Commit Graph

68 Commits

Author SHA1 Message Date
Alina Sbirlea ba48a2c5e8 [AliasAnalysis/NewPassManager] Invalidate AAManager less often.
Summary:
This is a redo of D60914.

The objective is to not invalidate AAManager, which is stateless, unless
there is an explicit invalidate in one of the AAResults.

To achieve this, this patch adds an API to PAC, to check precisely this:
is this analysis not invalidated explicitly == is this analysis not abandoned == is this analysis stateless, so preserved without explicitly being marked as preserved by everyone

Reviewers: chandlerc

Subscribers: mehdi_amini, jlebar, george.burgess.iv, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D61284

llvm-svn: 359622
2019-04-30 22:15:47 +00:00
Alina Sbirlea b341efce31 Revert [AliasAnalysis] AAResults preserves AAManager.
Triggers use-after-free.

llvm-svn: 359055
2019-04-24 00:28:29 +00:00
Alina Sbirlea a809e8e5e7 [AliasAnalysis] AAResults preserves AAManager.
Summary:
AAResults should not invalidate AAManager.
Update tests.

Reviewers: chandlerc

Subscribers: mehdi_amini, jlebar, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D60914

llvm-svn: 359014
2019-04-23 17:21:18 +00:00
Chandler Carruth 923ff550b9 [NewPM] Fix a nasty bug with analysis invalidation in the new PM.
The issue here is that we actually allow CGSCC passes to mutate IR (and
therefore invalidate analyses) outside of the current SCC. At a minimum,
we need to support mutating parent and ancestor SCCs to support the
ArgumentPromotion pass which rewrites all calls to a function.

However, the analysis invalidation infrastructure is heavily based
around not needing to invalidate the same IR-unit at multiple levels.
With Loop passes for example, they don't invalidate other Loops. So we
need to customize how we handle CGSCC invalidation. Doing this without
gratuitously re-running analyses is even harder. I've avoided most of
these by using an out-of-band preserved set to accumulate the cross-SCC
invalidation, but it still isn't perfect in the case of re-visiting the
same SCC repeatedly *but* it coming off the worklist. Unclear how
important this use case really is, but I wanted to call it out.

Another wrinkle is that in order for this to successfully propagate to
function analyses, we have to make sure we have a proxy from the SCC to
the Function level. That requires pre-creating the necessary proxy.

The motivating test case now works cleanly and is added for
ArgumentPromotion.

Thanks for the review from Philip and Wei!

Differential Revision: https://reviews.llvm.org/D59869

llvm-svn: 357137
2019-03-28 00:51:36 +00:00
Fedor Sergeev ee8d31c49e [New PM] Introducing PassInstrumentation framework
Pass Execution Instrumentation interface enables customizable instrumentation
of pass execution, as per "RFC: Pass Execution Instrumentation interface"
posted 06/07/2018 on llvm-dev@

The intent is to provide a common machinery to implement all
the pass-execution-debugging features like print-before/after,
opt-bisect, time-passes etc.

Here we get a basic implementation consisting of:
* PassInstrumentationCallbacks class that handles registration of callbacks
  and access to them.

* PassInstrumentation class that handles instrumentation-point interfaces
  that call into PassInstrumentationCallbacks.

* Callbacks accept StringRef which is just a name of the Pass right now.
  There were some ideas to pass an opaque wrapper for the pointer to pass instance,
  however it appears that pointer does not actually identify the instance
  (adaptors and managers might have the same address with the pass they govern).
  Hence it was decided to go simple for now and then later decide on what the proper
  mental model of identifying a "pass in a phase of pipeline" is.

* Callbacks accept llvm::Any serving as a wrapper for const IRUnit*, to remove direct dependencies
  on different IRUnits (e.g. Analyses).

* PassInstrumentationAnalysis analysis is explicitly requested from PassManager through
  usual AnalysisManager::getResult. All pass managers were updated to run that
  to get PassInstrumentation object for instrumentation calls.

* Using tuples/index_sequence getAnalysisResult helper to extract generic AnalysisManager's extra
  args out of a generic PassManager's extra args. This is the only way I was able to explicitly
  run getResult for PassInstrumentationAnalysis out of a generic code like PassManager::run or
  RepeatedPass::run.
  TODO: Upon lengthy discussions we agreed to accept this as an initial implementation
  and then get rid of getAnalysisResult by improving RepeatedPass implementation.

* PassBuilder takes PassInstrumentationCallbacks object to pass it further into
  PassInstrumentationAnalysis. Callbacks registration should be performed directly
  through PassInstrumentationCallbacks.

* new-pm tests updated to account for PassInstrumentationAnalysis being run

* Added PassInstrumentation tests to PassBuilderCallbacks unit tests.
  Other unit tests updated with registration of the now-required PassInstrumentationAnalysis.

  Made getName helper to return std::string (instead of StringRef initially) to fix
  asan builtbot failures on CGSCC tests.

Reviewers: chandlerc, philip.pfaffe
Differential Revision: https://reviews.llvm.org/D47858

llvm-svn: 342664
2018-09-20 17:08:45 +00:00
Eric Christopher 019889374b Temporarily Revert "[New PM] Introducing PassInstrumentation framework"
as it was causing failures in the asan buildbot.

