This PR fixes #74572 where the freeze instruction could be found twice
by the pass CanonicalizeFreezeInLoops, and then the compiling may crash
in second removal since the instruction has already gone.
This patch adds #include "llvm/ADT/SmallSet.h" to a couple of files
that are relying on transitive includes of SmallSet.h. It in turn
unblocks the removal of unnecessary includes of llvm/ADT/SmallSet.h in
several other files.
Summary:
If an induction variable is frozen and used, SCEV yields imprecise result
because it doesn't say anything about frozen variables.
Due to this reason, performance degradation happened after
https://reviews.llvm.org/D76483 is merged, causing
SCEV yield imprecise result and preventing LSR to optimize a loop.
The suggested solution here is to add a pass which canonicalizes frozen variables
inside a loop. To be specific, it pushes freezes out of the loop by freezing
the initial value and step values instead & dropping nsw/nuw flags from instructions used by freeze.
This solution was also mentioned at https://reviews.llvm.org/D70623 .
Reviewers: spatel, efriedma, lebedev.ri, fhahn, jdoerfert
Reviewed By: fhahn
Subscribers: nikic, mgorny, hiraditya, javed.absar, llvm-commits, sanwou01, nlopes
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D77523
