passes too many time.
I think this is actually the issue that someone raised with me at the
developer's meeting and in an email, but that we never really got to the
bottom of. Having all the testing utilities made it much easier to dig
down and uncover the core issue.
When a pass manager is running many passes over a single function, we
need it to invalidate the analyses between each run so that they can be
re-computed as needed. We also need to track the intersection of
preserved higher-level analyses across all the passes that we run (for
example, if there is one module analysis which all the function analyses
preserve, we want to track that and propagate it). Unfortunately, this
interacted poorly with any enclosing pass adaptor between two IR units.
It would see the intersection of preserved analyses, and need to
invalidate any other analyses, but some of the un-preserved analyses
might have already been invalidated *and recomputed*! We would fail to
propagate the fact that the analysis had already been invalidated.
The solution to this struck me as really strange at first, but the more
I thought about it, the more natural it seemed. After a nice discussion
with Duncan about it on IRC, it seemed even nicer. The idea is that
invalidating an analysis *causes* it to be preserved! Preserving the
lack of result is trivial. If it is recomputed, great. Until something
*else* invalidates it again, we're good.
The consequence of this is that the invalidate methods on the analysis
manager which operate over many passes now consume their
PreservedAnalyses object, update it to "preserve" every analysis pass to
which it delivers an invalidation (regardless of whether the pass
chooses to be removed, or handles the invalidation itself by updating
itself). Then we return this augmented set from the invalidate routine,
letting the pass manager take the result and use the intersection of
*that* across each pass run to compute the final preserved set. This
accounts for all the places where the early invalidation of an analysis
has already "preserved" it for a future run.
I've beefed up the testing and adjusted the assertions to show that we
no longer repeatedly invalidate or compute the analyses across nested
pass managers.
llvm-svn: 225333
WillNotOverflowUnsignedAdd's smarts will live in ValueTracking as
computeOverflowForUnsignedAdd. It now returns a tri-state result:
never overflows, always overflows and sometimes overflows.
llvm-svn: 225329
a specific analysis result.
This is quite handy to test things, and will also likely be very useful
for debugging issues. You could narrow down pass validation failures by
walking these invalidate pass runs up and down the pass pipeline, etc.
I've added support to the pass pipeline parsing to be able to create one
of these for any analysis pass desired.
Just adding this class uncovered one latent bug where the
AnalysisManager CRTP base class had a hard-coded Module type rather than
using IRUnitT.
I've also added tests for invalidation and caching of analyses in
a basic way across all the pass managers. These in turn uncovered two
more bugs where we failed to correctly invalidate an analysis -- its
results were invalidated but the key for re-running the pass was never
cleared and so it was never re-run. Quite nasty. I'm very glad to debug
this here rather than with a full system.
Also, yes, the naming here is horrid. I'm going to update some of the
names to be slightly less awful shortly. But really, I've no "good"
ideas for naming. I'll be satisfied if I can get it to "not bad".
llvm-svn: 225246
manager tests to use them and be significantly more comprehensive.
This, naturally, uncovered a bug where the CGSCC pass manager wasn't
printing analyses when they were run.
The only remaining core manipulator is I think an invalidate pass
similar to the require pass. That'll be next. =]
llvm-svn: 225240
when all are being preserved.
We want to short-circuit this for a couple of reasons. One, I don't
really want passes to grow a dependency on actually receiving their
invalidate call when they've been preserved. I'm thinking about removing
this entirely. But more importantly, preserving everything is likely to
be the common case in a lot of scenarios, and it would be really good to
bypass all of the invalidation and preservation machinery there.
Avoiding calling N opaque functions to try to invalidate things that are
by definition still valid seems important. =]
This wasn't really inpsired by much other than seeing the spam in the
logging for analyses, but it seems better ot get it checked in rather
than forgetting about it.
llvm-svn: 225163
manager.
This starts to allow us to test analyses more easily, but it's really
only the beginning. Some of the code here is still untestable without
manual changes to create analysis passes, but I wanted to factor it into
a small of chunks as possible.
Next up in order to be able to test things are, in no particular order:
- No-op analyses passes so we don't have to use real ones to exercise
the pass maneger itself.
- Automatic way of generating dummy passes that require an analysis be
run, including a variant that calls a 'print' method on a pass to make
it even easier to print out the results of an analysis.
- Dummy passes that invalidate all analyses for their IR unit so we can
test invalidation and re-runs.
- Automatic way to print each analysis pass as it is re-run.
- Automatic but optional verification of analysis passes everywhere
possible.
I'm not claiming I'll get to all of these immediately, but that's what
is in the pipeline at some stage. I'm fleshing out exactly what I need
and what to prioritize by working on converting analyses and then trying
to test the conversion. =]
llvm-svn: 225162
units.
