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Summary: JumpThreading for guards feature has been reverted at https://reviews.llvm.org/rL295200 due to the following problem: the feature used the following algorithm for detection of diamond patters: 1. Find a block with 2 predecessors; 2. Check that these blocks have a common single parent; 3. Check that the parent's terminator is a branch instruction. The problem is that these checks are insufficient. They may pass for a non-diamond construction in case if those two predecessors are actually the same block. This may happen if parent's terminator is a br (either conditional or unconditional) to a block that ends with "switch" instruction with exactly two branches going to one block. This patch re-enables the JumpThreading for guards and fixes this issue by adding the check that those found predecessors are actually different blocks. This guarantees that parent's terminator is a conditional branch with exactly 2 different successors, which is now ensured by assertions. It also adds two more tests for this situation (with parent's terminator being a conditional and an unconditional branch). Patch by Max Kazantsev! Reviewers: anna, sanjoy, reames Reviewed By: sanjoy Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D30036 llvm-svn: 295410 |
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| .. | ||
| 2008-11-27-EntryMunge.ll | ||
| 2010-08-26-and.ll | ||
| 2011-04-02-SimplifyDeadBlock.ll | ||
| 2011-04-14-InfLoop.ll | ||
| 2012-07-19-NoSuccessorIndirectBr.ll | ||
| and-and-cond.ll | ||
| and-cond.ll | ||
| assume-edge-dom.ll | ||
| assume.ll | ||
| basic.ll | ||
| branch-no-const.ll | ||
| compare.ll | ||
| conservative-lvi.ll | ||
| crash.ll | ||
| degenerate-phi.ll | ||
| guards.ll | ||
| implied-cond.ll | ||
| indirectbr.ll | ||
| induction.ll | ||
| landing-pad.ll | ||
| lvi-load.ll | ||
| no-irreducible-loops.ll | ||
| or-undef.ll | ||
| phi-eq.ll | ||
| phi-known.ll | ||
| pr9331.ll | ||
| pr15851_hang.ll | ||
| pr22086.ll | ||
| pr26096.ll | ||
| pr27840.ll | ||
| select.ll | ||
| static-profile.ll | ||
| thread-cmp.ll | ||
| thread-loads.ll | ||
| update-edge-weight.ll | ||