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(as.info)CRIS-Pic

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Symbols in position-independent code
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   When generating position-independent code (SVR4 PIC) for use in
cris-axis-linux-gnu shared libraries, symbol suffixes are used to
specify what kind of run-time symbol lookup will be used, expressed in
the object as different _relocation types_.  Usually, all absolute
symbol values must be located in a table, the _global offset table_,
leaving the code position-independent; independent of values of global
symbols and independent of the address of the code.  The suffix
modifies the value of the symbol, into for example an index into the
global offset table where the real symbol value is entered, or a
PC-relative value, or a value relative to the start of the global
offset table.  All symbol suffixes start with the character `:'
(omitted in the list below).  Every symbol use in code or a read-only
section must therefore have a PIC suffix to enable a useful shared
library to be created.  Usually, these constructs must not be used with
an additive constant offset as is usually allowed, i.e. no 4 as in
`symbol + 4' is allowed.  This restriction is checked at link-time, not
at assembly-time.

`GOT'
     Attaching this suffix to a symbol in an instruction causes the
     symbol to be entered into the global offset table.  The value is a
     32-bit index for that symbol into the global offset table.  The
     name of the corresponding relocation is `R_CRIS_32_GOT'.  Example:
     `move.d [$r0+extsym:GOT],$r9'

`GOT16'
     Same as for `GOT', but the value is a 16-bit index into the global
     offset table.  The corresponding relocation is `R_CRIS_16_GOT'.
     Example: `move.d [$r0+asymbol:GOT16],$r10'

`PLT'
     This suffix is used for function symbols.  It causes a _procedure
     linkage table_, an array of code stubs, to be created at the time
     the shared object is created or linked against, together with a
     global offset table entry.  The value is a pc-relative offset to
     the corresponding stub code in the procedure linkage table.  This
     arrangement causes the run-time symbol resolver to be called to
     look up and set the value of the symbol the first time the
     function is called (at latest; depending environment variables).
     It is only safe to leave the symbol unresolved this way if all
     references are function calls.  The name of the relocation is
     `R_CRIS_32_PLT_PCREL'.  Example: `add.d fnname:PLT,$pc'

`PLTG'
     Like PLT, but the value is relative to the beginning of the global
     offset table.  The relocation is `R_CRIS_32_PLT_GOTREL'.  Example:
     `move.d fnname:PLTG,$r3'

`GOTPLT'
     Similar to `PLT', but the value of the symbol is a 32-bit index
     into the global offset table.  This is somewhat of a mix between
     the effect of the `GOT' and the `PLT' suffix; the difference to
     `GOT' is that there will be a procedure linkage table entry
     created, and that the symbol is assumed to be a function entry and
     will be resolved by the run-time resolver as with `PLT'.  The
     relocation is `R_CRIS_32_GOTPLT'.  Example: `jsr
     [$r0+fnname:GOTPLT]'

`GOTPLT16'
     A variant of `GOTPLT' giving a 16-bit value.  Its relocation name
     is `R_CRIS_16_GOTPLT'.  Example: `jsr [$r0+fnname:GOTPLT16]'

`GOTOFF'
     This suffix must only be attached to a local symbol, but may be
     used in an expression adding an offset.  The value is the address
     of the symbol relative to the start of the global offset table.
     The relocation name is `R_CRIS_32_GOTREL'.  Example: `move.d
     [$r0+localsym:GOTOFF],r3'