125 Commits

Author SHA1 Message Date
Jordan Rose
81e339197e Second attempt to add iterator_range::empty()
Doing this makes MSVC complain that `empty(someRange)` could refer to
either C++17's std::empty or LLVM's llvm::empty, which previously we
avoided via SFINAE because std::empty is defined in terms of an empty
member rather than begin and end. So, switch callers over to the new
method as it is added.

https://reviews.llvm.org/D68439

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@373935 91177308-0d34-0410-b5e6-96231b3b80d8
2019-10-07 18:14:24 +00:00
Teresa Johnson
ef512ca8e6 Change TargetLibraryInfo analysis passes to always require Function
Summary:
This is the first change to enable the TLI to be built per-function so
that -fno-builtin* handling can be migrated to use function attributes.
See discussion on D61634 for background. This is an enabler for fixing
handling of these options for LTO, for example.

This change should not affect behavior, as the provided function is not
yet used to build a specifically per-function TLI, but rather enables
that migration.

Most of the changes were very mechanical, e.g. passing a Function to the
legacy analysis pass's getTLI interface, or in Module level cases,
adding a callback. This is similar to the way the per-function TTI
analysis works.

There was one place where we were looking for builtins but not in the
context of a specific function. See FindCXAAtExit in
lib/Transforms/IPO/GlobalOpt.cpp. I'm somewhat concerned my workaround
could provide the wrong behavior in some corner cases. Suggestions
welcome.

Reviewers: chandlerc, hfinkel

Subscribers: arsenm, dschuff, jvesely, nhaehnle, mehdi_amini, javed.absar, sbc100, jgravelle-google, eraman, aheejin, steven_wu, george.burgess.iv, dexonsmith, jfb, asbirlea, gchatelet, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D66428

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@371284 91177308-0d34-0410-b5e6-96231b3b80d8
2019-09-07 03:09:36 +00:00
Benjamin Kramer
755506e11d Revert "[CallGraph] Refine call graph for indirect calls with !callees metadata"
This reverts commit r369025. Crashes clang, test case is on the mailing
list.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@369096 91177308-0d34-0410-b5e6-96231b3b80d8
2019-08-16 10:59:18 +00:00
Mark Lacey
c4ed7f707a [CallGraph] Refine call graph for indirect calls with !callees metadata
For indirect call sites having a small set of possible callees,
!callees metadata can be used to indicate what those callees are.
This patch updates the call graph and lazy call graph analyses so
that they consider this metadata when encountering call sites. For
the call graph, it adds a new external call graph node to the graph
for each unique !callees metadata node. A call graph edge connects
an indirect call site with the external node associated with the
!callees metadata that is attached to it. And there is an edge from
this external node to each of the callees indicated by the metadata.
Similarly, for the lazy call graph, the patch adds Ref edges from a
caller to the possible callees indicated by the metadata.

The primary purpose of the patch is to facilitate iterating over the
functions in a module such that all of the callees indicated by a
given !callees metadata node will be visited prior to the functions
containing call sites annotated by that node. This property is
required by optimizations performing a bottom-up traversal of the
SCC DAG. For example, the inliner can be made to inline through an
indirect call. If the call site is annotated with !callees metadata,
this patch ensures that the inliner will have visited all of the
callees prior to the caller, allowing it to reliably compute the
cost of inlining one or more of the potential callees.

Original patch by @mssimpso. I've made some small changes to get it
to apply, build, and pass tests on the top of tree, as well as
some minor tweaks to formatting and functionality.

Subscribers: mehdi_amini, hiraditya, llvm-commits, mssimpso

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D39339

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@369025 91177308-0d34-0410-b5e6-96231b3b80d8
2019-08-15 17:47:53 +00:00
Fangrui Song
5ee6dfaf46 Change two unnecessary uses of llvm::size(C) to C.size()
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@368011 91177308-0d34-0410-b5e6-96231b3b80d8
2019-08-06 10:24:36 +00:00
Guozhi Wei
0fdc2d835f [LCG] Add aliased functions as LCG roots
Current LCG doesn't check aliased functions. So if an internal function has a public alias it will not be added to CG SCC, but it is still reachable from outside through the alias.
So this patch adds aliased functions to SCC.

