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There is a number of enviromental variables that can be used when
running SDCC to enable certain optimizations or force a specific program
behaviour. these variables are primarily for debugging purposes so
they can be enabled/disabled at will.
Currently there is only two such variables available:
- OPTIMIZE_BITFIELD_POINTER_GET
- When this variable exists, reading
of structure bitfields is optimized by directly loading FSR0 with
the address of the bitfield structure. Normally SDCC will cast the
bitfield structure to a bitfield pointer and then load FSR0. This
step saves data ram and code space for functions that make heavy use
of bitfields. (i.e., 80 bytes of code space are saved when compiling
malloc.c with this option).
- NO_REG_OPT
- Do not perform pCode registers optimization. This
should be used for debugging purposes. If bugs in the pcode optimizer
are found, users can benefit from temporarily disabling the optimizer
until the bug is fixed.
2008-12-05