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898 lines
36 KiB
Plaintext
This is Info file gcc.info, produced by Makeinfo version 1.67 from the
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input file gcc.texi.
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This file documents the use and the internals of the GNU compiler.
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Published by the Free Software Foundation 59 Temple Place - Suite 330
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Boston, MA 02111-1307 USA
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Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998
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Free Software Foundation, Inc.
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Permission is granted to make and distribute verbatim copies of this
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manual provided the copyright notice and this permission notice are
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preserved on all copies.
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Permission is granted to copy and distribute modified versions of
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this manual under the conditions for verbatim copying, provided also
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that the sections entitled "GNU General Public License," "Funding for
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Free Software," and "Protect Your Freedom--Fight `Look And Feel'" are
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included exactly as in the original, and provided that the entire
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resulting derived work is distributed under the terms of a permission
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notice identical to this one.
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Permission is granted to copy and distribute translations of this
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manual into another language, under the above conditions for modified
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versions, except that the sections entitled "GNU General Public
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License," "Funding for Free Software," and "Protect Your Freedom--Fight
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`Look And Feel'", and this permission notice, may be included in
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translations approved by the Free Software Foundation instead of in the
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original English.
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File: gcc.info, Node: DEC Alpha Options, Next: Clipper Options, Prev: Intel 960 Options, Up: Submodel Options
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DEC Alpha Options
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-----------------
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These `-m' options are defined for the DEC Alpha implementations:
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`-mno-soft-float'
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`-msoft-float'
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Use (do not use) the hardware floating-point instructions for
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floating-point operations. When `-msoft-float' is specified,
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functions in `libgcc1.c' will be used to perform floating-point
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operations. Unless they are replaced by routines that emulate the
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floating-point operations, or compiled in such a way as to call
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such emulations routines, these routines will issue floating-point
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operations. If you are compiling for an Alpha without
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floating-point operations, you must ensure that the library is
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built so as not to call them.
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Note that Alpha implementations without floating-point operations
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are required to have floating-point registers.
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`-mfp-reg'
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`-mno-fp-regs'
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Generate code that uses (does not use) the floating-point register
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set. `-mno-fp-regs' implies `-msoft-float'. If the floating-point
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register set is not used, floating point operands are passed in
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integer registers as if they were integers and floating-point
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results are passed in $0 instead of $f0. This is a non-standard
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calling sequence, so any function with a floating-point argument
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or return value called by code compiled with `-mno-fp-regs' must
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also be compiled with that option.
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A typical use of this option is building a kernel that does not
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use, and hence need not save and restore, any floating-point
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registers.
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`-mieee'
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The Alpha architecture implements floating-point hardware
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optimized for maximum performance. It is mostly compliant with
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the IEEE floating point standard. However, for full compliance,
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software assistance is required. This option generates code fully
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IEEE compliant code *except* that the INEXACT FLAG is not
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maintained (see below). If this option is turned on, the CPP
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macro `_IEEE_FP' is defined during compilation. The option is a
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shorthand for: `-D_IEEE_FP -mfp-trap-mode=su -mtrap-precision=i
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-mieee-conformant'. The resulting code is less efficient but is
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able to correctly support denormalized numbers and exceptional
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IEEE values such as not-a-number and plus/minus infinity. Other
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Alpha compilers call this option `-ieee_with_no_inexact'.
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`-mieee-with-inexact'
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This is like `-mieee' except the generated code also maintains the
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IEEE INEXACT FLAG. Turning on this option causes the generated
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code to implement fully-compliant IEEE math. The option is a
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shorthand for `-D_IEEE_FP -D_IEEE_FP_INEXACT' plus the three
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following: `-mieee-conformant', `-mfp-trap-mode=sui', and
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`-mtrap-precision=i'. On some Alpha implementations the resulting
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code may execute significantly slower than the code generated by
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default. Since there is very little code that depends on the
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INEXACT FLAG, you should normally not specify this option. Other
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Alpha compilers call this option `-ieee_with_inexact'.
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`-mfp-trap-mode=TRAP MODE'
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This option controls what floating-point related traps are enabled.
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Other Alpha compilers call this option `-fptm 'TRAP MODE. The
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trap mode can be set to one of four values:
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`n'
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This is the default (normal) setting. The only traps that
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are enabled are the ones that cannot be disabled in software
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(e.g., division by zero trap).
