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Diffstat (limited to 'gcc/tm.texi')
| -rw-r--r-- | gcc/tm.texi | 185 |
1 files changed, 121 insertions, 64 deletions
diff --git a/gcc/tm.texi b/gcc/tm.texi index cf11d7b5aff..bed9e0a4ff5 100644 --- a/gcc/tm.texi +++ b/gcc/tm.texi @@ -1,4 +1,4 @@ -@c Copyright (C) 1988,89,92,93,94,96,97,1998 Free Software Foundation, Inc. +@c Copyright (C) 1988,89,92,93,94,96,97,98,1999 Free Software Foundation, Inc. @c This is part of the GCC manual. @c For copying conditions, see the file gcc.texi. @@ -790,15 +790,24 @@ size of an integer. @findex STACK_BOUNDARY @item STACK_BOUNDARY +Define this macro if there is a guaranteed alignment for the stack +pointer on this machine. The definition is a C expression +for the desired alignment (measured in bits). This value is used as a +default if PREFERRED_STACK_BOUNDARY is not defined. + +@findex PREFERRED_STACK_BOUNDARY +@item PREFERRED_STACK_BOUNDARY Define this macro if you wish to preserve a certain alignment for the stack pointer. The definition is a C expression -for the desired alignment (measured in bits). +for the desired alignment (measured in bits). If STACK_BOUNDARY is +also defined, this macro must evaluate to a value equal to or larger +than STACK_BOUNDARY. -@cindex @code{PUSH_ROUNDING}, interaction with @code{STACK_BOUNDARY} +@cindex @code{PUSH_ROUNDING}, interaction with @code{PREFERRED_STACK_BOUNDARY} If @code{PUSH_ROUNDING} is not defined, the stack will always be aligned -to the specified boundary. If @code{PUSH_ROUNDING} is defined and specifies a -less strict alignment than @code{STACK_BOUNDARY}, the stack may be -momentarily unaligned while pushing arguments. +to the specified boundary. If @code{PUSH_ROUNDING} is defined and specifies +a less strict alignment than @code{PREFERRED_STACK_BOUNDARY}, the stack may +be momentarily unaligned while pushing arguments. @findex FUNCTION_BOUNDARY @item FUNCTION_BOUNDARY @@ -864,6 +873,18 @@ The typical use of this macro is to increase alignment for string constants to be word aligned so that @code{strcpy} calls that copy constants can be done inline. +@findex LOCAL_ALIGNMENT +@item LOCAL_ALIGNMENT (@var{type}, @var{basic-align}) +If defined, a C expression to compute the alignment for a variables in +the local 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. + +One use of this macro is to increase alignment of medium-size data to +make it all fit in fewer cache lines. + @findex EMPTY_FIELD_BOUNDARY @item EMPTY_FIELD_BOUNDARY Alignment in bits to be given to a structure bit field that follows an @@ -957,18 +978,18 @@ Like PCC_BITFIELD_TYPE_MATTERS except that its effect is limited to aligning a bitfield within the structure. @findex ROUND_TYPE_SIZE -@item ROUND_TYPE_SIZE (@var{struct}, @var{size}, @var{align}) -Define this macro as an expression for the overall size of a structure -(given by @var{struct} as a tree node) when the size computed from the -fields is @var{size} and the alignment is @var{align}. +@item ROUND_TYPE_SIZE (@var{type}, @var{computed}, @var{specified}) +Define this macro as an expression for the overall size of a type +(given by @var{type} as a tree node) when the size computed in the +usual way is @var{computed} and the alignment is @var{specified}. -The default is to round @var{size} up to a multiple of @var{align}. +The default is to round @var{computed} up to a multiple of @var{specified}. @findex ROUND_TYPE_ALIGN -@item ROUND_TYPE_ALIGN (@var{struct}, @var{computed}, @var{specified}) -Define this macro as an expression for the alignment of a structure -(given by @var{struct} as a tree node) if the alignment computed in the -usual way is @var{computed} and the alignment explicitly specified was +@item ROUND_TYPE_ALIGN (@var{type}, @var{computed}, @var{specified}) +Define this macro as an expression for the alignment of a type (given +by @var{type} as a tree node) if the alignment computed in the usual +way is @var{computed} and the alignment explicitly specified was @var{specified}. The default is to use @var{specified} if it is larger; otherwise, use @@ -1348,9 +1369,17 @@ preserve the entire contents of a register across a call. @findex fixed_regs @findex call_used_regs @item CONDITIONAL_REGISTER_USAGE -Zero or more C statements that may conditionally modify two variables -@code{fixed_regs} and @code{call_used_regs} (both of type @code{char -[]}) after they have been initialized from the two preceding macros. +Zero or more C statements that may conditionally modify four variables +@code{fixed_regs}, @code{call_used_regs}, @code{global_regs} +(these three are of type @code{char []}) and @code{reg_class_contents} +(of type @code{HARD_REG_SET}). +Before the macro is called @code{fixed_regs}, @code{call_used_regs} +and @code{reg_class_contents} have been initialized from +@code{FIXED_REGISTERS}, @code{CALL_USED_REGISTERS} and +@code{REG_CLASS_CONTENTS}, respectively, +@code{global_regs} has been cleared, and any @samp{-ffixed-@var{reg}}, +@samp{-fcall-used-@var{reg}} and @samp{-fcall-saved-@var{reg}} command +options have been applied. This is necessary in case the fixed or call-clobbered registers depend on target flags. @@ -1684,24 +1713,6 @@ 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. -@cindex death notes -@findex PRESERVE_DEATH_INFO_REGNO_P -@item PRESERVE_DEATH_INFO_REGNO_P (@var{regno}) -If defined, this is a C expression whose value is nonzero if correct -@code{REG_DEAD} notes are needed for hard register number @var{regno} -after reload. - -You would arrange to preserve death info for a register when some of the -code in the machine description which is executed to write the assembler -code looks at the death notes. This is necessary only when the actual -hardware feature which GNU CC thinks of as a register is not actually a -register of the usual sort. (It might, for example, be a hardware -stack.) - -It is also useful for peepholes and linker relaxation. - -If this macro is not defined, it means that no death notes need to be -preserved, and some may even be incorrect. This is the usual situation. @end table @node Register Classes @@ -2023,17 +2034,15 @@ is @code{BITS_PER_WORD} bits wide is correct for your machine. @findex SMALL_REGISTER_CLASSES @item SMALL_REGISTER_CLASSES -Normally the compiler avoids choosing registers that have been -explicitly mentioned in the rtl as spill registers (these registers are -normally those used to pass parameters and return values). However, -some machines have so few registers of certain classes that there -would not be enough registers to use as spill registers if this were -done. +On some machines, it is risky to let hard registers live across arbitrary +insns. Typically, these machines have instructions that require values +to be in specific registers (like an accumulator), and reload will fail +if the required hard register is used for another purpose across such an +insn. 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. +compiler will try to minimize the lifetime of hard registers. 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 @@ -2642,7 +2651,8 @@ allocated for arguments even when their values are passed in registers. The value of this macro is the size, in bytes, of the area reserved for -arguments passed in registers for the function represented by @var{fndecl}. +arguments passed in registers for the function represented by @var{fndecl}, +which can be zero if GNU CC is calling a library function. This space can be allocated by the caller, or be a part of the machine-dependent stack frame: @code{OUTGOING_REG_PARM_STACK_SPACE} says @@ -3729,11 +3739,8 @@ that were passed to @code{__builtin_saveregs}. If this macro is not defined, the compiler will output an ordinary call to the library function @samp{__builtin_saveregs}. -@c !!! a bug in texinfo; how to make the entry on the @item line allow -@c more than one line of text... help... --mew 10feb93 @findex SETUP_INCOMING_VARARGS -@item SETUP_INCOMING_VARARGS (@var{args_so_far}, @var{mode}, @var{type}, -@var{pretend_args_size}, @var{second_time}) +@item SETUP_INCOMING_VARARGS (@var{args_so_far}, @var{mode}, @var{type}, @var{pretend_args_size}, @var{second_time}) This macro offers an alternative to using @code{__builtin_saveregs} and defining the macro @code{EXPAND_BUILTIN_SAVEREGS}. Use it to store the anonymous register arguments into the stack so that all the arguments @@ -3779,6 +3786,15 @@ 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. + +@findex PRETEND_OUTGOING_VARARGS_NAMED +@item PRETEND_OUTGOING_VARARGS_NAMED +If you need to conditionally change ABIs so that one works with +@code{SETUP_INCOMING_VARARGS}, but the other works like neither +@code{SETUP_INCOMING_VARARGS} nor @code{STRICT_ARGUMENT_NAMING} was +defined, then