Commit Graph

10 Commits

Author SHA1 Message Date
Dehao Chen 34cfcb29aa Make ICP uses PSI to check for hotness.
Summary: Currently, ICP checks the count against a fixed value to see if it is hot enough to be promoted. This does not work for SamplePGO because sampled count may be much smaller. This patch uses PSI to check if the count is hot enough to be promoted.

Reviewers: davidxl, tejohnson, eraman

Reviewed By: davidxl

Subscribers: sanjoy, llvm-commits, mehdi_amini

Differential Revision: https://reviews.llvm.org/D36341

llvm-svn: 310416
2017-08-08 20:57:33 +00:00
Adam Nemet a67dfe3b04 Relax the matching in these tests
Looks like the template arguments are displayed differently depending on the
host compiler(?).  E.g.:

InnerAnalysisManagerProxy<CGSCCAnalysisManager
InnerAnalysisManagerProxy<llvm::AnalysisManager<llvm::LazyCallGraph::SCC, ...

Fix fallout after r309294

llvm-svn: 309297
2017-07-27 17:45:02 +00:00
Adam Nemet 0d8b5d6f69 [ICP] Migrate to OptimizationRemarkEmitter
This is a module pass so for the old PM, we can't use ORE, the function
analysis pass.  Instead ORE is created on the fly.

A few notes:

- isPromotionLegal is folded in the caller since we want to emit the Function
in the remark but we can only do that if the symbol table look-up succeeded.

- There was good test coverage for remarks in this pass.

- promoteIndirectCall uses ORE conditionally since it's also used from
SampleProfile which does not use ORE yet.

Fixes PR33792.

Differential Revision: https://reviews.llvm.org/D35929

llvm-svn: 309294
2017-07-27 16:54:15 +00:00
Adam Nemet ea06e6e865 Migrate SimplifyLibCalls to new OptimizationRemarkEmitter
Summary:
This changes SimplifyLibCalls to use the new OptimizationRemarkEmitter
API.

In fact, as SimplifyLibCalls is only ever called via InstCombine,
(as far as I can tell) the OptimizationRemarkEmitter is added there,
and then passed through to SimplifyLibCalls later.

I have avoided changing any remark text.

This closes PR33787

Patch by Sam Elliott!

Reviewers: anemet, davide

Reviewed By: anemet

Subscribers: davide, mehdi_amini, eraman, fhahn, llvm-commits

Differential Revision: https://reviews.llvm.org/D35608

llvm-svn: 309158
2017-07-26 19:03:18 +00:00
Philip Pfaffe 730f2f9bb6 [PM] Enable registration of out-of-tree passes with PassBuilder
Summary:
This patch adds a callback registration API to the PassBuilder,
enabling registering out-of-tree passes with it.

Through the Callback API, callers may register callbacks with the
various stages at which passes are added into pass managers, including
parsing of a pass pipeline as well as at extension points within the
default -O pipelines.

Registering utilities like `require<>` and `invalidate<>` needs to be
handled manually by the caller, but a helper is provided.

Additionally, adding passes at pipeline extension points is exposed
through the opt tool. This patch adds a `-passes-ep-X` commandline
option for every extension point X, which opt parses into pipelines
inserted into that extension point.

Reviewers: chandlerc

Reviewed By: chandlerc

Subscribers: lksbhm, grosser, davide, mehdi_amini, llvm-commits, mgorny

Differential Revision: https://reviews.llvm.org/D33464

llvm-svn: 307532
2017-07-10 10:57:55 +00:00
Chandler Carruth 20e588e1af [PM/Inliner] Make the new PM's inliner process call edges across an
entire SCC before iterating on newly-introduced call edges resulting
from any inlined function bodies.

This more closely matches the behavior of the old PM's inliner. While it
wasn't really clear to me initially, this behavior is actually essential
to the inliner behaving reasonably in its current design.

Because the inliner is fundamentally a bottom-up inliner and all of its
cost modeling is designed around that it often runs into trouble within
an SCC where we don't have any meaningful bottom-up ordering to use. In
addition to potentially cyclic, infinite inlining that we block with the
inline history mechanism, it can also take seemingly simple call graph
patterns within an SCC and turn them into *insanely* large functions by
accidentally working top-down across the SCC without any of the
threshold limitations that traditional top-down inliners use.

