[RFC][PR70841] Reassoc fails to handle FP division

[kugan <kugan dot vivekanandarajah at linaro dot org>]

Hi,

I tried to handle reassoc fails to handle FP division. I think the best 
way to do this is to do like what is done for MINUS_EXPR. I.e, convert 
the RDIV_EXPR to MULT_EXPR by (1/x) early and later in 
opt_rdiv_with_multiply, optimize it.

Here is a patch that passes bootstrap and regression testing on 
x86-64-linux-gnu.

Does this look Ok for trunk?

Thanks,
Kugan

gcc/testsuite/ChangeLog:

2016-05-05  Kugan Vivekanandarajah  <kuganv@linaro.org>

	PR middle-end/70841
	* gcc.dg/tree-ssa/pr70841.c: New test.

gcc/ChangeLog:

2016-05-05  Kugan Vivekanandarajah  <kuganv@linaro.org>

	PR middle-end/70841
	* tree-ssa-reassoc.c (should_break_up_rdiv): New.
	(break_up_rdiv): New
	(break_up_subtract_bb): Call should_break_up_rdiv and break_up_rdiv.
	(do_reassoc): Rename break_up_subtract_bb to break_up_subtract_and_div_bb.
	(sort_cmp_int): New.
	(opt_rdiv_with_multiply): New.
	(reassociate_bb): Call opt_rdiv_with_multiply.
	(do_reassoc): Renamed called function break_up_subtract_bb to
	break_up_subtract_and_div_bb.

Attachment: pr70841_2.txt
Description: Text document