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We just replaced SmallSet<T *, N> with SmallPtrSet<T *, N>, bypassing
the redirection found in SmallSet.h. With that, we no longer need to
include SmallSet.h in many files.
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If FunctionAttrs infers additional attributes on a function, it also
invalidates analysis on callers of that function. The way it does this
right now limits this to calls with matching signature. However, the
function attributes will also be used when the signatures do not match.
Use getCalledOperand() to avoid a signature check.
This is not a correctness fix, just improves analysis quality. I noticed
this due to
https://github.com/llvm/llvm-project/pull/144497#issuecomment-3199330709,
where LICM ends up with a stale MemoryDef that could be a MemoryUse
(which is a bug in LICM, but still non-optimal).
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This patch replaces SmallSet<T *, N> with SmallPtrSet<T *, N>. Note
that SmallSet.h "redirects" SmallSet to SmallPtrSet for pointer
element types:
template <typename PointeeType, unsigned N>
class SmallSet<PointeeType*, N> : public SmallPtrSet<PointeeType*, N>
{};
We only have 140 instances that rely on this "redirection", with the
vast majority of them under llvm/. Since relying on the redirection
doesn't improve readability, this patch replaces SmallSet with
SmallPtrSet for pointer element types.
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When inferring attributes, we should not bail out early on unknown calls
(such as virtual calls), as we may still have call-site attributes that
can be used for inference.
Fixes https://github.com/llvm/llvm-project/issues/150817.
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inference (#145739)
Avoid constructing invalid ConstantRange when Offset + Length in memset
overflows signed 64-bit integer space. This prevents assertion failures
when inferring the initializes attribute.
Fixes #140345
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(#138535)
For the purpose of inferring readonly/writeonly/readnone on arguments,
we only care about provenance captures, not address captures.
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Otherwise the range doesn't make sense since we interpret it as signed.
Fixes #134115
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This is a fairly light-weight traversal and is needed in instrumentation. No need to run the whole `FunctionAttrs` pass at this stage. To avoid layering issues, this patch factors `canRun` and related under Analysis/CFG.
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We can use *Set::insert_range to collapse:
for (auto Elem : Range)
Set.insert(E);
down to:
Set.insert_range(Range);
In some cases, we can further fold that into the set declaration.
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Matching the CaptureTracking change in abd97d9685c07c4787ff22e56c0a7b8963630063,
only directly infer captures(none) for
readonly+nocapture+willreturn+void.
Part of https://github.com/llvm/llvm-project/issues/129090.
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(#125880) (#128020)
Relative to the previous attempt this includes two fixes:
* Adjust callCapturesBefore() to not skip captures(ret: address,
provenance) arguments, as these will not count as a capture
at the call-site.
* When visiting uses during stack slot optimization, don't skip
the ModRef check for passthru captures. Calls can both modref
and be passthru for captures.
------
This extends CaptureTracking to support inferring non-trivial
CaptureInfos. The focus of this patch is to only support FunctionAttrs,
other users of CaptureTracking will be updated in followups.
The key API changes here are:
* DetermineUseCaptureKind() now returns a UseCaptureInfo where the UseCC
component specifies what is captured at that Use and the ResultCC
component specifies what may be captured via the return value of the
User. Usually only one or the other will be used (corresponding to
previous MAY_CAPTURE or PASSTHROUGH results), but both may be set for
call captures.
* The CaptureTracking::captures() extension point is passed this
UseCaptureInfo as well and then can decide what to do with it by
returning an Action, which is one of: Stop: stop traversal.
ContinueIgnoringReturn: continue traversal but don't follow the
instruction return value. Continue: continue traversal and follow the
instruction return value if it has additional CaptureComponents.
For now, this patch retains the (unsound) special logic for comparison
of null with a dereferenceable pointer. I'd like to switch key code to
take advantage of address/address_is_null before dropping it.
This PR mainly intends to introduce necessary API changes and basic
inference support, there are various possible improvements marked with
TODOs.
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The implementation doesn't use it, and is unlikely to use it in
the future.
The places that do set StoreCaptures=false, do so incorrectly and
would be broken if the parameter actually did anything.
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(#125880)"
This reverts commit 0fab404ee874bc5b0c442d1841c7d2005c3f8729.
