Hi Richard,

Thanks a lot for your review and reply, I've updated the patch accordingly.

Main changes compared to previous one:
  - Consider SVE (poly_int) on bit_field_ref size/offset.
  - Filter valid candidates with sbitmap first.
  - Support multiple modes (TODO 1).
  - Test cases: add SSE2 support for 1..5, update run result check for 1,
    add two more cases (5,6)to verify multiple mode support (x86).

Bootstrapped and regression test passed on powerpc64le-unknown-linux-gnu
and x86_64-linux-gnu.

Could you help to review it again?  Thanks in advance!

Kewen

----

gcc/ChangeLog

2019-07-08  Kewen Lin  <linkw@gcc.gnu.org>

	PR tree-optimization/88497
	* tree-ssa-reassoc.c (reassociate_bb): Swap the positions of 
	GIMPLE_BINARY_RHS check and gimple_visited_p check, call new 
	function undistribute_bitref_for_vector.
	(undistribute_bitref_for_vector): New function.
	(cleanup_vinfo_map): Likewise.
	(sort_by_mach_mode): Likewise.

gcc/testsuite/ChangeLog

2019-07-08  Kewen Lin  <linkw@gcc.gnu.org>

	* gcc.dg/tree-ssa/pr88497-1.c: New test.
	* gcc.dg/tree-ssa/pr88497-2.c: Likewise.
	* gcc.dg/tree-ssa/pr88497-3.c: Likewise.
	* gcc.dg/tree-ssa/pr88497-4.c: Likewise.
	* gcc.dg/tree-ssa/pr88497-5.c: Likewise.
	* gcc.dg/tree-ssa/pr88497-6.c: Likewise.
	* gcc.dg/tree-ssa/pr88497-7.c: Likewise.