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`u'
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In addition to the traps enabled by `n', underflow traps are
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enabled as well.
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`su'
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Like `su', but the instructions are marked to be safe for
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software completion (see Alpha architecture manual for
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details).
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`sui'
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Like `su', but inexact traps are enabled as well.
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`-mfp-rounding-mode=ROUNDING MODE'
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Selects the IEEE rounding mode. Other Alpha compilers call this
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option `-fprm 'ROUNDING MODE. The ROUNDING MODE can be one of:
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`n'
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Normal IEEE rounding mode. Floating point numbers are
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rounded towards the nearest machine number or towards the
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even machine number in case of a tie.
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`m'
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Round towards minus infinity.
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`c'
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Chopped rounding mode. Floating point numbers are rounded
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towards zero.
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`d'
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Dynamic rounding mode. A field in the floating point control
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register (FPCR, see Alpha architecture reference manual)
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controls the rounding mode in effect. The C library
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initializes this register for rounding towards plus infinity.
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Thus, unless your program modifies the FPCR, `d' corresponds
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to round towards plus infinity.
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`-mtrap-precision=TRAP PRECISION'
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In the Alpha architecture, floating point traps are imprecise.
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This means without software assistance it is impossible to recover
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from a floating trap and program execution normally needs to be
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terminated. GNU CC can generate code that can assist operating
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system trap handlers in determining the exact location that caused
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a floating point trap. Depending on the requirements of an
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application, different levels of precisions can be selected:
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`p'
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Program precision. This option is the default and means a
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trap handler can only identify which program caused a
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floating point exception.
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`f'
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Function precision. The trap handler can determine the
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function that caused a floating point exception.
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`i'
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Instruction precision. The trap handler can determine the
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exact instruction that caused a floating point exception.
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Other Alpha compilers provide the equivalent options called
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`-scope_safe' and `-resumption_safe'.
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`-mieee-conformant'
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This option marks the generated code as IEEE conformant. You must
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not use this option unless you also specify `-mtrap-precision=i'
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and either `-mfp-trap-mode=su' or `-mfp-trap-mode=sui'. Its only
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effect is to emit the line `.eflag 48' in the function prologue of
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the generated assembly file. Under DEC Unix, this has the effect
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that IEEE-conformant math library routines will be linked in.
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`-mbuild-constants'
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Normally GNU CC examines a 32- or 64-bit integer constant to see
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if it can construct it from smaller constants in two or three
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instructions. If it cannot, it will output the constant as a
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literal and generate code to load it from the data segment at
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runtime.
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Use this option to require GNU CC to construct *all* integer
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constants using code, even if it takes more instructions (the
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maximum is six).
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You would typically use this option to build a shared library
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dynamic loader. Itself a shared library, it must relocate itself
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in memory before it can find the variables and constants in its
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own data segment.
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`-malpha-as'
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`-mgas'
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Select whether to generate code to be assembled by the
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vendor-supplied assembler (`-malpha-as') or by the GNU assembler
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`-mgas'.
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`-mbwx'
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`-mno-bwx'
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`-mcix'
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`-mno-cix'
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`-mmax'
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`-mno-max'
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Indicate whether GNU CC should generate code to use the optional
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BWX, CIX, and MAX instruction sets. The default is to use the
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instruction sets supported by the CPU type specified via `-mcpu='
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option or that of the CPU on which GNU CC was built if none was
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specified.
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`-mcpu=CPU_TYPE'
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Set the instruction set, register set, and instruction scheduling
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parameters for machine type CPU_TYPE. You can specify either the
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`EV' style name or the corresponding chip number. GNU CC supports
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scheduling parameters for the EV4 and EV5 family of processors and
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will choose the default values for the instruction set from the
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processor you specify. If you do not specify a processor type,
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GNU CC will default to the processor on which the compiler was
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built.
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Supported values for CPU_TYPE are
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`ev4'
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`21064'
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Schedules as an EV4 and has no instruction set extensions.
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`ev5'
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`21164'
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Schedules as an EV5 and has no instruction set extensions.
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`ev56'
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`21164a'
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Schedules as an EV5 and supports the BWX extension.
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`pca56'
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`21164PC'
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Schedules as an EV5 and supports the BWX and MAX extensions.