Seems to break LTO builds of clang on Windows, see comments on
https://github.com/llvm/llvm-project/pull/125880
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Relative to the previous attempt, this adjusts isEscapeSource()
to not treat calls with captures(ret: address, provenance) or similar
arguments as escape sources. This addresses the miscompile reported at:
https://github.com/llvm/llvm-project/pull/125880#issuecomment-2656632577
The implementation uses a helper function on CallBase to make this
check a bit more efficient (e.g. by skipping the byval checks) as
checking attributes on all arguments if fairly expensive.
------
This extends CaptureTracking to support inferring non-trivial
CaptureInfos. The focus of this patch is to only support FunctionAttrs,
other users of CaptureTracking will be updated in followups.
The key API changes here are:
* DetermineUseCaptureKind() now returns a UseCaptureInfo where the UseCC
component specifies what is captured at that Use and the ResultCC
component specifies what may be captured via the return value of the
User. Usually only one or the other will be used (corresponding to
previous MAY_CAPTURE or PASSTHROUGH results), but both may be set for
call captures.
* The CaptureTracking::captures() extension point is passed this
UseCaptureInfo as well and then can decide what to do with it by
returning an Action, which is one of: Stop: stop traversal.
ContinueIgnoringReturn: continue traversal but don't follow the
instruction return value. Continue: continue traversal and follow the
instruction return value if it has additional CaptureComponents.
For now, this patch retains the (unsound) special logic for comparison
of null with a dereferenceable pointer. I'd like to switch key code to
take advantage of address/address_is_null before dropping it.
This PR mainly intends to introduce necessary API changes and basic
inference support, there are various possible improvements marked with
TODOs.
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This reverts commit ee655ca27aad466bcc54f6eba03f7e564940ad5a.
A miscompilation has been reported at:
https://github.com/llvm/llvm-project/pull/125880#issuecomment-2656632577
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Model C/C++ `errno` macro by adding a corresponding `errno`
memory location kind to the IR. Preliminary work to separate
`errno` writes from other memory accesses, to the benefit of
alias analyses and optimization correctness.
Previous discussion: https://discourse.llvm.org/t/rfc-modelling-errno-memory-effects/82972.
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This extends CaptureTracking to support inferring non-trivial
CaptureInfos. The focus of this patch is to only support FunctionAttrs,
other users of CaptureTracking will be updated in followups.
The key API changes here are:
* DetermineUseCaptureKind() now returns a UseCaptureInfo where the UseCC
component specifies what is captured at that Use and the ResultCC
component specifies what may be captured via the return value of the
User. Usually only one or the other will be used (corresponding to
previous MAY_CAPTURE or PASSTHROUGH results), but both may be set for
call captures.
* The CaptureTracking::captures() extension point is passed this
UseCaptureInfo as well and then can decide what to do with it by
returning an Action, which is one of: Stop: stop traversal.
ContinueIgnoringReturn: continue traversal but don't follow the
instruction return value. Continue: continue traversal and follow the
instruction return value if it has additional CaptureComponents.
For now, this patch retains the (unsound) special logic for comparison
of null with a dereferenceable pointer. I'd like to switch key code to
take advantage of address/address_is_null before dropping it.
This PR mainly intends to introduce necessary API changes and basic
inference support, there are various possible improvements marked with
TODOs.
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An argument graph node without uses forms a trivial SCC, which will
already be handled by the preceding branch.
If a node in the SCC points to a node with empty uses, then it will
be part of a different SCC, and as such assumed to be capturing
if it does not have an attribute. There is no need to handle them
separately.
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This PR removes the old `nocapture` attribute, replacing it with the new
`captures` attribute introduced in #116990. This change is
intended to be essentially NFC, replacing existing uses of `nocapture`
with `captures(none)` without adding any new analysis capabilities.
Making use of non-`none` values is left for a followup.
Some notes:
* `nocapture` will be upgraded to `captures(none)` by the bitcode
reader.
* `nocapture` will also be upgraded by the textual IR reader. This is to
make it easier to use old IR files and somewhat reduce the test churn in
this PR.
* Helper APIs like `doesNotCapture()` will check for `captures(none)`.
* MLIR import will convert `captures(none)` into an `llvm.nocapture`
attribute. The representation in the LLVM IR dialect should be updated
separately.
