Messages in this thread | | | Date | Mon, 24 Aug 1998 15:12:54 +0200 (CEST) | From | Andrea Arcangeli <> | Subject | Re: pre egcs-1.1 testing and Linux 2.1.x |
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On Mon, 24 Aug 1998, Philip Blundell wrote:
>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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