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0803b4eca8
llvm-mirror/test/Transforms/SimplifyCFG
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James Molloy 0803b4eca8 [SimplifyCFG] Change the algorithm in SinkThenElseCodeToEnd 
r279460 rewrote this function to be able to handle more than two incoming edges and took pains to ensure this didn't regress anything.

This time we change the logic for determining if an instruction should be sunk. Previously we used a single pass greedy algorithm - sink instructions until one requires more than one PHI node or we run out of instructions to sink.

This had the problem that sinking instructions that had non-identical but trivially the same operands needed extra logic so we sunk them aggressively. For example:

    %a = load i32* %b          %d = load i32* %b
    %c = gep i32* %a, i32 0    %e = gep i32* %d, i32 1

Sinking %c and %e would naively require two PHI merges as %a != %d. But the loads are obviously equivalent (and maybe can't be hoisted because there is no common predecessor).

This is why we implemented the fairly complex function areValuesTriviallySame(), to look through trivial differences like this. However it's just not clever enough.

Instead, throw areValuesTriviallySame away, use pointer equality to check equivalence of operands and switch to a two-stage algorithm.

In the "scan" stage, we look at every sinkable instruction in isolation from end of block to front. If it's sinkable, we keep track of all operands that required PHI merging.

In the "sink" stage, we iteratively sink the last non-terminator in the source blocks. But when calculating how many PHIs are actually required to be inserted (to work out if we should stop or not) we remove any values that have already been sunk from the set of PHI-merges required, which allows us to be more aggressive.

This turns an algorithm with potentially recursive lookahead (looking through GEPs, casts, loads and any other instruction potentially not CSE'd) to two linear scans.