Differential Revision: https://reviews.llvm.org/D59898



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@357795 91177308-0d34-0410-b5e6-96231b3b80d8
2019-04-05 18:51:08 +00:00
Chandler Carruth
6b547686c5 Update the file headers across all of the LLVM projects in the monorepo
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@351636 91177308-0d34-0410-b5e6-96231b3b80d8
2019-01-19 08:50:56 +00:00
Matthias Braun
b3bc95870d ADT/STLExtras: Introduce llvm::empty; NFC
This is modeled after C++17 std::empty().

Differential Revision: https://reviews.llvm.org/D53909

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@345679 91177308-0d34-0410-b5e6-96231b3b80d8
2018-10-31 00:23:23 +00:00
Vedant Kumar
ca6a4d968e [STLExtras] Add size() for ranges, and remove distance()
r332057 introduced distance() for ranges. Based on post-commit feedback,
this renames distance() to size(). The new size() is also only enabled
when the operation is O(1).

Differential Revision: https://reviews.llvm.org/D46976

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@332551 91177308-0d34-0410-b5e6-96231b3b80d8
2018-05-16 23:20:42 +00:00
Nicola Zaghen
0818e789cb Rename DEBUG macro to LLVM_DEBUG.
The DEBUG() macro is very generic so it might clash with other projects.
The renaming was done as follows:
- git grep -l 'DEBUG' | xargs sed -i 's/\bDEBUG\s\?(/LLVM_DEBUG(/g'
- git diff -U0 master | ../clang/tools/clang-format/clang-format-diff.py -i -p1 -style LLVM
- Manual change to APInt
- Manually chage DOCS as regex doesn't match it.

In the transition period the DEBUG() macro is still present and aliased
to the LLVM_DEBUG() one.

Differential Revision: https://reviews.llvm.org/D43624



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@332240 91177308-0d34-0410-b5e6-96231b3b80d8
2018-05-14 12:53:11 +00:00
Vedant Kumar
48fd38c573 [STLExtras] Add distance() for ranges, pred_size(), and succ_size()
This commit adds a wrapper for std::distance() which works with ranges.
As it would be a common case to write `distance(predecessors(BB))`, this
also introduces `pred_size()` and `succ_size()` helpers to make that
easier to write.

Differential Revision: https://reviews.llvm.org/D46668

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@332057 91177308-0d34-0410-b5e6-96231b3b80d8
2018-05-10 23:01:54 +00:00
Nico Weber
0f38c60baf IWYU for llvm-config.h in llvm, additions.
See r331124 for how I made a list of files missing the include.
I then ran this Python script:

    for f in open('filelist.txt'):
        f = f.strip()
        fl = open(f).readlines()

        found = False
        for i in xrange(len(fl)):
            p = '#include "llvm/'
            if not fl[i].startswith(p):
                continue
            if fl[i][len(p):] > 'Config':
                fl.insert(i, '#include "llvm/Config/llvm-config.h"\n')
                found = True
                break
        if not found:
            print 'not found', f
        else:
            open(f, 'w').write(''.join(fl))

and then looked through everything with `svn diff | diffstat -l | xargs -n 1000 gvim -p`
and tried to fix include ordering and whatnot.

No intended behavior change.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@331184 91177308-0d34-0410-b5e6-96231b3b80d8
2018-04-30 14:59:11 +00:00
Vedant Kumar
d924442186 Fix more spelling mistakes in comments of LLVM Analysis passes
Patch by Reshabh Sharma!

