Summary:
This patch introduces incremental edge insertions based on the Depth Based Search algorithm.
Insertions should work for both dominators and postdominators.
Reviewers: dberlin, grosser, davide, sanjoy, brzycki
Reviewed By: dberlin
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D35341
llvm-svn: 308054
Summary:
DominatorTreeBase used to have IsPostDominators (bool) member to indicate if the tree is a dominator or a postdominator tree. This made it possible to switch between the two 'modes' at runtime, but it isn't used in practice anywhere.
This patch makes IsPostDominator a template argument. This way, it is easier to switch between different algorithms at compile-time based on this argument and design external utilities around it. It also makes it impossible to incidentally assign a postdominator tree to a dominator tree (and vice versa), and to further simplify template code in GenericDominatorTreeConstruction.
Reviewers: dberlin, sanjoy, davide, grosser
Reviewed By: dberlin
Subscribers: mzolotukhin, llvm-commits
Differential Revision: https://reviews.llvm.org/D35315
llvm-svn: 308040
Summary: DominatorTreeBase and related classes used overcomplicated template machinery. This patch simplifies them and gets rid of DominatorTreeBaseTraits and DominatorTreeBaseByTraits, which weren't actually used outside the DomTree construction.
Reviewers: dberlin, sanjoy, davide, grosser
Reviewed By: dberlin, davide, grosser
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D35285
llvm-svn: 307953
Summary:
This patch improves verification by making `verifyReachablility` look for CFG not found in the DomTree.
It also makes the verification work with postdominators by handling virtual root.
Reviewers: dberlin, davide, grosser, sanjoy
Reviewed By: dberlin
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D35279
llvm-svn: 307936
This reverts commit r306907 and reapplies the patches in the title.
The patches used to make one of the
CodeGen/ARM/2011-02-07-AntidepClobber.ll test to fail because of a
missing null check.
llvm-svn: 306919
This reverts commit r306894.
Revert "[Dominators] Add NearestCommonDominator verification"
This reverts commit r306893.
Revert "[Dominators] Keep tree level in DomTreeNode and use it to find NCD and answer dominance queries"
This reverts commit r306892.
llvm-svn: 306907
Summary:
This patch adds another verification function for checking correctness of findNearestCommonDominator.
For every edge from U to V in the input graph, `NCD(U, V) == IDom(V) or V` -- the new function checks this condition.
Reviewers: dberlin, sanjoy, chandlerc
Reviewed By: dberlin
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D34575
llvm-svn: 306893
Summary:
This patch makes DomTreeNodes keep their level (depth) in the DomTree. By having this information always available, it is possible to speedup and simplify findNearestCommonDominator and certain dominance queries.
In the future, level information will be also needed to perform incremental updates.
My testing doesn't show any noticeable performance differences after applying this patch. There may be some improvements when other passes are thought to use the level information.
Reviewers: dberlin, sanjoy, chandlerc, grosser
Reviewed By: dberlin
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D34548
llvm-svn: 306892
Summary:
This patch makes DominatorTreeBase more readable by putting most important members on top of the class.
Before, the class looked like that: private -> protected (including data members) -> public -> protected.
The patch changes it to: protected (data members only) -> public -> protected -> public.
Reviewers: dberlin, sanjoy, chandlerc
Reviewed By: dberlin
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D34527
llvm-svn: 306714
Summary:
DominatorBase class was only used by DominatorTreeBase. It didn't provide any useful abstractions, nor simplified anything, so I see no point keeping it.
This commit removes the DominatorBase class and moves its content into DominatorTreeBase.
This is the first patch in a series that tries to make all DomTrees have a single virtual root, which will allow to further simplify code (especially when it comes to incremental updates).
Reviewers: dberlin, sanjoy, chandlerc
Reviewed By: dberlin
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D34493
llvm-svn: 306713
Summary:
This patch adds an additional level of verification - it checks parent and sibling properties of a tree. By definition, every tree with these two properties is a dominator tree.
It is possible to run those check by running llvm with `-verify-dom-info=1`.
Bootstrapping clang and building the llvm test suite with this option enabled doesn't yield any errors.
