On Mon, 23 Feb 2015, Jeff Law wrote:
On 02/23/15 11:38, Joseph Myers wrote:
(I wonder if convert_mult_to_fma is something that should move to
match-and-simplify infrastructure.)
Yea, it probably should.
Currently, it happens in a pass that is quite late. If it moves to
match-and-simplify, I am afraid it might inhibit some other optimizations
(we can turn plus+mult to fma but not the reverse), unless we use some way
to inhibit some patterns until a certain pass (possibly a simple "if", if
that's not too costly). Such "time-restricted" patterns might be useful
for other purposes: don't introduce complicated vector/complex operations
after the corresponding lowering passes, do narrowing until a certain
point but then prefer fast integer sizes, etc (I haven't thought about
those particular examples, they are only an illustration).
--
Marc Glisse
