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Re: [pooma-dev] Re: InlineEvaluator implementation question
From: |
Mark Mitchell |
Subject: |
Re: [pooma-dev] Re: InlineEvaluator implementation question |
Date: |
Mon, 16 Dec 2002 11:42:17 -0800 |
Hmm - as both, lhs and rhs are declared const, isnt this enough to tell
the compiler? Or has the compiler to assume every function call can have
a side-effect on any (but local) variable?
This is the classic "pointer aliasing" problem for compilers; the
modifications to lhs (via the write operatin in the loop) might,
from the compiler's point of view, change the rhs. The copies allow
a good compiler to tell that this cannot happen.
Well, at least gcc creates worse (larger) code with copying than without.
Yes; GCC has a ways to go in this regard.
--
Mark Mitchell address@hidden
CodeSourcery, LLC http://www.codesourcery.com