This reverts commit r342597.

llvm-svn: 342616
2018-09-20 05:16:29 +00:00
Fedor Sergeev a5f279ea89 [New PM] Introducing PassInstrumentation framework
Pass Execution Instrumentation interface enables customizable instrumentation
of pass execution, as per "RFC: Pass Execution Instrumentation interface"
posted 06/07/2018 on llvm-dev@

The intent is to provide a common machinery to implement all
the pass-execution-debugging features like print-before/after,
opt-bisect, time-passes etc.

Here we get a basic implementation consisting of:
* PassInstrumentationCallbacks class that handles registration of callbacks
  and access to them.

* PassInstrumentation class that handles instrumentation-point interfaces
  that call into PassInstrumentationCallbacks.

* Callbacks accept StringRef which is just a name of the Pass right now.
  There were some ideas to pass an opaque wrapper for the pointer to pass instance,
  however it appears that pointer does not actually identify the instance
  (adaptors and managers might have the same address with the pass they govern).
  Hence it was decided to go simple for now and then later decide on what the proper
  mental model of identifying a "pass in a phase of pipeline" is.

* Callbacks accept llvm::Any serving as a wrapper for const IRUnit*, to remove direct dependencies
  on different IRUnits (e.g. Analyses).

* PassInstrumentationAnalysis analysis is explicitly requested from PassManager through
  usual AnalysisManager::getResult. All pass managers were updated to run that
  to get PassInstrumentation object for instrumentation calls.

* Using tuples/index_sequence getAnalysisResult helper to extract generic AnalysisManager's extra
  args out of a generic PassManager's extra args. This is the only way I was able to explicitly
  run getResult for PassInstrumentationAnalysis out of a generic code like PassManager::run or
  RepeatedPass::run.
  TODO: Upon lengthy discussions we agreed to accept this as an initial implementation
  and then get rid of getAnalysisResult by improving RepeatedPass implementation.

* PassBuilder takes PassInstrumentationCallbacks object to pass it further into
  PassInstrumentationAnalysis. Callbacks registration should be performed directly
  through PassInstrumentationCallbacks.

* new-pm tests updated to account for PassInstrumentationAnalysis being run

* Added PassInstrumentation tests to PassBuilderCallbacks unit tests.
  Other unit tests updated with registration of the now-required PassInstrumentationAnalysis.

Reviewers: chandlerc, philip.pfaffe
Differential Revision: https://reviews.llvm.org/D47858

llvm-svn: 342597
2018-09-19 22:42:57 +00:00
Fedor Sergeev 25de3f83be Revert rL342544: [New PM] Introducing PassInstrumentation framework
A bunch of bots fail to compile unittests. Reverting.

llvm-svn: 342552
2018-09-19 14:54:48 +00:00
Fedor Sergeev 875c938fec [New PM] Introducing PassInstrumentation framework
Summary:
Pass Execution Instrumentation interface enables customizable instrumentation
of pass execution, as per "RFC: Pass Execution Instrumentation interface"
posted 06/07/2018 on llvm-dev@

The intent is to provide a common machinery to implement all
the pass-execution-debugging features like print-before/after,
opt-bisect, time-passes etc.

Here we get a basic implementation consisting of:
* PassInstrumentationCallbacks class that handles registration of callbacks
  and access to them.

* PassInstrumentation class that handles instrumentation-point interfaces
  that call into PassInstrumentationCallbacks.

* Callbacks accept StringRef which is just a name of the Pass right now.
  There were some ideas to pass an opaque wrapper for the pointer to pass instance,
  however it appears that pointer does not actually identify the instance
  (adaptors and managers might have the same address with the pass they govern).
  Hence it was decided to go simple for now and then later decide on what the proper
  mental model of identifying a "pass in a phase of pipeline" is.

* Callbacks accept llvm::Any serving as a wrapper for const IRUnit*, to remove direct dependencies
  on different IRUnits (e.g. Analyses).

* PassInstrumentationAnalysis analysis is explicitly requested from PassManager through
  usual AnalysisManager::getResult. All pass managers were updated to run that
  to get PassInstrumentation object for instrumentation calls.

* Using tuples/index_sequence getAnalysisResult helper to extract generic AnalysisManager's extra
  args out of a generic PassManager's extra args. This is the only way I was able to explicitly
  run getResult for PassInstrumentationAnalysis out of a generic code like PassManager::run or
  RepeatedPass::run.
  TODO: Upon lengthy discussions we agreed to accept this as an initial implementation
  and then get rid of getAnalysisResult by improving RepeatedPass implementation.

* PassBuilder takes PassInstrumentationCallbacks object to pass it further into
  PassInstrumentationAnalysis. Callbacks registration should be performed directly
  through PassInstrumentationCallbacks.

* new-pm tests updated to account for PassInstrumentationAnalysis being run

* Added PassInstrumentation tests to PassBuilderCallbacks unit tests.
  Other unit tests updated with registration of the now-required PassInstrumentationAnalysis.

Reviewers: chandlerc, philip.pfaffe
Differential Revision: https://reviews.llvm.org/D47858

llvm-svn: 342544
2018-09-19 12:25:52 +00:00
Fedor Sergeev 02e7f0247b [PM] pass -debug-pass-manager flag into FunctionToLoopPassAdaptor's canonicalization PM
Summary:
New pass manager driver passes DebugPM (-debug-pass-manager) flag into
individual PassManager constructors in order to enable debug logging.
FunctionToLoopPassAdaptor has its own internal LoopCanonicalizationPM
which never gets its debug logging enabled and that means canonicalization
passes like LoopSimplify are never present in -debug-pass-manager output.

