isImpliedCondition() currently handles and/or on the LHS, but not
on the RHS, resulting in asymmetric behavior. This patch adds two
new implication rules:
* LHS ==> (RHS1 || RHS2) if LHS ==> RHS1 or LHS ==> RHS2
* LHS ==> !(RHS1 && RHS2) if LHS ==> !RHS1 or LHS ==> !RHS2
Differential Revision: https://reviews.llvm.org/D125551
This adds two conjugated folds:
* A | B -> B if A implies B (https://alive2.llvm.org/ce/z/R6GU4j)
* A & B -> A if A implies B (https://alive2.llvm.org/ce/z/EGMqyy)
If A and B are icmps themselves, we will usually fold this through
other logic already (though the tests show a couple additional cases
we previously missed). However, isImpliedCond() also supports A
being of the form X & Y, which allows us to handle cases like
(X & Y) | B where X implies B. This addresses the regression from
D125398.
Something that notably doesn't work yet is the (X | Y) & B case.
This is due to an asymmetry in the isImpliedCondition()
implementation that will have to be addressed separately.
Differential Revision: https://reviews.llvm.org/D125530
Most of insertelement constant folding is blocked if the vector type
is scalable. I believe we can make an exception for inserting null
into an all zeros vector.
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D123413
Currently the fsub optimizations in InstSimplify don't know how to fold
-0.0 - (-X) to X when the constrained intrinsics are used. This adds partial
support. The rest of the support will come later with work on the IR
matchers.
This review is split out from D107285.
Differential Revision: https://reviews.llvm.org/D123396
With opaque pointers, we can eliminate zero-index GEPs even if
they have multiple indices, as this no longer impacts the result
type of the GEP.
This optimization is already done for instructions in InstSimplify,
but we were missing the corresponding constant expression handling.
The constexpr transform is a bit more powerful, because it can
produce a vector splat constant and also handles undef values --
it is an extension of an existing single-index transform.
This change was previously reverted because I forgot rerunning
update_test_checks.py and tests were not actually baseline.
Extracted from: https://reviews.llvm.org/D122757
Currently some optimizations are disabled because llvm::CannotBeNegativeZero()
does not know how to deal with the constrained intrinsics. This patch fixes
that by extending the existing implementation.
Differential Revision: https://reviews.llvm.org/D121483
The change fixes treatment of constrained compare intrinsics if
compared values are of vector type.
Differential revision: https://reviews.llvm.org/D110322
In D111530, I suggested that we add some relatively basic pattern-matching
folds for shifts and funnel shifts and avoid a more specialized solution
if possible.
We can start by implementing at least one of these in IR because it's
easier to write the code and verify with Alive2:
https://alive2.llvm.org/ce/z/qHpmNn
This will need to be adapted/extended for SDAG to handle the motivating
bug ( #49541 ) because the patterns only appear later with that example
(added some tests: bb850d422b)
This can be extended within InstSimplify to handle cases where we 'and'
with a shift too (in that case, kill the funnel shift).
We could also handle patterns where the shift and funnel shift directions
are inverted, but I think it's better to canonicalize that instead to
avoid pattern-match case explosion.
Differential Revision: https://reviews.llvm.org/D120253
The code was using exact sizing only, but since what we really need is just to make sure the offsets are in bounds, a minimum bound on the object size is sufficient.
To demonstrate the difference, support computing minimum sizes from obects of scalable vector type.
Remove some code which tried to handle the case of comparing two allocas where an object size could not be precisely computed. This code had zero coverage in tree, and at least one nasty bug.
The bug comes from the fact that the code uses the size of the result pointer as a proxy for whether the alloca can be of size zero. Since the result of an alloca is *always* a pointer type, and a pointer type can *never* be empty, this check was a nop. As a result, we blindly consider a zero offset from two allocas to never be equal. They can in fact be equal when one or more of the allocas is zero sized.
