This patch was landed in r231035 and reverted because it was buggy.
This is fixed version of the same change.
Summary:
This patch is an attempt at making `DenseMapIterator`s "fail-fast".
Fail-fast iterators that have been invalidated due to insertion into
the host `DenseMap` deterministically trip an assert (in debug mode)
on access, instead of non-deterministically hitting memory corruption
issues.
Reviewers: dexonsmith, dberlin, ruiu, chandlerc
Reviewed By: chandlerc
Subscribers: yaron.keren, chandlerc, llvm-commits
Differential Revision: http://reviews.llvm.org/D7931
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Without this, use of this copy ctor is deprecated in C++11 due to the
presence of a user-declared dtor.
Marking the class final is just a little extra security that there are
no further derived classes that may then end up using the intermediate
base class's copy assignment operator and cause slicing to occur.
I didn't bother marking the other (non-test) base class final, since it
has reference members so it won't have any implicit assignment operators
anyway. Open to ideas on that, though.
We probably want a warning about use of a slicing assignment operator,
then I wouldn't worry so much about marking the class as final.
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I tried making these private & friended to the BitVector, but that
didn't work - there's one use of BitVector::reference in Clang that
actually copies it into a local variable & uses it from there, rather
than just using the result of op[] in a temporary expression.
Whether or not this is desired is debatable (we could just fix that one
use in Clang) & it's not clear which way the C++ standard falls on this
for std::bitset's reference type (it has the same bug at least in
libstdc++, but Clang's -Wdeprecated doesn't flag it, because it's in a
standard header)
While it was only BitVector::reference's copy ctor that was referenced
by user code, I made SmallBitVector::reference's copy ctor public too,
for consistency.
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Summary:
This patch is an attempt at making `DenseMapIterator`s "fail-fast".
Fail-fast iterators that have been invalidated due to insertion into
the host `DenseMap` deterministically trip an assert (in debug mode)
on access, instead of non-deterministically hitting memory corruption
issues.
Reviewers: dexonsmith, dberlin, ruiu, chandlerc
Reviewed By: chandlerc
Subscribers: yaron.keren, chandlerc, llvm-commits
Differential Revision: http://reviews.llvm.org/D7931
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231035 91177308-0d34-0410-b5e6-96231b3b80d8
This has the nice property of compiling down to memcmp when feasible. An empty
ArrayRef can have a nullptr in its Data field. I didn't find anything in the
standard speaking against std::equal(nullptr, nullptr, nullptr) begin valid but
MSVC asserts. The way libstdc++ lowers std::equal down to memcmp also makes
invoking std::equal with a nullptr undefined behavior so checking is the only
way to be safe.
The extra check doesn't cost us perf either because we're essentially peeling
the loop header away from the rotated loop.
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With initializer lists there is a really neat idiomatic way to write
this, 'ArrayRef.equals({1, 2, 3, 4, 5})'. Remove the equal method which
always had a hard limit on the number of arguments. I considered
rewriting it with variadic templates but that's not really a good fit
for a function with homogeneous arguments.
'ArrayRef == {1, 2, 3, 4, 5}' would've been even more awesome, but C++11
doesn't allow init lists with binary operators.
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This looks ridiculous but SmallVector's realloc tricks really help with
large vectors of PODs, such as our virtreg IndexedMap.
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This assumes that
a) finding the bucket containing the value is LIKELY
b) finding an empty bucket is LIKELY
c) growing the table is UNLIKELY
I also switched the a) and b) cases for SmallPtrSet as we seem to use
the set mostly more for insertion than for checking existence.
In a simple benchmark consisting of 2^21 insertions of 2^20 unique
pointers into a DenseMap or SmallPtrSet a few percent speedup on average,
but nothing statistically significant.
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This patch introduces a new mechanism that allows IR modules to co-operatively
build pointer sets corresponding to addresses within a given set of
globals. One particular use case for this is to allow a C++ program to
efficiently verify (at each call site) that a vtable pointer is in the set
of valid vtable pointers for the class or its derived classes. One way of
doing this is for a toolchain component to build, for each class, a bit set
that maps to the memory region allocated for the vtables, such that each 1
bit in the bit set maps to a valid vtable for that class, and lay out the
vtables next to each other, to minimize the total size of the bit sets.
The patch introduces a metadata format for representing pointer sets, an
'@llvm.bitset.test' intrinsic and an LTO lowering pass that lays out the globals
and builds the bitsets, and documents the new feature.
Differential Revision: http://reviews.llvm.org/D7288
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This fixes an error introduced in r228934 where None was converted to
an int instead of the int being converted to an Optional as intended.
We make that sort of mistake a compile error by changing NoneType into
a scoped enum.
Finally, provide a static NoneType called None to avoid forcing all
users to spell it NoneType::None.
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If any of the bots complain (perhaps due to an antiquated version of an STL implementation), I will revert.
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classes. We can't use template aliases because on MSVC they don't appear
to work correctly in the common usage such as Format.h.
Many thanks to Zach for doing all the testing and debugging here. I just
slotted the fix into the code.
