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
Uniformity analysis is a generalization of divergence analysis to
include irreducible control flow:
1. The proposed spec presents a notion of "maximal convergence" that
captures the existing convention of converging threads at the
headers of natual loops.
2. Maximal convergence is then extended to irreducible cycles. The
identity of irreducible cycles is determined by the choices made
in a depth-first traversal of the control flow graph. Uniformity
analysis uses criteria that depend only on closed paths and not
cycles, to determine maximal convergence. This makes it a
conservative analysis that is independent of the effect of DFS on
CycleInfo.
3. The analysis is implemented as a template that can be
instantiated for both LLVM IR and Machine IR.
Validation:
- passes existing tests for divergence analysis
- passes new tests with irreducible control flow
- passes equivalent tests in MIR and GMIR
Based on concepts originally outlined by
Nicolai Haehnle <nicolai.haehnle@amd.com>
With contributions from Ruiling Song <ruiling.song@amd.com> and
Jay Foad <jay.foad@amd.com>.
Support for GMIR and lit tests for GMIR/MIR added by
Yashwant Singh <yashwant.singh@amd.com>.
Differential Revision: https://reviews.llvm.org/D130746
This adds a --filter option to llvm-symbolizer. This takes log-bearing
symbolizer markup from stdin and writes a human-readable version to
stdout.
For now, this only implements the "symbol" markup tag; all others are
passed through unaltered. This is a proof-of-concept bit of
functionalty; implement the various tags is more-or-less just a matter
of hooking up various parts of the Symbolize library to the architecture
established here.
Reviewed By: peter.smith
Differential Revision: https://reviews.llvm.org/D126980
This defines the new `@llvm.ptrauth.` pointer authentication intrinsics:
sign, auth, strip, blend, and sign_generic, documented in PointerAuth.md.
Pointer Authentication is a mechanism by which certain pointers are
signed. When a pointer gets signed, a cryptographic hash of its value
and other values (pepper and salt) is stored in unused bits of that
pointer.
Before the pointer is used, it needs to be authenticated, i.e., have its
signature checked. This prevents pointer values of unknown origin from
being used to replace the signed pointer value.
sign and auth provide the core operations. strip removes the ptrauth
bits from a signed pointer without checking them. sign_generic allows
signing non-pointer values. Finally, blend combines salt values
("discriminators") to derive more targeted and less reusable ones.
In later patches, we implement primary backend support for these
intrinsics using the AArch64 PAuth feature, and build on that to
implement the arm64e Darwin ABI and ELF PAuth ABI Extension in clang.
For more details, see the docs page, as well as our llvm-dev RFC:
http://lists.llvm.org/pipermail/llvm-dev/2019-October/136091.html
or our 2019 Developers' Meeting talk.
Differential Revision: https://reviews.llvm.org/D90868
Summary: A lot of this is work in progress...
Reviewers: kcc, pcc
Subscribers: cryptoad, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D69289
Adds links to Getting Started/Tutorials, User Guides, and Reference documentation pages to sidebar. Also adds a new section for LLVM IR on the Reference documentation page.
llvm-svn: 374214
Removes Programming Documentation page. Also moves existing topics on Programming Documentation page to User Guides and Reference pages.
llvm-svn: 373856
Moves existing article links on the Programming, Subsystem, and Reference documentation pages to new locations. Also moves Github Repository and Publications links to the sidebar.
llvm-svn: 373169