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ConstantRange's constructor asserts that the range not empty, except if
lower/upper are min or max values.
Check if the length is strictly positive instead of just non-negative so
std::nullopt is returned when the size is 0. If that's the case, the
access doesn't initialize anything.
This should fix a crash when building on macOS with ASan & UBsan after
https://github.com/llvm/llvm-project/pull/97373 /
https://github.com/llvm/llvm-project/pull/117104 landed:
https://green.lab.llvm.org/job/llvm.org/job/clang-stage2-cmake-RgSan/664/console
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To be conservative, explicitly exclude byval arguments, which
doesNotCapture() would otherwise allow. Even if byval has an
initializes attribute, it would only apply to the implicit
copy.
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Since byval arguments are passed via a hidden copy of the pointee, they
do not have the same semantics as normal pointer arguments. The callee
cannot capture or write to the pointer and the copy is a read of the
pointer.
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Bail out negative length while inferring initializes attr. Otherwise it
causes an assertion error:
`Attribute 'initializes' does not support unordered ranges`
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reland https://github.com/llvm/llvm-project/pull/97373 after fixing
clang tests.
Confirmed with "ninja check-llvm" and "ninja check-clang"
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This reverts commit 661c593850715881d2805a59e90e6d87d8b9fbb8.
Multiple buildbot failures, e.g. https://lab.llvm.org/buildbot/#/builders/108/builds/6096
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Add the "initializes" attribute inference.
This change is expected to have ~0.09% compile time regression, which
seems acceptable for interprocedural DSE.
https://llvm-compile-time-tracker.com/compare.php?from=9f10252c4ad7cffbbcf692fa9c953698f82ac4f5&to=56345c1cee4375eb5c28b8e7abf4803d20216b3b&stat=instructions%3Au
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Recursion here causes stack overflow on large inputs. Fixing by
unrolling via a stack.
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call a `cold` function"
Fixed up the uar test that was failing. It seems with the new `cold`
attribute the order of the functions is different. As far as I can
tell this is not a concern.
Closes #105559
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a `cold` function"
This reverts commit b7eac8c6fea1ba3930d08011a0e5e3a262bfaece.
Causing a test failure. Not 100% sure the issue so to reverting to
unblock pipeline.
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`cold` function
Closes #101298
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`getUnderlyingObjectAggressive` (#100102)"
Added handling for `AllocaInst`.
This reverts commit 1ee686a55aa6365eff39bbd1dc2059b16be6c2f1.
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`getUnderlyingObjectAggressive` (#100102)"
This reverts commit a213edd32abff8d154dad96824689b98ec7b5a35.
Assertion failures on buildbots.
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`getUnderlyingObjectAggressive` (#100102)
Thanks to #99509, we can fix
https://github.com/rust-lang/rust/issues/119573 too.
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Similar to https://github.com/llvm/llvm-project/pull/96902, this adds
`getDataLayout()` helpers to Function and GlobalValue, replacing the
current `getParent()->getDataLayout()` pattern.
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For inbounds GEPs, if the source pointer is non-null, the result must
also be non-null. However, this does not hold for non-inbounds GEPs.
Fixes https://github.com/llvm/llvm-project/issues/91177.
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Currently, when inferring noundef, we only check that the return value
is not undef/poison. However, we fail to account for the possibility
that a poison-generating return attribute will convert the value to
poison, and then violate the noundef attribute, resulting in immediate
UB.
For the relevant return attributes (align, nonnull and range), check
whether we can trivially re-prove the relevant property, otherwise do
not infer noundef.
This fixes the FunctionAttrs side of
https://github.com/llvm/llvm-project/issues/88026.
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Prior to #85863, the required parameters of llvm::isKnownNonZero were
Value and DataLayout. After, they are Value, Depth, and SimplifyQuery,
where SimplifyQuery is implicitly constructible from DataLayout. The
change to move Depth before SimplifyQuery needed callers to be updated
unnecessarily, and as commented in #85863, we actually want Depth to be
after SimplifyQuery anyway so that it can be defaulted and the caller
does not need to specify it.
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This patch converts `isKnownNonZero` to use SimplifyQuery. Then we can
use the context information from `DomCondCache`.
