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Re: GCC 4.2.0 boostrap problems on FreeBSD/ia64


Alexander Kabaev <kabaev@gmail.com> writes:

> The instruction below appears to be the problematic one, but I cannot
> tell why:
>
> [MMI]  st8 [r16]=r17

This insn looks completely benign, I'd rather it's the next insn that is
the problem:

        chk.a.clr r14, .L1063

This is a speculation check (see
<http://download.intel.com/design/Itanium/manuals/24531905.pdf> for the
Itanium Instruction Set Descriptions).  The insn checks the result of a
preceding advanced load and branches to the label if the check failed.
The branching behaviour of the insn may be unimplemented, and would have
to be emulated in the kernel, but apparently FreeBSD doesn't support it.

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
PGP key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."


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