Patch to purify some functions.

[Mark Mitchell]

Jan --

  I've been profiling the compiler a lot lately.  I haven't seen most
of those functions to be hot spots.

  And adding the attribute is risky: someone might forget that the
attribute is there, and add something non-pure to the function.  Then,
months later something will go awry and it will take a lot of work to
track it down.

  In the end, we want to do interprocedural and whole-program
analysis.  The compiler should figure out those functions are pure and
use that during optimization.  For now, I would just do nothing --
unless you can that the changes make a substantial difference in
compile-time performance, or a huge difference in space.

--
Mark Mitchell                   mark@codesourcery.com
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