Reviewers: dberlin, sanjoy, chandlerc
Reviewed By: dberlin
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D34482
llvm-svn: 306711
Summary: Helper functions (DFSPass, ReverseDFSPass, Eval) need SemiNCAInfo anyway, so it's simpler to have them there as member functions. This also makes them simpler by removing template boilerplate.
Reviewers: dberlin, sanjoy, chandlerc
Reviewed By: dberlin
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D34427
llvm-svn: 306579
Summary:
This moves SemiNCAInfo from DeminatorTreeBase to GenericDomTreeConstruction. It also put helper functions used during tree constructions in the same file.
The point of this change is to further clean up DominatorTreeBase and make it easier to construct and verify (in future patches).
Reviewers: dberlin, sanjoy, chandlerc
Reviewed By: dberlin
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D34420
llvm-svn: 306576
Summary: The temporary IDoms map was used only during DomTree calculation. We can move it to SNCAInfo so that it's no longer a DominatorTreeBase member.
Reviewers: sanjoy, dberlin, chandlerc
Reviewed By: dberlin
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D34317
llvm-svn: 306574
Summary:
The InfoRec struct is used only during tree construction, so there is no point having it as a DominatorTreeBase member.
This patch moves it into the Calculate function instead and makes it pass it to its helper functions.
Reviewers: sanjoy, dberlin, chandlerc
Reviewed By: dberlin
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D34305
llvm-svn: 306572
Summary: Number to node mapping in DominatorTreeBase is used only during calculation, so there is no point keeping is as a member variable. This patch moves this mapping to Calculate function and passes it to helper functions. It also makes the name more descriptive.
Reviewers: sanjoy, dberlin, davide, chandlerc
Reviewed By: dberlin
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D34295
llvm-svn: 306562
Summary:
This patch cleans up GenericDomTree.h by:
- removing unnecessary <NodeT> in DomTreeNodeBase
- removing unnecessary std::move on bools
- changing type of DFSNumIn/DFSNumOut from int to unsigned (since the members were used as unsigned anyway)
The changes don't affect behavior -- everything works as before.
Reviewers: sanjoy, dberlin, chandlerc
Reviewed By: dberlin
Subscribers: davide, llvm-commits
Differential Revision: https://reviews.llvm.org/D34229
llvm-svn: 305710
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).
llvm-svn: 304787
Use constant references rather than `const auto` which will cause the
copy constructor. These particular cases cause issues for the swift
compiler.
llvm-svn: 301237
Use children<> and nodes<> in appropriate places to cleanup the code.
Also, as part of the cleanup,
change the signature of DominatorTreeBase's Split.
It is a protected non-virtual member function called only twice,
both from within the class,
and the removed passed argument in both cases is '*this'.
The reason for the existence of that argument seems to be that
back before r43115 Split was a free function,
so an argument to get '*this' was needed - but now that is no longer the
case.
Patch by Yoav Ben-Shalom!
Differential Revision: https://reviews.llvm.org/D32118
llvm-svn: 300656
and also "clang-format GenericDomTreeConstruction.h, since the current
formatting makes it look like their is a bug in the loop indentation, and there
is not"
This reverts commit r296535.
There are still some open design questions which I would like to discuss. I
revert this for Daniel (who gave the OK), as he is on vacation.
llvm-svn: 296812
Summary:
Currently, our post-dom tree tries to ignore and remove the effects of
infinite loops. It fails miserably at this, because it tries to do it
ahead of time, and thus can only detect self-loops, and any other type
of infinite loop, it pretends doesn't exist at all.
This can, in a bunch of cases, lead to wrong answers and a completely
empty post-dom tree.
Wrong answer:
```
declare void foo()
define internal void @f() {
entry:
br i1 undef, label %bb35, label %bb3.i
bb3.i:
call void @foo()
br label %bb3.i
bb35.loopexit3:
br label %bb35
bb35:
ret void
}
```
We get:
```
Inorder PostDominator Tree:
[1] <<exit node>> {0,7}
[2] %bb35 {1,6}
[3] %bb35.loopexit3 {2,3}
[3] %entry {4,5}
```
This is a trivial modification of the testcase for PR 6047
Note that we pretend bb3.i doesn't exist.
We also pretend that bb35 post-dominates entry.