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Introduces a subset of C++14 integer sequences in STLExtras. This is
just enough to support unpacking a std::tuple into the arguments of
snprintf, we can add more of it when it's actually needed.
Also removes an ancient macro hack that leaks a macro into the global
namespace. Clean up users that made use of the convenient hack.
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Original commit message:
SmallVector: Resolve a long-standing fixme by using the existing unitialized_copy dispatch.
This makes append() use memcpy for trivially copyable types.
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This commit makes the following changes:
- Stop issuing a warning when the triples' string representations do not match
exactly if the Triple objects generated from the strings compare equal.
- On Apple platforms, choose the triple that has the larger minimum version
number.
rdar://problem/16743513
Differential Revision: http://reviews.llvm.org/D7591
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I just realized that the specialized metadata node patch I'm about to
commit won't compile on old compilers. Bump `hash_combine()`'s support
for non-variadic templates to 18 (I tested this by reversing the logic
in the #ifdef).
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This resolves the strange effect that emplace_back is only available
when the type contained in the vector is not trivially copyable.
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Add some API to `APSInt` to make it easier to compare with `int64_t`.
- `APSInt::compareValues(APSInt, APSInt)` returns 1, -1 or 0 for
greater, lesser, or equal, doing the right thing for mismatched
"has-sign" and bitwidths. This is just like `isSameValue()` (and is
now the implementation of it).
- `APSInt::get(int64_t)` gets a signed `APSInt`.
- `operator<(int64_t)`, etc., are implemented trivially via `get()`
and `compareValues()`.
- Also added `APSInt::getUnsigned(uint64_t)` to make it easier to test
`compareValues()`.
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This used to do something when we modeled the Cygwin and MinGW
environments as distinct OSs, but now it is not needed.
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Similar to the C++14 void specializations of these templates, useful as
a stop-gap until LLVM switches to '14.
Example use-cases in tblgen because I saw some functors that looked like
they could be simplified/refactored.
Reviewers: dexonsmith
Differential Revision: http://reviews.llvm.org/D7324
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Summary:
V8->V9:
- cleanup tests
V7->V8:
- addressed feedback from David:
- switched to range-based 'for' loops
- fixed formatting of tests
V6->V7:
- rebased and adjusted AsmPrinter args
- CamelCased .td, fixed formatting, cleaned up names, removed unused patterns
- diffstat: 3 files changed, 203 insertions(+), 227 deletions(-)
V5->V6:
- addressed feedback from Chandler:
- reinstated full verbose standard banner in all files
- fixed variables that were not in CamelCase
- fixed names of #ifdef in header files
- removed redundant braces in if/else chains with single statements
- fixed comments
- removed trailing empty line
- dropped debug annotations from tests
- diffstat of these changes:
46 files changed, 456 insertions(+), 469 deletions(-)
V4->V5:
- fix setLoadExtAction() interface
- clang-formated all where it made sense
V3->V4:
- added CODE_OWNERS entry for BPF backend
V2->V3:
- fix metadata in tests
V1->V2:
- addressed feedback from Tom and Matt
- removed top level change to configure (now everything via 'experimental-backend')
- reworked error reporting via DiagnosticInfo (similar to R600)
- added few more tests
- added cmake build
- added Triple::bpf
- tested on linux and darwin
V1 cover letter:
---------------------
recently linux gained "universal in-kernel virtual machine" which is called
eBPF or extended BPF. The name comes from "Berkeley Packet Filter", since
new instruction set is based on it.
This patch adds a new backend that emits extended BPF instruction set.
The concept and development are covered by the following articles:
http://lwn.net/Articles/599755/http://lwn.net/Articles/575531/http://lwn.net/Articles/603983/http://lwn.net/Articles/606089/http://lwn.net/Articles/612878/
One of use cases: dtrace/systemtap alternative.
bpf syscall manpage:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=b4fc1a460f3017e958e6a8ea560ea0afd91bf6fe
instruction set description and differences vs classic BPF:
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/networking/filter.txt
Short summary of instruction set:
- 64-bit registers
R0 - return value from in-kernel function, and exit value for BPF program
R1 - R5 - arguments from BPF program to in-kernel function
R6 - R9 - callee saved registers that in-kernel function will preserve
R10 - read-only frame pointer to access stack
- two-operand instructions like +, -, *, mov, load/store
- implicit prologue/epilogue (invisible stack pointer)
- no floating point, no simd
Short history of extended BPF in kernel:
interpreter in 3.15, x64 JIT in 3.16, arm64 JIT, verifier, bpf syscall in 3.18, more to come in the future.
It's a very small and simple backend.
There is no support for global variables, arbitrary function calls, floating point, varargs,
exceptions, indirect jumps, arbitrary pointer arithmetic, alloca, etc.
From C front-end point of view it's very restricted. It's done on purpose, since kernel
rejects all programs that it cannot prove safe. It rejects programs with loops
and with memory accesses via arbitrary pointers. When kernel accepts the program it is
guaranteed that program will terminate and will not crash the kernel.
This patch implements all 'must have' bits. There are several things on TODO list,
so this is not the end of development.
