This reverts commit 4aacc60fe7e1f7b3f788bba8382ea1fa5189ef3b.
The original implementation provided a simple method to check whether the forest
of nested cycles is well-formed. This is now augmented with other methods to
check well-formedness of every cycle, either individually, or as the entire
forest. These will be used by future transforms that modify CycleInfo.
The original implementation provided a simple method to check whether
the forest of nested cycles is well-formed. This is now augmented with
other methods to check well-formedness of all cycles, either
invdividually, or as the entire forest. These will be used by future
transforms that modify CycleInfo.
If an unreachable block B branches to a block S inside a cycle, it may
cause S to be incorrectly treated as an entry to the cycle. We avoid
that by skipping unreachable predecessors when locating entries.
Reverts 02940d6d2202. Fixes breakage in the modules build.
LLVM loops cannot represent irreducible structures in the CFG. This
change introduce the concept of cycles as a generalization of loops,
along with a CycleInfo analysis that discovers a nested
hierarchy of such cycles. This is based on Havlak (1997), Nesting of
Reducible and Irreducible Loops.
The cycle analysis is implemented as a generic template and then
instatiated for LLVM IR and Machine IR. The template relies on a new
GenericSSAContext template which must be specialized when used for
each IR.
This review is a restart of an older review request:
https://reviews.llvm.org/D83094
Original implementation by Nicolai Hähnle <nicolai.haehnle@amd.com>,
with recent refactoring by Sameer Sahasrabuddhe <sameer.sahasrabuddhe@amd.com>
Differential Revision: https://reviews.llvm.org/D112696
LLVM loops cannot represent irreducible structures in the CFG. This
change introduce the concept of cycles as a generalization of loops,
along with a CycleInfo analysis that discovers a nested
hierarchy of such cycles. This is based on Havlak (1997), Nesting of
Reducible and Irreducible Loops.
The cycle analysis is implemented as a generic template and then
instatiated for LLVM IR and Machine IR. The template relies on a new
GenericSSAContext template which must be specialized when used for
each IR.
This review is a restart of an older review request:
https://reviews.llvm.org/D83094
Original implementation by Nicolai Hähnle <nicolai.haehnle@amd.com>,
with recent refactoring by Sameer Sahasrabuddhe <sameer.sahasrabuddhe@amd.com>
Differential Revision: https://reviews.llvm.org/D112696