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`ev6'
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`21264'
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Schedules as an EV5 (until Digital releases the scheduling
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parameters for the EV6) and supports the BWX, CIX, and MAX
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extensions.
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File: gcc.info, Node: Clipper Options, Next: H8/300 Options, Prev: DEC Alpha Options, Up: Submodel Options
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Clipper Options
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---------------
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These `-m' options are defined for the Clipper implementations:
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`-mc300'
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Produce code for a C300 Clipper processor. This is the default.
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`-mc400'
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Produce code for a C400 Clipper processor i.e. use floating point
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registers f8..f15.
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File: gcc.info, Node: H8/300 Options, Next: SH Options, Prev: Clipper Options, Up: Submodel Options
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H8/300 Options
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--------------
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These `-m' options are defined for the H8/300 implementations:
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`-mrelax'
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Shorten some address references at link time, when possible; uses
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the linker option `-relax'. *Note `ld' and the H8/300:
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(ld.info)H8/300, for a fuller description.
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`-mh'
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Generate code for the H8/300H.
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`-ms'
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Generate code for the H8/S.
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`-mint32'
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Make `int' data 32 bits by default.
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`-malign-300'
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On the h8/300h, use the same alignment rules as for the h8/300.
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The default for the h8/300h is to align longs and floats on 4 byte
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boundaries. `-malign-300' causes them to be aligned on 2 byte
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boundaries. This option has no effect on the h8/300.
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File: gcc.info, Node: SH Options, Next: System V Options, Prev: H8/300 Options, Up: Submodel Options
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SH Options
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----------
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These `-m' options are defined for the SH implementations:
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`-m1'
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Generate code for the SH1.
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`-m2'
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Generate code for the SH2.
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`-m3'
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Generate code for the SH3.
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`-m3e'
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Generate code for the SH3e.
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`-mb'
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Compile code for the processor in big endian mode.
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`-ml'
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Compile code for the processor in little endian mode.
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`-mrelax'
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Shorten some address references at link time, when possible; uses
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the linker option `-relax'.
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File: gcc.info, Node: System V Options, Next: V850 Options, Prev: SH Options, Up: Submodel Options
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Options for System V
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--------------------
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These additional options are available on System V Release 4 for
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compatibility with other compilers on those systems:
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`-G'
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Create a shared object. It is recommended that `-symbolic' or
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`-shared' be used instead.
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`-Qy'
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Identify the versions of each tool used by the compiler, in a
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`.ident' assembler directive in the output.
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`-Qn'
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Refrain from adding `.ident' directives to the output file (this is
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the default).
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`-YP,DIRS'
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Search the directories DIRS, and no others, for libraries
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specified with `-l'.
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`-Ym,DIR'
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Look in the directory DIR to find the M4 preprocessor. The
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assembler uses this option.
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File: gcc.info, Node: V850 Options, Prev: System V Options, Up: Submodel Options
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V850 Options
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------------
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These `-m' options are defined for V850 implementations:
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`-mlong-calls'
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`-mno-long-calls'
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Treat all calls as being far away (near). If calls are assumed to
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be far away, the compiler will always load the functions address
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up into a register, and call indirect through the pointer.
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`-mno-ep'
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`-mep'
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Do not optimize (do optimize) basic blocks that use the same index
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pointer 4 or more times to copy pointer into the `ep' register, and
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use the shorter `sld' and `sst' instructions. The `-mep' option
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is on by default if you optimize.
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`-mno-prolog-function'
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`-mprolog-function'
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Do not use (do use) external functions to save and restore
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registers at the prolog and epilog of a function. The external
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functions are slower, but use less code space if more than one
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function saves the same number of registers. The
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`-mprolog-function' option is on by default if you optimize.
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`-mspace'
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Try to make the code as small as possible. At present, this just
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turns on the `-mep' and `-mprolog-function' options.
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`-mtda=N'
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Put static or global variables whose size is N bytes or less into
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the tiny data area that register `ep' points to. The tiny data
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area can hold up to 256 bytes in total (128 bytes for byte
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references).
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`-msda=N'
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Put static or global variables whose size is N bytes or less into
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the small data area that register `gp' points to. The small data
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area can hold up to 64 kilobytes.
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`-mzda=N'
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Put static or global variables whose size is N bytes or less into
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the first 32 kilobytes of memory.