Most of the code is a boiler plate code, copy-pasted from other backends.
Only odd things are lack or < and <= instructions, specialized load_byte intrinsics
and 'compare and goto' as single instruction.
Current instruction set is fixed, but more instructions can be added in the future.
Signed-off-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Subscribers: majnemer, chandlerc, echristo, joerg, pete, rengolin, kristof.beyls, arsenm, t.p.northover, tstellarAMD, aemerson, llvm-commits
Differential Revision: http://reviews.llvm.org/D6494
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manager to support the actual uses of it. =]
When I ported instcombine to the new pass manager I discover that it
didn't work because TLI wasn't available in the right places. This is
a somewhat surprising and/or subtle aspect of the new pass manager
design that came up before but I think is useful to be reminded of:
While the new pass manager *allows* a function pass to query a module
analysis, it requires that the module analysis is already run and cached
prior to the function pass manager starting up, possibly with
a 'require<foo>' style utility in the pass pipeline. This is an
intentional hurdle because using a module analysis from a function pass
*requires* that the module analysis is run prior to entering the
function pass manager. Otherwise the other functions in the module could
be in who-knows-what state, etc.
A somewhat surprising consequence of this design decision (at least to
me) is that you have to design a function pass that leverages
a module analysis to do so as an optional feature. Even if that means
your function pass does no work in the absence of the module analysis,
you have to handle that possibility and remain conservatively correct.
This is a natural consequence of things being able to invalidate the
module analysis and us being unable to re-run it. And it's a generally
good thing because it lets us reorder passes arbitrarily without
breaking correctness, etc.
This ends up causing problems in one case. What if we have a module
analysis that is *definitionally* impossible to invalidate. In the
places this might come up, the analysis is usually also definitionally
trivial to run even while other transformation passes run on the module,
regardless of the state of anything. And so, it follows that it is
natural to have a hard requirement on such analyses from a function
pass.
It turns out, that TargetLibraryInfo is just such an analysis, and
InstCombine has a hard requirement on it.
The approach I've taken here is to produce an analysis that models this
flexibility by making it both a module and a function analysis. This
exposes the fact that it is in fact safe to compute at any point. We can
even make it a valid CGSCC analysis at some point if that is useful.
However, we don't want to have a copy of the actual target library info
state for each function! This state is specific to the triple. The
somewhat direct and blunt approach here is to turn TLI into a pimpl,
with the state and mutators in the implementation class and the query
routines primarily in the wrapper. Then the analysis can lazily
construct and cache the implementations, keyed on the triple, and
on-demand produce wrappers of them for each function.
One minor annoyance is that we will end up with a wrapper for each
function in the module. While this is a bit wasteful (one pointer per
function) it seems tolerable. And it has the advantage of ensuring that
we pay the absolute minimum synchronization cost to access this
information should we end up with a nice parallel function pass manager
in the future. We could look into trying to mark when analysis results
are especially cheap to recompute and more eagerly GC-ing the cached
results, or we could look at supporting a variant of analyses whose
results are specifically *not* cached and expected to just be used and
discarded by the consumer. Either way, these seem like incremental
enhancements that should happen when we start profiling the memory and
CPU usage of the new pass manager and not before.
The other minor annoyance is that if we end up using the TLI in both
a module pass and a function pass, those will be produced by two
separate analyses, and thus will point to separate copies of the
implementation state. While a minor issue, I dislike this and would like
to find a way to cleanly allow a single analysis instance to be used
across multiple IR unit managers. But I don't have a good solution to
this today, and I don't want to hold up all of the work waiting to come
up with one. This too seems like a reasonable thing to incrementally
improve later.
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This makes it possible to move between SmallVectors of different sizes.
Thanks to Dave Blaikie and Duncan Smith for patch feedback.
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There is no reason for this state to be exposed as public. The single element
constructor was superfulous in light of the single element ArrayRef
constructor.
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utils/sort_includes.py.
I clearly haven't done this in a while, so more changed than usual. This
even uncovered a missing include from the InstrProf library that I've
added. No functionality changed here, just mechanical cleanup of the
include order.
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This default constructor is a bit weird. It left the range in an invalid
state. That might be reasonable so that you can construct a local
iterator range and assign to it based on some logic to compute the range
you want. If folks would like to support that use case, I can add it
back, but in 238-odd usages none have actually wanted to do this. ;]
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r221973 changed SmallVector::operator[] to use size_t instead of unsigned.
Before that, on 64bit platforms, when a large index (say -1) was passed,
truncating it to unsigned avoided an overflow when computing 'begin() + idx',
and failed the range checking assertion, as expected.
With r221973, idx isn't truncated, so the addition wraps to
'(char*)begin() - 1', and doesn't fire anymore when it should have done so.
This commit changes the comparison to instead compute 'end() - begin()'
(i.e., 'size()'), which avoids potentially overflowing additions, and
correctly triggers the assertion when values such as -1 are passed.
Note that the problem already existed before that revision, on platforms
where sizeof(size_t) == sizeof(unsigned).
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