3.17.4 Blackfin Options

-mcpu= cpu [ - sirevision ]

Specifies the name of the target Blackfin processor. Currently, cpu can be one of bf522, bf523, bf524, bf525, bf526, bf527, bf531, bf532, bf533, bf534, bf536, bf537, bf538, bf539, bf542, bf544, bf547, bf548, bf549, bf561. The optional sirevision specifies the silicon revision of the target Blackfin processor. Any workarounds available for the targeted silicon revision will be enabled. If sirevision is none, no workarounds are enabled. If sirevision is any, all workarounds for the targeted processor will be enabled. The __SILICON_REVISION__ macro is defined to two hexadecimal digits representing the major and minor numbers in the silicon revision. If sirevision is none, the __SILICON_REVISION__ is not defined. If sirevision is any, the __SILICON_REVISION__ is defined to be 0xffff. If this optional sirevision is not used, GCC assumes the latest known silicon revision of the targeted Blackfin processor.

Support for bf561 is incomplete. For bf561, Only the processor macro is defined. Without this option, bf532 is used as the processor by default. The corresponding predefined processor macros for cpu is to be defined. And for bfin-elf toolchain, this causes the hardware BSP provided by libgloss to be linked in if -msim is not given.

-msim

Specifies that the program will be run on the simulator. This causes the simulator BSP provided by libgloss to be linked in. This option has effect only for bfin-elf toolchain. Certain other options, such as -mid-shared-library and -mfdpic, imply -msim.

-momit-leaf-frame-pointer

Don't keep the frame pointer in a register for leaf functions. This avoids the instructions to save, set up and restore frame pointers and makes an extra register available in leaf functions. The option -fomit-frame-pointer removes the frame pointer for all functions which might make debugging harder.

-mspecld-anomaly

When enabled, the compiler will ensure that the generated code does not contain speculative loads after jump instructions. If this option is used, __WORKAROUND_SPECULATIVE_LOADS is defined.

-mno-specld-anomaly

Don't generate extra code to prevent speculative loads from occurring.

-mcsync-anomaly

When enabled, the compiler will ensure that the generated code does not contain CSYNC or SSYNC instructions too soon after conditional branches. If this option is used, __WORKAROUND_SPECULATIVE_SYNCS is defined.

-mno-csync-anomaly

Don't generate extra code to prevent CSYNC or SSYNC instructions from occurring too soon after a conditional branch.

-mlow-64k

When enabled, the compiler is free to take advantage of the knowledge that the entire program fits into the low 64k of memory.

-mno-low-64k

Assume that the program is arbitrarily large. This is the default.

-mstack-check-l1

Do stack checking using information placed into L1 scratchpad memory by the uClinux kernel.

-mid-shared-library

Generate code that supports shared libraries via the library ID method. This allows for execute in place and shared libraries in an environment without virtual memory management. This option implies -fPIC. With a bfin-elf target, this option implies -msim.

-mno-id-shared-library

Generate code that doesn't assume ID based shared libraries are being used. This is the default.

-mleaf-id-shared-library

Generate code that supports shared libraries via the library ID method, but assumes that this library or executable won't link against any other ID shared libraries. That allows the compiler to use faster code for jumps and calls.

-mno-leaf-id-shared-library

Do not assume that the code being compiled won't link against any ID shared libraries. Slower code will be generated for jump and call insns.

-mshared-library-id=n

Specified the identification number of the ID based shared library being compiled. Specifying a value of 0 will generate more compact code, specifying other values will force the allocation of that number to the current library but is no more space or time efficient than omitting this option.

-msep-data

Generate code that allows the data segment to be located in a different area of memory from the text segment. This allows for execute in place in an environment without virtual memory management by eliminating relocations against the text section.

-mno-sep-data

Generate code that assumes that the data segment follows the text segment. This is the default.

-mlong-calls

-mno-long-calls

Tells the compiler to perform function calls by first loading the address of the function into a register and then performing a subroutine call on this register. This switch is needed if the target function will lie outside of the 24 bit addressing range of the offset based version of subroutine call instruction.

This feature is not enabled by default. Specifying -mno-long-calls will restore the default behavior. Note these switches have no effect on how the compiler generates code to handle function calls via function pointers.

-mfast-fp

Link with the fast floating-point library. This library relaxes some of the IEEE floating-point standard's rules for checking inputs against Not-a-Number (NAN), in the interest of performance.

-minline-plt

Enable inlining of PLT entries in function calls to functions that are not known to bind locally. It has no effect without -mfdpic.