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`-mv850'
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Specify that the target processor is the V850.
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`-mbig-switch'
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Generate code suitable for big switch tables. Use this option
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only if the assembler/linker complain about out of range branches
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within a switch table.
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File: gcc.info, Node: Code Gen Options, Next: Environment Variables, Prev: Submodel Options, Up: Invoking GCC
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Options for Code Generation Conventions
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=======================================
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These machine-independent options control the interface conventions
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used in code generation.
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Most of them have both positive and negative forms; the negative form
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of `-ffoo' would be `-fno-foo'. In the table below, only one of the
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forms is listed--the one which is not the default. You can figure out
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the other form by either removing `no-' or adding it.
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`-fexceptions'
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Enable exception handling, and generate extra code needed to
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propagate exceptions. If you do not specify this option, GNU CC
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enables it by default for languages like C++ that normally require
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exception handling, and disabled for languages like C that do not
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normally require it. However, when compiling C code that needs to
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interoperate properly with exception handlers written in C++, you
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may need to enable this option. You may also wish to disable this
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option is you are compiling older C++ programs that don't use
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exception handling.
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`-fpcc-struct-return'
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Return "short" `struct' and `union' values in memory like longer
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||
ones, rather than in registers. This convention is less
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efficient, but it has the advantage of allowing intercallability
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between GNU CC-compiled files and files compiled with other
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compilers.
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The precise convention for returning structures in memory depends
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on the target configuration macros.
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Short structures and unions are those whose size and alignment
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match that of some integer type.
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`-freg-struct-return'
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Use the convention that `struct' and `union' values are returned
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in registers when possible. This is more efficient for small
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structures than `-fpcc-struct-return'.
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If you specify neither `-fpcc-struct-return' nor its contrary
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`-freg-struct-return', GNU CC defaults to whichever convention is
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standard for the target. If there is no standard convention, GNU
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CC defaults to `-fpcc-struct-return', except on targets where GNU
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CC is the principal compiler. In those cases, we can choose the
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standard, and we chose the more efficient register return
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alternative.
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`-fshort-enums'
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Allocate to an `enum' type only as many bytes as it needs for the
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declared range of possible values. Specifically, the `enum' type
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will be equivalent to the smallest integer type which has enough
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room.
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`-fshort-double'
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Use the same size for `double' as for `float'.
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`-fshared-data'
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||
Requests that the data and non-`const' variables of this
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||
compilation be shared data rather than private data. The
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||
distinction makes sense only on certain operating systems, where
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shared data is shared between processes running the same program,
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while private data exists in one copy per process.
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`-fno-common'
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||
Allocate even uninitialized global variables in the bss section of
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||
the object file, rather than generating them as common blocks.
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||
This has the effect that if the same variable is declared (without
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||
`extern') in two different compilations, you will get an error
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||
when you link them. The only reason this might be useful is if
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||
you wish to verify that the program will work on other systems
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||
which always work this way.
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||
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||
`-fno-ident'
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||
Ignore the `#ident' directive.
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||
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||
`-fno-gnu-linker'
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||
Do not output global initializations (such as C++ constructors and
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destructors) in the form used by the GNU linker (on systems where
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the GNU linker is the standard method of handling them). Use this
|
||
option when you want to use a non-GNU linker, which also requires
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||
using the `collect2' program to make sure the system linker
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||
includes constructors and destructors. (`collect2' is included in
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the GNU CC distribution.) For systems which *must* use
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||
`collect2', the compiler driver `gcc' is configured to do this
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||
automatically.
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||
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||
`-finhibit-size-directive'
|
||
Don't output a `.size' assembler directive, or anything else that
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||
would cause trouble if the function is split in the middle, and the
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||
two halves are placed at locations far apart in memory. This
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||
option is used when compiling `crtstuff.c'; you should not need to
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||
use it for anything else.
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||
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||
`-fverbose-asm'
|
||
Put extra commentary information in the generated assembly code to
|
||
make it more readable. This option is generally only of use to
|
||
those who actually need to read the generated assembly code
|
||
(perhaps while debugging the compiler itself).
|
||
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||
`-fno-verbose-asm', the default, causes the extra information to
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||
be omitted and is useful when comparing two assembler files.
