llvm-project/llvm/test/Transforms/LoopUnswitch
Hyojin Sung 4673f10568 [SimlifyCFG] Prevent passes from destroying canonical loop structure, especially for nested loops
When eliminating or merging almost empty basic blocks, the existence of non-trivial PHI nodes
is currently used to recognize potential loops of which the block is the header and keep the block.
However, the current algorithm fails if the loops' exit condition is evaluated only with volatile
values hence no PHI nodes in the header. Especially when such a loop is an outer loop of a nested
loop, the loop is collapsed into a single loop which prevent later optimizations from being
applied (e.g., transforming nested loops into simplified forms and loop vectorization).
    
The patch augments the existing PHI node-based check by adding a pre-test if the BB actually
belongs to a set of loop headers and not eliminating it if yes.

llvm-svn: 264697
2016-03-29 04:08:57 +00:00
..
2006-06-13-SingleEntryPHI.ll
2006-06-27-DeadSwitchCase.ll
2007-05-09-Unreachable.ll
2007-05-09-tl.ll
2007-07-12-ExitDomInfo.ll
2007-07-13-DomInfo.ll
2007-07-18-DomInfo.ll
2007-08-01-Dom.ll
2007-08-01-LCSSA.ll
2007-10-04-DomFrontier.ll
2008-06-02-DomInfo.ll
2008-06-17-DomFrontier.ll
2008-11-03-Invariant.ll
2010-11-18-LCSSA.ll
2011-06-02-CritSwitch.ll
2011-09-26-EHCrash.ll
2011-11-18-SimpleSwitch.ll Have a single way for creating unique value names. 2015-11-22 00:16:24 +00:00
2011-11-18-TwoSwitches-Threshold.ll
2011-11-18-TwoSwitches.ll Have a single way for creating unique value names. 2015-11-22 00:16:24 +00:00
2012-04-02-IndirectBr.ll
2012-04-30-LoopUnswitch-LPad-Crash.ll
2012-05-20-Phi.ll
2015-06-17-Metadata.ll [SimlifyCFG] Prevent passes from destroying canonical loop structure, especially for nested loops 2016-03-29 04:08:57 +00:00
2015-09-18-Addrspace.ll Remove handling of AddrSpaceCast in stripAndAccumulateInBoundsConstantOffsets 2015-09-23 19:48:43 +00:00
LIV-loop-condtion.ll [LoopUnswitch] Code refactoring to separate trivial loop unswitch and non-trivial loop unswitch in processCurrentLoop() 2015-07-22 05:26:29 +00:00
basictest.ll Teach LoopUnswitch not to perform non-trivial unswitching on loops containing convergent operations. 2015-10-09 18:40:20 +00:00
cleanuppad.ll [IR] Reformulate LLVM's EH funclet IR 2015-12-12 05:38:55 +00:00
cold-loop.ll [LoopUnswitch] Add block frequency analysis to recognize hot/cold regions 2015-09-29 05:03:32 +00:00
copy-metadata.ll [LoopUnswitch] Preserve make.implicit metadata for unswitched conditions 2015-08-05 21:13:26 +00:00
crash.ll
infinite-loop.ll [SimlifyCFG] Prevent passes from destroying canonical loop structure, especially for nested loops 2016-03-29 04:08:57 +00:00
preserve-analyses.ll
trivial-unswitch.ll [LoopUnswitch] Improve loop unswitch pass to find trivial unswitch conditions more effectively 2015-07-25 03:21:06 +00:00