Hello,

This patch improves reassociation folding for comparision. It expands
expressions within binary-AND/OR expression like (X | Y) == 0 to (X ==
0 && Y == 0)
and (X | Y) != 0 to (X != 0 || Y != 0).  This is necessary to allow
better reassociation
on weak pre-folded logical expressions.  This unfolding gets undone
anyway later by pass,
so no disadvantage gets introduced.
Also while going through BB-list, it tries to do some little
type-sinking for SSA sequences
like "D1 = (type) bool1; D2 = (type) bool2; D3 = D1 & D2;' to 'D1 =
bool1 & bool2; D2 = (type) D1;'.
This folding has the advantage to see better through intermediate
results with none-boolean type.
The function eliminate_redundant_comparison () got reworded so, that
doesn't break in all cases.
It now continues to find duplicates and tries to find inverse variant
(folded to constant). By this
change we don't combine possible weak optimizations too fast, before
we can find and handle
inverse or duplicates.

ChangeLog

	* tree-ssa-reassoc.c (is_boolean_compatible_type_p): New
	helper.
	(is_ior_ne_eq_cmp): Likewise.
	(build_inner_expand_ne_eq_cmp): Likewise.
	(build_expand_ne_eq_cmp): Likewise.
	(sink_cast_and_expand): Likewise.
	(build_and_add_sum): Add forward declaration.
	(remove_visited_stmt_chain): Likewise.
	(build_and_add_sum): Allow generation of unary expression.
	(eliminate_redundant_comparison): Rework this routine.
	(break_up_subtract_bb): Rename to break_up_operation_bb.
	Additional do logical unfolding for optimization and
	primitive type-sinking for type-casts on boolean-kind
	(do_reassoc): Rename break_up_subtract_bb to break_up_operation_bb.

ChangeLog

	* gcc.dg/binop-tand1.c
	* gcc.dg/binop-tand2.c
	* gcc.dg/binop-tand3.c
	* gcc.dg/binop-tand4.c
	* gcc.dg/binop-tor1.c
	* gcc.dg/binop-tor2.c
	* gcc.dg/binop-tor3.c
	* gcc.dg/binop-tor4.c
	* gcc.dg/binop-tor5.c

Bootstrapped and tested for x86_64-pc-linux-gnu for all standard
languages plus ADA and Obj-C++.
Ok for apply?

Regards,
Kai