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Backport fixes for JumpThreading/assume bug #106
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Summary: See D37528 for a previous (non-deferred) version of this patch and its description. Preserves dominance in a deferred manner using a new class DeferredDominance. This reduces the performance impact of updating the DominatorTree at every edge insertion and deletion. A user may call DDT->flush() within JumpThreading for an up-to-date DT. This patch currently has one flush() at the end of runImpl() to ensure DT is preserved across the pass. LVI is also preserved to help subsequent passes such as CorrelatedValuePropagation. LVI is simpler to maintain and is done immediately (not deferred). The code to perform the preversation was minimally altered and simply marked as preserved for the PassManager to be informed. This extends the analysis available to JumpThreading for future enhancements such as threading across loop headers. Reviewers: dberlin, kuhar, sebpop Reviewed By: kuhar, sebpop Subscribers: mgorny, dmgreen, kuba, rnk, rsmith, hiraditya, llvm-commits Differential Revision: https://reviews.llvm.org/D40146 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@322401 91177308-0d34-0410-b5e6-96231b3b80d8
Summary: The LazyValueInfo pass caches a copy of the DominatorTree when available. Whenever there are pending DominatorTree updates within JumpThreading's DeferredDominance object we cannot use the cached DT for LVI analysis. This commit adds the new methods enableDT() and disableDT() to LVI. JumpThreading also sets the appropriate usage model before calling LVI analysis methods. Fixes https://bugs.llvm.org/show_bug.cgi?id=36133 Reviewers: sebpop, dberlin, kuhar Reviewed by: sebpop, kuhar Subscribers: uabelho, llvm-commits, aprantl, hiraditya, a.elovikov Differential Revision: https://reviews.llvm.org/D42717 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@325356 91177308-0d34-0410-b5e6-96231b3b80d8
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This fixes the original cause for rust-lang/rust#48116 which was worked around by removing an assume() intrinsic call. We could still hit the bug, as we're still using assume() intrinsics in other places.