628288658c
Some dialects have semantics which is not well represented by common SSA structures with dominance constraints. This patch allows operations to declare the 'kind' of their contained regions. Currently, two kinds are allowed: "SSACFG" and "Graph". The only difference between them at the moment is that SSACFG regions are required to have dominance, while Graph regions are not required to have dominance. The intention is that this Interface would be generated by ODS for existing operations, although this has not yet been implemented. Presumably, if someone were interested in code generation, we might also have a "CFG" dialect, which defines control flow, but does not require SSA. The new behavior is mostly identical to the previous behavior, since registered operations without a RegionKindInterface are assumed to contain SSACFG regions. However, the behavior has changed for unregistered operations. Previously, these were checked for dominance, however the new behavior allows dominance violations, in order to allow the processing of unregistered dialects with Graph regions. One implication of this is that regions in unregistered operations with more than one op are no longer CSE'd (since it requires dominance info). I've also reorganized the LangRef documentation to remove assertions about "sequential execution", "SSA Values", and "Dominance". Instead, the core IR is simply "ordered" (i.e. totally ordered) and consists of "Values". I've also clarified some things about how control flow passes between blocks in an SSACFG region. Control Flow must enter a region at the entry block and follow terminator operation successors or be returned to the containing op. Graph regions do not define a notion of control flow. see discussion here: https://llvm.discourse.group/t/rfc-allowing-dialects-to-relax-the-ssa-dominance-condition/833/53 Differential Revision: https://reviews.llvm.org/D80358 |
||
|---|---|---|
| .. | ||
| cmake/modules | ||
| docs | ||
| examples | ||
| include | ||
| integration_test | ||
| lib | ||
| test | ||
| tools | ||
| unittests | ||
| utils | ||
| .clang-format | ||
| .clang-tidy | ||
| CMakeLists.txt | ||
| LICENSE.TXT | ||
| README.md | ||
Multi-Level Intermediate Representation
See https://mlir.llvm.org/ for more information.