-@c Copyright (C) 1988,89,92,93,94,96,97,98,1999 Free Software Foundation, Inc.
+@c Copyright (C) 1988,1989,1992,1993,1994,1995,1996,1997,1998,1999,2000
+@c Free Software Foundation, Inc.
@c This is part of the GCC manual.
@c For copying conditions, see the file gcc.texi.
* Assembler Format:: Defining how to write insns and pseudo-ops to output.
* Debugging Info:: Defining the format of debugging output.
* Cross-compilation:: Handling floating point for cross-compilers.
+* Mode Switching:: Insertion of mode-switching instructions.
* Misc:: Everything else.
@end menu
which are not accessible to the preprocessor. Otherwise, it should not
be defined.
+@findex NO_BUILTIN_WCHAR_TYPE
+@item NO_BUILTIN_WCHAR_TYPE
+If this macro is defined, the preprocessor will not define the builtin macro
+@code{__WCHAR_TYPE__}. The macro @code{__WCHAR_TYPE__} must then be
+defined by @code{CPP_SPEC} instead.
+
+This should be defined if @code{WCHAR_TYPE} depends on target dependent flags
+which are not accessible to the preprocessor. Otherwise, it should not
+be defined.
+
@findex SIGNED_CHAR_SPEC
@item SIGNED_CHAR_SPEC
A C string constant that tells the GCC driver program options to
@findex CC1_SPEC
@item CC1_SPEC
A C string constant that tells the GCC driver program options to
-pass to @code{cc1, cc1plus, f771, and the other language front ends}.
+pass to @code{cc1}, @code{cc1plus}, @code{f771}, and the other language
+front ends.
It can also specify how to translate options you give to GCC into options
for GCC to pass to front ends..
give to GCC into options for GCC to pass to the @code{cc1plus}.
Do not define this macro if it does not need to do anything.
+Note that everything defined in CC1_SPEC is already passed to
+@code{cc1plus} so there is no need to duplicate the contents of
+CC1_SPEC in CC1PLUS_SPEC.
@findex ASM_SPEC
@item ASM_SPEC
The definition should be an initializer for an array of structures.
Each array element should have four elements: the directory name (a
-string constant), the component name, and flag for C++-only directories,
+string constant), the component name (also a string constant), a 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
+or @samp{BINUTILS}. If the package is part of a vendor-supplied
operating system, code the component name as @samp{0}.
-
For example, here is the definition used for VAX/VMS:
@example
@item
The directories specified by the environment variable @code{LIBRARY_PATH}
-(native only, cross compilers do not use this).
+(or port-specific name; native only, cross compilers do not use this).
@item
The macro @code{STANDARD_EXEC_PREFIX}.
@code{target_flags}.
Define a macro @code{TARGET_@var{featurename}} for each such option.
-Its definition should test a bit in @code{target_flags}; for example:
+Its definition should test a bit in @code{target_flags}. It is
+recommended that a helper macro @code{TARGET_MASK_@var{featurename}}
+is defined for each bit-value to test, and used in
+@code{TARGET_@var{featurename}} and @code{TARGET_SWITCHES}. For
+example:
@smallexample
-#define TARGET_68020 (target_flags & 1)
+#define TARGET_MASK_68020 1
+#define TARGET_68020 (target_flags & TARGET_MASK_68020)
@end smallexample
One place where these macros are used is in the condition-expressions
@smallexample
#define TARGET_SWITCHES \
- @{ @{ "68020", 1, "" @}, \
- @{ "68000", -1, "Compile for the 68000" @}, \
- @{ "", 1, "" @}@}
+ @{ @{ "68020", TARGET_MASK_68020, "" @}, \
+ @{ "68000", -TARGET_MASK_68020, "Compile for the 68000" @}, \
+ @{ "", TARGET_MASK_68020, "" @}@}
@end smallexample
@findex TARGET_OPTIONS
Like PCC_BITFIELD_TYPE_MATTERS except that its effect is limited to
aligning a bitfield within the structure.
+@findex STRUCT_FORCE_BLK
+@item STRUCT_FORCE_BLK (@var{field})
+Return 1 if a structure containing @var{field} should be accessed using
+@code{BLKMODE}.
