[LoadStoreVectorizer] Postprocess and merge equivalence classes (#114501)

This patch introduces a new method:
void Vectorizer::mergeEquivalenceClasses(EquivalenceClassMap &EQClasses)
const

The method is called at the end of
Vectorizer::collectEquivalenceClasses() and is needed to merge
equivalence classes that differ only by their underlying objects (UO1
and UO2), where UO1 is 1-level-indirection underlying base for UO2. This
situation arises due to the limited lookup depth used during the search
of underlying bases with llvm::getUnderlyingObject(ptr).

Using any fixed lookup depth can result into creation of multiple
equivalence classes that only differ by 1-level indirection bases.

The new approach merges equivalence classes if they have adjacent bases
(1-level indirection). If a series of equivalence classes form ladder
formed of 1-step/level indirections, they are all merged into a single
equivalence class. This provides more opportunities for the load-store
vectorizer to generate better vectors.

---------

Signed-off-by: Klochkov, Vyacheslav N <vyacheslav.n.klochkov@intel.com>

0 files changed, 0 insertions, 0 deletions