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||
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||
`-fvolatile'
|
||
Consider all memory references through pointers to be volatile.
|
||
|
||
`-fvolatile-global'
|
||
Consider all memory references to extern and global data items to
|
||
be volatile.
|
||
|
||
`-fpic'
|
||
Generate position-independent code (PIC) suitable for use in a
|
||
shared library, if supported for the target machine. Such code
|
||
accesses all constant addresses through a global offset table
|
||
(GOT). The dynamic loader resolves the GOT entries when the
|
||
program starts (the dynamic loader is not part of GNU CC; it is
|
||
part of the operating system). If the GOT size for the linked
|
||
executable exceeds a machine-specific maximum size, you get an
|
||
error message from the linker indicating that `-fpic' does not
|
||
work; in that case, recompile with `-fPIC' instead. (These
|
||
maximums are 16k on the m88k, 8k on the Sparc, and 32k on the m68k
|
||
and RS/6000. The 386 has no such limit.)
|
||
|
||
Position-independent code requires special support, and therefore
|
||
works only on certain machines. For the 386, GNU CC supports PIC
|
||
for System V but not for the Sun 386i. Code generated for the IBM
|
||
RS/6000 is always position-independent.
|
||
|
||
`-fPIC'
|
||
If supported for the target machine, emit position-independent
|
||
code, suitable for dynamic linking and avoiding any limit on the
|
||
size of the global offset table. This option makes a difference
|
||
on the m68k, m88k, and the Sparc.
|
||
|
||
Position-independent code requires special support, and therefore
|
||
works only on certain machines.
|
||
|
||
`-ffixed-REG'
|
||
Treat the register named REG as a fixed register; generated code
|
||
should never refer to it (except perhaps as a stack pointer, frame
|
||
pointer or in some other fixed role).
|
||
|
||
REG must be the name of a register. The register names accepted
|
||
are machine-specific and are defined in the `REGISTER_NAMES' macro
|
||
in the machine description macro file.
|
||
|
||
This flag does not have a negative form, because it specifies a
|
||
three-way choice.
|
||
|
||
`-fcall-used-REG'
|
||
Treat the register named REG as an allocable register that is
|
||
clobbered by function calls. It may be allocated for temporaries
|
||
or variables that do not live across a call. Functions compiled
|
||
this way will not save and restore the register REG.
|
||
|
||
Use of this flag for a register that has a fixed pervasive role in
|
||
the machine's execution model, such as the stack pointer or frame
|
||
pointer, will produce disastrous results.
|
||
|
||
This flag does not have a negative form, because it specifies a
|
||
three-way choice.
|
||
|
||
`-fcall-saved-REG'
|
||
Treat the register named REG as an allocable register saved by
|
||
functions. It may be allocated even for temporaries or variables
|
||
that live across a call. Functions compiled this way will save
|
||
and restore the register REG if they use it.
|
||
|
||
Use of this flag for a register that has a fixed pervasive role in
|
||
the machine's execution model, such as the stack pointer or frame
|
||
pointer, will produce disastrous results.
|
||
|
||
A different sort of disaster will result from the use of this flag
|
||
for a register in which function values may be returned.
|
||
|
||
This flag does not have a negative form, because it specifies a
|
||
three-way choice.
|
||
|
||
`-fpack-struct'
|
||
Pack all structure members together without holes. Usually you
|
||
would not want to use this option, since it makes the code
|
||
suboptimal, and the offsets of structure members won't agree with
|
||
system libraries.
|
||
|
||
`-fcheck-memory-usage'
|
||
Generate extra code to check each memory access. GNU CC will
|
||
generate code that is suitable for a detector of bad memory
|
||
accesses such as `Checker'. If you specify this option, you can
|
||
not use the `asm' or `__asm__' keywords.
|
||
|
||
You must also specify this option when you compile functions you
|
||
call that have side effects. If you do not, you may get erroneous
|
||
messages from the detector. Normally, you should compile all
|
||
your code with this option. If you use functions from a library
|
||
that have side-effects (such as `read'), you may not be able to
|
||
recompile the library and specify this option. In that case, you
|
||
can enable the `-fprefix-function-name' option, which requests GNU
|
||
CC to encapsulate your code and make other functions look as if
|
||
they were compiled with `-fcheck-memory-usage'. This is done by
|
||
calling "stubs", which are provided by the detector. If you
|
||
cannot find or build stubs for every function you call, you may
|
||
have to specify `-fcheck-memory-usage' without
|
||
`-fprefix-function-name'.