Extending FunctionToLoopPassAdaptor's constructor and
createFunctionToLoopPassAdaptor wrapper with an optional
boolean DebugLogging argument.

Passing debug-logging flags there as appropriate.

Reviewers: chandlerc, davide

Reviewed By: davide

Subscribers: mehdi_amini, eraman, llvm-commits, JDevlieghere

Differential Revision: https://reviews.llvm.org/D41586

llvm-svn: 321548
2017-12-29 08:16:06 +00:00
Chandler Carruth 19913b22c0 [PM] Switch the CGSCC debug messages to use the standard LLVM debug
printing techniques with a DEBUG_TYPE controlling them.

It was a mistake to start re-purposing the pass manager `DebugLogging`
variable for generic debug printing -- those logs are intended to be
very minimal and primarily used for testing. More detailed and
comprehensive logging doesn't make sense there (it would only make for
brittle tests).

Moreover, we kept forgetting to propagate the `DebugLogging` variable to
various places making it also ineffective and/or unavailable. Switching
to `DEBUG_TYPE` makes this a non-issue.

llvm-svn: 310695
2017-08-11 05:47:13 +00:00
Chandler Carruth f59a838720 [PM/LCG] Teach the LazyCallGraph to maintain reference edges from every
function to every defined function known to LLVM as a library function.

LLVM can introduce calls to these functions either by replacing other
library calls or by recognizing patterns (such as memset_pattern or
vector math patterns) and replacing those with calls. When these library
functions are actually defined in the module, we need to have reference
edges to them initially so that we visit them during the CGSCC walk in
the right order and can effectively rebuild the call graph afterward.

This was discovered when building code with Fortify enabled as that is
a common case of both inline definitions of library calls and
simplifications of code into calling them.

This can in extreme cases of LTO-ing with libc introduce *many* more
reference edges. I discussed a bunch of different options with folks but
all of them are unsatisfying. They either make the graph operations
substantially more complex even when there are *no* defined libfuncs, or
they introduce some other complexity into the callgraph. So this patch
goes with the simplest possible solution of actual synthetic reference
edges. If this proves to be a memory problem, I'm happy to implement one
of the clever techniques to save memory here.

llvm-svn: 308088
2017-07-15 08:08:19 +00:00
Chandler Carruth f425292721 [PM] Fix a bug in the new loop PM when handling functions with no loops.
Without any loops, we don't even bother to build the standard analyses
used by loop passes. Without these, we can't run loop analyses or
invalidate them properly. Unfortunately, we did these things in the
wrong order which would allow a loop analysis manager's proxy to be
built but then not have the standard analyses built. When we went to do
the invalidation in the proxy thing would fall apart. In the test case
provided, it would actually crash.

The fix is to carefully check for loops first, and to in fact build the
standard analyses before building the proxy. This allows it to
correctly trigger invalidation for those standard analyses.

An alternative might seem to be  to look at whether there are any loops
when doing invalidation, but this doesn't work when during the loop
pipeline run we delete the last loop. I've even included that as a test
case. It is both simpler and more robust to defer building the proxy
until there are definitely the standard set of analyses and indeed
loops.

This bug was uncovered by enabling GlobalsAA in the pipeline.

llvm-svn: 294728
2017-02-10 08:26:58 +00:00
Davide Italiano 089a912365 [PM] Flesh out the new pass manager LTO pipeline.
Differential Revision:  https://reviews.llvm.org/D28996

llvm-svn: 292863
2017-01-24 00:57:39 +00:00
Chandler Carruth 17350de1ca [PM] Teach the loop PM to run LoopSimplify prior to the loop pipeline.
This adds the last remaining core feature of the loop pass pipeline in
the new PM and removes the last of the really egregious hacks in the
LICM tests.

Sadly, this requires really substantial changes in the unittests in
order to provide and maintain simplified loops. This is particularly
hard because for example LoopSimplify will try to fold undef branches to
an ideal direction and simplify the loop accordingly.

Differential Revision: https://reviews.llvm.org/D28766

llvm-svn: 292709
2017-01-21 03:48:51 +00:00
Michael Kuperstein 853e3337db [PM] Make default pipeline test for the new PM strict
Use CHECK-NEXT to verify that a test breaks whenever unexpected passes,
analyses, or invalidations show up in default pipelines. The test case
is constructed so that we don't expect to invalidate anything, and needs
to be kept that way.

The test is slightly less strict than we'd like because of differences
in type pretty-printing.

(Right now it does show some invalidations - all of those are intentional
and temporary.)

Differential Revision: https://reviews.llvm.org/D28887

llvm-svn: 292536
2017-01-19 23:39:28 +00:00
Michael Kuperstein c9bb572b73 Revert r292530 since it breaks buildbots.
llvm-svn: 292534
2017-01-19 23:22:55 +00:00
Michael Kuperstein 5a52af0f63 [PM] Make default pipeline test for the new PM strict
Use CHECK-NEXT to verify that a test breaks whenever unexpected passes,
analyses, or invalidations show up in default pipelines. The test case
is constructed so that we don't expect to invalidate anything, and needs
to be kept that way.