+
+Normally, this is not needed. See the file @file{c4x.h} for an example
+of how to use this macro to prevent a structure having a floating point
+field from being accessed in an integer mode.
+
@findex ROUND_TYPE_SIZE
@item ROUND_TYPE_SIZE (@var{type}, @var{computed}, @var{specified})
Define this macro as an expression for the overall size of a type
The default is to round @var{computed} up to a multiple of @var{specified}.
+@findex ROUND_TYPE_SIZE_UNIT
+@item ROUND_TYPE_SIZE_UNIT (@var{type}, @var{computed}, @var{specified})
+Similar to @code{ROUND_TYPE_SIZE}, but sizes and alignments are
+specified in units (bytes). If you define @code{ROUND_TYPE_SIZE},
+you must also define this macro and they must be defined consistently
+with each other.
+
@findex ROUND_TYPE_ALIGN
@item ROUND_TYPE_ALIGN (@var{type}, @var{computed}, @var{specified})
Define this macro as an expression for the alignment of a type (given
(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 are writing a new port, define @code{DEFAULT_VTABLE_THUNKS} to 1.
If you do not define this macro, the default for @samp{-fvtable-thunk} is 0.
@end table
@findex CHAR_TYPE_SIZE
@item CHAR_TYPE_SIZE
A C expression for the size in bits of the type @code{char} on the
-target machine. If you don't define this, the default is one quarter
-of a word. (If this would be less than one storage unit, it is rounded up
-to one unit.)
+target machine. If you don't define this, the default is
+@code{BITS_PER_UNIT}.
@findex MAX_CHAR_TYPE_SIZE
@item MAX_CHAR_TYPE_SIZE
* Values in Registers:: What kinds of values each reg can hold.
* Leaf Functions:: Renumbering registers for leaf functions.
* Stack Registers:: Handling a register stack such as 80387.
-* Obsolete Register Macros:: Macros formerly used for the 80387.
@end menu
@node Register Basics
@smallexample
#define HARD_REGNO_NREGS(REGNO, MODE) \
((GET_MODE_SIZE (MODE) + UNITS_PER_WORD - 1) \
- / UNITS_PER_WORD))
+ / UNITS_PER_WORD)
@end smallexample
@findex ALTER_HARD_SUBREG
@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
+registers. You should only define this macro if support for copying to/from
@code{CCmode} is incomplete.
@end table
@table @code
@findex LEAF_REGISTERS
@item LEAF_REGISTERS
-A C initializer for a vector, indexed by hard register number, which
+Name of a char vector, indexed by hard register number, which
contains 1 for a register that is allowable in a candidate for leaf
function treatment.
the stack.
@end table
-@node Obsolete Register Macros
-@subsection Obsolete Macros for Controlling Register Usage
-
-These features do not work very well. They exist because they used to
-be required to generate correct code for the 80387 coprocessor of the
-80386. They are no longer used by that machine description and may be
-removed in a later version of the compiler. Don't use them!
-
-@table @code
-@findex OVERLAPPING_REGNO_P
-@item OVERLAPPING_REGNO_P (@var{regno})
-If defined, this is a C expression whose value is nonzero if hard
-register number @var{regno} is an overlapping register. This means a
-hard register which overlaps a hard register with a different number.
-(Such overlap is undesirable, but occasionally it allows a machine to
-be supported which otherwise could not be.) This macro must return
-nonzero for @emph{all} the registers which overlap each other. GCC
-can use an overlapping register only in certain limited ways. It can
-be used for allocation within a basic block, and may be spilled for
-reloading; that is all.
-
-If this macro is not defined, it means that none of the hard registers
-overlap each other. This is the usual situation.
-
-@findex INSN_CLOBBERS_REGNO_P
-@item INSN_CLOBBERS_REGNO_P (@var{insn}, @var{regno})
-If defined, this is a C expression whose value should be nonzero if
-the insn @var{insn} has the effect of mysteriously clobbering the
-contents of hard register number @var{regno}. By ``mysterious'' we
-mean that the insn's RTL expression doesn't describe such an effect.
