This patch teaches the fully redundant load part of EarlyCSE how to forward from atomic and volatile loads and stores, and how to eliminate unordered atomics (only). This patch does not include dead store elimination support for unordered atomics, that will follow in the near future.
The basic idea is that we allow all loads and stores to be tracked by the AvailableLoad table. We store a bit in the table which tracks whether load/store was atomic, and then only replace atomic loads with ones which were also atomic.
No attempt is made to refine our handling of ordered loads or stores. Those are still treated as full fences. We could pretty easily extend the release fence handling to release stores, but that should be a separate patch.
Differential Revision: http://reviews.llvm.org/D15337
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The StringRef constructor is unnecessary (since we're converting to
std::string anyway), and having it requires an explicit call to
StringRef's or std::string's constructor.
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Summary:
Also add a stricter post-condition for IndVarSimplify.
Fixes PR25578. Test case by Michael Zolotukhin.
Reviewers: hfinkel, atrick, mzolotukhin
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D15059
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254950 ended up being not NFC. The previous code was overriding the flags for whether an instruction read or wrote memory using the target specific flags returned via TTI. I'd missed this in my refactoring. Since I mistakenly built only x86 and didn't notice the number of unsupported tests, I didn't catch that before the original checkin.
This raises an interesting issue though. Given we have function attributes (i.e. readonly, readnone, argmemonly) which describe the aliasing of intrinsics, why does TTI have this information overriding the instruction definition at all? I see no reason for this, but decided to preserve existing behavior for the moment. The root issue might be that we don't have a "writeonly" attribute.
Original commit message:
[EarlyCSE] Simplify and invert ParseMemoryInst [NFCI]
Restructure ParseMemoryInst - which was introduced to abstract over target specific load and stores instructions - to just query the underlying instructions. In theory, this could be slightly slower than caching the results, but in practice, it's very unlikely to be measurable.
The simple query scheme makes it far easier to understand, and much easier to extend with new queries. Given I'm about to need to add new query types, doing the cleanup first seemed worthwhile.
Do we still believe the target specific intrinsic handling is worthwhile in EarlyCSE? It adds quite a bit of complexity and makes the code harder to read. Being able to delete the abstraction entirely would be wonderful.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@254957 91177308-0d34-0410-b5e6-96231b3b80d8
It's causing test failures on AArch64. Due to a bad build config on my part, I apparently wasn't running the tests I thought I was.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@254954 91177308-0d34-0410-b5e6-96231b3b80d8
Restructure ParseMemoryInst - which was introduced to abstract over target specific load and stores instructions - to just query the underlying instructions. In theory, this could be slightly slower than caching the results, but in practice, it's very unlikely to be measurable.
The simple query scheme makes it far easier to understand, and much easier to extend with new queries. Given I'm about to need to add new query types, doing the cleanup first seemed worthwhile.
Do we still believe the target specific intrinsic handling is worthwhile in EarlyCSE? It adds quite a bit of complexity and makes the code harder to read. Being able to delete the abstraction entirely would be wonderful.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@254950 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Add a field on the PassManagerBuilder that clang or gold can use to pass
down a pointer to the function index in memory to use for importing when
the ThinLTO backend is triggered. Add support to supply this to the
function import pass.
Reviewers: joker.eph, dexonsmith
Subscribers: davidxl, llvm-commits, joker.eph
Differential Revision: http://reviews.llvm.org/D15024
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Summary:
There are `SelectPatternFlavor`s that don't represent min or max idioms,
and we should not be passing those to `getCmpPredicateForMinMax`.
Fixes PR25745.
Reviewers: majnemer
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D15249
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Summary: If the same pass manager is used for multiple modules ASAN
complains about GlobalsMD being initialized twice. Fix this by
resetting GlobalsMD in a new doFinalization method to allow this
use case.
Reviewers: kcc
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D14962
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When the notion of target specific memory intrinsics was introduced to EarlyCSE, the commit confused the notions of volatile and simple memory access. Since I'm about to start working on this area, cleanup the naming so that patches aren't horribly confusing. Note that the actual implementation was always bailing if the load or store wasn't simple.
Reminder:
- "volatile" - C++ volatile, can't remove any memory operations, but in principal unordered
- "ordered" - imposes ordering constraints on other nearby memory operations
- "atomic" - can't be split or sheared. In LLVM terms, all "ordered" operations are also atomic so the predicate "isAtomic" is often used.
- "simple" - a load which is none of the above. These are normal loads and what most of the optimizer works with.
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Summary:
In order to avoid calling pow function we generate repeated fmul when n is a
positive or negative whole number.
For each exponent we pre-compute Addition Chains in order to minimize the no.
of fmuls.
Refer: http://wwwhomes.uni-bielefeld.de/achim/addition_chain.html
We pre-compute addition chains for exponents upto 32 (which results in a max of
7 fmuls).
For eg:
4 = 2+2
5 = 2+3
6 = 3+3 and so on
Hence,
pow(x, 4.0) ==> y = fmul x, x
x = fmul y, y
ret x
For negative exponents, we simply compute the reciprocal of the final result.
Note: This transformation is only enabled under fast-math.
Patch by Mandeep Singh Grang <mgrang@codeaurora.org>
Reviewers: weimingz, majnemer, escha, davide, scanon, joerg
Subscribers: probinson, escha, llvm-commits
Differential Revision: http://reviews.llvm.org/D13994
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This precludes some more functional changes to perform bulk imports.
From: Mehdi Amini <mehdi.amini@apple.com>
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time.
