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<h3 class="section">10.9 Language-dependent trees</h3>
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Front ends may wish to keep some state associated with various GENERIC
trees while parsing. To support this, trees provide a set of flags
that may be used by the front end. They are accessed using
<code>TREE_LANG_FLAG_n</code> where ‘<samp><span class="samp">n</span></samp>’ is currently 0 through 6.
<p>If necessary, a front end can use some language-dependent tree
codes in its GENERIC representation, so long as it provides a
hook for converting them to GIMPLE and doesn't expect them to
work with any (hypothetical) optimizers that run before the
conversion to GIMPLE. The intermediate representation used while
parsing C and C++ looks very little like GENERIC, but the C and
C++ gimplifier hooks are perfectly happy to take it as input and
spit out GIMPLE.
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