBX_DEBUGGING_INFO} is
+defined, GNU CC uses @code{DBX_DEBUG}.
The value of this macro only affects the default debugging output; the
user can always get a specific type of output by using @samp{-gstabs},
-@samp{-gcoff}, @samp{-gdwarf}, or @samp{-gxcoff}.
+@samp{-gcoff}, @samp{-gdwarf-1}, @samp{-gdwarf-2}, or @samp{-gxcoff}.
@end table
@node DBX Options
Define this macro if GNU CC should produce dwarf format debugging output
in response to the @samp{-g} option.
+@findex DWARF2_DEBUGGING_INFO
+@item DWARF2_DEBUGGING_INFO
+Define this macro if GNU CC should produce dwarf version 2 format
+debugging output in response to the @samp{-g} option.
+
+To support optional call frame debugging information, you must also
+define @code{INCOMING_RETURN_ADDR_RTX} and either set
+@code{RTX_FRAME_RELATED_P} on the prologue insns if you use RTL for the
+prologue, or call @code{dwarf2out_def_cfa} and @code{dwarf2out_reg_save}
+as appropriate from @code{FUNCTION_PROLOGUE} if you don't.
+
+@findex DWARF2_FRAME_INFO
+@item DWARF2_FRAME_INFO
+Define this macro to a nonzero value if GNU CC should always output
+Dwarf 2 frame information. If @code{DWARF2_UNWIND_INFO}
+(@pxref{Exception Region Output} is nonzero, GNU CC will output this
+information not matter how you define @code{DWARF2_FRAME_INFO}.
+
+@findex LINKER_DOES_NOT_WORK_WITH_DWARF2
+@item LINKER_DOES_NOT_WORK_WITH_DWARF2
+Define this macro if the linker does not work with Dwarf version 2.
+Normally, if the user specifies only @samp{-ggdb} GNU CC will use Dwarf
+version 2 if available; this macro disables this. See the description
+of the @code{PREFERRED_DEBUGGING_TYPE} macro for more details.
+
@findex PUT_SDB_@dots{}
@item PUT_SDB_@dots{}
Define these macros to override the assembler syntax for the special
predicate can cause the compiler to malfunction). Instead, it allows
the table built by @file{genrecog} to be more compact and efficient,
thus speeding up the compiler. The most important predicates to include
-in the list specified by this macro are thoses used in the most insn
+in the list specified by this macro are those used in the most insn
patterns.
@findex CASE_VECTOR_MODE
An alias for a machine mode name. This is the machine mode that
elements of a jump-table should have.
+@findex CASE_VECTOR_SHORTEN_MODE
+@item CASE_VECTOR_SHORTEN_MODE (@var{min_offset}, @var{max_offset}, @var{body})
+Optional: return the preferred mode for an @code{addr_diff_vec}
+when the minimum and maximum offset are known. If you define this,
+it enables extra code in branch shortening to deal with @code{addr_diff_vec}.
+To make this work, you also have to define INSN_ALIGN and
+make the alignment for @code{addr_diff_vec} explicit.
+The @var{body} argument is provided so that teh offset_unsigned and scale
+flags can be updated.
+
@findex CASE_VECTOR_PC_RELATIVE
@item CASE_VECTOR_PC_RELATIVE
-Define this macro if jump-tables should contain relative addresses.
+Define this macro to be a C expression to indicate when jump-tables
+should contain relative addresses. If jump-tables never contain
+relative addresses, then you need not define this macro.
@findex CASE_DROPS_THROUGH
@item CASE_DROPS_THROUGH
@code{NIL}. On machines where this macro is defined, you will normally
define it as the constant @code{SIGN_EXTEND} or @code{ZERO_EXTEND}.
+@findex SHORT_IMMEDIATES_SIGN_EXTEND
+@item SHORT_IMMEDIATES_SIGN_EXTEND
+Define this macro if loading short immediate values into registers sign
+extends.
+
@findex IMPLICIT_FIX_EXPR
@item IMPLICIT_FIX_EXPR
An alias for a tree code that should be used by default for conversion
If defined, a C statement that assigns default attributes to
newly defined @var{type}.
+@findex MERGE_MACHINE_TYPE_ATTRIBUTES
+@item MERGE_MACHINE_TYPE_ATTRIBUTES (@var{type1}, @var{type2})
+Define this macro if the merging of type attributes needs special handling.
+If defined, the result is a list of the combined TYPE_ATTRIBUTES of
+@var{type1} and @var{type2}. It is assumed that comptypes has already been
+called and returned 1.
+
+@findex MERGE_MACHINE_DECL_ATTRIBUTES
+@item MERGE_MACHINE_DECL_ATTRIBUTES (@var{olddecl}, @var{newdecl})
+Define this macro if the merging of decl attributes needs special handling.
+If defined, the result is a list of the combined DECL_MACHINE_ATTRIBUTES of
+@var{olddecl} and @var{newdecl}. @var{newdecl} is a duplicate declaration
+of @var{olddecl}. Examples of when this is needed are when one attribute
+overrides another, or when an attribute is nullified by a subsequent
+definition.