llvm-svn: 280216
2016-08-31 10:46:23 +00:00
..
AArch64 [SimplifyCFG] Rewrite SinkThenElseCodeToEnd 2016-08-22 19:07:15 +00:00
AMDGPU AMDGPU: Fix some places missed in rename 2015-06-19 17:39:03 +00:00
ARM [ARM] add overrides for isCheapToSpeculateCttz() and isCheapToSpeculateCtlz() 2015-11-10 19:24:31 +00:00
Mips [MIPS] add overrides for isCheapToSpeculateCttz() and isCheapToSpeculateCtlz() 2015-11-11 17:24:56 +00:00
PowerPC [CodeGenPrepare] Removed duplicate logic. SimplifyCFG already knows how to speculate calls to cttz/ctlz. 2015-02-13 14:15:48 +00:00
SPARC
X86 [SimlifyCFG] Prevent passes from destroying canonical loop structure, especially for nested loops 2016-03-29 04:08:57 +00:00
2002-05-21-PHIElimination.ll
2002-09-24-PHIAssertion.ll
2003-03-07-DominateProblem.ll
2003-08-05-InvokeCrash.ll Move the personality function from LandingPadInst to Function 2015-06-17 20:52:32 +00:00
2003-08-17-BranchFold.ll
2003-08-17-BranchFoldOrdering.ll
2003-08-17-FoldSwitch-dbg.ll [opaque pointer type] Add textual IR support for explicit type parameter to gep operator 2015-03-13 18:20:45 +00:00
2003-08-17-FoldSwitch.ll regenerate checks 2016-03-28 22:12:21 +00:00
2004-12-10-SimplifyCFGCrash.ll
2005-06-16-PHICrash.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
2005-08-01-PHIUpdateFail.ll [opaque pointer type] Add textual IR support for explicit type parameter to getelementptr instruction 2015-02-27 19:29:02 +00:00
2005-10-02-InvokeSimplify.ll Move the personality function from LandingPadInst to Function 2015-06-17 20:52:32 +00:00
2005-12-03-IncorrectPHIFold.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
2006-02-17-InfiniteUnroll.ll
2006-06-12-InfLoop.ll
2006-08-03-Crash.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
2006-10-19-UncondDiv.ll
2006-12-08-Ptr-ICmp-Branch.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
2007-11-22-InvokeNoUnwind.ll Move the personality function from LandingPadInst to Function 2015-06-17 20:52:32 +00:00
2007-12-21-Crash.ll [opaque pointer type] Add textual IR support for explicit type parameter to the call instruction 2015-04-16 23:24:18 +00:00
2008-01-02-hoist-fp-add.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
2008-05-16-PHIBlockMerge.ll [SimlifyCFG] Prevent passes from destroying canonical loop structure, especially for nested loops 2016-03-29 04:08:57 +00:00
2008-07-13-InfLoopMiscompile.ll remove the metadata added with r267827 2016-04-30 00:02:36 +00:00
2008-09-08-MultiplePred.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
2008-09-17-SpeculativeHoist.ll
2008-10-03-SpeculativelyExecuteBeforePHI.ll
2008-12-06-SingleEntryPhi.ll
2008-12-16-DCECond.ll [opaque pointer type] Add textual IR support for explicit type parameter to the call instruction 2015-04-16 23:24:18 +00:00
2009-01-18-PHIPropCrash.ll
2009-05-12-externweak.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
2010-03-30-InvokeCrash.ll Move the personality function from LandingPadInst to Function 2015-06-17 20:52:32 +00:00
2011-03-08-UnreachableUse.ll
2011-09-05-TrivialLPad.ll Move the personality function from LandingPadInst to Function 2015-06-17 20:52:32 +00:00
assume.ll
attr-convergent.ll [SimplifyCFG] Don't fold conditional branches that contain calls to convergent functions. 2016-02-12 21:01:36 +00:00
attr-noduplicate.ll [opaque pointer type] Add textual IR support for explicit type parameter to getelementptr instruction 2015-02-27 19:29:02 +00:00
basictest.ll [SimplifyCFG] Prefer a simplification based on a dominating condition. 2016-05-06 14:25:14 +00:00
branch-cond-merge.ll
branch-cond-prop.ll
branch-fold-dbg.ll [PR27284] Reverse the ownership between DICompileUnit and DISubprogram. 2016-04-15 15:57:41 +00:00
branch-fold-test.ll
branch-fold-threshold.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
branch-fold.ll
branch-phi-thread.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
BrUnwind.ll
bug-25299.ll [SimplifyCFG] Extend SimplifyResume to handle phi of trivial landing pad. 2016-01-10 05:48:01 +00:00