(Right now it does show some invalidations - all of those are intentional
and temporary.)

Differential Revision: https://reviews.llvm.org/D28887

llvm-svn: 292530
2017-01-19 22:55:46 +00:00
Michael Kuperstein 8ecc38ef85 [PM] Add LoopVectorize to the default module pipeline
LV no longer "requires" LCSSA and LoopSimplify, and instead forms
them internally as required. So, there's nothing preventing it from
being enabled.

llvm-svn: 292464
2017-01-19 02:21:54 +00:00
Chandler Carruth b6e32daa81 [PM] Teach the LoopPassManager to automatically canonicalize loops by
runnig LCSSA over them prior to running the loop pipeline.

This also teaches the loop PM to verify that LCSSA form is preserved
throughout the pipeline's run across the loop nest.

Most of the test updates just leverage this new functionality. One has to be
relaxed with the new PM as IVUsers is less powerful when it sees LCSSA input.

Differential Revision: https://reviews.llvm.org/D28743

llvm-svn: 292241
2017-01-17 19:18:12 +00:00
Chandler Carruth 410eaeb064 [PM] Rewrite the loop pass manager to use a worklist and augmented run
arguments much like the CGSCC pass manager.

This is a major redesign following the pattern establish for the CGSCC layer to
support updates to the set of loops during the traversal of the loop nest and
to support invalidation of analyses.

An additional significant burden in the loop PM is that so many passes require
access to a large number of function analyses. Manually ensuring these are
cached, available, and preserved has been a long-standing burden in LLVM even
with the help of the automatic scheduling in the old pass manager. And it made
the new pass manager extremely unweildy. With this design, we can package the
common analyses up while in a function pass and make them immediately available
to all the loop passes. While in some cases this is unnecessary, I think the
simplicity afforded is worth it.

This does not (yet) address loop simplified form or LCSSA form, but those are
the next things on my radar and I have a clear plan for them.

While the patch is very large, most of it is either mechanically updating loop
passes to the new API or the new testing for the loop PM. The code for it is
reasonably compact.

I have not yet updated all of the loop passes to correctly leverage the update
mechanisms demonstrated in the unittests. I'll do that in follow-up patches
along with improved FileCheck tests for those passes that ensure things work in
more realistic scenarios. In many cases, there isn't much we can do with these
until the loop simplified form and LCSSA form are in place.

Differential Revision: https://reviews.llvm.org/D28292

llvm-svn: 291651
2017-01-11 06:23:21 +00:00
Chandler Carruth 69c5cc69ed [PM] Actually commit the test update that was supposed to accompany
r290644. Sorry for this.

llvm-svn: 290646
2016-12-28 02:31:24 +00:00
Chandler Carruth aa35167578 [PM] Teach BasicAA how to invalidate its result object.
This requires custom handling because BasicAA caches handles to other
analyses and so it needs to trigger indirect invalidation.

This fixes one of the common crashes when using the new PM in real
pipelines. I've also tweaked a regression test to check that we are at
least handling the most immediate case.

I'm going to work at re-structuring this test some to both scale better
(rather than all being in one file) and check more invalidation paths in
a follow-up commit, but I wanted to get the basic bug fix in place.

llvm-svn: 290603
2016-12-27 10:30:45 +00:00
Chandler Carruth 81c8edaf5c [PM] Disable more of the loop passes -- LCSSA and LoopSimplify are also
not really wired into the loop pass manager in a way that will let us
productively use these passes yet.

This lets the new PM get farther in basic testing which is useful for
establishing a good baseline of "doesn't explode". There are still
plenty of crashers in basic testing though, this just gets rid of some
noise that is well understood and not representing a specific or narrow
bug.

llvm-svn: 290601
2016-12-27 10:16:46 +00:00
Chandler Carruth 17c630a09c [PM] Teach the AAManager and AAResults layer (the worst offender for
inter-analysis dependencies) to use the new invalidation infrastructure.

This teaches it to invalidate itself when any of the peer function
AA results that it uses become invalid. We do this by just tracking the
originating IDs. I've kept it in a somewhat clunky API since some users
of AAResults are outside the new PM right now. We can clean this API up
if/when those users go away.

Secondly, it uses the registration on the outer analysis manager proxy
to trigger deferred invalidation when a module analysis result becomes
invalid.

I've included test cases that specifically try to trigger use-after-free
in both of these cases and they would crash or hang pretty horribly for
me even without ASan. Now they work nicely.

The `InvalidateAnalysis` utility pass required some tweaking to be
useful in this context and it still is pretty garbage. I'd like to
switch it back to the previous implementation and teach the explicit
invalidate method on the AnalysisManager to take care of correctly
triggering indirect invalidation, but I wanted to go ahead and send this
out so folks could see how all of this stuff works together in practice.
And, you know, that it does actually work. =]

Differential Revision: https://reviews.llvm.org/D27205

llvm-svn: 290595
2016-12-27 08:44:39 +00:00
Chandler Carruth 060ad61fbe [PM] Add support for building a default AA pipeline to the PassBuilder.
Pretty boring and lame as-is but necessary. This is definitely a place
we'll end up with extension hooks longer term. =]

Differential Revision: https://reviews.llvm.org/D28076

llvm-svn: 290449
2016-12-23 20:38:19 +00:00
Chandler Carruth 0d1d49507b [PM] Loosen the check ever so slightly -- MSVC appears to not include
a space after the comma in template arguments with our hacky type name
system.

llvm-svn: 290331
2016-12-22 07:53:20 +00:00
Chandler Carruth ee6865f425 [PM] Make a couple of CHECK lines a bit more precise, NFC.
I was staring at these and didn't realize these were module-layer
proxies as opposed to some other layer. Justin and I have a plan to
rename things to make the names themselves much easier to reason about,
but I at least want the CHECK lines to be precise for now.

llvm-svn: 290328
2016-12-22 07:14:35 +00:00
Chandler Carruth e3f5064b72 [PM] Introduce a reasonable port of the main per-module pass pipeline
from the old pass manager in the new one.