-
-If this macro is not defined, it means that no insn clobbers registers
-mysteriously. This is the usual situation; all else being equal,
-it is best for the RTL expression to show all the activity.
-
-@end table
-
@node Register Classes
@section Register Classes
@cindex register class definitions
* Caller Saves::
* Function Entry::
* Profiling::
+* Inlining::
@end menu
@node Frame Layout
You only need to define this macro if you want to support call frame
debugging information like that provided by DWARF 2.
+If this RTL is a @code{REG}, you should also define
+DWARF_FRAME_RETURN_COLUMN to @code{DWARF_FRAME_REGNUM (REGNO)}.
+
@findex INCOMING_FRAME_SP_OFFSET
@item INCOMING_FRAME_SP_OFFSET
A C expression whose value is an integer giving the offset, in bytes,
debugging information like that provided by DWARF 2.
@findex ARG_POINTER_CFA_OFFSET
-@item ARG_POINTER_CFA_OFFSET
+@item ARG_POINTER_CFA_OFFSET (@var{fundecl})
A C expression whose value is an integer giving the offset, in bytes,
from the argument pointer to the canonical frame address (cfa). The
final value should coincide with that calculated by
@code{INCOMING_FRAME_SP_OFFSET}. Which is unfortunately not usable
during virtual register instantiation.
-You only need to define this macro if you want to support call frame
-debugging information like that provided by DWARF 2.
+The default value for this macro is @code{FIRST_PARM_OFFSET (fundecl)},
+which is correct for most machines; in general, the arguments are found
+immediately before the stack frame. Note that this is not the case on
+some targets that save registers into the caller's frame, such as SPARC
+and rs6000, and so such targets need to define this macro.
+
+You only need to define this macro if the default is incorrect, and you
+want to support call frame debugging information like that provided by
+DWARF 2.
+
+@findex SMALL_STACK
+@item SMALL_STACK
+Define this macro if the stack size for the target is very small. This
+has the effect of disabling gcc's builtin @samp{alloca}, though
+@samp{__builtin_alloca} is not affected.
@end table
@node Stack Checking
code on certain machines. If the macro is not defined in target
header files, it defaults to 0.
+@findex PUSH_ARGS
+@item PUSH_ARGS
+A C expression. If nonzero, push insns will be used to pass
+outgoing arguments.
+If the target machine does not have a push instruction, set it to zero.
+That directs GCC to use an alternate strategy: to
+allocate the entire argument block and then store the arguments into
+it. When PUSH_ARGS is nonzero, PUSH_ROUNDING must be defined too.
+On some machines, the definition
+
+@findex PUSH_ROUNDING
+@item PUSH_ROUNDING (@var{npushed})
+A C expression that is the number of bytes actually pushed onto the
+stack when an instruction attempts to push @var{npushed} bytes.
@findex PUSH_ROUNDING
@item PUSH_ROUNDING (@var{npushed})
A C expression that is the number of bytes actually pushed onto the
stack when an instruction attempts to push @var{npushed} bytes.
-
-If the target machine does not have a push instruction, do not define
-this macro. That directs GCC to use an alternate strategy: to
-allocate the entire argument block and then store the arguments into
-it.
On some machines, the definition
@findex ACCUMULATE_OUTGOING_ARGS
@findex current_function_outgoing_args_size
@item ACCUMULATE_OUTGOING_ARGS
-If defined, the maximum amount of space required for outgoing arguments
+A C expression. If nonzero, the maximum amount of space required for outgoing arguments
will be computed and placed into the variable
@code{current_function_outgoing_args_size}. No space will be pushed
onto the stack for each call; instead, the function prologue should
increase the stack frame size by this amount.
-Defining both @code{PUSH_ROUNDING} and @code{ACCUMULATE_OUTGOING_ARGS}
+Setting both @code{PUSH_ARGS} and @code{ACCUMULATE_OUTGOING_ARGS}
is not proper.
@findex REG_PARM_STACK_SPACE
big-endian machines, the default is to pad downward for an argument of
constant size shorter than an @code{int}, and upward otherwise.