Differential Revision: https://reviews.llvm.org/D43939

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@326601 91177308-0d34-0410-b5e6-96231b3b80d8
2018-03-02 18:57:02 +00:00
Malcolm Parsons
5fc96281fc Fix typos of occurred and occurrence
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@323318 91177308-0d34-0410-b5e6-96231b3b80d8
2018-01-24 10:33:39 +00:00
Aaron Ballman
1d03d382c1 Reverting r315590; it did not include changes for llvm-tblgen, which is causing link errors for several people.
Error LNK2019 unresolved external symbol "public: void __cdecl `anonymous namespace'::MatchableInfo::dump(void)const " (?dump@MatchableInfo@?A0xf4f1c304@@QEBAXXZ) referenced in function "public: void __cdecl `anonymous namespace'::AsmMatcherEmitter::run(class llvm::raw_ostream &)" (?run@AsmMatcherEmitter@?A0xf4f1c304@@QEAAXAEAVraw_ostream@llvm@@@Z) llvm-tblgen D:\llvm\2017\utils\TableGen\AsmMatcherEmitter.obj 1


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@315854 91177308-0d34-0410-b5e6-96231b3b80d8
2017-10-15 14:32:27 +00:00
Don Hinton
5298935fe7 [dump] Remove NDEBUG from test to enable dump methods [NFC]
Summary:
Add LLVM_FORCE_ENABLE_DUMP cmake option, and use it along with
LLVM_ENABLE_ASSERTIONS to set LLVM_ENABLE_DUMP.

Remove NDEBUG and only use LLVM_ENABLE_DUMP to enable dump methods.

Move definition of LLVM_ENABLE_DUMP from config.h to llvm-config.h so
it'll be picked up by public headers.

Differential Revision: https://reviews.llvm.org/D38406

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@315590 91177308-0d34-0410-b5e6-96231b3b80d8
2017-10-12 16:16:06 +00:00
Eugene Zelenko
c5e4ac86db [Analysis] Fix some Clang-tidy modernize-use-using and Include What You Use warnings; other minor fixes (NFC).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310766 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-11 21:30:02 +00:00
Chandler Carruth
0302f3db41 [LCG] Fix an assert in a on-scope-exit lambda that checked the contents
of the returned value.

Checking the returned value from inside of a scoped exit isn't actually
valid. It happens to work when NRVO fires and the stars align, which
they reliably do with Clang but don't, for example, on MSVC builds.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310547 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-10 03:05:21 +00:00
Chandler Carruth
722597ed5b [LCG] Completely remove the map-based association of post-order numbers
to Nodes when removing ref edges from a RefSCC.

This map based association turns out to be pretty expensive for large
RefSCCs and pointless as we already have embedded data members inside
nodes that we use to track the DFS state. We can reuse one of those and
the map becomes unnecessary.

This also fuses the update of those numbers into the scan across the
pending stack of nodes so that we don't walk the nodes twice during the
DFS.

With this I expect the new PM to be faster than the old PM for the test
case I have been optimizing. That said, it also seems simpler and more
direct in many ways. The side storage was always pretty awkward.

The last remaining hot-spot in the profile of the LCG once this is done
will be the edge iterator walk in the DFS. I'll take a look at improving
that next.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310456 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-09 09:37:39 +00:00
Chandler Carruth
5428aff18c [LCG] Special case when removing a ref edge from a RefSCC leaves
that RefSCC still connected.

This is common and can be handled much more efficiently. As soon as we
know we've covered every node in the RefSCC with the DFS, we can simply
reset our state and return. This avoids numerous data structure updates
and other complexity.

On top of other changes, this appears to get new PM back to parity with
the old PM for a large protocol buffer message source code. The dense
map updates are very hot in this function.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310451 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-09 09:14:34 +00:00
Chandler Carruth
affd12878e [LCG] Switch one of the update methods for the LazyCallGraph to support
limited batch updates.

Specifically, allow removing multiple reference edges starting from
a common source node. There are a few constraints that play into
supporting this form of batching:

1) The way updates occur during the CGSCC walk, about the most we can
   functionally batch together are those with a common source node. This
   also makes the batching simpler to implement, so it seems
   a worthwhile restriction.
2) The far and away hottest function for large C++ files I measured
   (generated code for protocol buffers) showed a huge amount of time
   was spent removing ref edges specifically, so it seems worth focusing
   there.
3) The algorithm for removing ref edges is very amenable to this
   restricted batching. There are just both API and implementation
   special casing for the non-batch case that gets in the way. Once
   removed, supporting batches is nearly trivial.

