ANSI-C Section 2.1.2.3

[David Hough]

Bob Corbett pointed out that I was quite wrong; after the parentheses
battle, the optimizer guys must have run out of steam, because
	a + 32760 + b + 5
must be evaluated in left to right order
	(((a + 32760) + b) + 5)

In the context of numeric-interest, this means that this aspect of
expression evaluation doesn't require any further standardization
to produce identical results on all IEEE implementations; that only
leaves base conversion, extended-precision evaluation, and elementary
transcendental functions to consider...