The problem here is the infamous one direction known safe. I was
hesitant to turn it off before b/c of the potential for regressions
without an actual bug from users hitting the problem. This is that bug ;
).
The main performance impact of having known safe in both directions is
that often times it is very difficult to find two releases without a use
in-between them since we are so conservative with determining potential
uses. The one direction known safe gets around that problem by taking
advantage of many situations where we have two retains in a row,
allowing us to avoid that problem. That being said, the one direction
known safe is unsafe. Consider the following situation:
retain(x)
retain(x)
call(x)
call(x)
release(x)
Then we know the following about the reference count of x:
// rc(x) == N (for some N).
retain(x)
// rc(x) == N+1
retain(x)
// rc(x) == N+2
call A(x)
call B(x)
// rc(x) >= 1 (since we can not release a deallocated pointer).
release(x)
// rc(x) >= 0
That is all the information that we can know statically. That means that
we know that A(x), B(x) together can release (x) at most N+1 times. Lets
say that we remove the inner retain, release pair.
// rc(x) == N (for some N).
retain(x)
// rc(x) == N+1
call A(x)
call B(x)
// rc(x) >= 1
release(x)
// rc(x) >= 0
We knew before that A(x), B(x) could release x up to N+1 times meaning
that rc(x) may be zero at the release(x). That is not safe. On the other
hand, consider the following situation where we have a must use of
release(x) that x must be kept alive for after the release(x)**. Then we
know that:
// rc(x) == N (for some N).
retain(x)
// rc(x) == N+1
retain(x)
// rc(x) == N+2
call A(x)
call B(x)
// rc(x) >= 2 (since we know that we are going to release x and that that release can not be the last use of x).
release(x)
// rc(x) >= 1 (since we can not deallocate the pointer since we have a must use after x).
…
// rc(x) >= 1
use(x)
Thus we know that statically the calls to A(x), B(x) can together only
release rc(x) N times. Thus if we remove the inner retain, release pair:
// rc(x) == N (for some N).
retain(x)
// rc(x) == N+1
call A(x)
call B(x)
// rc(x) >= 1
…
// rc(x) >= 1
use(x)
We are still safe unless in the final … there are unbalanced retains,
releases which would have caused the program to blow up anyways even
before optimization occurred. The simplest form of must use is an
additional release that has not been paired up with any retain (if we
had paired the release with a retain and removed it we would not have
the additional use). This fits nicely into the ARC framework since
basically what you do is say that given any nested releases regardless
of what is in between, the inner release is known safe. This enables us to get
back the lost performance.
<rdar://problem/19023795>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232351 91177308-0d34-0410-b5e6-96231b3b80d8
This will be tested in the next commit (which required it). The commit
is going to update a bunch of tests at the same time.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232350 91177308-0d34-0410-b5e6-96231b3b80d8
This code was casting regions of a memory buffer to a couple of
different structs. This is wrong in a few ways:
1. It breaks aliasing rules.
2. If the buffer isn't aligned, it hits undefined behaviour.
3. It completely ignores endianness differences.
4. The structs being defined for this aren't specifying their padding
properly, so this doesn't even represent the data properly on some
platforms.
This commit is mostly NFC, except that it fixes reading coverage for
32 bit binaries as a side effect of getting rid of the mispadded
structs. I've included a test for that.
I've also baked in that we only handle little endian more explicitly,
since that was true in practice already. I'll fix this to handle
endianness properly in a followup commit.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232346 91177308-0d34-0410-b5e6-96231b3b80d8
No need to emit a DW_LNS_advance_pc with a 0 increment. Found out while
comparing dsymutil's and LLVM's line table encoding. Not a correctenss
fix, just a small encoding size optimization.
I'm not sure how to generate a sequence that triggers this, and moreover
llvm-dwardump doesn't dump the line table program, thus the effort
involved in creating a testcase for this trivial patch seemed out of
proportion.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232332 91177308-0d34-0410-b5e6-96231b3b80d8
Use an overload instead of a default argument for `Metadata::dump()`.
The latter seems to require calling `dump(nullptr)` explicitly when
using a debugger, where as the former doesn't.
Other than utility for debugging, there's NFC here.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232315 91177308-0d34-0410-b5e6-96231b3b80d8
Change accessors to downcast to `MDLocalVariable` and `MDExpression`,
now that we have -verify checks in place to confirm that it's safe.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232299 91177308-0d34-0410-b5e6-96231b3b80d8
Verify that debug info intrinsic arguments are valid. (These checks
will not recurse through the full debug info graph, so they don't need
to be cordoned of in `DebugInfoVerifier`.)