clamp.ll [SimplifyCFG] Add test for r229099 2015-02-13 11:08:40 +00:00
combine-parallel-mem-md.ll [SimplifyCFG] Preserve !llvm.mem.parallel_loop_access when merging 2016-04-26 02:06:06 +00:00
common-dest-folding.ll [opaque pointer type] Add textual IR support for explicit type parameter to the call instruction 2015-04-16 23:24:18 +00:00
ConditionalTrappingConstantExpr.ll [Constant] remove fdiv and frem from canTrap() 2016-08-29 15:27:17 +00:00
CoveredLookupTable.ll
dbginfo.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
dce-cond-after-folding-terminator.ll
DeadSetCC.ll
duplicate-landingpad.ll Move the personality function from LandingPadInst to Function 2015-06-17 20:52:32 +00:00
duplicate-phis.ll
empty-catchpad.ll [WinEH] Simplify unreachable catchpads 2016-01-05 02:37:41 +00:00
empty-cleanuppad.ll [SimplifyCFG] Don't kill empty cleanuppads with multiple uses 2016-06-04 23:50:03 +00:00
EmptyBlockMerge.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
EqualPHIEdgeBlockMerge.ll [SimlifyCFG] Prevent passes from destroying canonical loop structure, especially for nested loops 2016-03-29 04:08:57 +00:00
extract-cost.ll
ForwardSwitchConditionToPHI.ll
guards.ll [SimplifyCFG] Fold llvm.guard(false) to unreachable 2016-04-21 05:09:12 +00:00
hoist-common-code.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
hoist-dbgvalue.ll [PR27284] Reverse the ownership between DICompileUnit and DISubprogram. 2016-04-15 15:57:41 +00:00
hoist-with-range.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
HoistCode.ll
implied-cond-matching-false-dest.ll [ValueTracking] Improve isImpliedCondition when the dominating cond is false. 2016-04-25 17:23:36 +00:00
implied-cond-matching-imm.ll [ValueTracking] Improve isImpliedCondition for matching LHS and Imm RHSs. 2016-05-05 15:39:18 +00:00
implied-cond-matching.ll Fix typo from r267432. 2016-04-25 18:20:27 +00:00
implied-cond.ll [SimplifyCFG] Constant fold a branch implied by it's incoming edge 2015-10-29 03:11:49 +00:00
indirectbr.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
InfLoop.ll [SimplifyCFG] Fix for "endless" loop after dead code removal (Alternative to 2016-02-03 23:54:25 +00:00
invoke_unwind.ll [SimplifyCFG] Extend SimplifyResume to handle phi of trivial landing pad. 2016-01-10 05:48:01 +00:00
invoke.ll Revert "[SimplifyCFG] Stop inserting calls to llvm.trap for UB" 2016-06-25 08:19:55 +00:00
iterative-simplify.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
lifetime.ll Revert "[SimplifyCFG] Extend TryToSimplifyUncondBranchFromEmptyBlock for empty block including lifetime intrinsics" 2016-05-02 19:43:22 +00:00
MagicPointer.ll [opaque pointer type] Add textual IR support for explicit type parameter to gep operator 2015-03-13 18:20:45 +00:00
merge-cleanuppads.ll [SimplifyCFG] Merge together cleanuppads 2016-02-20 01:07:45 +00:00
merge-cond-stores-2.ll Tweak unnamed label syntax in textual IR for easier matching in tests. 2016-01-27 21:53:08 +00:00
merge-cond-stores.ll Revert "Don't create unnecessary PHIs" 2015-12-14 22:36:57 +00:00
multiple-phis.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
no_speculative_loads_with_asan.ll [asan] Disabling speculative loads under asan. Patch by Mike Aizatsky 2015-10-14 00:21:05 +00:00
no_speculative_loads_with_tsan.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
noreturn-call.ll
phi-undef-loadstore.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
PhiBlockMerge2.ll
PhiBlockMerge.ll regenerate checks 2016-03-28 22:12:21 +00:00
PhiEliminate2.ll propagate 'unpredictable' metadata on select instructions 2016-03-17 15:30:52 +00:00
PhiEliminate3.ll
PhiEliminate.ll
PHINode.ll
PhiNoEliminate.ll
PR9946.ll
PR16069.ll regenerate checks 2016-03-28 22:12:21 +00:00
PR17073.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
PR25267.ll [SimplifyCFG] Don't use-after-free an SSA value 2015-10-21 18:22:24 +00:00
PR27615-simplify-cond-br.ll [SimplifyCFG] isSafeToSpeculateStore now ignores debug info 2016-05-04 15:40:57 +00:00
PR29163.ll [SimplifyCFG] Hoisting invalidates metadata 2016-08-29 17:14:08 +00:00
