[PATCH] Factor out division by squares and remove division around comparisons (0/2)

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

Hi all,

This patch is split from part (1/2). It includes the patterns that have 
been moved out of fold-const.c


It also removes an (almost entirely) redundant pattern:

    (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2)

which was only used in special cases, either with combinations
of flags like -fno-reciprocal-math -funsafe-math-optimizations
and cases where C was sNaN, or small enough to result in infinity.

This pattern is covered by:

   (A / C1) +- (A / C2) -> (with O1 and reciprocal math)
   A * (1 / C1) +- A * (1 / C2) ->
   A * (1 / C1 +- 1 / C2)

The previous pattern required funsafe-math-optimizations.

To adjust for this case, the testcase has been updated to require O1 so 
that the optimization is still performed.


This pattern is moved verbatim into match.pd:

    (A / C) +- (B / C) -> (A +- B) / C.

OK for trunk?

Jackson

gcc/

2017-08-30  Jackson Woodruff  <jackson.woodruff@arm.com>

	PR 71026/tree-optimization
	* match.pd: Move RDIV patterns from fold-const.c
	* fold-const.c (distribute_real_division): Removed.
	(fold_binary_loc): Remove calls to distribute_real_divison.

gcc/testsuite/

2017-08-30  Jackson Woodruff  <jackson.woodruff@arm.com>

	PR 71026/tree-optimization
	* gcc/testsuire/gcc.dg/fold-div-1.c: Use O1.

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