This does modify the API in an interesting way -- now, we only preserve
the target RefSCC when the RefSCC structure is unchanged. In the face of
any splits, we create brand new RefSCC objects. However, all of the
users were OK with it that I could find. Only the unittest needed
interesting updates here.

How much does batching these updates help? I instrumented the compiler
when run over a very large generated source file for a protocol buffer
and found that the majority of updates are intrinsically updating one
function at a time. However, nearly 40% of the total ref edges removed
are removed as part of a batch of removals greater than one, so these
are the cases batching can help with.

When compiling the IR for this file with 'opt' and 'O3', this patch
reduces the total time by 8-9%.

Differential Revision: https://reviews.llvm.org/D36352

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310450 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-09 09:05:27 +00:00
Chandler Carruth
0b26163a3b [LCG] Remove yet another variable only used inside of asserts.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310174 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-05 08:33:16 +00:00
Benjamin Kramer
e291555dd3 [LCG] Fold otherwise unused variable into assert.
No functionality change intended.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310173 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-05 08:28:48 +00:00
Chandler Carruth
3ae1e28f67 [LCG] Completely remove the parent set and leaf tracking for RefSCCs.
After the previous series of patches, this is now trivial and deletes
a pretty astonishing amount of complexity. This has been a long time
coming, as the move toward a PO sequence of RefSCCs started eroding the
underlying use cases for this half of the data structure.

Among the biggest advantages here is that now there aren't two
independent data structures that need to stay in sync.

Some of my profiling has also indicated that updating the parent sets
was among the most expensive parts of the lazy call graph. Eliminating
it whole sale is likely to be a nice win in terms of compile time.

Last but not least, I had discussed with some folks previously keeping
it around for asserts and other correctness checking, but once the
fundamentals of the parent and child checking were implemented without
the parent sets their value in correctness checking was tiny and no
where near worth the cost of the complexity required to keep everything
up-to-date.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310171 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-05 07:37:00 +00:00
Chandler Carruth
8d16ccbe0f [LCG] Re-implement the basic isParentOf, isAncestorOf, isChildOf, and
isDescendantOf methods on RefSCCs in terms of the forward edges rather
than the parent sets.

This is technically slower, but probably not interestingly slower, and
all of these routines were already so expensive that they're guarded
behind both !NDEBUG and EXPENSIVE_CHECKS.

This removes another non-critical usage of parent sets.

I've also added some comments to try and help clarify to any potential
users the costs of these routines. They're mostly useful for debugging,
asserts, or other queries.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310170 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-05 06:24:09 +00:00
Chandler Carruth
95f263eb86 [LCG] Add the concept of a "dead" node and use it to avoid a complex
walk over the parent set.

When removing a single function from the call graph, we previously would
walk the entire RefSCC's parent set and then walk every outgoing edge
just to find the ones to remove. In addition to this being quite high
complexity in theory, it is also the last fundamental use of the parent
sets.

With this change, when we remove a function we transform the node
containing it to be recognizably "dead" and then teach the edge
iterators to recognize edges to such nodes and skip them the same way
they skip null edges.

We can't move fully to using "dead" nodes -- when disconnecting two live
nodes we need to null out the edge. But the complexity this adds to the
edge sequence isn't too bad and the simplification of lazily handling
this seems like a significant win.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310169 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-05 05:47:37 +00:00
Chandler Carruth
d2f3f4a06a [LCG] Replace an implicit bool operator with a named function. (NFC)
The definition of 'false' here was already pretty vague and debatable,
and I'm about to add another potential 'false' that would actually make
much more sense in a bool operator. Especially given how rarely this is
used, a nicely named method seems better.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310165 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-05 04:04:06 +00:00
Chandler Carruth
9468df99c1 [LCG] When removing a dead function and clearing out the data
structures, actually null out the graph pointers as well. We won't ever
update these, and we certainly shouldn't be calling any methods on them,
so it seems good to defensively nuke them.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310164 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-05 03:37:39 +00:00
Chandler Carruth
e9f7200d87 [LCG] Rather than walking the directed graph structure to update graph
pointers in node objects, just walk the map from function to node.

