https://gcc.gnu.org/bugzilla/show_bug.cgi?id=21485
Jeffrey A. Law <law at redhat dot com> changed:
What |Removed |Added
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CC| |law at redhat dot com
--- Comment #62 from Jeffrey A. Law <law at redhat dot com> ---
So one thing that seems to ever so slightly improve this code is to realize
that as we come around to the top of the loop the test _14 < j_20 can be
rewritten as _14 != j_20 (we already know that _14 <= j_20).
That's quite a surprise as all that seems to do is allow propagation of j_20
for _14 in a later PHI node and we do less use work in PRE -- so it seems like
a step backwards at this point.
But then sink comes along and moves two address computations and a load into a
more control dependent block. LIM4 later pulls the two address computations
totally out of the loop.
But that all seems to be relatively accidental improvements based on PRE not
seeing a transformation.
