Summary:
In the benchmark (https://github.com/vetter/shoc) we are researching,
the duplicated load is not eliminated because MemoryDependenceAnalysis
hit the BlockScanLimit. This patch change it into a command line option
instead of a hardcoded value.
Patched by Xuetian Weng.
Test Plan: test/Analysis/MemoryDependenceAnalysis/memdep-block-scan-limit.ll
Reviewers: jingyue, reames
Subscribers: reames, llvm-commits
Differential Revision: http://reviews.llvm.org/D11366
llvm-svn: 242842
This will allow classes to implement the AA interface without deriving
from the class or referencing an internal enum of some other class as
their return types.
Also, to a pretty fundamental extent, concepts such as 'NoAlias',
'MayAlias', and 'MustAlias' are first class concepts in LLVM and we
aren't saving anything by scoping them heavily.
My mild preference would have been to use a scoped enum, but that
feature is essentially completely broken AFAICT. I'm extremely
disappointed. For example, we cannot through any reasonable[1] means
construct an enum class (or analog) which has scoped names but converts
to a boolean in order to test for the possibility of aliasing.
[1]: Richard Smith came up with a "solution", but it requires class
templates, and lots of boilerplate setting up the enumeration multiple
times. Something like Boost.PP could potentially bundle this up, but
even that would be quite painful and it doesn't seem realistically worth
it. The enum class solution would probably work without the need for
a bool conversion.
Differential Revision: http://reviews.llvm.org/D10495
llvm-svn: 240255
that it is its own entity in the form of MemoryLocation, and update all
the callers.
This is an entirely mechanical change. References to "Location" within
AA subclases become "MemoryLocation", and elsewhere
"AliasAnalysis::Location" becomes "MemoryLocation". Hope that helps
out-of-tree folks update.
llvm-svn: 239885
port it to the new pass manager.
All this does is extract the inner "location" class used by AA into its
own full fledged type. This seems *much* cleaner as MemoryDependence and
soon MemorySSA also use this heavily, and it doesn't make much sense
being inside the AA infrastructure.
This will also make it much easier to break apart the AA infrastructure
into something that stands on its own rather than using the analysis
group design.
There are a few places where this makes APIs not make sense -- they were
taking an AliasAnalysis pointer just to build locations. I'll try to
clean those up in follow-up commits.
Differential Revision: http://reviews.llvm.org/D10228
llvm-svn: 239003
Unreachable values may use themselves in strange ways due to their
dominance property. Attempting to translate through them can lead to
infinite recursion, crashing LLVM. Instead, claim that we weren't able
to translate the value.
This fixes PR23096.
llvm-svn: 238702
Summary:
This lets us use range based for loops.
Reviewers: chandlerc
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D9169
llvm-svn: 235416
CallSite roughly behaves as a common base CallInst and InvokeInst. Bring
the behavior closer to that model by making upcasts explicit. Downcasts
remain implicit and work as before.
Following dyn_cast as a mental model checking whether a Value *V isa
CallSite now looks like this:
if (auto CS = CallSite(V)) // think dyn_cast
instead of:
if (CallSite CS = V)
This is an extra token but I think it is slightly clearer. Making the
ctor explicit has the advantage of not accidentally creating nullptr
CallSites, e.g. when you pass a Value * to a function taking a CallSite
argument.
llvm-svn: 234601
A load from an invariant location is assumed to not alias any otherwise potentially aliasing stores. Our implementation only applied this rule to store instructions themselves whereas they it should apply for any memory accessing instruction. This results in both FRE and PRE becoming more effective at eliminating invariant loads.
Note that as a follow on change I will likely move this into AliasAnalysis itself. That's where the TBAA constant flag is handled and the semantics are essentially the same. I'd like to separate the semantic change from the refactoring and thus have extended the hack that's already in MemoryDependenceAnalysis for this change.
Differential Revision: http://reviews.llvm.org/D8591
llvm-svn: 233140
r216771 introduced a change to MemoryDependenceAnalysis that allowed it
to reason about acquire/release operations. However, this change does
not ensure that the acquire/release operations pair. Unfortunately,
this leads to miscompiles as we won't see an acquire load as properly
memory effecting. This largely reverts r216771.
This fixes PR22708.
llvm-svn: 232889
Summary:
Now that the DataLayout is a mandatory part of the module, let's start
cleaning the codebase. This patch is a first attempt at doing that.
This patch is not exactly NFC as for instance some places were passing
a nullptr instead of the DataLayout, possibly just because there was a
default value on the DataLayout argument to many functions in the API.