It doesn't have stable ordering, but works just as well and is much
simpler. We don't need ordering when just updating internal pointers.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310163 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-05 03:37:39 +00:00
Chandler Carruth
fa104687bc [LCG] Remove the complex walk of the parent sets to update graph
pointers.

This is completely unnecessary as we have a trivial list of RefSCCs now
that we can walk.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310162 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-05 03:37:38 +00:00
Chandler Carruth
854685a9f9 [LCG] Remove the use of the parent sets to compute connectivity when
merging RefSCCs.

The logic to directly use the reference edges is simpler and not
substantially slower (despite the comments to the contrary) because this
is not actually an especially hot part of LCG in practice.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310161 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-05 03:37:37 +00:00
Chandler Carruth
ee48043ceb [PM/LCG] Follow-up fix to r308088 to handle deletion of library
functions.

In the prior commit, we provide ordering to the LCG between functions
and library function definitions that they might begin to call through
transformations. But we still would delete these library functions from
the call graph if they became dead during inlining.

While this immediately crashed, it also exposed a loss of information.
We shouldn't remove definitions of library functions that can still
usefully participate in the LCG-powered CGSCC optimization process. If
new call edges are formed, we want to have definitions to be called.

We can still remove these functions if truly dead using global-dce, etc,
but removing them during the CGSCC walk is premature.

This fixes a crash in the new PM when optimizing some unusual libraries
that end up with "internal" lib functions such as the code in the "R"
language's libraries.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@308417 91177308-0d34-0410-b5e6-96231b3b80d8
2017-07-19 04:12:25 +00:00
Chandler Carruth
ed504111e8 [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.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@308088 91177308-0d34-0410-b5e6-96231b3b80d8
2017-07-15 08:08:19 +00:00
Chandler Carruth
fe40a5a3de [PM] Fix a nasty bug in the new PM where we failed to properly
invalidation of analyses when merging SCCs.

While I've added a bunch of testing of this, it takes something much
more like the inliner to really trigger this as you need to have
partially-analyzed SCCs with updates at just the right time. So I've
added a direct test for this using the inliner and verifying the
domtree. Without the changes here, this test ends up finding a stale
dominator tree.

However, to handle this properly, we need to invalidate analyses
*before* merging the SCCs. After talking to Philip and Sanjoy about this
they convinced me this was the right approach. To do this, we need
a callback mechanism when merging SCCs so we can observe the cycle that
will be merged before the merge happens. This API update ended up being
surprisingly easy.

With this commit, the new PM passes the test-suite again. It hadn't
since MemorySSA was enabled for EarlyCSE as that also will find this bug
very quickly.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@307498 91177308-0d34-0410-b5e6-96231b3b80d8
2017-07-09 13:45:11 +00:00
Chandler Carruth
e3e43d9d57 Sort the remaining #include lines in include/... and lib/....
I did this a long time ago with a janky python script, but now
clang-format has built-in support for this. I fed clang-format every
line with a #include and let it re-sort things according to the precise
LLVM rules for include ordering baked into clang-format these days.

I've reverted a number of files where the results of sorting includes
isn't healthy. Either places where we have legacy code relying on
particular include ordering (where possible, I'll fix these separately)
or where we have particular formatting around #include lines that
I didn't want to disturb in this patch.

This patch is *entirely* mechanical. If you get merge conflicts or
anything, just ignore the changes in this patch and run clang-format
over your #include lines in the files.

Sorry for any noise here, but it is important to keep these things
stable. I was seeing an increasing number of patches with irrelevant
re-ordering of #include lines because clang-format was used. This patch
at least isolates that churn, makes it easy to skip when resolving
conflicts, and gets us to a clean baseline (again).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@304787 91177308-0d34-0410-b5e6-96231b3b80d8
2017-06-06 11:49:48 +00:00
Francis Visoiu Mistrih
114240abb9 [LCG] Fix EXPENSIVE_CHECKS typo. NFC
Differential Revision: https://reviews.llvm.org/D30434

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2017-02-28 18:34:55 +00:00
Chandler Carruth
cfe129ba52 [PM/LCG] Teach LCG to support spurious reference edges.
Somewhat amazingly, this only requires teaching it to clean them up when
deleting a dead function from the graph. And we already have exactly the
necessary data structures to do that in the parent RefSCCs.