With those checks in place, changing the `DbgIntrinsicInst` accessors to
downcast to `MDLocalVariable` and `MDExpression` is natural (added isa
specializations in `Metadata.h` to support this).
Added tests to `test/Verifier` for the new -verify checks, and fixed the
debug info in all the in-tree tests.
If you have out-of-tree testcases that have started to fail to -verify,
hopefully the verify checks are helpful. The most likely problem is
that the expression argument is `!{}` (instead of `!MDExpression()`).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232296 91177308-0d34-0410-b5e6-96231b3b80d8
This is already assumed to be non-null above due to a dyn_cast<>. Also
remove extraneous braces around statement.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232292 91177308-0d34-0410-b5e6-96231b3b80d8
Summary: This is a first step toward getting proper support for aggregate loads and stores.
Test Plan: Added unittests
Reviewers: reames, chandlerc
Reviewed By: chandlerc
Subscribers: majnemer, joker.eph, chandlerc, llvm-commits
Differential Revision: http://reviews.llvm.org/D7780
Patch by Amaury Sechet
From: Mehdi Amini <mehdi.amini@apple.com>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232284 91177308-0d34-0410-b5e6-96231b3b80d8
This involved threading the type-to-gep through a data structure, since
the code was relying on the pointer type to carry this information. I
imagine there will be a lot of this work across the project... slow
work chasing each use case, but the assertions will help keep me honest.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232277 91177308-0d34-0410-b5e6-96231b3b80d8
Replumb the `AsmWriter` so that `Metadata::print()` is generally useful.
(Similarly change `Metadata::printAsOperand()`.)
- `SlotTracker` now has a mode where all metadata will be correctly
numbered when initializing a `Module`. Normally, `Metadata` only
referenced from within `Function`s gets numbered when the `Function`
is incorporated.
- `Metadata::print()` and `Metadata::printAsOperand()` (and
`Metadata::dump()`) now take an optional `Module` argument. When
provided, `SlotTracker` is initialized with the new mode, and the
numbering will be complete and consistent for all calls to `print()`.
- `Value::print()` uses the new `SlotTracker` mode when printing
intrinsics with `MDNode` operands, `MetadataAsValue` operands, or the
bodies of functions. Thus, metadata numbering will be consistent
between calls to `Metadata::print()` and `Value::print()`.
- `Metadata::print()` (and `Metadata::dump()`) now print the full
definition of `MDNode`s:
!5 = !{!6, !"abc", !7}
This matches behaviour for `Value::print()`, which includes the name
of instructions.
- Updated call sites in `Verifier` to call `print()` instead of
`printAsOperand()`.
All this, so that `Verifier` can print out useful failure messages that
involve `Metadata` for PR22777.
Note that `Metadata::printAsOperand()` previously took an optional
`bool` and `Module` operand. The former was cargo-culted from
`Value::printAsOperand()` and wasn't doing anything useful. The latter
didn't give consistent results (without the new `SlotTracker` mode).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232275 91177308-0d34-0410-b5e6-96231b3b80d8
Adding nullptr to all the IRBuilder stuff because it's the first thing
that fails to build when testing without the back-compat functions, so
I'll keep having to re-add these locally for each chunk of migration I
do. Might as well check them in to save me the churn. Eventually I'll
have to migrate these too, but I'm going breadth-first.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232270 91177308-0d34-0410-b5e6-96231b3b80d8
Given that the stated purpose of `CheckFailed()` is to provide a nice
spot for a breakpoint, it'd be nice not to have to use a regex to break
on it. Recover the ability to simply use `b CheckFailed` by
specializing the message-only version, and by changing the variadic
version to call into the message-only version.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232268 91177308-0d34-0410-b5e6-96231b3b80d8
Specifically, if there are copy-like instructions in the loop header
they are moved into the loop close to their uses. This reduces the live
intervals of the values and can avoid register spills.
This is working towards a fix for http://llvm.org/PR22230.
Review: http://reviews.llvm.org/D7259
Next steps:
- Find a better cost model (which non-copy instructions should be sunk?)
- Make this dependent on register pressure
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232262 91177308-0d34-0410-b5e6-96231b3b80d8
I'm just going to migrate these in a pretty ad-hoc & incremental way -
providing the backwards compatible API for now, then locally removing
it, fixing a few callers, adding it back in and commiting those callers.
Rinse, repeat.