|
||
|
||
`-fprefix-function-name'
|
||
Request GNU CC to add a prefix to the symbols generated for
|
||
function names. GNU CC adds a prefix to the names of functions
|
||
defined as well as functions called. Code compiled with this
|
||
option and code compiled without the option can't be linked
|
||
together, unless or stubs are used.
|
||
|
||
If you compile the following code with `-fprefix-function-name'
|
||
extern void bar (int);
|
||
void
|
||
foo (int a)
|
||
{
|
||
return bar (a + 5);
|
||
|
||
}
|
||
|
||
GNU CC will compile the code as if it was written:
|
||
extern void prefix_bar (int);
|
||
void
|
||
prefix_foo (int a)
|
||
{
|
||
return prefix_bar (a + 5);
|
||
}
|
||
This option is designed to be used with `-fcheck-memory-usage'.
|
||
|
||
`-fstack-check'
|
||
Generate code to verify that you do not go beyond the boundary of
|
||
the stack. You should specify this flag if you are running in an
|
||
environment with multiple threads, but only rarely need to specify
|
||
it in a single-threaded environment since stack overflow is
|
||
automatically detected on nearly all systems if there is only one
|
||
stack.
|
||
|
||
`+e0'
|
||
`+e1'
|
||
Control whether virtual function definitions in classes are used to
|
||
generate code, or only to define interfaces for their callers.
|
||
(C++ only).
|
||
|
||
These options are provided for compatibility with `cfront' 1.x
|
||
usage; the recommended alternative GNU C++ usage is in flux.
|
||
*Note Declarations and Definitions in One Header: C++ Interface.
|
||
|
||
With `+e0', virtual function definitions in classes are declared
|
||
`extern'; the declaration is used only as an interface
|
||
specification, not to generate code for the virtual functions (in
|
||
this compilation).
|
||
|
||
With `+e1', G++ actually generates the code implementing virtual
|
||
functions defined in the code, and makes them publicly visible.
|
||
|
||
|
||
File: gcc.info, Node: Environment Variables, Next: Running Protoize, Prev: Code Gen Options, Up: Invoking GCC
|
||
|
||
Environment Variables Affecting GNU CC
|
||
======================================
|
||
|
||
This section describes several environment variables that affect how
|
||
GNU CC operates. They work by specifying directories or prefixes to use
|
||
when searching for various kinds of files.
|
||
|
||
Note that you can also specify places to search using options such as
|
||
`-B', `-I' and `-L' (*note Directory Options::.). These take
|
||
precedence over places specified using environment variables, which in
|
||
turn take precedence over those specified by the configuration of GNU
|
||
CC. *Note Driver::.
|
||
|
||
`TMPDIR'
|
||
If `TMPDIR' is set, it specifies the directory to use for temporary
|
||
files. GNU CC uses temporary files to hold the output of one
|
||
stage of compilation which is to be used as input to the next
|
||
stage: for example, the output of the preprocessor, which is the
|
||
input to the compiler proper.
|
||
|
||
`GCC_EXEC_PREFIX'
|
||
If `GCC_EXEC_PREFIX' is set, it specifies a prefix to use in the
|
||
names of the subprograms executed by the compiler. No slash is
|
||
added when this prefix is combined with the name of a subprogram,
|
||
but you can specify a prefix that ends with a slash if you wish.
|
||
|
||
If GNU CC cannot find the subprogram using the specified prefix, it
|
||
tries looking in the usual places for the subprogram.
|
||
|
||
The default value of `GCC_EXEC_PREFIX' is `PREFIX/lib/gcc-lib/'
|
||
where PREFIX is the value of `prefix' when you ran the `configure'
|
||
script.
|
||
|
||
Other prefixes specified with `-B' take precedence over this
|
||
prefix.
|
||
|
||
This prefix is also used for finding files such as `crt0.o' that
|
||
are used for linking.
|
||
|
||
In addition, the prefix is used in an unusual way in finding the
|
||
directories to search for header files. For each of the standard
|
||
directories whose name normally begins with
|
||
`/usr/local/lib/gcc-lib' (more precisely, with the value of
|
||
`GCC_INCLUDE_DIR'), GNU CC tries replacing that beginning with the
|
||
specified prefix to produce an alternate directory name. Thus,
|
||
with `-Bfoo/', GNU CC will search `foo/bar' where it would
|
||
normally search `/usr/local/lib/bar'. These alternate directories
|
||
are searched first; the standard directories come next.