preserve-branchweights-partial.ll IR: Make metadata typeless in assembly 2014-12-15 19:07:53 +00:00
preserve-branchweights-switch-create.ll IR: Make metadata typeless in assembly 2014-12-15 19:07:53 +00:00
preserve-branchweights.ll Follow-up patch of http://reviews.llvm.org/D19948 to handle missing profiles when simplifying CFG. 2016-05-18 22:41:03 +00:00
preserve-load-metadata-2.ll Preserve load alignment and dereferenceable metadata during some transformations 2015-11-02 17:53:51 +00:00
preserve-load-metadata-3.ll Preserve load alignment and dereferenceable metadata during some transformations 2015-11-02 17:53:51 +00:00
preserve-load-metadata.ll Preserve load alignment and dereferenceable metadata during some transformations 2015-11-02 17:53:51 +00:00
preserve-make-implicit-on-switch-to-br.ll [ConstantFoldTerminator] Preserve make.implicit metadata when converting SwitchInst to BranchInst 2015-08-07 19:30:12 +00:00
rangereduce.ll Actually, r277337 was fine. Just kill the DAGs that made the test allow nondeterminism. 2016-08-05 14:58:34 +00:00
return-merge.ll
seh-nounwind.ll Move the personality function from LandingPadInst to Function 2015-06-17 20:52:32 +00:00
select-gep.ll [opaque pointer type] Add textual IR support for explicit type parameter to getelementptr instruction 2015-02-27 19:29:02 +00:00
sink-common-code.ll [SimplifyCFG] Change the algorithm in SinkThenElseCodeToEnd 2016-08-31 10:46:23 +00:00
speculate-math.ll Revert "Revert "[SimplifyCFG] allow speculation of exactly one expensive instruction (PR24818)"" 2016-01-27 02:59:41 +00:00
speculate-store.ll [SimplifyCFG] propagate branch metadata when creating select (PR26636) 2016-03-26 23:30:50 +00:00
speculate-vector-ops.ll
speculate-with-offset.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
SpeculativeExec.ll Revert "Revert "Strip metadata when speculatively hoisting instructions (r252604)" 2015-11-18 14:50:18 +00:00
statepoint-invoke-unwind.ll [gc.statepoint] Change gc.statepoint intrinsic's return type to token type instead of i32 type 2015-12-26 07:54:32 +00:00
switch_create.ll Teaching SimplifyCFG to recognize the Or-Mask trick that InstCombine uses to 2016-06-24 01:59:00 +00:00
switch_switch_fold.ll use FileCheck for tighter checking 2016-03-16 23:39:37 +00:00
switch_thread.ll reduce check strings; no need to check IR comments 2016-03-16 23:22:01 +00:00
switch-dead-default.ll [SimplifyCFG] Use known bits to eliminate dead switch defaults 2015-09-10 17:44:47 +00:00
switch-masked-bits.ll [SimplifyCFG] eliminate switch cases based on known range of switch condition 2016-05-20 14:53:09 +00:00
switch-on-const-select.ll
switch-range-to-icmp.ll SimplifyCFG: don't remove unreachable default switch destinations 2015-01-26 19:52:32 +00:00
switch-simplify-crash.ll
switch-to-br.ll Add some tests for SimplifyCFG's ConstantFoldTerminator(). NFC. 2014-12-04 22:19:25 +00:00
switch-to-icmp.ll
switch-to-select-multiple-edge-per-block-phi.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
switch-to-select-two-case.ll SimplifyCFG: don't remove unreachable default switch destinations 2015-01-26 19:52:32 +00:00
trap-debugloc.ll Revert "[SimplifyCFG] Stop inserting calls to llvm.trap for UB" 2016-06-25 08:19:55 +00:00
trapping-load-unreachable.ll Revert "[SimplifyCFG] Stop inserting calls to llvm.trap for UB" 2016-06-25 08:19:55 +00:00
two-entry-phi-return.ll [SimplifyCFG] propagate branch metadata when creating select (PR27344) 2016-04-15 15:32:12 +00:00
UncondBranchToReturn.ll
unreachable-blocks.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
unreachable-cleanuppad.ll [SimplifyCFG] Do not blindly remove unreachable blocks 2016-02-24 10:02:16 +00:00
UnreachableEliminate.ll [SimplifyCFG] Replace calls to null/undef with unreachable 2016-06-25 07:37:27 +00:00
volatile-phioper.ll [opaque pointer type] Add textual IR support for explicit type parameter to the call instruction 2015-04-16 23:24:18 +00:00
wineh-unreachable.ll [SimplifyCFG] Further improve our ability to remove redundant catchpads 2016-01-05 07:42:17 +00:00