This was debated back and forth a bunch, but using references is now
clearly cleaner. Of all the code written using pointers thus far, in
only one place did it really make more sense to have a pointer. In most
cases, this just removes immediate dereferencing from the code. I think
it is much better to get errors on null IR units earlier, potentially
at compile time, than to delay it.
Most notably, the legacy pass manager uses references for its routines
and so as more and more code works with both, the use of pointers was
likely to become really annoying. I noticed this when I ported the
domtree analysis over and wrote the entire thing with references only to
have it fail to compile. =/ It seemed better to switch now than to
delay. We can, of course, revisit this is we learn that references are
really problematic in the API.
llvm-svn: 225145
from before I removed thet non-const use of the function.
The unused variable that held the const_cast was already kindly removed
by Michael.
llvm-svn: 225143
a cache of assumptions for a single function, and an immutable pass that
manages those caches.
The motivation for this change is two fold. Immutable analyses are
really hacks around the current pass manager design and don't exist in
the new design. This is usually OK, but it requires that the core logic
of an immutable pass be reasonably partitioned off from the pass logic.
This change does precisely that. As a consequence it also paves the way
for the *many* utility functions that deal in the assumptions to live in
both pass manager worlds by creating an separate non-pass object with
its own independent API that they all rely on. Now, the only bits of the
system that deal with the actual pass mechanics are those that actually
need to deal with the pass mechanics.
Once this separation is made, several simplifications become pretty
obvious in the assumption cache itself. Rather than using a set and
callback value handles, it can just be a vector of weak value handles.
The callers can easily skip the handles that are null, and eventually we
can wrap all of this up behind a filter iterator.
For now, this adds boiler plate to the various passes, but this kind of
boiler plate will end up making it possible to port these passes to the
new pass manager, and so it will end up factored away pretty reasonably.
llvm-svn: 225131
PHI nodes can have zero operands in the middle of a transform. It is
expected that utilities in Analysis don't freak out when this happens.
Note that it is considered invalid to allow these misshapen phi nodes to
make it to another pass.
This fixes PR22086.
llvm-svn: 225126
We would sometimes leave the out-param APInts untouched while going
through computeKnownBits. While I don't know of a way to trigger a bug
involving this in practice, it goes against the overall design of
computeKnownBits.
Found via code inspection.
llvm-svn: 225109
WillNotOverflowUnsignedMul's smarts will live in ValueTracking as
computeOverflowForUnsignedMul. It now returns a tri-state result:
never overflows, always overflows and sometimes overflows.
llvm-svn: 225076
GlobalAlias handling used to be after GlobalValue handling, which meant it was, in practice, dead code. r220165 moved GlobalAlias handling to be before GlobalValue handling, but also moved it to be before the max depth check, causing an assert due to a recursion depth limit violation.
This moves GlobalAlias handling forward to where it's safe, and changes the GlobalValue handling to only look at GlobalObjects.
Differential Revision: http://reviews.llvm.org/D6758
llvm-svn: 224765
(X & INT_MIN) ? X & INT_MAX : X into X & INT_MAX
(X & INT_MIN) ? X : X & INT_MAX into X
(X & INT_MIN) ? X | INT_MIN : X into X
(X & INT_MIN) ? X : X | INT_MIN into X | INT_MIN
llvm-svn: 224669
We can always choose an value for undef which might cause %V to shift
out an important bit except for one case, when %V is zero.
However, shl behaves like an identity function when the right hand side
is zero.
llvm-svn: 224405
isKnownPredicate.
The motivation for this change is to optimize away checks in loops
like this:
limit = min(t, len)
for (i = 0 to limit)
if (i >= len || i < 0) throw_array_of_of_bounds();
a[i] = ...
Differential Revision: http://reviews.llvm.org/D6635
llvm-svn: 224285
- by Ella Bolshinsky
The alias analysis is used define whether the given instruction
is a barrier for store sinking. For 2 identical stores, following
instructions are checked in the both basic blocks, to determine
whether they are sinking barriers.
http://reviews.llvm.org/D6420
llvm-svn: 224247
Split `Metadata` away from the `Value` class hierarchy, as part of
PR21532. Assembly and bitcode changes are in the wings, but this is the
bulk of the change for the IR C++ API.
I have a follow-up patch prepared for `clang`. If this breaks other
sub-projects, I apologize in advance :(. Help me compile it on Darwin
I'll try to fix it. FWIW, the errors should be easy to fix, so it may
be simpler to just fix it yourself.
This breaks the build for all metadata-related code that's out-of-tree.
Rest assured the transition is mechanical and the compiler should catch
almost all of the problems.
Here's a quick guide for updating your code:
- `Metadata` is the root of a class hierarchy with three main classes:
`MDNode`, `MDString`, and `ValueAsMetadata`. It is distinct from
the `Value` class hierarchy. It is typeless -- i.e., instances do
*not* have a `Type`.
