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.
Namespaces are terminated with a closing comment in the majority of the
codebase so do the same here for consistency. Also format code within
some namespaces to make clang-format happy.
This is a reboot of the original design and implementation by
Nicolai Haehnle <nicolai.haehnle@amd.com>:
https://reviews.llvm.org/D85603
This change also obsoletes an earlier attempt at restarting the work on
convergence tokens:
https://reviews.llvm.org/D104504
Changes relative to D85603:
1. Clean up the definition of a "convergent operation", a convergent
call and convergent function.
2. Clean up the relationship between dynamic instances, sets of threads and
convergence tokens.
3. Redistribute the formal rules into the definitions of the convergence
intrinsics.
4. Expand on the semantics of entering a function from outside LLVM,
and the environment-defined outcome of the entry intrinsic.
5. Replace the term "cycle" with "closed path". The static rules are defined
in terms of closed paths, and then a relation is established with cycles.
6. Specify that if a function contains a controlled convergent operation, then
all convergent operations in that function must be controlled.
7. Describe an optional procedure to infer tokens for uncontrolled convergent
operations.
8. Introduce controlled maximal convergence-before and controlled m-converged
property as an update to the original properties in UniformityAnalysis.
9. Additional constraint that a cycle heart can only occur in the header of a
reducible cycle (natural loop).
Reviewed By: nhaehnle
Differential Revision: https://reviews.llvm.org/D147116
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