I'm not trying to support (initially) the numerous options that are
currently available to customize the pass pipeline. If we end up really
wanting them, we can add them later, but I suspect many are no longer
interesting. The simplicity of omitting them will help a lot as we sort
out what the pipeline should look like in the new PM.

I've also documented to the best of my ability *why* each pass or group
of passes is used so that reading the pipeline is more helpful. In many
cases I think we have some questionable choices of ordering and I've
left FIXME comments in place so we know what to come back and revisit
going forward. But for now, I've left it as similar to the current
pipeline as I could.

Lastly, I've had to comment out several places where passes are not
ported to the new pass manager or where the loop pass infrastructure is
not yet ready. I did at least fix a few bugs in the loop pass
infrastructure uncovered by running the full pipeline, but I didn't want
to go too far in this patch -- I'll come back and re-enable these as the
infrastructure comes online. But I'd like to keep the comments in place
because I don't want to lose track of which passes need to be enabled
and where they go.

One thing that seemed like a significant API improvement was to require
that we don't build pipelines for O0. It seems to have no real benefit.

I've also switched back to returning pass managers by value as at this
API layer it feels much more natural to me for composition. But if
others disagree, I'm happy to go back to an output parameter.

I'm not 100% happy with the testing strategy currently, but it seems at
least OK. I may come back and try to refactor or otherwise improve this
in subsequent patches but I wanted to at least get a good starting point
in place.

Differential Revision: https://reviews.llvm.org/D28042

llvm-svn: 290325
2016-12-22 06:59:15 +00:00
Chandler Carruth cef2482875 [PM] Further broaden this test's regex as both the CGSCC and Function
inner AM proxies are now being rendered differently.

llvm-svn: 289319
2016-12-10 07:59:59 +00:00
Chandler Carruth d8aecb0e5c [PM] Try to support the new spelling of one of the proxy names that are
showing up on the build bots.

llvm-svn: 289318
2016-12-10 07:46:51 +00:00
Chandler Carruth 6b9816477b [PM] Support invalidation of inner analysis managers from a pass over the outer IR unit.
Summary:
This never really got implemented, and was very hard to test before
a lot of the refactoring changes to make things more robust. But now we
can test it thoroughly and cleanly, especially at the CGSCC level.

The core idea is that when an inner analysis manager proxy receives the
invalidation event for the outer IR unit, it needs to walk the inner IR
units and propagate it to the inner analysis manager for each of those
units. For example, each function in the SCC needs to get an
invalidation event when the SCC gets one.

The function / module interaction is somewhat boring here. This really
becomes interesting in the face of analysis-backed IR units. This patch
effectively handles all of the CGSCC layer's needs -- both invalidating
SCC analysis and invalidating function analysis when an SCC gets
invalidated.

However, this second aspect doesn't really handle the
LoopAnalysisManager well at this point. That one will need some change
of design in order to fully integrate, because unlike the call graph,
the entire function behind a LoopAnalysis's results can vanish out from
under us, and we won't even have a cached API to access. I'd like to try
to separate solving the loop problems into a subsequent patch though in
order to keep this more focused so I've adapted them to the API and
updated the tests that immediately fail, but I've not added the level of
testing and validation at that layer that I have at the CGSCC layer.

An important aspect of this change is that the proxy for the
FunctionAnalysisManager at the SCC pass layer doesn't work like the
other proxies for an inner IR unit as it doesn't directly manage the
FunctionAnalysisManager and invalidation or clearing of it. This would
create an ever worsening problem of dual ownership of this
responsibility, split between the module-level FAM proxy and this
SCC-level FAM proxy. Instead, this patch changes the SCC-level FAM proxy
to work in terms of the module-level proxy and defer to it to handle
much of the updates. It only does SCC-specific invalidation. This will
become more important in subsequent patches that support more complex
invalidaiton scenarios.

Reviewers: jlebar

Subscribers: mehdi_amini, mcrosier, mzolotukhin, llvm-commits

Differential Revision: https://reviews.llvm.org/D27197

llvm-svn: 289317
2016-12-10 06:34:44 +00:00
Chandler Carruth 8882346842 [PM] Introduce basic update capabilities to the new PM's CGSCC pass
manager, including both plumbing and logic to handle function pass
updates.

There are three fundamentally tied changes here:
1) Plumbing *some* mechanism for updating the CGSCC pass manager as the
   CG changes while passes are running.
2) Changing the CGSCC pass manager infrastructure to have support for
   the underlying graph to mutate mid-pass run.
3) Actually updating the CG after function passes run.