This allows ArgPromote to work in a much simpler way be merely letting
reference edges linger in the graph after the causing IR is deleted. We
will clean up these edges when we run any function pass over the IR, but
don't remove them eagerly.

This avoids all of the quadratic update issues both in the current pass
manager and in my previous attempt with the new pass manager.

Differential Revision: https://reviews.llvm.org/D29579

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2017-02-09 23:30:14 +00:00
Chandler Carruth
396f7202af [PM/LCG] Teach the LazyCallGraph how to replace a function without
disturbing the graph or having to update edges.

This is motivated by porting argument promotion to the new pass manager.
Because of how LLVM IR Function objects work, in order to change their
signature a new object needs to be created. This is efficient and
straight forward in the IR but previously was very hard to implement in
LCG. We could easily replace the function a node in the graph
represents. The challenging part is how to handle updating the edges in
the graph.

LCG previously used an edge to a raw function to represent a node that
had not yet been scanned for calls and references. This was the core
of its laziness. However, that model causes this kind of update to be
very hard:
1) The keys to lookup an edge need to be `Function*`s that would all
   need to be updated when we update the node.
2) There will be some unknown number of edges that haven't transitioned
   from `Function*` edges to `Node*` edges.

All of this complexity isn't necessary. Instead, we can always build
a node around any function, always pointing edges at it and always using
it as the key to lookup an edge. To maintain the laziness, we need to
sink the *edges* of a node into a secondary object and explicitly model
transitioning a node from empty to populated by scanning the function.
This design seems much cleaner in a number of ways, but importantly
there is now exactly *one* place where the `Function*` has to be
updated!

Some other cleanups that fall out of this include having something to
model the *entry* edges more accurately. Rather than hand rolling parts
of the node in the graph itself, we have an explicit `EdgeSequence`
object that gives us exactly the functionality needed. We also have
a consistent place to define the edge iterators and can use them for
both the entry edges and the internal edges of the graph.

The API used to model the separation between a node and its edges is
intentionally very thin as most clients are expected to deal with nodes
that have populated edges. We model this exactly as an optional does
with an additional method to populate the edges when that is
a reasonable thing for a client to do. This is based on API design
suggestions from Richard Smith and David Blaikie, credit goes to them
for helping pick how to model this without it being either too explicit
or too implicit.

The patch is somewhat noisy due to shifting around iterator types and
new syntax for walking the edges of a node, but most of the
functionality change is in the `Edge`, `EdgeSequence`, and `Node` types.

Differential Revision: https://reviews.llvm.org/D29577

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2017-02-09 23:24:13 +00:00
Chandler Carruth
5681e380e0 [PM/LCG] Fix the no-asserts build after r294227. Sorry for the noise.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294235 91177308-0d34-0410-b5e6-96231b3b80d8
2017-02-06 20:59:07 +00:00
Chandler Carruth
3a190c34ce [PM/LCG] Remove the lazy RefSCC formation from the LazyCallGraph during
iteration.

The lazy formation of RefSCCs isn't really the most important part of
the laziness here -- that has to do with walking the functions
themselves -- and isn't essential to maintain. Originally, there were
incremental update algorithms that relied on updates happening
predominantly near the most recent RefSCC formed, but those have been
replaced with ones that have much tighter general case bounds at this
point. We do still perform asserts that only scale well due to this
incrementality, but those are easy to place behind EXPENSIVE_CHECKS.

Removing this simplifies the entire analysis by having a single up-front
step that builds all of the RefSCCs in a direct Tarjan walk. We can even
easily replace this with other or better algorithms at will and with
much less confusion now that there is no iterator-based incremental
logic involved. This removes a lot of complexity from LCG.

