* expr.c (expr): Move code setting "retval" to the end of the loop,
and rearrange for efficiency. For "PIC code" subtraction, use
"rightseg" rather than recalculating. For "symbol OP symbol"
subtract, set "retval" to absolute_section if symbols in same
section.
* symbols.c (resolve_symbol_value): Resolve "sym +/- expr" to an
O_symbol. Simplify a +/- b code. Allow equality and non-equality
comparisons on symbols from any section. Allow other comparison
operators as for subtraction.
(symbol_equated_reloc_p): New predicate function.
* symbols.h (symbol_equated_reloc_p): Declare.
* write.c (adjust_reloc_syms): Use symbol_equated_reloc_p.
(write_relocs): Likewise.
(write_object_file): Likewise.
(relax_segment <rs_machine_dependent>): Ensure segment for
expression syms is set correctly.
* config/tc-mips.c (md_estimate_size_before_relax): Likewise.
* config/tc-i386.c (md_assemble <Output jumps>): Don't lose part
of a complex expression when setting up frag_var.