Using the GNU Compiler Collection (GCC): V850 Options

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3.18.50 V850 Options

These ‘-m’ options are defined for V850 implementations:

-mlong-calls
-mno-long-calls

Treat all calls as being far away (near). If calls are assumed to be far away, the compiler always loads the function’s address into a register, and calls indirect through the pointer.

-mno-ep
-mep

Do not optimize (do optimize) basic blocks that use the same index pointer 4 or more times to copy pointer into the ep register, and use the shorter sld and sst instructions. The -mep option is on by default if you optimize.

-mno-prolog-function
-mprolog-function

Do not use (do use) external functions to save and restore registers at the prologue and epilogue of a function. The external functions are slower, but use less code space if more than one function saves the same number of registers. The -mprolog-function option is on by default if you optimize.

-mspace

Try to make the code as small as possible. At present, this just turns on the -mep and -mprolog-function options.

-mtda=n

Put static or global variables whose size is n bytes or less into the tiny data area that register ep points to. The tiny data area can hold up to 256 bytes in total (128 bytes for byte references).

-msda=n

Put static or global variables whose size is n bytes or less into the small data area that register gp points to. The small data area can hold up to 64 kilobytes.

-mzda=n

Put static or global variables whose size is n bytes or less into the first 32 kilobytes of memory.

-mv850

Specify that the target processor is the V850.

-mv850e3v5

Specify that the target processor is the V850E3V5. The preprocessor constant __v850e3v5__ is defined if this option is used.

-mv850e2v4

Specify that the target processor is the V850E3V5. This is an alias for the -mv850e3v5 option.

-mv850e2v3

Specify that the target processor is the V850E2V3. The preprocessor constant __v850e2v3__ is defined if this option is used.

-mv850e2

Specify that the target processor is the V850E2. The preprocessor constant __v850e2__ is defined if this option is used.

-mv850e1

Specify that the target processor is the V850E1. The preprocessor constants __v850e1__ and __v850e__ are defined if this option is used.

-mv850es

Specify that the target processor is the V850ES. This is an alias for the -mv850e1 option.

-mv850e

Specify that the target processor is the V850E. The preprocessor constant __v850e__ is defined if this option is used.

If neither -mv850 nor -mv850e nor -mv850e1 nor -mv850e2 nor -mv850e2v3 nor -mv850e3v5 are defined then a default target processor is chosen and the relevant ‘__v850*__’ preprocessor constant is defined.

The preprocessor constants __v850 and __v851__ are always defined, regardless of which processor variant is the target.

-mdisable-callt
-mno-disable-callt

This option suppresses generation of the CALLT instruction for the v850e, v850e1, v850e2, v850e2v3 and v850e3v5 flavors of the v850 architecture.

This option is enabled by default when the RH850 ABI is in use (see -mrh850-abi), and disabled by default when the GCC ABI is in use. If CALLT instructions are being generated then the C preprocessor symbol __V850_CALLT__ is defined.

-mrelax
-mno-relax

Pass on (or do not pass on) the -mrelax command-line option to the assembler.

-mlong-jumps
-mno-long-jumps

Disable (or re-enable) the generation of PC-relative jump instructions.

-msoft-float
-mhard-float

Disable (or re-enable) the generation of hardware floating point instructions. This option is only significant when the target architecture is ‘V850E2V3’ or higher. If hardware floating point instructions are being generated then the C preprocessor symbol __FPU_OK__ is defined, otherwise the symbol __NO_FPU__ is defined.

-mloop

Enables the use of the e3v5 LOOP instruction. The use of this instruction is not enabled by default when the e3v5 architecture is selected because its use is still experimental.

-mrh850-abi
-mghs

Enables support for the RH850 version of the V850 ABI. This is the default. With this version of the ABI the following rules apply:

  • Integer sized structures and unions are returned via a memory pointer rather than a register.
  • Large structures and unions (more than 8 bytes in size) are passed by value.
  • Functions are aligned to 16-bit boundaries.
  • The -m8byte-align command-line option is supported.
  • The -mdisable-callt command-line option is enabled by default. The -mno-disable-callt command-line option is not supported.

When this version of the ABI is enabled the C preprocessor symbol __V850_RH850_ABI__ is defined.

-mgcc-abi

Enables support for the old GCC version of the V850 ABI. With this version of the ABI the following rules apply:

  • Integer sized structures and unions are returned in register r10.
  • Large structures and unions (more than 8 bytes in size) are passed by reference.
  • Functions are aligned to 32-bit boundaries, unless optimizing for size.
  • The -m8byte-align command-line option is not supported.
  • The -mdisable-callt command-line option is supported but not enabled by default.

When this version of the ABI is enabled the C preprocessor symbol __V850_GCC_ABI__ is defined.

-m8byte-align
-mno-8byte-align

Enables support for double and long long types to be aligned on 8-byte boundaries. The default is to restrict the alignment of all objects to at most 4-bytes. When -m8byte-align is in effect the C preprocessor symbol __V850_8BYTE_ALIGN__ is defined.

-mbig-switch

Generate code suitable for big switch tables. Use this option only if the assembler/linker complain about out of range branches within a switch table.

-mapp-regs

This option causes r2 and r5 to be used in the code generated by the compiler. This setting is the default.

-mno-app-regs

This option causes r2 and r5 to be treated as fixed registers.

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