This is particularly ugly because instcombine contains the exact opposite rule. If instcombine reaches the allocas first, it combines them into one (making them equal). If instsimplify reaches the compare first, it would consider them not equal. This creates all kinds of fun scenarios for order of optimization reaching different and contradictory conclusions.
Currently the fsub optimizations in InstSimplify don't know how to fold
X - -0.0 to X when we know X is not zero and the constrained intrinsics
are used. This adds the support.
This review is split out from D107285.
Differential Revision: https://reviews.llvm.org/D119746
A more general enhancement needs to add tests and make sure
that intrinsics that return structs are correct. There are also
target-specific intrinsics, and I'm not sure what behavior is
expected for those.
A more general enhancement needs to add tests and make sure
that intrinsics that return structs are correct. There are also
target-specific intrinsics, and I'm not sure what behavior is
expected for those.
Currently the fsub optimizations in InstSimplify don't know how to fold X
- +0.0 to X when using the constrained intrinsics. This adds the support.
This review is split out from D107285.
Differential Revision: https://reviews.llvm.org/D118928
The change implements constant folding of ‘llvm.experimental.constrained.fcmp’
and ‘llvm.experimental.constrained.fcmps’ intrinsics.
Differential Revision: https://reviews.llvm.org/D110322
With opaque pointers, it's possible to directly call a function with
a different signature, without an intermediate bitcast. However,
lot's of code using getCalledFunction() reasonably assumes that the
signatures match (which is always true without opaque pointers).
Add an explicit check to that effect.
The test case is from D105313, where I ran into the problem, but on
further investigation this also affects lots of other code, we just
have little coverage with mismatching signatures. The change from
D105313 is still desirable for other reasons, but this patch
addresses the root problem when it comes to opaque pointers.
Differential Revision: https://reviews.llvm.org/D105733
Use the new PM syntax when specifying the pipeline in regression
tests previously running
"opt -newgvn ..."
Instead we now do
"opt -passes=newgvn ..."
Notice that this also changes the aa-pipeline to become the default
aa-pipeline instead of just basic-aa. Since these tests haven't been
explicitly requesting basic-aa in the past (compared to the test cases
updated in a separate patch involving "-basic-aa -newgvn") it is
assumed that the exact aa-pipeline isn't important for the validity
of the test cases. An alternative could have been to add
-aa-pipeline=basic-aa as well to the run lines, but that might just
add clutter in case the test cases do not care about the aa-pipeline.
This is another step to move away from the legacy PM syntax when
specifying passes in opt.
Differential Revision: https://reviews.llvm.org/D118341
The behavior in Analysis (knownbits) implements poison semantics already,
and we expect the transforms (for example, in instcombine) derived from
those semantics, so this patch changes the LangRef and remaining code to
be consistent. This is one more step in removing "undef" from LLVM.
Without this, I think https://github.com/llvm/llvm-project/issues/53330
has a legitimate complaint because that report wants to allow subsequent
code to mask off bits, and that is allowed with undef values. The clang
builtins are not actually documented anywhere AFAICT, but we might want
to add that to remove more uncertainty.
Differential Revision: https://reviews.llvm.org/D117912
Peculiarly, the necessary code to handle pointers (including the
check for non-integral address spaces) is already in place,
because we were already allowing vectors of pointers here, just
not plain pointers.
The reinterpret load code will convert undef values into zero.
Check the uniform value case before it to produce a better result
for all-undef initializers.
However, the uniform value handling will return the uniform value
even if the access is out of bounds, while the reinterpret load
code will return undef. Add an explicit check to retain the
previous result in this case.
We could use knownbits on both operands for even more folds (and there are
already tests in place for that), but this is enough to recover the example
from:
https://github.com/llvm/llvm-project/issues/51934
(the tests are derived from the code in that example)
I am assuming no noticeable compile-time impact from this because udiv/urem
are rare opcodes.
Differential Revision: https://reviews.llvm.org/D116616