|
||
|
||
`COMPILER_PATH'
|
||
The value of `COMPILER_PATH' is a colon-separated list of
|
||
directories, much like `PATH'. GNU CC tries the directories thus
|
||
specified when searching for subprograms, if it can't find the
|
||
subprograms using `GCC_EXEC_PREFIX'.
|
||
|
||
`LIBRARY_PATH'
|
||
The value of `LIBRARY_PATH' is a colon-separated list of
|
||
directories, much like `PATH'. When configured as a native
|
||
compiler, GNU CC tries the directories thus specified when
|
||
searching for special linker files, if it can't find them using
|
||
`GCC_EXEC_PREFIX'. Linking using GNU CC also uses these
|
||
directories when searching for ordinary libraries for the `-l'
|
||
option (but directories specified with `-L' come first).
|
||
|
||
`C_INCLUDE_PATH'
|
||
`CPLUS_INCLUDE_PATH'
|
||
`OBJC_INCLUDE_PATH'
|
||
These environment variables pertain to particular languages. Each
|
||
variable's value is a colon-separated list of directories, much
|
||
like `PATH'. When GNU CC searches for header files, it tries the
|
||
directories listed in the variable for the language you are using,
|
||
after the directories specified with `-I' but before the standard
|
||
header file directories.
|
||
|
||
`DEPENDENCIES_OUTPUT'
|
||
If this variable is set, its value specifies how to output
|
||
dependencies for Make based on the header files processed by the
|
||
compiler. This output looks much like the output from the `-M'
|
||
option (*note Preprocessor Options::.), but it goes to a separate
|
||
file, and is in addition to the usual results of compilation.
|
||
|
||
The value of `DEPENDENCIES_OUTPUT' can be just a file name, in
|
||
which case the Make rules are written to that file, guessing the
|
||
target name from the source file name. Or the value can have the
|
||
form `FILE TARGET', in which case the rules are written to file
|
||
FILE using TARGET as the target name.
|
||
|
||
|
||
File: gcc.info, Node: Running Protoize, Prev: Environment Variables, Up: Invoking GCC
|
||
|
||
Running Protoize
|
||
================
|
||
|
||
The program `protoize' is an optional part of GNU C. You can use it
|
||
to add prototypes to a program, thus converting the program to ANSI C
|
||
in one respect. The companion program `unprotoize' does the reverse:
|
||
it removes argument types from any prototypes that are found.
|
||
|
||
When you run these programs, you must specify a set of source files
|
||
as command line arguments. The conversion programs start out by
|
||
compiling these files to see what functions they define. The
|
||
information gathered about a file FOO is saved in a file named `FOO.X'.
|
||
|
||
After scanning comes actual conversion. The specified files are all
|
||
eligible to be converted; any files they include (whether sources or
|
||
just headers) are eligible as well.
|
||
|
||
But not all the eligible files are converted. By default,
|
||
`protoize' and `unprotoize' convert only source and header files in the
|
||
current directory. You can specify additional directories whose files
|
||
should be converted with the `-d DIRECTORY' option. You can also
|
||
specify particular files to exclude with the `-x FILE' option. A file
|
||
is converted if it is eligible, its directory name matches one of the
|
||
specified directory names, and its name within the directory has not
|
||
been excluded.
|
||
|
||
Basic conversion with `protoize' consists of rewriting most function
|
||
definitions and function declarations to specify the types of the
|
||
arguments. The only ones not rewritten are those for varargs functions.
|
||
|
||
`protoize' optionally inserts prototype declarations at the
|
||
beginning of the source file, to make them available for any calls that
|
||
precede the function's definition. Or it can insert prototype
|
||
declarations with block scope in the blocks where undeclared functions
|
||
are called.
|
||
|
||
Basic conversion with `unprotoize' consists of rewriting most
|
||
function declarations to remove any argument types, and rewriting
|
||
function definitions to the old-style pre-ANSI form.
|
||
|
||
Both conversion programs print a warning for any function
|
||
declaration or definition that they can't convert. You can suppress
|
||
these warnings with `-q'.
