RealView Compilation Tools Compiler Reference Guide - ARM ...

Compiler Command-line Options
Default
If you do not specify an --apcs option, the compiler assumes
--apcs=/nointerwork/noropi/norwpi.
Usage
/[no]interwork
/[no]ropi
By default, code is generated:
• without interworking support, that is /nointerwork, unless
you specify a --cpu option that corresponds to architecture
ARMv5T or later
• with interworking support, that is /interwork, for ARMv5T
or later. This is because ARMv5T or later provides direct
interworking support.
If you select the /ropi qualifier to generate ROPI code, the
compiler:
• addresses read-only code and data PC-relative
• sets the Position Independent (PI) attribute on read-only
output sections.
Note
--apcs=/ropi is not supported when compiling C++.
/[no]rwpi
If you select the /rwpi qualifier to generate RWPI code, the
compiler:
• addresses writable data using offsets from the static base
register sb. This means that:
— the base address of the RW data region can be fixed at
runtime
— data can have multiple instances
— data can be, but does not have to be,
position-independent.
• sets the PI attribute on read/write output sections.
Note
Because the --lower_rwpi option is the default, code that is not
RWPI is automatically transformed into equivalent code that is
RWPI. This static initialization is done at runtime by the C++
constructor mechanism, even for C.
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