I can separate them if necessary, but I think its really useful to have
them together as the needs of #3 drove #2, and that in turn drove #1.

The plumbing technique is to extend the "run" method signature with
extra arguments. We provide the call graph that intrinsically is
available as it is the basis of the pass manager's IR units, and an
output parameter that records the results of updating the call graph
during an SCC passes's run. Note that "...UpdateResult" isn't a *great*
name here... suggestions very welcome.

I tried a pretty frustrating number of different data structures and such
for the innards of the update result. Every other one failed for one
reason or another. Sometimes I just couldn't keep the layers of
complexity right in my head. The thing that really worked was to just
directly provide access to the underlying structures used to walk the
call graph so that their updates could be informed by the *particular*
nature of the change to the graph.

The technique for how to make the pass management infrastructure cope
with mutating graphs was also something that took a really, really large
number of iterations to get to a place where I was happy. Here are some
of the considerations that drove the design:

- We operate at three levels within the infrastructure: RefSCC, SCC, and
  Node. In each case, we are working bottom up and so we want to
  continue to iterate on the "lowest" node as the graph changes. Look at
  how we iterate over nodes in an SCC running function passes as those
  function passes mutate the CG. We continue to iterate on the "lowest"
  SCC, which is the one that continues to contain the function just
  processed.

- The call graph structure re-uses SCCs (and RefSCCs) during mutation
  events for the *highest* entry in the resulting new subgraph, not the
  lowest. This means that it is necessary to continually update the
  current SCC or RefSCC as it shifts. This is really surprising and
  subtle, and took a long time for me to work out. I actually tried
  changing the call graph to provide the opposite behavior, and it
  breaks *EVERYTHING*. The graph update algorithms are really deeply
  tied to this particualr pattern.

- When SCCs or RefSCCs are split apart and refined and we continually
  re-pin our processing to the bottom one in the subgraph, we need to
  enqueue the newly formed SCCs and RefSCCs for subsequent processing.
  Queuing them presents a few challenges:
  1) SCCs and RefSCCs use wildly different iteration strategies at
     a high level. We end up needing to converge them on worklist
     approaches that can be extended in order to be able to handle the
     mutations.
  2) The order of the enqueuing need to remain bottom-up post-order so
     that we don't get surprising order of visitation for things like
     the inliner.
  3) We need the worklists to have set semantics so we don't duplicate
     things endlessly. We don't need a *persistent* set though because
     we always keep processing the bottom node!!!! This is super, super
     surprising to me and took a long time to convince myself this is
     correct, but I'm pretty sure it is... Once we sink down to the
     bottom node, we can't re-split out the same node in any way, and
     the postorder of the current queue is fixed and unchanging.
  4) We need to make sure that the "current" SCC or RefSCC actually gets
     enqueued here such that we re-visit it because we continue
     processing a *new*, *bottom* SCC/RefSCC.

- We also need the ability to *skip* SCCs and RefSCCs that get merged
  into a larger component. We even need the ability to skip *nodes* from
  an SCC that are no longer part of that SCC.

This led to the design you see in the patch which uses SetVector-based
worklists. The RefSCC worklist is always empty until an update occurs
and is just used to handle those RefSCCs created by updates as the
others don't even exist yet and are formed on-demand during the
bottom-up walk. The SCC worklist is pre-populated from the RefSCC, and
we push new SCCs onto it and blacklist existing SCCs on it to get the
desired processing.

We then *directly* update these when updating the call graph as I was
never able to find a satisfactory abstraction around the update
strategy.

Finally, we need to compute the updates for function passes. This is
mostly used as an initial customer of all the update mechanisms to drive
their design to at least cover some real set of use cases. There are
a bunch of interesting things that came out of doing this:

- It is really nice to do this a function at a time because that
  function is likely hot in the cache. This means we want even the
  function pass adaptor to support online updates to the call graph!

- To update the call graph after arbitrary function pass mutations is
  quite hard. We have to build a fairly comprehensive set of
  data structures and then process them. Fortunately, some of this code
  is related to the code for building the cal graph in the first place.
  Unfortunately, very little of it makes any sense to share because the
  nature of what we're doing is so very different. I've factored out the
  one part that made sense at least.

- We need to transfer these updates into the various structures for the
  CGSCC pass manager. Once those were more sanely worked out, this
  became relatively easier. But some of those needs necessitated changes
  to the LazyCallGraph interface to make it significantly easier to
  extract the changed SCCs from an update operation.

- We also need to update the CGSCC analysis manager as the shape of the
  graph changes. When an SCC is merged away we need to clear analyses
  associated with it from the analysis manager which we didn't have
  support for in the analysis manager infrsatructure. New SCCs are easy!
  But then we have the case that the original SCC has its shape changed
  but remains in the call graph. There we need to *invalidate* the
  analyses associated with it.

- We also need to invalidate analyses after we *finish* processing an
  SCC. But the analyses we need to invalidate here are *only those for
  the newly updated SCC*!!! Because we only continue processing the
  bottom SCC, if we split SCCs apart the original one gets invalidated
  once when its shape changes and is not processed farther so its
  analyses will be correct. It is the bottom SCC which continues being
  processed and needs to have the "normal" invalidation done based on
  the preserved analyses set.

All of this is mostly background and context for the changes here.

Many thanks to all the reviewers who helped here. Especially Sanjoy who
caught several interesting bugs in the graph algorithms, David, Sean,
and others who all helped with feedback.

