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Diffstat (limited to 'gcc/doc/invoke.texi')
| -rw-r--r-- | gcc/doc/invoke.texi | 119 |
1 files changed, 118 insertions, 1 deletions
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index 7b20ced5483..b45df833f2e 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -783,6 +783,16 @@ See RS/6000 and PowerPC Options. -msim -mmvme -mads -myellowknife -memb -msdata @gol -msdata=@var{opt} -mvxworks -G @var{num} -pthread} +@emph{RX Options} +@gccoptlist{-m64bit-doubles -m32bit-doubles -mieee -mno-ieee@gol +-mbig-endian-data -mlittle-endian-data @gol +-msmall-data @gol +-msim -mno-sim@gol +-mas100-syntax -mno-as100-syntax@gol +-mrelax@gol +-mmax-constant-size=@gol +-mint-register=} + @emph{S/390 and zSeries Options} @gccoptlist{-mtune=@var{cpu-type} -march=@var{cpu-type} @gol -mhard-float -msoft-float -mhard-dfp -mno-hard-dfp @gol @@ -9530,6 +9540,7 @@ platform. * picoChip Options:: * PowerPC Options:: * RS/6000 and PowerPC Options:: +* RX Options:: * S/390 and zSeries Options:: * Score Options:: * SH Options:: @@ -10943,7 +10954,7 @@ These @samp{-m} options are defined for the DEC Alpha/VMS implementations: @table @gcctabopt @item -mvms-return-codes @opindex mvms-return-codes -Return VMS condition codes from main. The default is to return POSIX +Return VMS condition codes from main. The default is to return POSIX style condition (e.g.@: error) codes. @item -mdebug-main=@var{prefix} @@ -15362,6 +15373,112 @@ This option sets flags for both the preprocessor and linker. @end table +@node RX Options +@subsection RX Options +@cindex RX Options + +These @option{-m} options are defined for RX implementations: + +@table @gcctabopt +@item -m64bit-doubles +@itemx -m32bit-doubles +@opindex m64bit-doubles +@opindex m32bit-doubles +Make the @code{double} data type be 64-bits (@option{-m64bit-doubles}) +or 32-bits (@option{-m32bit-doubles}) in size. The default is +@option{-m32bit-doubles}. @emph{Note} the RX's hardware floating +point instructions are only used for 32-bit floating point values, and +then only if @option{-ffast-math} has been specified on the command +line. This is because the RX FPU instructions do not properly support +denormal (or sub-normal) values. + +@item -mbig-endian-data +@itemx -mlittle-endian-data +@opindex mbig-endian-data +@opindex mlittle-endian-data +Store data (but not code) in the big-endian format. The default is +@option{-mlittle-endian-data}, ie to store data in the little endian +format. + +@item -msmall-data-limit=@var{N} +@opindex msmall-data-limit +Specifies the maximum size in bytes of global and static variables +which can be placed into the small data area. Using the small data +area can lead to smaller and faster code, but the size of area is +limited and it is up to the programmer to ensure that the area does +not overflow. Also when the small data area is used one of the RX's +registers (@code{r13}) is reserved for use pointing to this area, so +it is no longer available for use by the compiler. This could result +in slower and/or larger code if variables which once could have been +held in @code{r13} are now pushed onto the stack. + +Note, common variables (variables which have not been initialised) and +constants are not placed into the small data area as they are assigned +to other sections in the output executeable. + +The default value is zero, which disables this feature. Note, this +feature is not enabled by default with higher optimization levels +(@option{-O2} etc) because of the potentially deterimental effects of +reserving register @code{r13}. It is up to the programmer to +experiment and discover whether this feature is of benefit to their +program. + +@item -msim +@item -mno-sim +@opindex msim +@opindex mno-sim +Use the simulator runtime. The default is to use the libgloss board +specific runtime. + +@item -mas100-syntax +@item -mno-as100-syntax +@opindex mas100-syntax +@opindex mno-as100-syntax +When generating assembler output use a syntax that is compatible with +Renesas's AS100 assembler. This syntax can also be handled by the GAS +assembler but it has some restrictions so generating it is not the +default option. + +@item -mmax-constant-size=@var{N} +@opindex mmax-constant-size +Specifies the maxium size, in bytes, of a constant that can be used as +an operand in a RX instruction. Although the RX instruction set does +allow consants of up to 4 bytes in length to be used in instructions, +a longer value equates to a longer instruction. Thus in some +circumstances it can be beneficial to restrict the size of constants +that are used in instructions. Constants that are too big are instead +placed into a constant pool and referenced via register indirection. + +The value @var{N} can be between 0 and 3. A value of 0, the default, +means that constants of any size are allowed. + +@item -mrelax +@opindex mrelax +Enable linker relaxation. Linker relaxation is a process whereby the +linker will attempt to reduce the size of a program by finding shorter +versions of various instructions. Disabled by default. + +@item -mint-register=@var{N} +@opindex mint-register +Specify the number of registers to reserve for fast interrupt handler +functions. The value @var{N} can be between 0 and 4. A value of 1 +means that register @code{r13} will be reserved for ther exclusive use +of fast interrupt handlers. A value of 2 reserves @code{r13} and +@code{r12}. A value of 3 reserves @code{r13}, @code{r12} and +@code{r11}, and a value of 4 reserves @code{r13} through @code{r10}. +A value of 0, the default, does not reserve any registers. +@end table + +@emph{Note:} The generic GCC command line @option{-ffixed-@var{reg}} +has special significance to the RX port when used with the +@code{interrupt} function attribute. This attribute indicates a +function intended to process fast interrupts. GCC will will ensure +that it only uses the registers @code{r10}, @code{r11}, @code{r12} +and/or @code{r13} and only provided that the normal use of the +corresponding registers have been restricted via the +@option{-ffixed-@var{reg}} or @option{-mint-register} command line +options. + @node S/390 and zSeries Options @subsection S/390 and zSeries Options @cindex S/390 and zSeries Options |