Fixes https://github.com/llvm/llvm-project/issues/85823.
Alive2: https://alive2.llvm.org/ce/z/QUvHVj
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attribute (#76691)
MemorySanitizer assumes that the definition and declaration of a
function will be consistent. If we add `noundef` for some definitions,
it will break msan.
Fix buildbot failure caused by #76553.
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This patch deduces `noundef` attributes for return values.
IIUC, a function returns `noundef` values iff all of its return values
are guaranteed not to be `undef` or `poison`.
Definition of `noundef` from LangRef:
```
noundef
This attribute applies to parameters and return values. If the value representation contains any
undefined or poison bits, the behavior is undefined. Note that this does not refer to padding
introduced by the type’s storage representation.
```
Alive2: https://alive2.llvm.org/ce/z/g8Eis6
Compile-time impact: http://llvm-compile-time-tracker.com/compare.php?from=30dcc33c4ea3ab50397a7adbe85fe977d4a400bd&to=c5e8738d4bfbf1e97e3f455fded90b791f223d74&stat=instructions:u
|stage1-O3|stage1-ReleaseThinLTO|stage1-ReleaseLTO-g|stage1-O0-g|stage2-O3|stage2-O0-g|stage2-clang|
|--|--|--|--|--|--|--|
|+0.01%|+0.01%|-0.01%|+0.01%|+0.03%|-0.04%|+0.01%|
The motivation of this patch is to reduce the number of `freeze` insts
and enable more optimizations.
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(#76372)
This patch adds missing `norecurse` attrs to funcs that only call intrinsics with `nocallback` attrs.
Fixes the regression found in https://github.com/dtcxzyw/llvm-opt-benchmark/pull/45#discussion_r1436148743.
The function loses `norecurse` attr because it calls `@llvm.fabs.f64`, which is not marked as `norecurse`.
Since `norecurse` is not a default attribute of intrinsics and it is
ambiguous for intrinsics, I decided to use the existing `callback`
attributes.
> nocallback
This attribute indicates that the function is only allowed to jump back
into caller’s module by a return or an exception, and is not allowed to
jump back by invoking a callback function, a direct, possibly
transitive, external function call, use of longjmp, or other means. It
is a compiler hint that is used at module level to improve dataflow
analysis, dropped during linking, and has no effect on functions defined
in the current module.
See also https://llvm.org/docs/LangRef.html#function-attributes.
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This adds a writable attribute, which in conjunction with
dereferenceable(N) states that a spurious store of N bytes is
introduced on function entry. This implies that this many bytes
are writable without trapping or introducing data races. See
https://llvm.org/docs/Atomics.html#optimization-outside-atomic for
why the second point is important.
This attribute can be added to sret arguments. I believe Rust will
also be able to use it for by-value (moved) arguments. Rust likely
won't be able to use it for &mut arguments (tree borrows does not
appear to allow spurious stores).
In this patch the new attribute is only used by LICM scalar promotion.
However, the actual motivation for this is to fix a correctness issue
in call slot optimization, which needs this attribute to avoid
optimization regressions.
Followup to the discussion on D157499.
Differential Revision: https://reviews.llvm.org/D158081
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Fixes #68270
The function attribute analysis handles many instructions, like
addrspacecast, which do not themselves read or write memory but which
transform pointers into other values in the same alias set.
There are intrinsic functions, such as ptrmask or the AMDGPU-specific
make.buffer.rsrc, which also preserve membership in alias sets without
capturing. This commit adds the addrspacecast-like behavior to these
calls.
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When inferring readonly/writeonly on arguments, if the argument is
passed to a call, we should only check the ArgMem effects implied by the
call -- we don't care whether the call reads/writes non-arg memory
(captured pointers are not relevant here, because they will abort the
analysis entirely).
This also fixes a regression that was introduced when moving to
MemoryEffects: The code was still checking the old WriteOnly attribute
on functions, which no longer exists.
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When inspecting the function body, we can't simply ignore effects
of functions in the SCC entirely, because an argmem access of a
recursive call might result in an access to another location in
the callee.
Fix this by separately tracking memory effects that would occur if
the SCC accesses argmem, and then later add those.
Fixes https://github.com/llvm/llvm-project/issues/63936.
Differential Revision: https://reviews.llvm.org/D155956
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