Fixes#133344
Proof: https://alive2.llvm.org/ce/z/X3Uh23
InstCombine couldn't optimize `i1` because `canonicalizeICmpBool()` was
transforming the comparison into bitwise operations before
`foldICmpTruncWithTruncOrExt()` was called.
This PR solves the ordering issue by placing
`foldICmpTruncWithTruncOrExt()` before `canonicalizeICmpBool()`.
I believe this will not cause any regressions since all tests are
passing.
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.
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.
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.
This allows optimization of more signed floor implementations when the
divisor is a known power of two to an arithmetic shift.
Proof for the implemented optimizations:
https://alive2.llvm.org/ce/z/j6C-Nz
Proof for the test cases:
https://alive2.llvm.org/ce/z/M_PBjw
---------
Co-authored-by: Jacob Young <jacobly0@users.noreply.github.com>
If the bitwidth is 2 and we add two 1s, the result may overflow.
This is fine in terms of correctness, but triggers the APInt ctor
assertion. Fix this by performing the calculation directly on APInts.
Fixes the issue reported in:
https://github.com/llvm/llvm-project/pull/114539#issuecomment-2574845003
With the introduction of CmpPredicate in 51a895a (IR: introduce struct
with CmpInst::Predicate and samesign), PatternMatch is one of the first
key pieces of infrastructure that must be updated to match a CmpInst
respecting samesign information. Implement this change to Cmp-matchers.
This is a preparatory step in migrating the codebase over to
CmpPredicate. Since we no functional changes are desired at this stage,
we have chosen not to migrate CmpPredicate::operator==(CmpPredicate)
calls to use CmpPredicate::getMatching(), as that would have visible
impact on tests that are not yet written: instead, we call
CmpPredicate::operator==(Predicate), preserving the old behavior, while
also inserting a few FIXME comments for follow-ups.
Introduce llvm::CmpPredicate, an abstraction over a floating-point
predicate, and a pack of an integer predicate with samesign information,
in order to ease extending large portions of the codebase that take a
CmpInst::Predicate to respect the samesign flag.
We have chosen to demonstrate the utility of this new abstraction by
migrating parts of ValueTracking, InstructionSimplify, and InstCombine
from CmpInst::Predicate to llvm::CmpPredicate. There should be no
functional changes, as we don't perform any extra optimizations with
samesign in this patch, or use CmpPredicate::getMatching.
The design approach taken by this patch allows for unaudited callers of
APIs that take a llvm::CmpPredicate to silently drop the samesign
information; it does not pose a correctness issue, and allows us to
migrate the codebase piece-wise.
Unsigned icmp of gep nuw folds to unsigned icmp of offsets. Unsigned
icmp of gep nusw nuw folds to unsigned samesign icmp of offsets.
Proofs: https://alive2.llvm.org/ce/z/VEwQY8
Inside foldICmpUsingKnownBits(), instead of rolling our own logic based
on min/max values, make use of ICmpInst::compare() working on KnownBits.
This gives better results for the equality predicates. In practice, the
improvement is only for pointers, because isKnownNonEqual() handles the
non-pointer case.
I've adjusted some tests to prevent the new fold from triggering, to
retain their original intent of testing constant expressions.
We can turn:
```
%add = add i8 %arg, C1
%and = and i8 %add, C2
%cmp = icmp eq i1 %and, C3
```
into:
```
%and = and i8 %arg, C2
%cmp = icmp eq i1 %and, (C3 - C1) & C2
```
This is only worth doing if the sequence is the sole user of the addition
operation.
Rename the function to reflect its correct behavior and to be consistent
with `Module::getOrInsertFunction`. This is also in preparation of
adding a new `Intrinsic::getDeclaration` that will have behavior similar
to `Module::getFunction` (i.e, just lookup, no creation).
Extend decomposeBitTestICmp() to handle cases where the resulting
comparison is of the form `icmp (X & Mask) pred C` with non-zero
`C`. Add a flag to allow code to opt-in to this behavior and use it in
the "log op of icmp" fold infrastructure.
This addresses regressions from #97289.
Proofs: https://alive2.llvm.org/ce/z/hUhdbU
decomposeBitTestICmp() currently returns the result via two out
parameters plus an in-place modification of Pred. This changes it to
return an optional struct instead.
The motivation here is twofold. First, I'd like to extend this code to
handle cases where the comparison is against a value other than zero,
which would mean yet another out parameter. Second, while doing that I
was badly bitten by the in-place modification, so I'd like to get rid of
it.
InstCombine already has some rules for `icmp ptrtoint, ptrtoint` to drop
the casts and compare the source values. This change adds the same for
the reverse case with `inttoptr`.
The motivation of this patch is to fold more generalized patterns like
`icmp ult (shl nuw 16, X), 64 -> icmp ult X, 2`.
Alive2: https://alive2.llvm.org/ce/z/gyqjQH