define this macro to return nonzero if +@code{SETUP_INCOMING_VARARGS} is used, zero otherwise. +Otherwise, you should not define this macro. @end table @node Trampolines @@ -4165,7 +4181,7 @@ This is about addressing modes. @table @code @findex HAVE_POST_INCREMENT @item HAVE_POST_INCREMENT -Define this macro if the machine supports post-increment addressing. +A C expression that is nonzero the machine supports post-increment addressing. @findex HAVE_PRE_INCREMENT @findex HAVE_POST_DECREMENT @@ -4392,16 +4408,6 @@ an immediate operand on the target machine. You can assume that @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 @@ -4767,6 +4773,42 @@ the corresponding number of memory-to-memory @emph{sequences}. If you don't define this, a reasonable default is used. +@findex MOVE_BY_PIECES_P +@item MOVE_BY_PIECES_P (@var{size}, @var{alignment}) +A C expression used to determine whether @code{move_by_pieces} will be used to +copy a chunk of memory, or whether some other block move mechanism +will be used. Defaults to 1 if @code{move_by_pieces_ninsns} returns less +than @code{MOVE_RATIO}. + +@findex MOVE_MAX_PIECES +@item MOVE_MAX_PIECES +A C expression used by @code{move_by_pieces} to determine the largest unit +a load or store used to copy memory is. Defaults to @code{MOVE_MAX}. + +@findex USE_LOAD_POST_INCREMENT +@item USE_LOAD_POST_INCREMENT (@var{mode}) +A C expression used to determine whether a load postincrement is +a good thing for @code{move_by_pieces} to use for a given mode. Defaults +to the value of @code{HAVE_POST_INCREMENT}. + +@findex USE_LOAD_PRE_INCREMENT +@item USE_LOAD_PRE_INCREMENT (@var{mode}) +A C expression used to determine whether a load preincrement is +a good thing for @code{move_by_pieces} to use for a given mode. Defaults +to the value of @code{HAVE_PRE_INCREMENT}. + +@findex USE_STORE_POST_INCREMENT +@item USE_STORE_POST_INCREMENT (@var{mode}) +A C expression used to determine whether a store postincrement is +a good thing for @code{move_by_pieces} to use for a given mode. Defaults +to the value of @code{HAVE_POST_INCREMENT}. + +@findex USE_STORE_PRE_INCREMENT +@item USE_STORE_PRE_INCREMENT (@var{mode}) +This macro is used to determine whether a store preincrement is +a good thing for @code{move_by_pieces} to use for a given mode. Defaults +to the value of @code{HAVE_PRE_INCREMENT}. + @findex NO_FUNCTION_CSE @item NO_FUNCTION_CSE Define this macro if it is as good or better to call a constant @@ -5940,13 +5982,20 @@ names. @findex ASM_OUTPUT_DESTRUCTOR This is like @code{ASM_OUTPUT_CONSTRUCTOR} but used for termination functions rather than initialization functions. + +When @code{ASM_OUTPUT_CONSTRUCTOR} and @code{ASM_OUTPUT_DESTRUCTOR} are +defined, the initializaiton routine generated for the generated object +file will have static linkage. @end table If your system uses @code{collect2} as the means of processing constructors, then that program normally uses @code{nm} to scan an -object file for constructor functions to be called. On certain kinds of -systems, you can define these macros to make @code{collect2} work faster -(and, in some cases, make it work at all): +object file for constructor functions to be called. On such systems you +must not define @code{ASM_OUTPUT_CONSTRUCTOR} and @code{ASM_OUTPUT_DESTRUCTOR} +as the object file's initialization routine must have global scope. + +On certain kinds of systems, you can define these macros to make +@code{collect2} work faster (and, in some cases, make it work at all): @table @code @findex OBJECT_FORMAT_COFF @@ -6393,6 +6442,14 @@ section. A C statement to output to the stdio stream @var{stream} an assembler command to advance the location counter to a multiple of 2 to the @var{power} bytes. @var{power} will be a C expression of type @code{int}. + +@findex ASM_OUTPUT_MAX_SKIP_ALIGN +@item ASM_OUTPUT_MAX_SKIP_ALIGN (@var{stream}, @var{power}, @var{max_skip}) +A C statement to output to the stdio stream @var{stream} an assembler +command to advance the location counter to a multiple of 2 to the +@var{power} bytes, but only if @var{max_skip} or fewer bytes are needed to +satisfy the alignment request. @var{power} and @var{max_skip} will be +a C expression of type @code{int}. @end table @need 3000 @@ -7551,7 +7608,7 @@ 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} +@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 |