Compiler options

When you run GCC, you can use command-line options to choose machine-specific details. For information on all the GCC command-line options, see section `GNU CC Command Options' in Using GNU CC.

GCC options for architecture and code generation

-m1

Generate code for the Hitachi SH-1 chip. This is the default behavior for the Hitachi SH configuration.

-m2

Generate code for the Hitachi SH-2 chip.

-m3

Generate code for the Hitachi SH-3 chip.

-mfastcode

Generate fast code, rather than small code.

-msmallcode

Generate small code, rather than fast code.

-mnosave

Use a different calling convention. The registers `R8', `R9', `R10', and `R11' are all call-used with this setting (see section Calling conventions).

-mhitachi

Use Hitachi's calling convention rather than that for GCC. The registers `MACH' and `MACL' are saved with this setting (see section Calling conventions).

-mbsr

Use bsr calls to code backward-referenced within the function. Note: This may fail if the target is too far away.

-mshortaddr

Assume that all static data fits into 16 bits, and keep pointers to them in word-length rather than long-length pointers.

-mbigtable

Generate jump tables for switch statements using four-byte offsets rather than the standard two-byte offset. This option is necessary when the code within a switch statement is larger that 32k. If the option is needed and not supplied, the assembler will generate errors.

GCC options for floating point

Floating point subroutines

Two kinds of floating point subroutines are useful with GCC:

1. Software implementations of the basic functions (floating-point multiply, divide, add, subtract), for use when there is no hardware floating-point support.
2. General-purpose mathematical subroutines. The Developer's Kit from Cygnus Support includes an implementation of the standard C mathematical subroutine library. See section `Mathematical Functions' in The Cygnus C Math Library.