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    SubjectRe: egcs 1.0.1 miscompiles Linux 2.0.33

    In message <199803091917.OAA22156@dcl.MIT.EDU>you write:
    > Could you please explain the syntax of an earlyclobber (I never
    > heard of it). I would undergo the task of patching Linux-Kernel's
    > asms, since I'd like to stop the debate about an EGCS/Kernel
    > mismatch. EGCS is a valuable project a nd compiling a kernel should
    > not delay using it.
    > Is someone in the EGCS project working on clarifying the documentation?
    > In the past few days, I've heard at least one EGCS developer admit that
    > the documentation is "ambiguous", and Linus's original position was that
    > he would gladly fix the Linux sources to match the _documented_
    > behaviour of GCC, and he then listed a few reasons why he thought the
    > existing GCC documentation supported his interpretation.
    I will update the egcs docs as soon as we've agreed on the technical
    details about how to handle these situations.

    I think we're close, but I don't want to start changing the docs then
    find out y'all don't agree with the direction I'm heading.

    > Some of the mail messages in this thread look like they would be fine
    > fodder for clarifying EGCS's documentation (in particular the mail
    > message I'm currently replying to --- please, put lots of detail and
    > example in the docs!! This current message was good that way.)
    I'd probably sit down a review all of this discussion before updating
    the docs. The key things off the top of my head that need updating:

    * Clarify that overlapping inputs and clobbers are wrong.

    * Clarify that a clobbered reg can not be used for an input
    operand or the address of any operand.

    * Clarify that earlyclobbered outputs with a matching input
    is the right way to handle this situation.

    * Clarify issues relating to the maximum number of registers
    that can be used in an asm.

    * Doc new switch (assuming that's the direction we want to go).

    > A conditional switch sounds like a good compromise. But IMHO getting
    > the documentation updated is just as important....
    Yup. It's the poor documentation that helped get us into this
    situation to start with :-)


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