The new overloaded function is used when an attribute is added to a
large number of slots of an AttributeSet (for example, to function
parameters). This is much faster than calling AttributeSet::addAttribute
once per slot, because AttributeSet::getImpl (which calls
FoldingSet::FIndNodeOrInsertPos) is called only once per function
instead of once per slot.
With this commit, clang compiles a file which used to take over 22
minutes in just 13 seconds.
rdar://problem/23581000
Differential Revision: http://reviews.llvm.org/D15085
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When linking static archive, there is no individual module files to
load. Instead they can be mmap'ed and could be initialized from a
buffer directly. The callback provide flexibility to override the
scheme for loading module from the summary.
Differential Revision: http://reviews.llvm.org/D15101
From: Mehdi Amini <mehdi.amini@apple.com>
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The linker never takes ownership of a module or changes which module it
is refering to, making it natural to use references.
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The difference is that now we don't error on out-of-comdat access to
internal global values. We copy them instead. This seems to match the
expectation of COFF linkers (see pr25686).
Original message:
Start deciding earlier what to link.
A traditional linker is roughly split in symbol resolution and
"copying
stuff".
The two tasks are badly mixed in lib/Linker.
This starts splitting them apart.
With this patch there are no direct call to linkGlobalValueBody or
linkGlobalValueProto. Everything is linked via WapValue.
This also includes a few fixes:
* A GV goes undefined if the comdat is dropped (comdat11.ll).
* We error if an internal GV goes undefined (comdat13.ll).
* We don't link an unused comdat.
The first two match the behavior of an ELF linker. The second one is
equivalent to running globaldce on the input.
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The current code does not take alloca array size into account and,
as a result, considers any access past the first array element to be
unsafe.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@254350 91177308-0d34-0410-b5e6-96231b3b80d8
A traditional linker is roughly split in symbol resolution and "copying
stuff".
The two tasks are badly mixed in lib/Linker.
This starts splitting them apart.
With this patch there are no direct call to linkGlobalValueBody or
linkGlobalValueProto. Everything is linked via WapValue.
This also includes a few fixes:
* A GV goes undefined if the comdat is dropped (comdat11.ll).
* We error if an internal GV goes undefined (comdat13.ll).
* We don't link an unused comdat.
The first two match the behavior of an ELF linker. The second one is
equivalent to running globaldce on the input.
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This one is enabled only under -ffast-math. There are cases where the
difference between the value computed and the correct value is huge
even for ffast-math, e.g. as Steven pointed out:
x = -1, y = -4
log(pow(-1), 4) = 0
4*log(-1) = NaN
I checked what GCC does and apparently they do the same optimization
(which result in the dramatic difference). Future work might try to
make this (slightly) less worse.
Differential Revision: http://reviews.llvm.org/D14400
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This fixes buildbots in systems that std::to_string is not present. It
also tidies the output of the diagnostic to render doubles a bit better
(thanks Ben Kramer for help with string streams and format).
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This adds two thresholds to the sample profiler to affect inlining
decisions: the concept of global hotness and coldness.
Functions that have accumulated more than a certain fraction of samples at
runtime, are annotated with the InlineHint attribute. Conversely,
functions that accumulate less than a certain fraction of samples, are
annotated with the Cold attribute.
This is very similar to the hints emitted by Clang when using
instrumentation profiles.
Notice that this is a very blunt instrument. A function may have
globally collected a significant fraction of samples, but that does not
necessarily mean that every callsite for that function is hot.
Ideally, we would annotate each callsite with the samples collected at
that callsite. This way, the inliner can incorporate all these weights
into its cost model.
Once the inliner offers this functionality, we can change the hints
emitted here to a more precise per-callsite annotation. For now, this is
providing some measure of speedups with our internal benchmarks. I've
observed speedups of up to 23% (though the geo mean is about 3%). I expect
these numbers to improve as the inliner gets better annotations.
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Based on testing of internal benchmarks, I'm lowering this threshold to
a value of 0.1%. This means that SamplePGO will respect 99.9% of the
original inline decisions when following a profile.
The performance difference is noticeable in some tests. With the
previous threshold, the speedups over baseline -O2 was about 0.63%. With
the new default, the speedups are around 3% on average.
The point of this threshold is not to do more aggressive inlining. When
an inlined callsite crosses this threshold, SamplePGO will redo the
inline decision so that it can better apply the input profile.
By respecting most original inline decisions, we can apply more of the
input profile because the shape of the code follows the profile more
closely.
In the next series, I'll be looking at adding some inline hints for the
cold callsites and for toplevel functions that are hot/cold as well.
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Now the ValueMapper has two callbacks. The first one maps the
declaration. The ValueMapper records the mapping and then materializes
the body/initializer.
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This patch changes the DFSan instrumentation for aarch64 to instead
of using fixes application mask defined by SANITIZER_AARCH64_VMA
to read the application shadow mask value from compiler-rt. The value
is initialized based on runtime VAM detection.
Along with this patch a compiler-rt one will also be added to export
the shadow mask variable.
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The order in which instructions are truncated in truncateToMinimalBitwidths
effects code generation. Switch to a map with a determinisic order, since the
iteration order over a DenseMap is not defined.
This code is not hot, so the difference in container performance isn't
interesting.
Many thanks to David Blaikie for making me aware of MapVector!
Fixes PR25490.
Differential Revision: http://reviews.llvm.org/D14981
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They are as much trouble as aliases to declarations. They are requiring
the code generator to define a symbol with the same value as another
symbol, but the second symbol is undefined.
If representing this is important for some optimization, we could add
support for available_externally aliases. They would be *required* to
point to a declaration (or available_externally definition).
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