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llvm-mirror/lib/Transforms/Scalar
Chandler Carruth 46bbc995de [LPM] Make LoopSimplify no longer a LoopPass and instead both a utility
function and a FunctionPass.

This has many benefits. The motivating use case was to be able to
compute function analysis passes *after* running LoopSimplify (to avoid
invalidating them) and then to run other passes which require
LoopSimplify. Specifically passes like unrolling and vectorization are
critical to wire up to BranchProbabilityInfo and BlockFrequencyInfo so
that they can be profile aware. For the LoopVectorize pass the only
things in the way are LoopSimplify and LCSSA. This fixes LoopSimplify
and LCSSA is next on my list.

There are also a bunch of other benefits of doing this:
- It is now very feasible to make more passes *preserve* LoopSimplify
  because they can simply run it after changing a loop. Because
  subsequence passes can assume LoopSimplify is preserved we can reduce
  the runs of this pass to the times when we actually mutate a loop
  structure.
- The new pass manager should be able to more easily support loop passes
  factored in this way.
- We can at long, long last observe that LoopSimplify is preserved
  across SCEV. This *halves* the number of times we run LoopSimplify!!!

Now, getting here wasn't trivial. First off, the interfaces used by
LoopSimplify are all over the map regarding how analysis are updated. We
end up with weird "pass" parameters as a consequence. I'll try to clean
at least some of this up later -- I'll have to have it all clean for the
new pass manager.

Next up I discovered a really frustrating bug. LoopUnroll *claims* to
preserve LoopSimplify. That's actually a lie. But the way the
LoopPassManager ends up running the passes, it always ran LoopSimplify
on the unrolled-into loop, rectifying this oversight before any
verification could kick in and point out that in fact nothing was
preserved. So I've added code to the unroller to *actually* simplify the
surrounding loop when it succeeds at unrolling.

The only functional change in the test suite is that we now catch a case
that was previously missed because SCEV and other loop transforms see
their containing loops as simplified and thus don't miss some
opportunities. One test case has been converted to check that we catch
this case rather than checking that we miss it but at least don't get
the wrong answer.

Note that I have #if-ed out all of the verification logic in
LoopSimplify! This is a temporary workaround while extracting these bits
from the LoopPassManager. Currently, there is no way to have a pass in
the LoopPassManager which preserves LoopSimplify along with one which
does not. The LPM will try to verify on each loop in the nest that
LoopSimplify holds but the now-Function-pass cannot distinguish what
loop is being verified and so must try to verify all of them. The inner
most loop is clearly no longer simplified as there is a pass which
didn't even *attempt* to preserve it. =/ Once I get LCSSA out (and maybe
LoopVectorize and some other fixes) I'll be able to re-enable this check
and catch any places where we are still failing to preserve
LoopSimplify. If this causes problems I can back this out and try to
commit *all* of this at once, but so far this seems to work and allow
much more incremental progress.

llvm-svn: 199884
2014-01-23 11:23:19 +00:00
..
ADCE.cpp Use SmallVectorImpl::iterator/const_iterator instead of SmallVector to avoid specifying the vector size. 2013-07-04 01:31:24 +00:00
CMakeLists.txt Add a Scalarizer pass. 2013-11-22 16:58:05 +00:00
CodeGenPrepare.cpp [opt][PassInfo] Allow opt to run passes that need target machine. 2014-01-16 21:44:34 +00:00
ConstantProp.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
CorrelatedValuePropagation.cpp CVP: If we have a PHI with an incoming select, try to skip the select. 2013-02-24 15:34:43 +00:00
DCE.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
DeadStoreElimination.cpp [PM] Split DominatorTree into a concrete analysis result object which 2014-01-13 13:07:17 +00:00
EarlyCSE.cpp [PM] Split DominatorTree into a concrete analysis result object which 2014-01-13 13:07:17 +00:00
FlattenCFGPass.cpp Factor FlattenCFG out from SimplifyCFG 2013-08-06 02:43:45 +00:00
GlobalMerge.cpp Change tabs to spaces. 2013-07-22 21:11:30 +00:00
GVN.cpp [PM] Split DominatorTree into a concrete analysis result object which 2014-01-13 13:07:17 +00:00
IndVarSimplify.cpp [PM] Split DominatorTree into a concrete analysis result object which 2014-01-13 13:07:17 +00:00
JumpThreading.cpp Don't eliminate a partially redundant load if it's in a landing pad. 2013-10-21 04:09:17 +00:00
LICM.cpp [PM] Split DominatorTree into a concrete analysis result object which 2014-01-13 13:07:17 +00:00
LLVMBuild.txt Add proper dependencies to LLVMBuild.txt in llvm/lib. 2013-12-10 05:39:34 +00:00
LoopDeletion.cpp [PM] Split DominatorTree into a concrete analysis result object which 2014-01-13 13:07:17 +00:00
LoopIdiomRecognize.cpp [PM] Split DominatorTree into a concrete analysis result object which 2014-01-13 13:07:17 +00:00
LoopInstSimplify.cpp [PM] Split DominatorTree into a concrete analysis result object which 2014-01-13 13:07:17 +00:00
LoopRerollPass.cpp [PM] Split DominatorTree into a concrete analysis result object which 2014-01-13 13:07:17 +00:00
LoopRotation.cpp [PM] Split DominatorTree into a concrete analysis result object which 2014-01-13 13:07:17 +00:00
LoopStrengthReduce.cpp Loop strength reduce: fix function name. 2014-01-22 13:27:00 +00:00
LoopUnrollPass.cpp [LPM] Make LoopSimplify no longer a LoopPass and instead both a utility 2014-01-23 11:23:19 +00:00
LoopUnswitch.cpp [PM] Split DominatorTree into a concrete analysis result object which 2014-01-13 13:07:17 +00:00
LowerAtomic.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
Makefile
MemCpyOptimizer.cpp Handle an addrspacecast case in memcpyopt 2014-01-22 21:53:19 +00:00
PartiallyInlineLibCalls.cpp Turn MipsOptimizeMathLibCalls into a target-independent scalar transform 2013-08-23 10:27:02 +00:00
Reassociate.cpp Put the functionality for printing a value to a raw_ostream as an 2014-01-09 02:29:41 +00:00
Reg2Mem.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
SampleProfile.cpp [PM] Split DominatorTree into a concrete analysis result object which 2014-01-13 13:07:17 +00:00
Scalar.cpp [cleanup] Move the Dominators.h and Verifier.h headers into the IR 2014-01-13 09:26:24 +00:00
Scalarizer.cpp Fix Scalarizer insertion point when replacing PHIs with insertelements 2013-12-23 14:51:56 +00:00
ScalarReplAggregates.cpp [PM] Split DominatorTree into a concrete analysis result object which 2014-01-13 13:07:17 +00:00
SCCP.cpp Use SmallVectorImpl& instead of SmallVector to avoid repeating small vector size. 2013-07-14 04:42:23 +00:00
SimplifyCFGPass.cpp Reapply r188119 now that the bug it exposed is fixed. 2013-08-12 22:38:43 +00:00
Sink.cpp [PM] Split DominatorTree into a concrete analysis result object which 2014-01-13 13:07:17 +00:00
SROA.cpp [SROA] Fix a bug which could cause the common type finding to return 2014-01-21 23:16:05 +00:00
StructurizeCFG.cpp [PM] Split DominatorTree into a concrete analysis result object which 2014-01-13 13:07:17 +00:00
TailRecursionElimination.cpp TRE: Move class into anonymous namespace. 2013-07-24 16:12:08 +00:00