+@findex PAD_VARARGS_DOWN
+@item PAD_VARARGS_DOWN
+If defined, a C expression which determines whether the default
+implementation of va_arg will attempt to pad down before reading the
+next argument, if that argument is smaller than its aligned space as
+controlled by @code{PARM_BOUNDARY}. If this macro is not defined, all such
+arguments are padded down if @code{BYTES_BIG_ENDIAN} is true.
+
@findex FUNCTION_ARG_BOUNDARY
@item FUNCTION_ARG_BOUNDARY (@var{mode}, @var{type})
If defined, a C expression that gives the alignment boundary, in bits,
@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
+argument is loaded first. This macro only affects arguments
passed in registers.
@end table
@findex EPILOGUE_USES
@item EPILOGUE_USES (@var{regno})
-Define this macro as a C expression that is nonzero for registers are
+Define this macro as a C expression that is nonzero for registers that are
used by the epilogue or the @samp{return} pattern. The stack and frame
pointer registers are already be assumed to be used as needed.
be clobbered by a function call, including condition codes. The
@code{asm} statement will be mostly likely needed to handle this
task. Local labels in the assembler code can be concatenated with the
-string @var{id}, to obtain a unique lable name.
+string @var{id}, to obtain a unique label name.
Registers or condition codes clobbered by @code{FUNCTION_PROLOGUE} or
@code{FUNCTION_EPILOGUE} must be saved in the macros
support block profiling.
@end table
+@node Inlining
+@subsection Permitting inlining of functions with attributes
+@cindex inlining
+
+By default if a function has a target specific attribute attached to it,
+it will not be inlined. This behaviour can be overridden if the target
+defines the @samp{FUNCTION_ATTRIBUTE_INLINABLE_P} macro. This macro
+takes one argument, a @samp{DECL} describing the function. It should
+return non-zero if the function can be inlined, otherwise it should
+return 0.
+
@node Varargs
@section Implementing the Varargs Macros
@cindex varargs implementation
machines that pass all their arguments on the stack.
The argument @var{args_so_far} is the @code{CUMULATIVE_ARGS} data
-structure, containing the values that obtain after processing of the
+structure, containing the values that are obtained after processing the
named arguments. The arguments @var{mode} and @var{type} describe the
last named argument---its machine mode and its data type as a tree node.
@findex EXTRA_CC_MODES
@item EXTRA_CC_MODES
-A list of names to be used for additional modes for condition code
-values in registers (@pxref{Jump Patterns}). These names are added
-to @code{enum machine_mode} and all have class @code{MODE_CC}. By
-convention, they should start with @samp{CC} and end with @samp{mode}.
+A list of additional modes for condition code values in registers
+(@pxref{Jump Patterns}). This macro should expand to a sequence of
+calls of the macro @code{CC} separated by white space. @code{CC} takes
+two arguments. The first is the enumeration name of the mode, which
+should begin with @samp{CC} and end with @samp{mode}. The second is a C
+string giving the printable name of the mode; it should be the same as
+the first argument, but with the trailing @samp{mode} removed.
-You should only define this macro if your machine does not use @code{cc0}
-and only if additional modes are required.
-
-@findex EXTRA_CC_NAMES
-@item EXTRA_CC_NAMES
-A list of C strings giving the names for the modes listed in
-@code{EXTRA_CC_MODES}. For example, the Sparc defines this macro and
-@code{EXTRA_CC_MODES} as
+You should only define this macro if additional modes are required.
+A sample definition of @code{EXTRA_CC_MODES} is:
@smallexample
-#define EXTRA_CC_MODES CC_NOOVmode, CCFPmode, CCFPEmode
-#define EXTRA_CC_NAMES "CC_NOOV", "CCFP", "CCFPE"
+#define EXTRA_CC_MODES \
+ CC(CC_NOOVmode, "CC_NOOV") \
+ CC(CCFPmode, "CCFP") \
+ CC(CCFPEmode, "CCFPE")
@end smallexample
-This macro is not required if @code{EXTRA_CC_MODES} is not defined.