Another advantage of moving in this direction is that it simplifies
testing the system substantially as we no longer have to worry about
observing and mutating the graph half-way through the RefSCC formation.

We still need a somewhat special iterator for RefSCCs because we want
the iterator to remain stable in the face of graph updates. However,
this now merely involves relative indexing to the current RefSCC's
position in the sequence which isn't too hard.

Differential Revision: https://reviews.llvm.org/D29381

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2017-02-06 19:38:06 +00:00
Matthias Braun
88d207542b Cleanup dump() functions.
We had various variants of defining dump() functions in LLVM. Normalize
them (this should just consistently implement the things discussed in
http://lists.llvm.org/pipermail/cfe-dev/2014-January/034323.html

For reference:
- Public headers should just declare the dump() method but not use
  LLVM_DUMP_METHOD or #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
- The definition of a dump method should look like this:
  #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
  LLVM_DUMP_METHOD void MyClass::dump() {
    // print stuff to dbgs()...
  }
  #endif

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2017-01-28 02:02:38 +00:00
Chandler Carruth
6fbb41e40a [PM] Teach the CGSCC's CG update utility to more carefully invalidate
analyses when we're about to break apart an SCC.

We can't wait until after breaking apart the SCC to invalidate things:
1) Which SCC do we then invalidate? All of them?
2) Even if we invalidate all of them, a newly created SCC may not have
   a proxy that will convey the invalidation to functions!

Previously we only invalidated one of the SCCs and too late. This led to
stale analyses remaining in the cache. And because the caching strategy
actually works, they would get used and chaos would ensue.

Doing invalidation early is somewhat pessimizing though if we *know*
that the SCC structure won't change. So it turns out that the design to
make the mutation API force the caller to know the *kind* of mutation in
advance was indeed 100% correct and we didn't do enough of it. So this
change also splits two cases of switching a call edge to a ref edge into
two separate APIs so that callers can clearly test for this and take the
easy path without invalidating when appropriate. This is particularly
important in this case as we expect most inlines to be between functions
in separate SCCs and so the common case is that we don't have to so
aggressively invalidate analyses.

The LCG API change in turn needed some basic cleanups and better testing
in its unittest. No interesting functionality changed there other than
more coverage of the returned sequence of SCCs.

While this seems like an obvious improvement over the current state, I'd
like to revisit the core concept of invalidating within the CG-update
layer at all. I'm wondering if we would be better served forcing the
callers to handle the invalidation beforehand in the cases that they
can handle it. An interesting example is when we want to teach the
inliner to *update and preserve* analyses. But we can cross that bridge
when we get there.

With this patch, the new pass manager an build all of the LLVM test
suite at -O3 and everything passes. =D I haven't bootstrapped yet and
I'm sure there are still plenty of bugs, but this gives a nice baseline
so I'm going to increasingly focus on fleshing out the missing
functionality, especially the bits that are just turned off right now in
order to let us establish this baseline.

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2016-12-28 10:34:50 +00:00
Chandler Carruth
3ab88a9f0d [LCG] Teach the ref edge removal to handle a ref edge that is trivial
due to a call cycle.

This actually crashed the ref removal before.

I've added a unittest that covers this kind of interesting graph
structure and mutation.

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2016-12-28 02:24:58 +00:00
Chandler Carruth
410e7953c3 [LCG] Minor cleanup to the LCG walk over a function, NFC.
This just hoists the check for declarations up a layer which allows
various sets used in the walk to be smaller. Also moves the relevant
comments to match, and catches a few other cleanups in this code.

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2016-12-09 00:46:44 +00:00
Chandler Carruth
742805e0ea [LCG] Add basic verification of the parent set and fix bugs it uncovers.
The existing unittests actually cover this now that we verify things.

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2016-12-07 01:42:40 +00:00
Chandler Carruth
04d64487f9 [LCG] Add some much needed asserts and verify runs to uncover
a hilarious bug and fix it.

We somehow were never verifying the RefSCCs newly formed when
splitting an existing one apart, and when verifying them we weren't
really checking the SCC indices mapping effectively.