Even though it is not purely NFC, there is no change in the
validation.
I turned as many pointer to DataLayout to references, this helped
figuring out all the places where a nullptr could come up.
I had initially a local version of this patch broken into over 30
independant, commits but some later commit were cleaning the API and
touching part of the code modified in the previous commits, so it
seemed cleaner without the intermediate state.
Test Plan:
Reviewers: echristo
Subscribers: llvm-commits
From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 231740
Summary:
DataLayout keeps the string used for its creation.
As a side effect it is no longer needed in the Module.
This is "almost" NFC, the string is no longer
canonicalized, you can't rely on two "equals" DataLayout
having the same string returned by getStringRepresentation().
Get rid of DataLayoutPass: the DataLayout is in the Module
The DataLayout is "per-module", let's enforce this by not
duplicating it more than necessary.
One more step toward non-optionality of the DataLayout in the
module.
Make DataLayout Non-Optional in the Module
Module->getDataLayout() will never returns nullptr anymore.
Reviewers: echristo
Subscribers: resistor, llvm-commits, jholewinski
Differential Revision: http://reviews.llvm.org/D7992
From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 231270
This change is a logical suspect in 22587 and 22590. Given it's of minimal importanance and I can't get clang to build on my home machine, I'm reverting so that I can deal with this next week.
llvm-svn: 229322
Canonicalize access to function attributes to use the simpler API.
getAttributes().getAttribute(AttributeSet::FunctionIndex, Kind)
=> getFnAttribute(Kind)
getAttributes().hasAttribute(AttributeSet::FunctionIndex, Kind)
=> hasFnAttribute(Kind)
llvm-svn: 229192
Two minor tweaks I noticed when reading through the code:
- No need to recompute begin() on every iteration. We're not modifying the instructions in this loop.
- We can ignore PHINodes and Dbg intrinsics. The current code does this anyways, but it will spend slightly more time doing so and will count towards the limit of instructions in the block. It seems really silly to give up due the presence of PHIs...
Differential Revision: http://reviews.llvm.org/D7624
llvm-svn: 229175
According to my reading of the LangRef, volatiles are only ordered with respect to other volatiles. It is entirely legal and profitable to forward unrelated loads over the volatile load. This patch implements this for GVN by refining the transition rules MemoryDependenceAnalysis uses when encountering a volatile.
The added test cases show where the extra flexibility is profitable for local dependence optimizations. I have a related change (227110) which will extend this to non-local dependence (i.e. PRE), but that's essentially orthogonal to the semantic change in this patch. I have tested the two together and can confirm that PRE works over a volatile load with both changes. I will be submitting a PRE w/volatiles test case seperately in the near future.
Differential Revision: http://reviews.llvm.org/D6901
llvm-svn: 227112
This change is mostly motivated by exposing information about the original query instruction to the actual scanning work in getPointerDependencyFrom when used by GVN PRE. In a follow up change, I will use this to be more precise with regards to the semantics of volatile instructions encountered in the scan of a basic block.
Worth noting, is that this change (despite appearing quite simple) is not semantically preserving. By providing more information to the helper routine, we allow some optimizations to kick in that weren't previously able to (when called from this code path.) In particular, we see that treatment of !invariant.load becomes more precise. In theory, we might see a difference with an ordered/atomic instruction as well, but I'm having a hard time actually finding a test case which shows that.
Test wise, I've included new tests for !invariant.load which illustrate this difference. I've also included some updated TBAA tests which highlight that this change isn't needed for that optimization to kick in - it's handled inside alias analysis itself.
Eventually, it would be nice to factor the !invariant.load handling inside alias analysis as well.
Differential Revision: http://reviews.llvm.org/D6895
llvm-svn: 227110
Previously, MemDepPrinter handled volatile and unordered accesses without involving MemoryDependencyAnalysis. By making a slight tweak to the documented interface - which is respected by both callers - we can move this responsibility to MDA for the benefit of any future callers. This is basically just cleanup.
In the future, we may decide to extend MDA's non local dependency analysis to return useful results for ordered or volatile loads. I believe (but have not really checked in detail) that local dependency analyis does get useful results for ordered, but not volatile, loads.
llvm-svn: 225483
Previously, MemoryDependenceAnalysis::getNonLocalPointerDependency was taking a list of properties about the instruction being queried. Since I'm about to need one more property to be passed down through the infrastructure - I need to know a query instruction is non-volatile in an inner helper - fix the interface once and for all.