Consider this diabolical monster.cpp file that Richard Smith came up
with to help demonstrate this issue:
```
template <int N> extern const char *str;

void g(const char *);

template <bool K, int N> void f(bool *B, bool *E) {
  if (K)
    g(str<N>);
  if (B == E)
    return;
  if (*B)
    f<true, N + 1>(B + 1, E);
  else
    f<false, N + 1>(B + 1, E);
}
template <> void f<false, MAX>(bool *B, bool *E) { return f<false, 0>(B, E); }
template <> void f<true, MAX>(bool *B, bool *E) { return f<true, 0>(B, E); }

extern bool *arr, *end;
void test() { f<false, 0>(arr, end); }
```

When compiled with '-DMAX=N' for various values of N, this will create an SCC
with a reasonably large number of functions. Previously, the inliner would try
to exhaust the inlining candidates in a single function before moving on. This,
unfortunately, turns it into a top-down inliner within the SCC. Because our
thresholds were never built for that, we will incrementally decide that it is
always worth inlining and proceed to flatten the entire SCC into that one
function.

What's worse, we'll then proceed to the next function, and do the exact same
thing except we'll skip the first function, and so on. And at each step, we'll
also make some of the constant factors larger, which is awesome.

The fix in this patch is the obvious one which makes the new PM's inliner use
the same technique used by the old PM: consider all the call edges across the
entire SCC before beginning to process call edges introduced by inlining. The
result of this is essentially to distribute the inlining across the SCC so that
every function incrementally grows toward the inline thresholds rather than
allowing the inliner to grow one of the functions vastly beyond the threshold.
The code for this is a bit awkward, but it works out OK.

We could consider in the future doing something more powerful here such as
prioritized order (via lowest cost and/or profile info) and/or a code-growth
budget per SCC. However, both of those would require really substantial work
both to design the system in a way that wouldn't break really useful
abstraction decomposition properties of the current inliner and to be tuned
across a reasonably diverse set of code and workloads. It also seems really
risky in many ways. I have only found a single real-world file that triggers
the bad behavior here and it is generated code that has a pretty pathological
pattern. I'm not worried about the inliner not doing an *awesome* job here as
long as it does *ok*. On the other hand, the cases that will be tricky to get
right in a prioritized scheme with a budget will be more common and idiomatic
for at least some frontends (C++ and Rust at least). So while these approaches
are still really interesting, I'm not in a huge rush to go after them. Staying
even closer to the existing PM's behavior, especially when this easy to do,
seems like the right short to medium term approach.

I don't really have a test case that makes sense yet... I'll try to find a
variant of the IR produced by the monster template metaprogram that is both
small enough to be sane and large enough to clearly show when we get this wrong
in the future. But I'm not confident this exists. And the behavior change here
*should* be unobservable without snooping on debug logging. So there isn't
really much to test.

The test case updates come from two incidental changes:
1) We now visit functions in an SCC in the opposite order. I don't think there
   really is a "right" order here, so I just update the test cases.
2) We no longer compute some analyses when an SCC has no call instructions that
   we consider for inlining.

llvm-svn: 297374
2017-03-09 11:35:40 +00:00
Chandler Carruth 6acdca78a0 [PH] Replace uses of AssertingVH from members of analysis results with
a lazy-asserting PoisoningVH.

AssertVH is fundamentally incompatible with cache-invalidation of
analysis results. The invaliadtion happens after the AssertingVH has
already fired. Instead, use a PoisoningVH that will assert if the
dangling handle is ever used rather than merely be assigned or
destroyed.

This patch also removes all of the (numerous) doomed attempts to work
around this fundamental incompatibility. It is a pretty significant
simplification IMO.

The most interesting change is in the Inliner where we still do some
clearing because we don't want to rely on the coarse grained
invalidation strategy of the containing pass manager. However, I prefer
the approach that contains this logic to the cleanup phase of the
Inliner, and I think we could enhance the CGSCC analysis management
layer to make this even better in the future if desired.

The rest is straight cleanup.

I've also added a test for one of the harder cases to work around: when
a *module analysis* contains many AssertingVHes pointing at functions.

Differential Revision: https://reviews.llvm.org/D29006

llvm-svn: 292928
2017-01-24 12:55:57 +00:00
Chandler Carruth d7e0e6b514 [PM] Further fixes to the test case in r292863.
This should hopefully fix the MSVC failures remaining.

llvm-svn: 292887
2017-01-24 05:30:41 +00:00
Davide Italiano ea2dc02668 [PM] Try to make all three compilers happy when it comes to pretty printing.
Modeled after a similar change from Michael Kuperstein. Let's hope this
sticks together.

llvm-svn: 292872
2017-01-24 01:45:53 +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