-
@findex SELECT_CC_MODE
@item SELECT_CC_MODE (@var{op}, @var{x}, @var{y})
Returns a mode from class @code{MODE_CC} to be used when comparison
@findex CANONICALIZE_COMPARISON
@item CANONICALIZE_COMPARISON (@var{code}, @var{op0}, @var{op1})
-One some machines not all possible comparisons are defined, but you can
+On some machines not all possible comparisons are defined, but you can
convert an invalid comparison into a valid one. For example, the Alpha
does not have a @code{GT} comparison, but you can use an @code{LT}
comparison instead and swap the order of the operands.
and likewise for @code{HImode}.
@findex SLOW_UNALIGNED_ACCESS
-@item SLOW_UNALIGNED_ACCESS
-Define this macro to be the value 1 if unaligned accesses have a cost
-many times greater than aligned accesses, for example if they are
-emulated in a trap handler.
+@item SLOW_UNALIGNED_ACCESS (@var{mode}, @var{alignment})
+Define this macro to be the value 1 if memory accesses described by the
+@var{mode} and @var{alignment} parameters have a cost many times greater
+than aligned accesses, for example if they are emulated in a trap
+handler.
When this macro is non-zero, the compiler will act as if
@code{STRICT_ALIGNMENT} were non-zero when generating code for block
Therefore, do not set this macro non-zero if unaligned accesses only add a
cycle or two to the time for a memory access.
-If the value of this macro is always zero, it need not be defined.
+If the value of this macro is always zero, it need not be defined. If
+this macro is defined, it should produce a non-zero value when
+@code{STRICT_ALIGNMENT} is non-zero.
@findex DONT_REDUCE_ADDR
@item DONT_REDUCE_ADDR
@findex MOVE_RATIO
@item MOVE_RATIO
The threshold of number of scalar memory-to-memory move insns, @emph{below}
-which a sequence of insns should be generated instead of a
+which a sequence of insns should be generated instead of a
string move insn or a library call. Increasing the value will always
make code faster, but eventually incurs high cost in increased code size.
-Note that on machines with no memory-to-memory move insns, this macro denotes
-the corresponding number of memory-to-memory @emph{sequences}.
+Note that on machines where the corresponding move insn is a
+@code{define_expand} that emits a sequence of insns, this macro counts
+the number of such sequences.
If you don't define this, a reasonable default is used.
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, GCC will use
-the symbol name prefixed by @samp{.} as the section name.
+the symbol name prefixed by @samp{.} as the section name. Note - this
+macro can now be called for unitialised data items as well as
+initialised data and functions.
@end table
@node PIC
for the file format in use is appropriate.
@findex OUTPUT_QUOTED_STRING
-@item OUTPUT_QUOTED_STRING (@var{stream}, @var{name})
+@item OUTPUT_QUOTED_STRING (@var{stream}, @var{string})
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, GCC will only call it to output filenames to
pool before the function.
@findex ASM_OUTPUT_POOL_PROLOGUE
-@item ASM_OUTPUT_POOL_PROLOGUE (@var{file} @var{funname} @var{fundecl} @var{size})
+@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
constant pool for a function. @var{funname} is a string giving
the name of the function. Should the return type of the function
@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, GCC wil use it
+is no corresponding variable. If you define this macro, GCC will 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.
@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, GCC wil use it
+is no corresponding variable. If you define this macro, GCC will 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
fprintf (@var{stream}, "L%s%d:\n", @var{prefix}, @var{num})
@end example
+@findex ASM_OUTPUT_ALTERNATE_LABEL_NAME
+@item ASM_OUTPUT_ALTERNATE_LABEL_NAME (@var{stream}, @var{string})
+A C statement to output to the stdio stream @var{stream} the string
+@var{string}.
+
+The default definition of this macro is as follows:
+
+@example
+fprintf (@var{stream}, "%s:\n", LABEL_ALTERNATE_NAME (INSN))
+@end example
+
@findex ASM_GENERATE_INTERNAL_LABEL
@item ASM_GENERATE_INTERNAL_LABEL (@var{string}, @var{prefix}, @var{num})
A C statement to store into the string @var{string} a label whose name
A C statement to output to the stdio stream @var{stream} assembler code
which defines (equates) the symbol @var{name} to have the value @var{value}.