I also added some assertions and behaviour clarifications around volatile and ordered field accesses. At the moment, this is mostly to document expected behaviour. The only non-standard instructions which can currently reach this are atomic, but unordered, loads and stores. Neither ordered or volatile accesses can reach here.
The call in GVN is protected by an isSimple check when it first considers the load. The calls in MemDepPrinter are protected by isUnordered checks. Both utilities also check isVolatile for loads and stores.
llvm-svn: 225481
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
This is to be consistent with StringSet and ultimately with the standard
library's associative container insert function.
This lead to updating SmallSet::insert to return pair<iterator, bool>,
and then to update SmallPtrSet::insert to return pair<iterator, bool>,
and then to update all the existing users of those functions...
llvm-svn: 222334
- Problem
One program takes ~3min to compile under -O2. This happens after a certain
function A is inlined ~700 times in a function B, inserting thousands of new
BBs. This leads to 80% of the compilation time spent in
GVN::processNonLocalLoad and
MemoryDependenceAnalysis::getNonLocalPointerDependency, while searching for
nonlocal information for basic blocks.
Usually, to avoid spending a long time to process nonlocal loads, GVN bails out
if it gets more than 100 deps as a result from
MD->getNonLocalPointerDependency. However this only happens *after* all
nonlocal information for BBs have been computed, which is the bottleneck in
this scenario. For instance, there are 8280 times where
getNonLocalPointerDependency returns deps with more than 100 bbs and from
those, 600 times it returns more than 1000 blocks.
- Solution
Bail out early during the nonlocal info computation whenever we reach a
specified threshold. This patch proposes a 100 BBs threshold, it also
reduces the compile time from 3min to 23s.
- Testing
The test-suite presented no compile nor execution time regressions.
Some numbers from my machine (x86_64 darwin):
- 17s under -Oz (which avoids inlining).
- 1.3s under -O1.
- 2m51s under -O2 ToT
*** 23s under -O2 w/ Result.size() > 100
- 1m54s under -O2 w/ Result.size() > 500
With NumResultsLimit = 100, GVN yields the same outcome as in the
unlimited 3min version.
http://reviews.llvm.org/D5532
rdar://problem/18188041
llvm-svn: 218792
This change, which allows @llvm.assume to be used from within computeKnownBits
(and other associated functions in ValueTracking), adds some (optional)
parameters to computeKnownBits and friends. These functions now (optionally)
take a "context" instruction pointer, an AssumptionTracker pointer, and also a
DomTree pointer, and most of the changes are just to pass this new information
when it is easily available from InstSimplify, InstCombine, etc.
As explained below, the significant conceptual change is that known properties
of a value might depend on the control-flow location of the use (because we
care that the @llvm.assume dominates the use because assumptions have
control-flow dependencies). This means that, when we ask if bits are known in a
value, we might get different answers for different uses.
The significant changes are all in ValueTracking. Two main changes: First, as
with the rest of the code, new parameters need to be passed around. To make
this easier, I grouped them into a structure, and I made internal static
versions of the relevant functions that take this structure as a parameter. The
new code does as you might expect, it looks for @llvm.assume calls that make
use of the value we're trying to learn something about (often indirectly),
attempts to pattern match that expression, and uses the result if successful.
By making use of the AssumptionTracker, the process of finding @llvm.assume
calls is not expensive.
Part of the structure being passed around inside ValueTracking is a set of
already-considered @llvm.assume calls. This is to prevent a query using, for
example, the assume(a == b), to recurse on itself. The context and DT params
are used to find applicable assumptions. An assumption needs to dominate the
context instruction, or come after it deterministically. In this latter case we
only handle the specific case where both the assumption and the context
instruction are in the same block, and we need to exclude assumptions from
being used to simplify their own ephemeral values (those which contribute only
to the assumption) because otherwise the assumption would prove its feeding
comparison trivial and would be removed.
This commit adds the plumbing and the logic for a simple masked-bit propagation
(just enough to write a regression test). Future commits add more patterns
(and, correspondingly, more regression tests).
llvm-svn: 217342
Summary:
MemoryDependenceAnalysis is currently cautious when the QueryInstr is an atomic
load or store, but I forgot to check for atomic cmpxchg/atomicrmw. This patch
is a way of fixing that, and making it less brittle (i.e. no risk that I forget
another possible kind of atomic, even if the IR ends up changing in the future),
by adding a fallback checking mayReadOrWriteFromMemory.
