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These are the `-m' options defined for the S/390 and zSeries architecture.
-mhard-float
-msoft-float
-mhard-dfp
-mno-hard-dfp
-mlong-double-64
-mlong-double-128
long double
type. A size
of 64bit makes the long double
type equivalent to the double
type. This is the default.
-mbackchain
-mno-backchain
In general, code compiled with -mbackchain is call-compatible with code compiled with -mmo-backchain; however, use of the backchain for debugging purposes usually requires that the whole binary is built with -mbackchain. Note that the combination of -mbackchain, -mpacked-stack and -mhard-float is not supported. In order to build a linux kernel use -msoft-float.
The default is to not maintain the backchain.
-mpacked-stack
-mno-packed-stack
As long as the stack frame backchain is not used, code generated with -mpacked-stack is call-compatible with code generated with -mno-packed-stack. Note that some non-FSF releases of GCC 2.95 for S/390 or zSeries generated code that uses the stack frame backchain at run time, not just for debugging purposes. Such code is not call-compatible with code compiled with -mpacked-stack. Also, note that the combination of -mbackchain, -mpacked-stack and -mhard-float is not supported. In order to build a linux kernel use -msoft-float.
The default is to not use the packed stack layout.
-msmall-exec
-mno-small-exec
bras
instruction
to do subroutine calls.
This only works reliably if the total executable size does not
exceed 64k. The default is to use the basr
instruction instead,
which does not have this limitation.
-m64
-m31
-mzarch
-mesa
-mmvcle
-mno-mvcle
mvcle
instruction
to perform block moves. When -mno-mvcle is specified,
use a mvc
loop instead. This is the default unless optimizing for
size.
-mdebug
-mno-debug
-march=
cpu-type-mtune=
cpu-type-mtpf-trace
-mno-tpf-trace
-mfused-madd
-mno-fused-madd
-mwarn-framesize=
framesize-mwarn-dynamicstack
-mstack-guard=
stack-guard-mstack-size=
stack-size