* real.c (real_hash): New.
* real.h: Declare it.
* cse.c (canon_hash): Use it.
* cselib.c (hash_rtx): Likewise.
* emit-rtl.c (const_double_htab_hash): Likewise.
* rtl.h (CONST_DOUBLE_REAL_VALUE): New.
* varasm.c (struct rtx_const): Reduce vector size; separate
integer and fp vectors.
(HASHBITS): Remove.
(const_hash_1): Rename from const_hash. Use real_hash. Do not
take modulus MAX_HASH_TABLE.
(const_hash): New. Do take modulus MAX_HASH_TABLE.
(output_constant_def): Do not take modulus MAX_HASH_TABLE.
(SYMHASH): Don't use HASHBITS.
(decode_rtx_const): Copy only active bits from REAL_VALUE_TYPE.
Fix CONST_VECTOR thinko wrt fp vectors. Fix kind comparison.
(simplify_subtraction): Fix kind comparison.
(const_hash_rtx): Return unsigned int. Don't use HASHBITS.
Use a union to pun integer array.
* config/rs6000/rs6000.c (rs6000_hash_constant): Use real_hash;
only hash two words of integral CONST_DOUBLE.