Thanks to Philip Reames for finding this bug and suggesting this solution in
http://reviews.llvm.org/D4845
Sadly, I don't see how to add a test for this, since the passes depending on
MemoryDependenceAnalysis won't trigger for an atomic rmw anyway. Does anyone
see a way for testing it?
Test Plan: none possible at first sight
Reviewers: jfb, reames
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D5019
llvm-svn: 216940
Even loads/stores that have a stronger ordering than monotonic can be safe.
The rule is no release-acquire pair on the path from the QueryInst, assuming that
the QueryInst is not atomic itself.
llvm-svn: 216771
- add check for volatile (probably unneeded, but I agree that we should be conservative about it).
- strengthen condition from isUnordered() to isSimple(), as I don't understand well enough Unordered semantics (and it also matches the comment better this way) to be confident in the previous behaviour (thanks for catching that one, I had missed the case Monotonic/Unordered).
- separate a condition in two.
- lengthen comment about aliasing and loads
- add tests in GVN/atomic.ll
llvm-svn: 215943
In order to enable the preservation of noalias function parameter information
after inlining, and the representation of block-level __restrict__ pointer
information (etc.), additional kinds of aliasing metadata will be introduced.
This metadata needs to be carried around in AliasAnalysis::Location objects
(and MMOs at the SDAG level), and so we need to generalize the current scheme
(which is hard-coded to just one TBAA MDNode*).
This commit introduces only the necessary refactoring to allow for the
introduction of other aliasing metadata types, but does not actually introduce
any (that will come in a follow-up commit). What it does introduce is a new
AAMDNodes structure to hold all of the aliasing metadata nodes associated with
a particular memory-accessing instruction, and uses that structure instead of
the raw MDNode* in AliasAnalysis::Location, etc.
No functionality change intended.
llvm-svn: 213859
definition below all the header #include lines, lib/Analysis/...
edition.
This one has a bit extra as there were *other* #define's before #include
lines in addition to DEBUG_TYPE. I've sunk all of them as a block.
llvm-svn: 206843
This compiles with no changes to clang/lld/lldb with MSVC and includes
overloads to various functions which are used by those projects and llvm
which have OwningPtr's as parameters. This should allow out of tree
projects some time to move. There are also no changes to libs/Target,
which should help out of tree targets have time to move, if necessary.
llvm-svn: 203083
can be used by both the new pass manager and the old.
This removes it from any of the virtual mess of the pass interfaces and
lets it derive cleanly from the DominatorTreeBase<> template. In turn,
tons of boilerplate interface can be nuked and it turns into a very
straightforward extension of the base DominatorTree interface.
The old analysis pass is now a simple wrapper. The names and style of
this split should match the split between CallGraph and
CallGraphWrapperPass. All of the users of DominatorTree have been
updated to match using many of the same tricks as with CallGraph. The
goal is that the common type remains the resulting DominatorTree rather
than the pass. This will make subsequent work toward the new pass
manager significantly easier.
Also in numerous places things became cleaner because I switched from
re-running the pass (!!! mid way through some other passes run!!!) to
directly recomputing the domtree.
llvm-svn: 199104
directory. These passes are already defined in the IR library, and it
doesn't make any sense to have the headers in Analysis.
Long term, I think there is going to be a much better way to divide
these matters. The dominators code should be fully separated into the
abstract graph algorithm and have that put in Support where it becomes
obvious that evn Clang's CFGBlock's can use it. Then the verifier can
manually construct dominance information from the Support-driven
interface while the Analysis library can provide a pass which both
caches, reconstructs, and supports a nice update API.
But those are very long term, and so I don't want to leave the really
confusing structure until that day arrives.
llvm-svn: 199082
with and without -g.
Adding a test case to make sure that the threshold used in the memory
dependence analysis is respected. The test case also checks that debug
intrinsics are not counted towards this threshold.
Differential Revision: http://llvm-reviews.chandlerc.com/D2141
llvm-svn: 194646
BitVector/SmallBitVector::reference::operator bool remain implicit since
they model more exactly a bool, rather than something else that can be
boolean tested.
The most common (non-buggy) case are where such objects are used as
return expressions in bool-returning functions or as boolean function
arguments. In those cases I've used (& added if necessary) a named
function to provide the equivalent (or sometimes negative, depending on
convenient wording) test.
One behavior change (YAMLParser) was made, though no test case is
included as I'm not sure how to reach that code path. Essentially any
comparison of llvm::yaml::document_iterators would be invalid if neither
iterator was at the end.
