[PATCH] Factor out division by squares and remove division around comparisons (2/2)

[Jackson Woodruff <jackson dot woodruff at foss dot arm dot com>]

Hi all,

The patch implements the some of the division optimizations discussed in
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71026 .

We now reassociate (as discussed in the bug report):

    x / (y * y) -> x  * (1 / y) * (1 / y)

If it is reasonable to do so. This is done with
-funsafe-math-optimizations.

Bootstrapped and regtested with part (1/2). OK for trunk?

Jackson

gcc/

2017-08-03  Jackson Woodruff  <jackson.woodruff@arm.com>

	PR 71026/tree-optimization
	* tree-ssa-math-opts (is_division_by_square,
	is_square_of, insert_sqaure_reciprocals): New.
	(insert_reciprocals): Change to insert reciprocals
	before a division by a square.
	(execute_cse_reciprocals_1): Change to consider
	division by a square.


gcc/testsuite

2017-08-03  Jackson Woodruff  <jackson.woodruff@arm.com>

	PR 71026/tree-optimization
	* gcc.dg/associate_division_1.c: New.

Attachment: patchfile-2
Description: Text document