While it's true that it does not exit in a theoretical sense, it's not
really helpful to try to ignore the effect and pretend that bb35
post-dominates entry. Worse, we pretend the infinite loop does
nothing (it's usually considered a side-effect), and doesn't even
exist, even when it calls a function. Sadly, this makes it impossible
to use when you are trying to move code safely. All compilers also
create virtual or real single exit nodes (including us), and connect
infinite loops there (which this patch does). In fact, others have
worked around our behavior here, to the point of building their own
post-dom trees:
https://zneak.github.io/fcd/2016/02/17/structuring.html and pointing
out the region infrastructure is near-useless for them with postdom in
this state :(
Completely empty post-dom tree:
```
define void @spam() #0 {
bb:
br label %bb1
bb1: ; preds = %bb1, %bb
br label %bb1
bb2: ; No predecessors!
ret void
}
```
Printing analysis 'Post-Dominator Tree Construction' for function 'foo':
=============================--------------------------------
Inorder PostDominator Tree:
[1] <<exit node>> {0,1}
:(
(note that even if you ignore the effects of infinite loops, bb2
should be present as an exit node that post-dominates nothing).
This patch changes post-dom to properly handle infinite loops and does
root finding during calculation to prevent empty tress in such cases.
We match gcc's (and the canonical theoretical) behavior for infinite
loops (find the backedge, connect it to the exit block).
Testcases coming as soon as i finish running this on a ton of random graphs :)
Reviewers: chandlerc, davide
Subscribers: bryant, llvm-commits
Differential Revision: https://reviews.llvm.org/D29705
llvm-svn: 296535
Summary:
Convert all obvious node_begin/node_end and child_begin/child_end
pairs to range based for.
Sending for review in case someone has a good idea how to make
graph_children able to be inferred. It looks like it would require
changing GraphTraits to be two argument or something. I presume
inference does not happen because it would have to check every
GraphTraits in the world to see if the noderef types matched.
Note: This change was 3-staged with clang as well, which uses
Dominators/etc from LLVM.
Reviewers: chandlerc, tstellarAMD, dblaikie, rsmith
Subscribers: arsenm, llvm-commits, nhaehnle
Differential Revision: https://reviews.llvm.org/D29767
llvm-svn: 294620
Summary:
GenericDomTreeConstruction had its own written DFS walk.
It is basically identical to the DFS walk df_* is doing in the iterators.
the one difference is that df_iterator uses an internal visited set.
The GenericDomTreeConstruction one reused a field in an existing densemap lookup.
Time-wise, this way is actually more cache-friendly (the previous way has a random store
into a successor's info, the new way does that store at the same time and in the same place
as other stores to the same info)
It costs some very small amount of memory to do this, and one we pay in some other part of
dom tree construction *anyway*, so we aren't really increasing dom tree constructions's
peak memory usage.
It could still be changed to use the old field with a little work on df_ext_* if we care
(and if someone find performance regressions)
Reviewers: chandlerc
Reviewed By: chandlerc
Subscribers: Eugene.Zelenko, llvm-commits
Differential Revision: https://reviews.llvm.org/D8932
llvm-svn: 294339
In some cases StructurizeCfg updates root node, but dominator info
remains unchanges, it causes crash when expensive checks are enabled.
To cope with this problem a new method was added to DominatorTreeBase
that allows adding new root nodes, it is called in StructurizeCfg to
put dominator tree in sync.
This change fixes PR27488.
Differential Revision: https://reviews.llvm.org/D28114
llvm-svn: 291530
Currently nodes_iterator may dereference to a NodeType* or a NodeType&. Make them all dereference to NodeType*, which is NodeRef later.
Differential Revision: https://reviews.llvm.org/D23704
Differential Revision: https://reviews.llvm.org/D23705
llvm-svn: 279326
Summary:
Looking at the implementation, GenericDomTree has more specific
requirements on NodeRef, e.g. NodeRefObject->getParent() should compile,
and NodeRef should be a pointer. We can remove the pointer requirement,
but it seems to have little gain, given the limited use cases.
Also changed GraphTraits<Inverse<Inverse<T>> to be more accurate.
Reviewers: dblaikie, chandlerc
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D23593
llvm-svn: 278961
Summary:
Historically, we had a switch in the Makefiles for turning on "expensive
checks". This has never been ported to the cmake build, but the
(dead-ish) code is still around.
