Re: slow V3 configures (was Re: ICE during bootstrap.)

[Phil Edwards <pedwards at disaster dot jaj dot com>]

On Tue, Dec 05, 2000 at 11:53:57AM -0800, Benjamin Kosnik wrote:
>
> Following phil's advice and changing to
> 
>    test-for-cached-answer-oh-it's-there-never-mind
>    else
>      push-current-language-on-stack
>      set-current-language-to-C++
>      test and cache
>      pop-language-from-stack
>    end   
> 
> seems like the best approach.

The odd thing is...  this is what should be happening now.  All the
push-set-test-cache-pop stuff is done inside the list of commands "to be
run if the value isn't cached".  We still get serious pauses.

Anyhow, I patched all the math tests to explictly do the same test that
AC_CACHE_VAL does before calling AC_CACHE_VAL itself.  The speedup is
/considerable/.  The config.cache and bits/c++config.h results are identical.

One downside:  it's AC_CACHE_VAL that does the printing of "(cached)".
My change means that a cached value still shows on the screen as

    checking for _expf declaration... no
    checking for _fabsf declaration... no
    checking for _floorf declaration... no
    checking for _fmodf declaration... no
    checking for _frexpf declaration... no
    checking for _ldexpf declaration... no

etc, like regular tests.  Just a /lot/ faster.  :-)  This may not be
acceptable; what do y'all think?  I'm hesitant to try and use the $ac_*
variables controlling echo(1)'s no-newline behavior, for some reason.


Phil

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