Re: [avr-gcc-list] possible 4.1.2 bug

[Joerg Wunsch]

John Regehr <address@hidden> wrote:

> Doh.  I figured that this sort of constraint would be implicit from
> the instructions used.

Inline asm is just like expanding a macro to the compiler: the actual
contents of the assembly is opaque to the compiler, it only performs
parameter replacement on it.  The constraints are thus telling the
compiler about what the parameters actually have to look like.

The advantage of that scheme is that you can implement virtually
anything as an opaque block of machine code, yet still benefit from
the normal operand allocation the compiler is using internally anyway
(including all possible optimizations on the operands).

-- 
cheers, J"org               .-.-.   --... ...--   -.. .  DL8DTL

http://www.sax.de/~joerg/                        NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)