Patch to remove useless non_lvalue calls

[Joseph S. Myers]

On Fri, 15 Oct 2004, Tom Tromey wrote:

> I don't think gcj generates or uses NON_LVALUE_EXPR.  It is only
> mentioned in two places, and in both situations it is just treated
> identically to some other tree code.

Good, so it's just C and C++ that care about lvalue-ness of trees.  C I 
can readily fix.  C++ may be a bit more work to fix (and I wouldn't be 
particularly confident of any C++ patch I did for this being safe for 
4.0), but once these languages are fixed we can get rid of 
NON_LVALUE_EXPR, reduce the number of different conversion tree codes 
about, stop creating the unnecessary NON_LVALUE_EXPR tree nodes and avoid 
all the checks for this tree code.

-- 
Joseph S. Myers               http://www.srcf.ucam.org/~jsm28/gcc/
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