- `MDNode`'s operands are all `Metadata *` (instead of `Value *`).
- `TrackingVH<MDNode>` and `WeakVH` referring to metadata can be
replaced with `TrackingMDNodeRef` and `TrackingMDRef`, respectively.
If you're referring solely to resolved `MDNode`s -- post graph
construction -- just use `MDNode*`.
- `MDNode` (and the rest of `Metadata`) have only limited support for
`replaceAllUsesWith()`.
As long as an `MDNode` is pointing at a forward declaration -- the
result of `MDNode::getTemporary()` -- it maintains a side map of its
uses and can RAUW itself. Once the forward declarations are fully
resolved RAUW support is dropped on the ground. This means that
uniquing collisions on changing operands cause nodes to become
"distinct". (This already happened fairly commonly, whenever an
operand went to null.)
If you're constructing complex (non self-reference) `MDNode` cycles,
you need to call `MDNode::resolveCycles()` on each node (or on a
top-level node that somehow references all of the nodes). Also,
don't do that. Metadata cycles (and the RAUW machinery needed to
construct them) are expensive.
- An `MDNode` can only refer to a `Constant` through a bridge called
`ConstantAsMetadata` (one of the subclasses of `ValueAsMetadata`).
As a side effect, accessing an operand of an `MDNode` that is known
to be, e.g., `ConstantInt`, takes three steps: first, cast from
`Metadata` to `ConstantAsMetadata`; second, extract the `Constant`;
third, cast down to `ConstantInt`.
The eventual goal is to introduce `MDInt`/`MDFloat`/etc. and have
metadata schema owners transition away from using `Constant`s when
the type isn't important (and they don't care about referring to
`GlobalValue`s).
In the meantime, I've added transitional API to the `mdconst`
namespace that matches semantics with the old code, in order to
avoid adding the error-prone three-step equivalent to every call
site. If your old code was:
MDNode *N = foo();
bar(isa <ConstantInt>(N->getOperand(0)));
baz(cast <ConstantInt>(N->getOperand(1)));
bak(cast_or_null <ConstantInt>(N->getOperand(2)));
bat(dyn_cast <ConstantInt>(N->getOperand(3)));
bay(dyn_cast_or_null<ConstantInt>(N->getOperand(4)));
you can trivially match its semantics with:
MDNode *N = foo();
bar(mdconst::hasa <ConstantInt>(N->getOperand(0)));
baz(mdconst::extract <ConstantInt>(N->getOperand(1)));
bak(mdconst::extract_or_null <ConstantInt>(N->getOperand(2)));
bat(mdconst::dyn_extract <ConstantInt>(N->getOperand(3)));
bay(mdconst::dyn_extract_or_null<ConstantInt>(N->getOperand(4)));
and when you transition your metadata schema to `MDInt`:
MDNode *N = foo();
bar(isa <MDInt>(N->getOperand(0)));
baz(cast <MDInt>(N->getOperand(1)));
bak(cast_or_null <MDInt>(N->getOperand(2)));
bat(dyn_cast <MDInt>(N->getOperand(3)));
bay(dyn_cast_or_null<MDInt>(N->getOperand(4)));
- A `CallInst` -- specifically, intrinsic instructions -- can refer to
metadata through a bridge called `MetadataAsValue`. This is a
subclass of `Value` where `getType()->isMetadataTy()`.
`MetadataAsValue` is the *only* class that can legally refer to a
`LocalAsMetadata`, which is a bridged form of non-`Constant` values
like `Argument` and `Instruction`. It can also refer to any other
`Metadata` subclass.
(I'll break all your testcases in a follow-up commit, when I propagate
this change to assembly.)
llvm-svn: 223802
When a loop gets bundled up, its outgoing edges are quite large, and can
just barely overflow 64-bits. If one successor has multiple incoming
edges -- and that successor is getting all the incoming mass --
combining just its edges can overflow. Handle that by saturating rather
than asserting.
This fixes PR21622.
llvm-svn: 223500
Reapply r223347, with a fix to not crash on uninserted instructions (or more
precisely, instructions in uninserted blocks). bugpoint was able to reduce the
test case somewhat, but it is still somewhat large (and relies on setting
things up to be simplified during inlining), so I've not included it here.
Nevertheless, it is clear what is going on and why.
Original commit message:
Restrict somewhat the memory-allocation pointer cmp opt from r223093
Based on review comments from Richard Smith, restrict this optimization from
applying to globals that might resolve lazily to other dynamically-loaded
modules, and also from dynamic allocas (which might be transformed into malloc
calls). In short, take extra care that the compared-to pointer is really
simultaneously live with the memory allocation.
llvm-svn: 223371
I'm recommiting the codegen part of the patch.
The vectorizer part will be send to review again.