|
||
|
||
The output from `protoize' or `unprotoize' replaces the original
|
||
source file. The original file is renamed to a name ending with
|
||
`.save'. If the `.save' file already exists, then the source file is
|
||
simply discarded.
|
||
|
||
`protoize' and `unprotoize' both depend on GNU CC itself to scan the
|
||
program and collect information about the functions it uses. So
|
||
neither of these programs will work until GNU CC is installed.
|
||
|
||
Here is a table of the options you can use with `protoize' and
|
||
`unprotoize'. Each option works with both programs unless otherwise
|
||
stated.
|
||
|
||
`-B DIRECTORY'
|
||
Look for the file `SYSCALLS.c.X' in DIRECTORY, instead of the
|
||
usual directory (normally `/usr/local/lib'). This file contains
|
||
prototype information about standard system functions. This option
|
||
applies only to `protoize'.
|
||
|
||
`-c COMPILATION-OPTIONS'
|
||
Use COMPILATION-OPTIONS as the options when running `gcc' to
|
||
produce the `.X' files. The special option `-aux-info' is always
|
||
passed in addition, to tell `gcc' to write a `.X' file.
|
||
|
||
Note that the compilation options must be given as a single
|
||
argument to `protoize' or `unprotoize'. If you want to specify
|
||
several `gcc' options, you must quote the entire set of
|
||
compilation options to make them a single word in the shell.
|
||
|
||
There are certain `gcc' arguments that you cannot use, because they
|
||
would produce the wrong kind of output. These include `-g', `-O',
|
||
`-c', `-S', and `-o' If you include these in the
|
||
COMPILATION-OPTIONS, they are ignored.
|
||
|
||
`-C'
|
||
Rename files to end in `.C' instead of `.c'. This is convenient
|
||
if you are converting a C program to C++. This option applies
|
||
only to `protoize'.
|
||
|
||
`-g'
|
||
Add explicit global declarations. This means inserting explicit
|
||
declarations at the beginning of each source file for each function
|
||
that is called in the file and was not declared. These
|
||
declarations precede the first function definition that contains a
|
||
call to an undeclared function. This option applies only to
|
||
`protoize'.
|
||
|
||
`-i STRING'
|
||
Indent old-style parameter declarations with the string STRING.
|
||
This option applies only to `protoize'.
|
||
|
||
`unprotoize' converts prototyped function definitions to old-style
|
||
function definitions, where the arguments are declared between the
|
||
argument list and the initial `{'. By default, `unprotoize' uses
|
||
five spaces as the indentation. If you want to indent with just
|
||
one space instead, use `-i " "'.
|
||
|
||
`-k'
|
||
Keep the `.X' files. Normally, they are deleted after conversion
|
||
is finished.
|
||
|
||
`-l'
|
||
Add explicit local declarations. `protoize' with `-l' inserts a
|
||
prototype declaration for each function in each block which calls
|
||
the function without any declaration. This option applies only to
|
||
`protoize'.
|
||
|
||
`-n'
|
||
Make no real changes. This mode just prints information about the
|
||
conversions that would have been done without `-n'.
|
||
|
||
`-N'
|
||
Make no `.save' files. The original files are simply deleted.
|
||
Use this option with caution.
|
||
|
||
`-p PROGRAM'
|
||
Use the program PROGRAM as the compiler. Normally, the name `gcc'
|
||
is used.
|
||
|
||
`-q'
|
||
Work quietly. Most warnings are suppressed.
|
||
|
||
`-v'
|
||
Print the version number, just like `-v' for `gcc'.
|
||
|
||
If you need special compiler options to compile one of your program's
|
||
source files, then you should generate that file's `.X' file specially,
|
||
by running `gcc' on that source file with the appropriate options and
|
||
the option `-aux-info'. Then run `protoize' on the entire set of
|
||
files. `protoize' will use the existing `.X' file because it is newer
|
||
than the source file. For example:
|
||
|
||
gcc -Dfoo=bar file1.c -aux-info
|
||
protoize *.c
|
||
|
||
You need to include the special files along with the rest in the
|
||
`protoize' command, even though their `.X' files already exist, because
|
||
otherwise they won't get converted.
|
||
|
||
*Note Protoize Caveats::, for more information on how to use
|
||
`protoize' successfully.
|
||
|