If we had been, it would have been blindingly obvious that right after
putting something int `RC.SCCs` we should update `RC.SCCIndices` instead
of `SCCIndices` which we were about to clear and rebuild anyways. =[

Anyways, this is thoroughly covered by existing tests now that we
actually verify things properly.

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2016-12-06 10:29:23 +00:00
Chandler Carruth
33d568124e [PM] Change the static object whose address is used to uniquely identify
analyses to have a common type which is enforced rather than using
a char object and a `void *` type when used as an identifier.

This has a number of advantages. First, it at least helps some of the
confusion raised in Justin Lebar's code review of why `void *` was being
used everywhere by having a stronger type that connects to documentation
about this.

However, perhaps more importantly, it addresses a serious issue where
the alignment of these pointer-like identifiers was unknown. This made
it hard to use them in pointer-like data structures. We were already
dodging this in dangerous ways to create the "all analyses" entry. In
a subsequent patch I attempted to use these with TinyPtrVector and
things fell apart in a very bad way.

And it isn't just a compile time or type system issue. Worse than that,
the actual alignment of these pointer-like opaque identifiers wasn't
guaranteed to be a useful alignment as they were just characters.

This change introduces a type to use as the "key" object whose address
forms the opaque identifier. This both forces the objects to have proper
alignment, and provides type checking that we get it right everywhere.
It also makes the types somewhat less mysterious than `void *`.

We could go one step further and introduce a truly opaque pointer-like
type to return from the `ID()` static function rather than returning
`AnalysisKey *`, but that didn't seem to be a clear win so this is just
the initial change to get to a reliably typed and aligned object serving
is a key for all the analyses.

Thanks to Richard Smith and Justin Lebar for helping pick plausible
names and avoid making this refactoring many times. =] And thanks to
Sean for the super fast review!

While here, I've tried to move away from the "PassID" nomenclature
entirely as it wasn't really helping and is overloaded with old pass
manager constructs. Now we have IDs for analyses, and key objects whose
address can be used as IDs. Where possible and clear I've shortened this
to just "ID". In a few places I kept "AnalysisID" to make it clear what
was being identified.

Differential Revision: https://reviews.llvm.org/D27031

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2016-11-23 17:53:26 +00:00
Chandler Carruth
ecfbd3fb80 [LCG] Add a previously missing assert about the relationship of RefSCCs.
No intended change, everything seems to be in working order already.

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2016-11-22 21:40:10 +00:00
Chandler Carruth
2fb7ff7c1d [LCG] Add utilities to compute parent and ascestor relationships between
SCCs.

These will be fairly expensive routines to call and might be abused in
real code, but are quite useful when debugging or in asserts and are
reasonable and well formed properties to query.

I've used one of them in an assert that was requested in a code review
here. In subsequent commits I'll start using these routines more
heavily, for example in unittests etc. But this at least gets the
groundwork in place.

Differential Revision: https://reviews.llvm.org/D25506

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2016-11-22 19:23:31 +00:00
Chandler Carruth
94162a40bb [LCG] Add the necessary functionality to the LazyCallGraph to support inlining.
The basic inlining operation makes the following changes to the call graph:
1) Add edges that were previously transitive edges. This is always trivial and
   this patch gives the LCG helper methods to make this more convenient.
2) Remove the inlined edge. We had existing support for this, but it contained
   bugs that needed to be fixed. Testing in the same pattern as the inliner
   exposes these bugs very nicely.
3) Delete a function when it becomes dead because it is internal and all calls
   have been inlined. The LCG had no support at all for this operation, so this
   adds that support.

Two unittests have been added that exercise this specific mutation pattern to
the call graph. They were extremely effective in uncovering bugs. Sadly,
a large fraction of the code here is just to implement those unit tests, but
I think they're paying for themselves. =]

This was split out of a patch that actually uses the routines to
implement inlining in the new pass manager in order to isolate (with
unit tests) the logic that was entirely within the LCG.

Many thanks for the careful review from folks! There will be a few minor
follow-up patches based on the comments in the review as well.

Differential Revision: https://reviews.llvm.org/D24225

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2016-10-12 07:59:56 +00:00