This helped uncover a couple of bugs in Clang - test cases provided for
those in a separate commit along with similar changes to `operator bool`
instances in Clang.
llvm-svn: 181868
PR15000 has a testcase where the time to compile was bordering on 30s. When I
dropped the limit value to 100, it became a much more managable 6s. The compile
time seems to increase in a roughly linear fashion based on increasing the limit
value. (See the runtimes below.)
So, let's lower the limit to 100 so that they can get a more reasonable compile
time.
Limit Value Time
----------- ----
10 0.9744s
20 1.8035s
30 2.3618s
40 2.9814s
50 3.6988s
60 4.5486s
70 4.9314s
80 5.8012s
90 6.4246s
100 7.0852s
110 7.6634s
120 8.3553s
130 9.0552s
140 9.6820s
150 9.8804s
160 10.8901s
170 10.9855s
180 12.0114s
190 12.6816s
200 13.2754s
210 13.9942s
220 13.8097s
230 14.3272s
240 15.7753s
250 15.6673s
260 16.0541s
270 16.7625s
280 17.3823s
290 18.8213s
300 18.6120s
310 20.0333s
320 19.5165s
330 20.2505s
340 20.7068s
350 21.1833s
360 22.9216s
370 22.2152s
380 23.9390s
390 23.4609s
400 24.0426s
410 24.6410s
420 26.5208s
430 27.7155s
440 26.4142s
450 28.5646s
460 27.3494s
470 29.7255s
480 29.4646s
490 30.5001s
llvm-svn: 179713
The "invariant.load" metadata indicates the memory unit being accessed is immutable.
A load annotated with this metadata can be moved across any store.
As I am not sure if it is legal to move such loads across barrier/fence, this
change dose not allow such transformation.
rdar://11311484
Thank Arnold for code review.
llvm-svn: 176562
These are two related changes (one in llvm, one in clang).
LLVM:
- rename address_safety => sanitize_address (the enum value is the same, so we preserve binary compatibility with old bitcode)
- rename thread_safety => sanitize_thread
- rename no_uninitialized_checks -> sanitize_memory
CLANG:
- add __attribute__((no_sanitize_address)) as a synonym for __attribute__((no_address_safety_analysis))
- add __attribute__((no_sanitize_thread))
- add __attribute__((no_sanitize_memory))
for S in address thread memory
If -fsanitize=S is present and __attribute__((no_sanitize_S)) is not
set llvm attribute sanitize_S
llvm-svn: 176075
into their new header subdirectory: include/llvm/IR. This matches the
directory structure of lib, and begins to correct a long standing point
of file layout clutter in LLVM.
There are still more header files to move here, but I wanted to handle
them in separate commits to make tracking what files make sense at each
layer easier.
The only really questionable files here are the target intrinsic
tablegen files. But that's a battle I'd rather not fight today.
I've updated both CMake and Makefile build systems (I think, and my
tests think, but I may have missed something).
I've also re-sorted the includes throughout the project. I'll be
committing updates to Clang, DragonEgg, and Polly momentarily.
llvm-svn: 171366
directly.
This is in preparation for removing the use of the 'Attribute' class as a
collection of attributes. That will shift to the AttributeSet class instead.
llvm-svn: 171253
Sooooo many of these had incorrect or strange main module includes.
I have manually inspected all of these, and fixed the main module
include to be the nearest plausible thing I could find. If you own or
care about any of these source files, I encourage you to take some time
and check that these edits were sensible. I can't have broken anything
(I strictly added headers, and reordered them, never removed), but they
may not be the headers you'd really like to identify as containing the
API being implemented.
Many forward declarations and missing includes were added to a header
files to allow them to parse cleanly when included first. The main
module rule does in fact have its merits. =]
llvm-svn: 169131
loads. It's not really profitable and may result in GVN going into an infinite
loop when it hits constructs like this:
%x = gep %some.type %x, ...
Found via an LTO build of LLVM.
llvm-svn: 166490
We use the enums to query whether an Attributes object has that attribute. The
opaque layer is responsible for knowing where that specific attribute is stored.
llvm-svn: 165488
If an allocation has a must-alias relation to the access pointer, we treat it
as a Def. Otherwise, without this check, the code here was just skipping over
the allocation call and ignoring it. I noticed this by inspection and don't
have a specific testcase that it breaks, but it seems like we need to treat
a may-alias allocation as a Clobber.
llvm-svn: 163127
This code used to only handle malloc-like calls, which do not read memory.
r158919 changed it to check isNoAliasFn(), which includes strdup-like and
realloc-like calls, but it was not checking for dependencies on the memory
read by those calls.
llvm-svn: 163106
This disables malloc-specific optimization when -fno-builtin (or -ffreestanding)
is specified. This has been a problem for a long time but became more severe
with the recent memory builtin improvements.