+@findex SET_ASM_OP
If SET_ASM_OP is defined, a default definition is provided which is
correct for most systems.
@findex ASM_OUTPUT_DEF_FROM_DECLS
-@item ASM_OUTPUT_DEF (@var{stream}, @var{decl_of_name}, @var{decl_of_value})
+@item ASM_OUTPUT_DEF_FROM_DECLS (@var{stream}, @var{decl_of_name}, @var{decl_of_value})
A C statement to output to the stdio stream @var{stream} assembler code
which defines (equates) the symbol whoes tree node is @var{decl_of_name}
to have the value of the tree node @var{decl_of_value}. This macro will
and @var{low} are already known by the assembler so that the difference
resolves into a constant.
+@findex SET_ASM_OP
If SET_ASM_OP is defined, a default definition is provided which is
correct for most systems.
to be done at such a time. Most machine descriptions do not currently
define the macro.
+Unless it's necessary to inspect the @var{label} parameter, it is better
+to set the variable @var{align_jumps} in the target's
+@code{OVERRIDE_OPTIONS}. Otherwise, you should try to honour the user's
+selection in @var{align_jumps} in a @code{LABEL_ALIGN_AFTER_BARRIER}
+implementation.
+
+@findex LABEL_ALIGN_AFTER_BARRIER_MAX_SKIP
+@item LABEL_ALIGN_AFTER_BARRIER_MAX_SKIP
+The maximum number of bytes to skip when applying
+@code{LABEL_ALIGN_AFTER_BARRIER}. This works only if
+@code{ASM_OUTPUT_MAX_SKIP_ALIGN} is defined.
+
@findex LOOP_ALIGN
@item LOOP_ALIGN (@var{label})
The alignment (log base 2) to put in front of @var{label}, which follows
to be done at such a time. Most machine descriptions do not currently
define the macro.
+Unless it's necessary to inspect the @var{label} parameter, it is better
+to set the variable @var{align_loops} in the target's
+@code{OVERRIDE_OPTIONS}. Otherwise, you should try to honour the user's
+selection in @var{align_loops} in a @code{LOOP_ALIGN} implementation.
+
+@findex LOOP_ALIGN_MAX_SKIP
+@item LOOP_ALIGN_MAX_SKIP
+The maximum number of bytes to skip when applying @code{LOOP_ALIGN}.
+This works only if @code{ASM_OUTPUT_MAX_SKIP_ALIGN} is defined.
+
@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.
+Unless it's necessary to inspect the @var{label} parameter, it is better
+to set the variable @var{align_labels} in the target's
+@code{OVERRIDE_OPTIONS}. Otherwise, you should try to honour the user's
+selection in @var{align_labels} in a @code{LABEL_ALIGN} implementation.
+
+@findex LABEL_ALIGN_MAX_SKIP
+@item LABEL_ALIGN_MAX_SKIP
+The maximum number of bytes to skip when applying @code{LABEL_ALIGN}.
+This works only if @code{ASM_OUTPUT_MAX_SKIP_ALIGN} is defined.
+
@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
to use the name of the text section itself, rather than an explicit label,
to indicate the beginning of the text section, define this macro to zero.
+@findex DWARF2_ASM_LINE_DEBUG_INFO
+@item DWARF2_ASM_LINE_DEBUG_INFO
+Define this macro to be a nonzero value if the assembler can generate Dwarf 2
+line debug info sections. This will result in much more compact line number
+tables, and hence is desirable if it works.
+
@findex PUT_SDB_@dots{}
@item PUT_SDB_@dots{}
Define these macros to override the assembler syntax for the special
and has the type @code{REAL_VALUE_TYPE}.
@end table
+@node Mode Switching
+@section Mode Switching Instructions
+@cindex mode switching
+The following macros control mode switching optimizations:
+
+@table @code
+@findex OPTIMIZE_MODE_SWITCHING
+@item OPTIMIZE_MODE_SWITCHING (@var{entity})
+Define this macro if the port needs extra instructions inserted for mode
+switching in an optimizing compilation.