The assertions should ensure that if I get this wrong we'll find out
about it and not just have one giant patch to revert, recommit, revert,
recommit, etc.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232240 91177308-0d34-0410-b5e6-96231b3b80d8
Also replace an old use of qsort with it. Compiles down to the same thing but
gives us some type safety. Safes a couple of kb on CommandLine.o.
NFC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232236 91177308-0d34-0410-b5e6-96231b3b80d8
The linker on that platform may re-order symbols or strip dead symbols, which
will break bit set checks. Avoid this by hiding the symbols from the linker.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232235 91177308-0d34-0410-b5e6-96231b3b80d8
This fixes pr22854.
The core issue on the bug is that there are multiple instructions that
print the same in assembly. In fact, there doesn't seem to be any
syntax for specifying that a constant that fits in 8 bits should use a 32 bit
immediate.
The attached patch changes fast isel to consider i16immSExt8,
i32immSExt8, and i64immSExt8. They were disabled because fastisel didn’t know
to call the predicate back in the day.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232223 91177308-0d34-0410-b5e6-96231b3b80d8
This speeds up llvm-ar building lib64/libclangSema.a with debug IR files
from 8.658015807 seconds to just 0.351036519 seconds :-)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232221 91177308-0d34-0410-b5e6-96231b3b80d8
This happened to be fairly easy to support backwards compatibility based
on the number of operands (old format had an even number, new format has
one more operand so an odd number).
test/Bitcode/old-aliases.ll already appears to test old gep operators
(if I remove the backwards compatibility in the BitcodeReader, this and
another test fail) so I'm not adding extra test coverage here.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232216 91177308-0d34-0410-b5e6-96231b3b80d8
I don't think we test invalid bitcode records in any detail, so no test
here - just a change for consistency with existing error checks in
surrounding code.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232215 91177308-0d34-0410-b5e6-96231b3b80d8
This reapplies the patch previously committed at revision 232190. This was
reverted at revision 232196 as it caused test failures in tests that did not
expect operands to be commuted. I have made the tests more resilient to
reassociation in revision 232206.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232209 91177308-0d34-0410-b5e6-96231b3b80d8
fix missed bits which were left over after r231987
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232208 91177308-0d34-0410-b5e6-96231b3b80d8
As a follow-up to r232200, add an `-instcombine` to canonicalize scalar
allocations to `i32 1`. Since r232200, `iX 1` (for X != 32) are only
created by RAUWs, so this shouldn't fire too often. Nevertheless, it's
a cheap check and a nice cleanup.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232202 91177308-0d34-0410-b5e6-96231b3b80d8
Move type promotion of the size of the array allocation to the end of
`simplifyAllocaArraySize()`. This avoids promoting the type of the
array size if it's a `ConstantInt`, since the next -instcombine
iteration will drop it to a scalar allocation anyway. Similarly, this
avoids promoting the type if it's an `UndefValue`, in which case the
alloca gets RAUW'ed.
This is NFC when considered over the lifetime of -instcombine, since
it's just reducing the number of iterations needed to reach fixed point.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232201 91177308-0d34-0410-b5e6-96231b3b80d8
Write the `alloca` array size explicitly when it's non-canonical.
Previously, if the array size was `iX 1` (where X is not 32), the type
would mutate to `i32` when round-tripping through assembly.
The testcase I added fails in `verify-uselistorder` (as well as
`FileCheck`), since the use-lists for `i32 1` and `i64 1` change.
(Manman Ren came across this when running `verify-uselistorder` on some
non-trivial, optimized code as part of PR5680.)
The type mutation started with r104911, which allowed array sizes to be
something other than an `i32`. Starting with r204945, we
"canonicalized" to `i64` on 64-bit platforms -- and then on every
round-trip through assembly, mutated back to `i32`.
I bundled a fixup for `-instcombine` to avoid r204945 on scalar
allocations. (There wasn't a clean way to sequence this into two
commits, since the assembly change on its own caused testcase churn, and
the `-instcombine` change can't be tested without the assembly changes.)
An obvious alternative fix -- change `AllocaInst::AllocaInst()`,
`AsmWriter` and `LLParser` to treat `intptr_t` as the canonical type for
scalar allocations -- was rejected out of hand, since this required
teaching them each about the data layout.
A follow-up commit will add an `-instcombine` to canonicalize the scalar
allocation array size to `i32 1` rather than leaving `iX 1` alone.
rdar://problem/20075773
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232200 91177308-0d34-0410-b5e6-96231b3b80d8
