PR #125442 replaces the pass-based Polly architecture with a monolithic pass consisting of phases. Reasons listed in https://github.com/llvm/llvm-project/pull/125442. With this change, the SCoP-passes became redundant problematic versions of the same functionality and are removed.
Reapply of a22d1c2225543aa9ae7882f6b1a97ee7b2c95574. Using this PR for pre-merge CI. Instead of relying on any pass manager to schedule Polly's passes, add Polly's own pipeline manager which is seen as a monolithic pass in LLVM's pass manager. Polly's former passes are now phases of the new PhaseManager component. Relying on LLVM's pass manager (the legacy as well as the New Pass Manager) to manage Polly's phases never was a good fit that the PhaseManager resolves: * Polly passes were modifying analysis results, in particular RegionInfo and ScopInfo. This means that there was not just one unique and "definite" analysis result, the actual result depended on which analyses ran prior, and the pass manager was not allowed to throw away cached analyses or prior SCoP optimizations would have been forgotten. The LLVM pass manger's persistance of analysis results is not contractual but designed for caching. * Polly depends on a particular execution order of passes and regions (e.g. regression tests, invalidation of consecutive SCoPs). LLVM's pass manager does not guarantee any excecution order. * Polly does not completely preserve DominatorTree, RegionInfo, LoopInfo, or ScalarEvolution, but only as-needed for Polly's own uses. Because the ScopDetection object stores references to those analyses, it still had to lie to the pass manager that they would be preserved, or the pass manager would have released and recomputed the invalidated analysis objects that ScopDetection/ScopInfo was still referencing. To ensure that no non-Polly pass would see these not-completely-preserved analyses, all analyses still had to be thrown away after the ScopPassManager, respectively with a BarrierNoopPass in case of the LPM. * The NPM's PassInstrumentation wraps the IR unit into an `llvm::Any` object, but implementations such as PrintIRInstrumentation call llvm_unreachable on encountering an unknown IR unit, such as SCoPs, with no extension points to add support. Hence LLVM crashes when dumping IR between SCoP passes (such as `-print-before-changed` with Polly being active). The new PhaseManager uses some command line options that previously belonged to Polly's legacy passes, such as `-polly-print-detect` (so the option will continue to work). Hence the LPM support is incompatible with the new approach and support for it is removed.
When Polly generates a false runtime condition (RTC), the associated Polly generated loop is never executed and is eventually eliminated. As a result, the fallback loop becomes the default execution path. Disabling vectorization for this fallback loop will be counterproductive. This patch ensures that vectorization is only disabled when the RTC is not false (no Codegen failure).
This reverts commit e987ab11a6f3d3965ef26fc42c82db3e8b1d56f5. This broke premerge: 1. https://lab.llvm.org/staging/#/builders/192/builds/9521 2. https://github.com/llvm/llvm-project/actions/runs/19054182009 Notably this did not break inside the PR. Not exactly sure why. I realize that there is a lot of test churn here, but they're largely in polly where commit frequency is much lower, so a reapply of the patch should be clean.
Instead of relying on any pass manager to schedule Polly's passes, add Polly's own pipeline manager which is seen as a monolithic pass in LLVM's pass manager. Polly's former passes are now phases of the new PhaseManager component. Relying on LLVM's pass manager (the legacy as well as the New Pass Manager) to manage Polly's phases never was a good fit that the PhaseManager resolves: * Polly passes were modifying analysis results, in particular RegionInfo and ScopInfo. This means that there was not just one unique and "definite" analysis result, the actual result depended on which analyses ran prior, and the pass manager was not allowed to throw away cached analyses or prior SCoP optimizations would have been forgotten. The LLVM pass manger's persistance of analysis results is not contractual but designed for caching. * Polly depends on a particular execution order of passes and regions (e.g. regression tests, invalidation of consecutive SCoPs). LLVM's pass manager does not guarantee any excecution order. * Polly does not completely preserve DominatorTree, RegionInfo, LoopInfo, or ScalarEvolution, but only as-needed for Polly's own uses. Because the ScopDetection object stores references to those analyses, it still had to lie to the pass manager that they would be preserved, or the pass manager would have released and recomputed the invalidated analysis objects that ScopDetection/ScopInfo was still referencing. To ensure that no non-Polly pass would see these not-completely-preserved analyses, all analyses still had to be thrown away after the ScopPassManager, respectively with a BarrierNoopPass in case of the LPM. * The NPM's PassInstrumentation wraps the IR unit into an `llvm::Any` object, but implementations such as PrintIRInstrumentation call llvm_unreachable on encountering an unknown IR unit, such as SCoPs, with no extension points to add support. Hence LLVM crashes when dumping IR between SCoP passes (such as `-print-before-changed` with Polly being active). The new PhaseManager uses some command line options that previously belonged to Polly's legacy passes, such as `-polly-print-detect` (so the option will continue to work). Hence the LPM support is incompatible with the new approach and support for it is removed.
Some of the changes in the patch include: 1. Using iterators instead of instruction pointers when applicable. 2. Modifying Polly functions to accept iterators instead of inst pointers. 3. Updating API usages such as use begin instead of front.
As part of the effort to transition to using Debug Records instead of Debug intrinsics, some API/argument changes are necessary to achieve the desired behavior from Debug Records. This particular fix involves passing iterators instead of instruction pointers to the SetInsertPoint function. While this is crucial in certain areas, it may be more than needed in others, but it does not cause any harm.
Part of #123569