Since the memory builtin functions are used everywhere, this required passing
TLI in many places. This means that functions that now have an optional TLI
argument, like RecursivelyDeleteTriviallyDeadFunctions, won't remove dead
mallocs anymore if the TLI argument is missing. I've updated most passes to do
the right thing.
Fixes PR13694 and probably others.
llvm-svn: 162841
Currently, if GetLocation reports that it did not find a valid pointer (this is the case for volatile load/stores),
we ignore the result. This patch adds code to handle the cases where we did not obtain a valid pointer.
rdar://11872864 PR12899
llvm-svn: 161802
- provide more extensive set of functions to detect library allocation functions (e.g., malloc, calloc, strdup, etc)
- provide an API to compute the size and offset of an object pointed by
Move a few clients (GVN, AA, instcombine, ...) to the new API.
This implementation is a lot more aggressive than each of the custom implementations being replaced.
Patch reviewed by Nick Lewycky and Chandler Carruth, thanks.
llvm-svn: 158919
so that it can be reused in MemCpyOptimizer. This analysis is needed to remove
an unnecessary memcpy when returning a struct into a local variable.
rdar://11341081
PR12686
llvm-svn: 156776
captured. This allows the tracker to look at the specific use, which may be
especially interesting for function calls.
Use this to fix 'nocapture' deduction in FunctionAttrs. The existing one does
not iterate until a fixpoint and does not guarantee that it produces the same
result regardless of iteration order. The new implementation builds up a graph
of how arguments are passed from function to function, and uses a bottom-up walk
on the argument-SCCs to assign nocapture. This gets us nocapture more often, and
does so rather efficiently and independent of iteration order.
llvm-svn: 147327
and stores capture) to permit the caller to see each capture point and decide
whether to continue looking.
Use this inside memdep to do an analysis that basicaa won't do. This lets us
solve another devirtualization case, fixing PR8908!
llvm-svn: 144580
The limit in this patch is probably too high, but it is enough to stop DSE from going completely insane on a testcase I have (which has a single block with around 50,000 non-aliasing stores in it).
rdar://9471075
llvm-svn: 133111
redundant with partially-aliasing loads.
When computing what portion of a clobbering load value is needed,
it doesn't consider phi-translation which may have occurred
between the clobbing load and the redundant load.
llvm-svn: 132631
In the given testcase, the "Clobber" was pointing to a load, and GVN was incorrectly assuming that meant that the "Clobber" load overlapped the load being analyzed (when they are actually unrelated).
The included testcase tests both this commit and r132434.
Part two of rdar://9429882. (r132434 was mislabeled.)
llvm-svn: 132442
wider load would allow elimination of subsequent loads, and when the wider
load is still a native integer type. This eliminates a ton of loads on
various benchmarks involving struct fields, though it is somewhat hobbled
by clang not being very aggressive about field alignment.
This is yet another step along the way towards resolving PR6627.
llvm-svn: 130390
an earlier load could be widened to encompass a later load. For example,
if we see:
X = load i8* P, align 4
Y = load i8* (P+3), align 1
and we have a 32-bit native integer type, we can widen the former load
to i32 which then makes the second load redundant. GVN can't actually
do anything with this load/load relation yet, so this isn't testable, but
it is the next step to resolving PR6627, and a fairly general class of
"merge neighboring loads" missed optimizations.
llvm-svn: 130250
return it as a clobber. This allows GVN to do smart things.
Enhance GVN to be smart about the case when a small load is clobbered
by a larger overlapping load. In this case, forward the value. This
allows us to compile stuff like this:
int test(void *P) {
int tmp = *(unsigned int*)P;
return tmp+*((unsigned char*)P+1);
}
into:
_test: ## @test
movl (%rdi), %ecx
movzbl %ch, %eax
addl %ecx, %eax
ret
which has one load. We already handled the case where the smaller
load was from a must-aliased base pointer.
llvm-svn: 130180
with BasicAA's DecomposeGEPExpression, which recently began
using a TargetData. This fixes PR8968, though the testcase
is awkward to reduce.
Also, update several off GetUnderlyingObject's users
which happen to have a TargetData handy to pass it in.
llvm-svn: 124134