+
+For an example, the SH4 can perform both single and double precision
+floating point operations, but to perform a single precision operation,
+the FPSCR PR bit has to be cleared, while for a double precision
+operation, this bit has to be set. Changing the PR bit requires a general
+purpose register as a scratch register, hence these FPSCR sets have to
+be inserted before reload, i.e. you can't put this into instruction emitting
+or MACHINE_DEPENDENT_REORG.
+
+You can have multiple entities that are mode-switched, and select at run time
+which entities actually need it. @code{OPTIMIZE_MODE_SWITCHING} should
+return non-zero for any @var{entity} that that needs mode-switching.
+If you define this macro, you also have to define
+@code{NUM_MODES_FOR_MODE_SWITCHING}, @code{MODE_NEEDED},
+@code{MODE_PRIORITY_TO_MODE} and @code{EMIT_MODE_SET}.
+@code{MODE_AT_ENTRY} and @code{MODE_USES_IN_EXIT_BLOCK} are optional.
+
+@findex NUM_MODES_FOR_MODE_SWITCHING
+@item NUM_MODES_FOR_MODE_SWITCHING
+If you define @code{OPTIMIZE_MODE_SWITCHING}, you have to define this as
+initializer for an array of integers. Each initializer element
+N refers to an entity that needs mode switching, and specifies the number
+of different modes that might need to be set for this entity.
+The position of the initializer in the initializer - starting counting at
+zero - determines the integer that is used to refer to the mode-switched
+entity in question.
+In macros that take mode arguments / yield a mode result, modes are
+represented as numbers 0 .. N - 1. N is used to specify that no mode
+switch is needed / supplied.
+
+@findex MODE_USES_IN_EXIT_BLOCK
+@item MODE_USES_IN_EXIT_BLOCK
+If this macro is defined, it is called for each exit block when mode switching
+optimization is performed. Its return value should be the pattern of an insn,
+or a sequence of insns. It is emitted before the return insn / use insns at
+the end of the exit block.
+
+This is done before insns are examined for their need of any mode switching.
+
+@findex MODE_NEEDED
+@item MODE_NEEDED (@var{entity}, @var{insn})
+@var{entity} is an integer specifying a mode-switched entity. If
+@code{OPTIMIZE_MODE_SWITCHING} is defined, you must define this macro to
+return an integer value not larger than the corresponding element in
+NUM_MODES_FOR_MODE_SWITCHING, to denote the mode that @var{entity} must
+be switched into prior to the execution of INSN.
+
+@findex MODE_AT_ENTRY
+@item MODE_AT_ENTRY (@var{entity})
+If this macro is defined, it is evaluated for every @var{entity} that needs
+mode switching. It should evaluate to an integer, which is a mode that
+@var{entity} is assumed to be switched to at function entry.
+
+@findex MODE_PRIORITY_TO_MODE
+@item MODE_PRIORITY_TO_MODE (@var{entity}, @var{n})
+This macro specifies the order in which modes for ENTITY are processed.
+0 is the highest priority, NUM_MODES_FOR_MODE_SWITCHING[ENTITY] - 1 the
+lowest. The value of the macro should be an integer designating a mode
+for ENTITY. For any fixed @var{entity}, @code{mode_priority_to_mode}
+(@var{entity}, @var{n}) shall be a bijection in 0 ..
+@code{num_modes_for_mode_switching}[@var{entity}] - 1 .
+
+@findex EMIT_MODE_SET
+@item EMIT_MODE_SET (@var{entity}, @var{mode}, @var{hard_regs_live})
+Generate one or more insns to set @var{entity} to @var{mode}.
+@var{hard_reg_live} is the set of hard registers live at the point where
+the insn(s) are to be inserted.
+@end table
+
@node Misc
@section Miscellaneous Parameters
@cindex parameters, miscellaneous
in the list specified by this macro are those used in the most insn
patterns.