+
+@findex SET_DEFAULT_DECL_ATTRIBUTES
+@item SET_DEFAULT_DECL_ATTRIBUTES (@var{decl}, @var{attributes})
+If defined, a C statement that assigns default attributes to
+newly defined @var{decl}.
+
@findex DOLLARS_IN_IDENTIFIERS
@item DOLLARS_IN_IDENTIFIERS
Define this macro to control use of the character @samp{$} in identifier
-names. The value should be 0, 1, or 2. 0 means @samp{$} is not allowed
-by default; 1 means it is allowed by default if @samp{-traditional} is
-used; 2 means it is allowed by default provided @samp{-ansi} is not used.
+names. 0 means @samp{$} is not allowed by default; 1 means it is allowed.
1 is the default; there is no need to define this macro in that case.
+This macro controls the compiler proper; it does not affect the preprocessor.
@findex NO_DOLLAR_IN_LABEL
@item NO_DOLLAR_IN_LABEL
Define this if your @code{exit} function needs to do something
besides calling an external function @code{_cleanup} before
terminating with @code{_exit}. The @code{EXIT_BODY} macro is
-only needed if netiher @code{HAVE_ATEXIT} nor
+only needed if neither @code{HAVE_ATEXIT} nor
@code{INIT_SECTION_ASM_OP} are defined.
@findex INSN_SETS_ARE_DELAYED
delayed branch scheduling. On those machines, define this macro as a C
statement to act on the code starting at @var{insn}.
+@findex MULTIPLE_SYMBOL_SPACES
+@item MULTIPLE_SYMBOL_SPACES
+Define this macro if in some cases global symbols from one translation
+unit may not be bound to undefined symbols in another translation unit
+without user intervention. For instance, under Microsoft Windows
+symbols must be explicitly imported from shared libraries (DLLs).
+
@findex GIV_SORT_CRITERION
@item GIV_SORT_CRITERION (@var{giv1}, @var{giv2})
In some cases, the strength reduction optimization pass can produce better
offsets in addresses. Thus sorting to put the smallest address first
allows the most combinations to be found.
+@findex ISSUE_RATE
+@item ISSUE_RATE
+A C expression that returns how many instructions can be issued at the
+same time if the machine is a superscalar machine. This is only used by
+the @samp{Haifa} scheduler, and not the traditional scheduler.
+
+@findex MD_SCHED_INIT
+@item MD_SCHED_INIT (@var{file}, @var{verbose}
+A C statement which is executed by the @samp{Haifa} scheduler at the
+beginning of each block of instructions that are to be scheduled.
+@var{file} is either a null pointer, or a stdio stream to write any
+debug output to. @var{verbose} is the verbose level provided by
+@samp{-fsched-verbose-}@var{n}.
+
+@findex MD_SCHED_REORDER
+@item MD_SCHED_REORDER (@var{file}, @var{verbose}, @var{ready}, @var{n_ready})
+A C statement which is executed by the @samp{Haifa} scheduler after it
+has scheduled the ready list to allow the machine description to reorder
+it (for example to combine two small instructions together on
+@samp{VLIW} machines). @var{file} is either a null pointer, or a stdio
+stream to write any debug output to. @var{verbose} is the verbose level
+provided by @samp{-fsched-verbose-}@var{n}. @var{ready} is a pointer to
+the ready list of instructions that are ready to be scheduled.
+@var{n_ready} is the number of elements in the ready list. The
+scheduler reads the ready list in reverse order, starting with
+@var{ready}[@var{n_ready}-1] and going to @var{ready}[0].
+
+@findex MD_SCHED_VARIABLE_ISSUE
+@item MD_SCHED_VARIABLE_ISSUE (@var{file}, @var{verbose}, @var{insn}, @var{more})
+A C statement which is executed by the @samp{Haifa} scheduler after it
+has scheduled an insn from the ready list. @var{file} is either a null
+pointer, or a stdio stream to write any debug output to. @var{verbose}
+is the verbose level provided by @samp{-fsched-verbose-}@var{n}.
+@var{insn} is the instruction that was scheduled. @var{more} is the
+number of instructions that can be issued in the current cycle. The
+@samp{MD_SCHED_VARIABLE_ISSUE} macro is responsible for updating the
+value of @var{more} (typically by @var{more}--).
+
+@findex MAX_INTEGER_COMPUTATION_MODE
+@item MAX_INTEGER_COMPUTATION_MODE
+Define this to the largest integer machine mode which can be used for
+operations other than load, store and copy operations.
+
+You need only define this macro if the target holds values larger than
+@code{word_mode} in general purpose registers. Most targets should not define
+this macro.
+
+@findex NEED_MATH_LIBRARY
+@item NEED_MATH_LIBRARY
+Define this macro as a C expression that is nonzero if @code{g++} should
+automatically link in the math library or to zero if @code{g++} should not
+automatically link in the math library.
+
+You need only define this macro if the target does not always need the math
+library linked into C++ programs.
@end table
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