Differential Revision: http://reviews.llvm.org/D21464

llvm-svn: 279618
2016-08-24 09:37:14 +00:00
Chandler Carruth 8abdf75d6b [PM] Introduce an abstraction for all the analyses over a particular IR
unit for use in the PreservedAnalyses set.

This doesn't have any important functional change yet but it cleans
things up and makes the analysis substantially more efficient by
avoiding querying through the type erasure for every analysis.

I also think it makes it much easier to reason about how analyses are
preserved when walking across pass managers and across IR unit
abstractions.

Thanks to Sean and Mehdi both for the comments and suggestions.

Differential Revision: https://reviews.llvm.org/D23691

llvm-svn: 279360
2016-08-20 04:57:28 +00:00
Chandler Carruth a053a88df5 [PM] Change the name of the repeating utility to something less
overloaded (and simpler).

Sean rightly pointed out in code review that we've started using
"wrapper pass" as a specific part of the old pass manager, and in fact
it is more applicable there. Here, we really have a pass *template* to
build a repeated pass, so call it that.

llvm-svn: 277689
2016-08-04 03:52:53 +00:00
Chandler Carruth 241bf2456f [PM] Add a generic 'repeat N times' pass wrapper to the new pass
manager.

While this has some utility for debugging and testing on its own, it is
primarily intended to demonstrate the technique for adding custom
wrappers that can provide more interesting interation behavior in
a nice, orthogonal, and composable layer.

Being able to write these kinds of very dynamic and customized controls
for running passes was one of the motivating use cases of the new pass
manager design, and this gives a hint at how they might look. The actual
logic is tiny here, and most of this is just wiring in the pipeline
parsing so that this can be widely used.

I'm adding this now to show the wiring without a lot of business logic.
This is a precursor patch for showing how a "iterate up to N times as
long as we devirtualize a call" utility can be added as a separable and
composable component along side the CGSCC pass management.

Differential Revision: https://reviews.llvm.org/D22405

llvm-svn: 277581
2016-08-03 07:44:48 +00:00
Chandler Carruth dca834089a [PM] Improve the debugging and logging facilities of the CGSCC bits of
the new pass manager.

This adds operator<< overloads for the various bits of the
LazyCallGraph, dump methods for use from the debugger, and debug logging
using them to the CGSCC pass manager.

Having this was essential for debugging the call graph update patch, and
I've extracted what I could from that patch here to minimize the delta.

llvm-svn: 273961
2016-06-27 23:26:08 +00:00
Chandler Carruth 4c660f7087 [CG] Add a new pass manager printer pass for the old call graph and
actually finish wiring up the old call graph.

There were bugs in the old call graph that hadn't been caught because it
wasn't being tested. It wasn't being tested because it wasn't in the
pipeline system and we didn't have a printing pass to run in tests. This
fixes all of that.

As for why I'm still keeping the old call graph alive its so that I can
port GlobalsAA to the new pass manager with out forking it to work with
the lazy call graph. That's clearly the right eventual design, but it
seems pragmatic to defer that until its necessary. The old call graph
works just fine for GlobalsAA.

llvm-svn: 263104
2016-03-10 11:24:11 +00:00
Chandler Carruth 61440d225b [PM] Port memdep to the new pass manager.
This is a fairly straightforward port to the new pass manager with one
exception. It removes a very questionable use of releaseMemory() in
the old pass to invalidate its caches between runs on a function.
I don't think this is really guaranteed to be safe. I've just used the
more direct port to the new PM to address this by nuking the results
object each time the pass runs. While this could cause some minor malloc
traffic increase, I don't expect the compile time performance hit to be
noticable, and it makes the correctness and other aspects of the pass
much easier to reason about. In some cases, it may make things faster by
making the sets and maps smaller with better locality. Indeed, the
measurements collected by Bruno (thanks!!!) show mostly compile time
improvements.

There is sadly very limited testing at this point as there are only two
tests of memdep, and both rely on GVN. I'll be porting GVN next and that
will exercise this heavily though.

Differential Revision: http://reviews.llvm.org/D17962

llvm-svn: 263082
2016-03-10 00:55:30 +00:00
Chandler Carruth 8b5a7419b8 [PM] Wire up optimization levels and default pipeline construction APIs
in the PassBuilder.

These are really just stubs for now, but they give a nice API surface
that Clang or other tools can start learning about and enabling for
experimentation.

I've also wired up parsing various synthetic module pass names to
generate these set pipelines. This allows the pipelines to be combined
with other passes and have their order controlled, with clear separation
between the *kind* of canned pipeline, and the *level* of optimization
to be used within that canned pipeline.

The most interesting part of this patch is almost certainly the spec for
the different optimization levels. I don't think we can ever have hard
and fast rules that would make it easy to determine whether a particular
optimization makes sense at a particular level -- it will always be in
large part a judgement call. But hopefully this will outline the
expected rationale that should be used, and the direction that the
pipelines should be taken. Much of this was based on a long llvm-dev
discussion I started years ago to try and crystalize the intent behind
these pipelines, and now, at long long last I'm returning to the task of
actually writing it down somewhere that we can cite and try to be
consistent with.