+@item SPECIAL_MODE_PREDICATES
+@findex SPECIAL_MODE_PREDICATES
+Define this if you have special predicates that know special things
+about modes. Genrecog will warn about certain forms of
+@code{match_operand} without a mode; if the operand predicate is
+listed in @code{SPECIAL_MODE_PREDICATES}, the warning will be
+suppressed.
+
+Here is an example from the IA-32 port (@code{ext_register_operand}
+specially checks for @code{HImode} or @code{SImode} in preparation
+for a byte extraction from @code{%ah} etc.).
+
+@smallexample
+#define SPECIAL_MODE_PREDICATES \
+ "ext_register_operand",
+@end smallexample
+
@findex CASE_VECTOR_MODE
@item CASE_VECTOR_MODE
An alias for a machine mode name. This is the machine mode that
instructions.
@findex FLOAT_STORE_FLAG_VALUE
-@item FLOAT_STORE_FLAG_VALUE
-A C expression that gives a non-zero floating point value that is
+@item FLOAT_STORE_FLAG_VALUE (@var{mode})
+A C expression that gives a non-zero @code{REAL_VALUE_TYPE} value that is
returned when comparison operators with floating-point results are true.
Define this macro on machine that have comparison operations that return
floating-point values. If there are no such operations, do not define
appropriate rtl instructions. It is used only when compiling the end of
@code{main}.
-@item HAVE_ATEXIT
-@findex HAVE_ATEXIT
-Define this if the target system supports the function
-@code{atexit} from the ANSI C standard. If this is not defined,
-and @code{INIT_SECTION_ASM_OP} is not defined, a default
-@code{exit} function will be provided to support C++.
+@item NEED_ATEXIT
+@findex NEED_ATEXIT
+Define this if the target system lacks the function @code{atexit}
+from the ANSI C standard. If this macro is defined, a default definition
+will be provided to support C++. If @code{ON_EXIT} is not defined,
+a default @code{exit} function will also be provided.
+
+@item ON_EXIT
+@findex ON_EXIT
+Define this macro if the target has another way to implement atexit
+functionality without replacing @code{exit}. For instance, SunOS 4 has
+a similar @code{on_exit} library function.
+
+The definition should be a functional macro which can be used just like
+the @code{atexit} function.
@item EXIT_BODY
@findex EXIT_BODY
without user intervention. For instance, under Microsoft Windows
symbols must be explicitly imported from shared libraries (DLLs).
+@findex MD_ASM_CLOBBERS
+@item MD_ASM_CLOBBERS
+A C statement that adds to @var{CLOBBERS} @code{STRING_CST} trees for
+any hard regs the port wishes to automatically clobber for all asms.
+
@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.
+same time if the machine is a superscalar machine.
@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
+A C statement which is executed by the 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},
- @var{clock}, @var{can_issue_more})
-A C statement which is executed by the @samp{Haifa} scheduler after it
+@item MD_SCHED_REORDER (@var{file}, @var{verbose}, @var{ready}, @var{n_ready}, @var{clock}, @var{can_issue_more})
+A C statement which is executed by the 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
@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
+A C statement which is executed by the 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}.
separate math library.
You need only define this macro if the default of @samp{"-lm"} is wrong.
+
+@findex LIBRARY_PATH_ENV
+@item LIBRARY_PATH_ENV
+Define this macro as a C string constant for the environment variable that
+specifies where the linker should look for libraries.
+
+You need only define this macro if the default of @samp{"LIBRARY_PATH"}
+is wrong.
+
+@findex TARGET_HAS_F_SETLKW
+@item TARGET_HAS_F_SETLKW
+Define this macro if the target supports file locking with fcntl / F_SETLKW.
+Note that this functionality is part of POSIX.
+Defining @code{TARGET_HAS_F_SETLKW} will enable the test coverage code
+to use file locking when exiting a program, which avoids race conditions
+if the program has forked.
+
+@findex MAX_CONDITIONAL_EXECUTE
+@item MAX_CONDITIONAL_EXECUTE
+
+A C expression for the maximum number of instructions to execute via
+conditional execution instructions instead of a branch. A value of
+@code{BRANCH_COST}+1 is the default if the machine does not use cc0, and
+1 if it does use cc0.
@end table
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