>Precisely, and my objection to Andrea's patch was that it just disabled more
>optimisations, again to hide the bug.
Hmm, Philip you _could_ be right.
>Andrea wrote:
>
>>What I think is that the optimization code I commented out is buggy and
>>the bug is triggered by the regparm attribute.
>
>I think it's more subtle than that. The bug is not in the optimisations per
>se, it's in the register allocator and just happens to be provoked more often
>by higher optimisation (particularly when regparm is in use, because that
>increases register pressure significantly near function calls).
Are you sure? Did you tried it in practice? I thought that was the RTL
code generated by the optimization function (not arch dependent) that was
buggy:
GOOD RTL -> buggy optimization function -> BAD RTL
The RTL is arch indipendent.
As you say it could be also that:
GOOD RTL -> not buggy optimization function -> GOOD RTL 2
and that:
GOOD RTL -> buggy asm generator -> GOOD ASM
GOOD RTL 2 -> buggy asm generator -> BAD ASM
It should be trivial to understand this for a gcc hacker (it' s not for me
;-).
Andrea[s] Arcangeli
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