Differential Revision: http://reviews.llvm.org/D12826

llvm-svn: 262196
2016-02-28 22:16:03 +00:00
Chandler Carruth 30811a4dde [PM] Loosen the regex for the proxy template name even further to cope
with 'class' keywords in the template arguments and other silliness.

llvm-svn: 262130
2016-02-27 11:07:16 +00:00
Chandler Carruth 08a25ce0e3 [PM] Use a boring regex instead of explicitly naming the analysis
manager as some compilers print the typedef name and others print the
"canonical" name of the underlying class template.

This isn't really an important artifact of the test anyways so it seems
fine to just loosen the test assertions here.

llvm-svn: 262129
2016-02-27 10:48:14 +00:00
Chandler Carruth 2a54094d40 [PM] Provide two templates for the two directionalities of analysis
manager proxies and use those rather than repeating their definition
four times.

There are real differences between the two directions: outer AMs are
const and don't need to have invalidation tracked. But every proxy in
a particular direction is identical except for the analysis manager type
and the IR unit they proxy into. This makes them prime candidates for
nice templates.

I've started introducing explicit template instantiation declarations
and definitions as well because we really shouldn't be emitting all this
everywhere. I'm going to go back and add the same for the other
templates like this in a follow-up patch.

I've left the analysis manager as an opaque type rather than using two
IR units and requiring it to be an AnalysisManager template
specialization. I think its important that users retain the ability to
provide their own custom analysis management layer and provided it has
the appropriate API everything should Just Work.

llvm-svn: 262127
2016-02-27 10:38:10 +00:00
Chandler Carruth 3a63435551 [PM] Introduce CRTP mixin base classes to help define passes and
analyses in the new pass manager.

These just handle really basic stuff: turning a type name into a string
statically that is nice to print in logs, and getting a static unique ID
for each analysis.

Sadly, the format of passes in anonymous namespaces makes using their
names in tests really annoying so I've customized the names of the no-op
passes to keep tests sane to read.

This is the first of a few simplifying refactorings for the new pass
manager that should reduce boilerplate and confusion.

llvm-svn: 262004
2016-02-26 11:44:45 +00:00
Chandler Carruth 395fe57374 [PM] Add the IR unit type to the pass manager's logging and make all of
the testing more more explicit.

This will currently fail on platforms without support for getTypeName.
While an assert failure seems too harsh, I'm hoping we're OK with the
regression test failure, and I'd like to find out about what platforms
actually exist in this state if there are any so we can get
implementations in place for them.

But if we just can't fix all the host compilers to have a reasonably
portable variant of getTypeName and are worried about xfailing this test
on those platforms, I can add the horrible regular expression magic to
make the tests support "unknown" here as well.

llvm-svn: 261853
2016-02-25 10:27:39 +00:00
Chandler Carruth edf5996b06 [PM/AA] Teach the new pass manager to use pass-by-lambda for registering
analysis passes, support pre-registering analyses, and use that to
implement parsing and pre-registering a custom alias analysis pipeline.

With this its possible to configure the particular alias analysis
pipeline used by the AAManager from the commandline of opt. I've updated
the test to show this effectively in use to build a pipeline including
basic-aa as part of it.

My big question for reviewers are around the APIs that are used to
expose this functionality. Are folks happy with pass-by-lambda to do
pass registration? Are folks happy with pre-registering analyses as
a way to inject customized instances of an analysis while still using
the registry for the general case?

Other thoughts of course welcome. The next round of patches will be to
add the rest of the alias analyses into the new pass manager and wire
them up here so that they can be used from opt. This will require
extending the (somewhate limited) functionality of AAManager w.r.t.
module passes.

Differential Revision: http://reviews.llvm.org/D17259

llvm-svn: 261197
2016-02-18 09:45:17 +00:00
Chandler Carruth bece8d517d [PM/AA] Wire BasicAA's new pass manager class up to the pass registry.
This ensures that all of the various pieces are working. The next patch
will wire up commandline-driven alias analysis chain building and allow
BasicAA to work with the AAManager.

llvm-svn: 260838
2016-02-13 23:46:24 +00:00
Chandler Carruth 6f5770b10f [PM/AA] Actually wire the AAManager I built for the new pass manager
into the new pass manager and fix the latent bugs there.

This lets everything live together nicely, but it isn't really useful
yet. I never finished wiring the AA layer up for the new pass manager,
and so subsequent patches will change this to do that wiring and get AA
stuff more fully integrated into the new pass manager. Turns out this is
necessary even to get functionattrs ported over. =]

llvm-svn: 260836
2016-02-13 23:32:00 +00:00
Chandler Carruth 9f8d9b613c [PM] Teach the module-to-function adaptor to not run function passes
over declarations.

This is both quite unproductive and causes things to crash, for example
domtree would just assert.

I've added a declaration and a domtree run to the basic high-level tests
for the new pass manager.

llvm-svn: 227724
2015-02-01 10:47:25 +00:00
Chandler Carruth e038552c8a [PM] Port TTI to the new pass manager, introducing a TargetIRAnalysis to
produce it.

This adds a function to the TargetMachine that produces this analysis
via a callback for each function. This in turn faves the way to produce
a *different* TTI per-function with the correct subtarget cached.

I've also done the necessary wiring in the opt tool to thread the target
machine down and make it available to the pass registry so that we can
construct this analysis from a target machine when available.

llvm-svn: 227721
2015-02-01 10:11:22 +00:00