This will also make it easier to turn it on in buildbots.
Reviewers: chandlerc
Subscribers: jyknight, mzolotukhin, RKSimon, gberry, llvm-commits
Differential Revision: http://reviews.llvm.org/D19723
llvm-svn: 268050
This reverts commit r249783, fully reinstating r249782. I've fixed the
bug in clang: it was a non-const iterator that dereferenced to const
(but had an implicit conversion to non-const).
llvm-svn: 249850
Apparently the iterators in `clang::CFGBlock` have an auto-conversion to
`CFGBlock *`, but the dereference operator gives `const CFGBlock &`.
Until I have a moment to fix that, revert the GenericDomTree chagnes
from r249782.
llvm-svn: 249783
Stop converting implicitly between iterators and pointers/references in
lib/IR. For convenience, I've added a `getIterator()` accessor to
`ilist_node` so that callers don't need to know how to spell the
iterator class (i.e., they can use `X.getIterator()` instead of
`Function::iterator(X)`).
I'll eventually disallow these implicit conversions entirely, but
there's a lot of code, so it doesn't make sense to do it all in one
patch. One library or so at a time.
Why? To root out cases of `getNextNode()` and `getPrevNode()` being
used in iterator logic. The design of `ilist` makes that invalid when
the current node could be at the back of the list, but it happens to
"work" right now because of a bug where those functions never return
`nullptr` if you're using a half-node sentinel. Before I can fix the
function, I have to remove uses of it that rely on it misbehaving.
(Maybe the function should just be deleted anyway? But I don't want
deleting it -- potentially a huge project -- to block fixing
ilist/iplist.)
llvm-svn: 249782
Note: I'm am not trying to describe what "should be"; I'm only describing what is true today.
This came out of my recent question to llvm-dev titled: When can the dominator tree not contain a node for a basic block?
Differential Revision: http://reviews.llvm.org/D13078
llvm-svn: 248417
The patch is generated using this command:
tools/clang/tools/extra/clang-tidy/tool/run-clang-tidy.py -fix \
-checks=-*,llvm-namespace-comment -header-filter='llvm/.*|clang/.*' \
llvm/lib/
Thanks to Eugene Kosov for the original patch!
llvm-svn: 240137
Summary:
There are a number of passes that could be sped up by using dominator tree DFS numbers to order or compare things across multiple bbs
(MemorySSA, MergedLoadStoreMotion, EarlyCSE, Sinking, GVN, NewGVN, for starters :P).
For example, GVN/CSE elimination can be done with a simple stack/etc (instead of full-on scoped hash table or repeated leader set walks)
if the DFS pair is stored next to leaders.
The dominator tree keeps them, and the DOM tree nodes expose them as public, but you have no guarantee they are up to date (and in fact,
if you split blocks or whatever during your pass, they definitely won't be)
This means passes either have to compute their own versions[1], or make 32 queries, or ....
Rather than try to hide this, i just made the API public, and make it do nothing if the numbers are already valid.
[1] Which we want as a non-recursive walk, which is not pretty, sadly,
because it cannot use the depth first iterators since you don't get called on the way back up. So you either have to do one walk with po_iterator
and one with df_iterator, or write your own non-recursive walk that looks identical to the one in updateDFSNumbers.
Reviewers: chandlerc
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D8946
llvm-svn: 234930
Now that the passes are wrappers around this, we no longer need
a vtable, virtual destructor, and other associated mess. This is
particularly nice to me as this is a class template. =]
llvm-svn: 225970
into the new pass manager's analysis cache which stores results
by-value.
Technically speaking, the dom trees were originally not movable but
copyable! This, unsurprisingly, didn't work at all -- the copy was
shallow and just resulted in rampant memory corruption. This change
explicitly forbids copying (as it would need to be a deep copy) and
makes them explicitly movable with the unsurprising boiler plate to
member-wise move them because we can't rely on MSVC to generate this
code for us. =/
llvm-svn: 225966
class members are implicitly "inline", no key word needed.
Naturally, this could change how LLVM inlines these functions because
<GRR>, but that's not an excuse to use the keyword. ;]
llvm-svn: 225939
