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LEGITIMATE_CONSTANT_P



As it is now, LEGITIMATE_CONSTANT_P does not take any mode argument.
This is unfortunate, because sometimes the mode can make a lot of
difference:

On the x86, all floating point doubles (except 0. and 1.) are faster to
load from memory, so LEGITIMATE_CONSTANT_P rejects any CONST_DOUBLES
but 0. and 1. .
However, integer constants use CONST_DOUBLE too - even SImode if the
value is too large to be 32 bit signed.  now SImode constant are forced
into memory - that is indeed a slowdown.