Masked Vector Load and Store Intrinsics.
Introduced new target-independent intrinsics in order to support masked vector loads and stores. The loop vectorizer optimizes loops containing conditional memory accesses by generating these intrinsics for existing targets AVX2 and AVX-512. The vectorizer asks the target about availability of masked vector loads and stores.
Added SDNodes for masked operations and lowering patterns for X86 code generator.
Examples:
<16 x i32> @llvm.masked.load.v16i32(i8* %addr, <16 x i32> %passthru, i32 4 /* align */, <16 x i1> %mask)
declare void @llvm.masked.store.v8f64(i8* %addr, <8 x double> %value, i32 4, <8 x i1> %mask)
Scalarizer for other targets (not AVX2/AVX-512) will be done in a separate patch.
http://reviews.llvm.org/D6191
llvm-svn: 223348
Based on review comments from Richard Smith, restrict this optimization from
applying to globals that might resolve lazily to other dynamically-loaded
modules, and also from dynamic allocas (which might be transformed into malloc
calls). In short, take extra care that the compared-to pointer is really
simultaneously live with the memory allocation.
llvm-svn: 223347
System memory allocation functions, which are identified at the IR level by the
noalias attribute on the return value, must return a pointer into a memory region
disjoint from any other memory accessible to the caller. We can use this
property to simplify pointer comparisons between allocated memory and local
stack addresses and the addresses of global variables. Neither the stack nor
global variables can overlap with the region used by the memory allocator.
Fixes PR21556.
llvm-svn: 223093
The statepoint intrinsics are intended to enable precise root tracking through the compiler as to support garbage collectors of all types. The addition of the statepoint intrinsics to LLVM should have no impact on the compilation of any program which does not contain them. There are no side tables created, no extra metadata, and no inhibited optimizations.
A statepoint works by transforming a call site (or safepoint poll site) into an explicit relocation operation. It is the frontend's responsibility (or eventually the safepoint insertion pass we've developed, but that's not part of this patch series) to ensure that any live pointer to a GC object is correctly added to the statepoint and explicitly relocated. The relocated value is just a normal SSA value (as seen by the optimizer), so merges of relocated and unrelocated values are just normal phis. The explicit relocation operation, the fact the statepoint is assumed to clobber all memory, and the optimizers standard semantics ensure that the relocations flow through IR optimizations correctly.
This is the first patch in a small series. This patch contains only the IR parts; the documentation and backend support will be following separately. The entire series can be seen as one combined whole in http://reviews.llvm.org/D5683.
Reviewed by: atrick, ributzka
llvm-svn: 223078
This reverts commit r222632 (and follow-up r222636), which caused a host
of LNT failures on an internal bot. I'll respond to the commit on the
list with a reproduction of one of the failures.
Conflicts:
lib/Target/X86/X86TargetTransformInfo.cpp
llvm-svn: 222936
This restores our ability to optimize:
(X & C) ? X & ~C : X into X & ~C
(X & C) ? X : X & ~C into X
(X & C) ? X | C : X into X
(X & C) ? X : X | C into X | C
llvm-svn: 222868
If solveBlockValue() needs results from predecessors that are not already
computed, it returns false with the intention of resuming when the dependencies
have been resolved. However, the computation would never be resumed since an
'overdefined' result had been placed in the cache, preventing any further
computation.
The point of placing the 'overdefined' result in the cache seems to have been
to break cycles, but we can check for that when inserting work items in the
BlockValue stack instead. This makes the "stop and resume" mechanism of
solveBlockValue() work as intended, unlocking more analysis.
Using this patch shaves 120 KB off a 64-bit Chromium build on Linux.
I benchmarked compiling bzip2.c at -O2 but couldn't measure any difference in
compile time.
Tests by Jiangning Liu from r215343 / PR21238, Pete Cooper, and me.
Differential Revision: http://reviews.llvm.org/D6397
llvm-svn: 222768
clearly only exactly equal width ptrtoint and inttoptr casts are no-op
casts, it says so right there in the langref. Make the code agree.
Original log from r220277:
Teach the load analysis to allow finding available values which require
inttoptr or ptrtoint cast provided there is datalayout available.
Eventually, the datalayout can just be required but in practice it will
always be there today.
To go with the ability to expose available values requiring a ptrtoint
or inttoptr cast, helpers are added to perform one of these three casts.
These smarts are necessary to finish canonicalizing loads and stores to
the operational type requirements without regressing fundamental
combines.
I've added some test cases. These should actually improve as the load
combining and store combining improves, but they may fundamentally be
highlighting some missing combines for select in addition to exercising
the specific added logic to load analysis.
llvm-svn: 222739
This handles cases where we are comparing a masked value against itself.
The analysis could be further improved by making it recursive but such
expense is not currently justified.
llvm-svn: 222716
