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Re: [m68k] Fix and improve ColdFire function prologue/epiloguegeneration (respin)
Bernardo Innocenti <bernie@develer.com> writes:
> Another odd thing about EH problems. The m68k backend defines this
> macro:
>
> /* Describe how we implement __builtin_eh_return. */
> #define EH_RETURN_DATA_REGNO(N) \
> ((N) < 2 ? (N) : INVALID_REGNUM)
>
>
> But docs I've read explicitly say that it must _NOT_ use scratch
> registers:
Were did you read that?
`EH_RETURN_DATA_REGNO (N)'
A C expression whose value is the Nth register number used for
data by exception handlers, or `INVALID_REGNUM' if fewer than N
registers are usable.
The exception handling library routines communicate with the
exception handlers via a set of agreed upon registers. Ideally
these registers should be call-clobbered; it is possible to use
call-saved registers, but may negatively impact code size. The
target must support at least 2 data registers, but should define 4
if there are enough free registers.
Andreas.
--
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux AG, Deutschherrnstr. 15-19, D-90429 Nürnberg
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