[LLVM][IR] Use splat syntax when printing Constant[Data]Vector. (#112548)

[InstCombine] Remove some of the complexity-based canonicalization (#91185)

The idea behind this canonicalization is that it allows us to handle less
patterns, because we know that some will be can

[InstCombine] Remove some of the complexity-based canonicalization (#91185)

The idea behind this canonicalization is that it allows us to handle less
patterns, because we know that some will be canonicalized away. This is
indeed very useful to e.g. know that constants are always on the right.

However, this is only useful if the canonicalization is actually
reliable. This is the case for constants, but not for arguments: Moving
these to the right makes it look like the "more complex" expression is
guaranteed to be on the left, but this is not actually the case in
practice. It fails as soon as you replace the argument with another
instruction.

The end result is that it looks like things correctly work in tests,
while they actually don't. We use the "thwart complexity-based
canonicalization" trick to handle this in tests, but it's often a
challenge for new contributors to get this right, and based on the
regressions this PR originally exposed, we clearly don't get this right
in many cases.

For this reason, I think that it's better to remove this complexity
canonicalization. It will make it much easier to write tests for
commuted cases and make sure that they are handled.

show more ...

[InstCombine] Handle commuted variants in or of xor pattern

This pattern only handled commutation in the "or", while all
involved operations are commutative. Make sure we handle all
sixteen patterns.

[InstCombine] Add proper test coverage for or of xors pattern (NFC)

Test all commuted variants of the pattern, most of which currently
fail to fold.

[InstCombine] Clean up bitwise folds without one-use check (#80587)

This patch removes some bitwise folds that fail to check the one-use
constraint on the operands.
See also the comments
https://

[InstCombine] Clean up bitwise folds without one-use check (#80587)

This patch removes some bitwise folds that fail to check the one-use
constraint on the operands.
See also the comments
https://github.com/llvm/llvm-project/pull/77231#issuecomment-1904090035.

show more ...

[InstCombine] Simplify and/or by replacing operands with constants (#77231)

This patch tries to simplify `X | Y` by replacing occurrences of `Y` in
`X` with 0. Similarly, it tries to simplify `X &

[InstCombine] Simplify and/or by replacing operands with constants (#77231)

This patch tries to simplify `X | Y` by replacing occurrences of `Y` in
`X` with 0. Similarly, it tries to simplify `X & Y` by replacing
occurrences of `Y` in `X` with -1.

Alive2: https://alive2.llvm.org/ce/z/cNjDTR
Note: As the current implementation is too conservative in the one-use
checks, I cannot remove other existing hard-coded simplifications if
they involves more than two instructions (e.g, `A & ~(A ^ B) --> A &
B`).

Compile-time impact:
http://llvm-compile-time-tracker.com/compare.php?from=a085402ef54379758e6c996dbaedfcb92ad222b5&to=9d655c6685865ffce0ad336fed81228f3071bd03&stat=instructions%3Au

|stage1-O3|stage1-ReleaseThinLTO|stage1-ReleaseLTO-g|stage1-O0-g|stage2-O3|stage2-O0-g|stage2-clang|
|--|--|--|--|--|--|--|
|+0.01%|-0.00%|+0.00%|-0.02%|+0.01%|+0.02%|-0.01%|

Fixes #76554.

show more ...

[InstSimplify] Simplify the expression `(a^c)&(a^~c)` to zero and (a^c) | (a^~c) to minus one (#76637)

Changes the InstSimplify pass of the LLVM optimizer, such that the
aforementioned expression i

[InstSimplify] Simplify the expression `(a^c)&(a^~c)` to zero and (a^c) | (a^~c) to minus one (#76637)

Changes the InstSimplify pass of the LLVM optimizer, such that the
aforementioned expression is reduced to zero if c2==~c1.
Alive2: https://alive2.llvm.org/ce/z/xkQiid
Fixes https://github.com/llvm/llvm-project/issues/75692.

show more ...

[test][InstCombine] Update some test cases to use opaque pointers

These tests cases were converted using the script at
https://gist.github.com/nikic/98357b71fd67756b0f064c9517b62a34

Differential Re

[test][InstCombine] Update some test cases to use opaque pointers

These tests cases were converted using the script at
https://gist.github.com/nikic/98357b71fd67756b0f064c9517b62a34

Differential Revision: https://reviews.llvm.org/D135094

show more ...

[InstCombine] reduce another or-xor bitwise logic pattern

~(A & ?) | (A ^ B) --> ~((A & ?) & B)
https://alive2.llvm.org/ce/z/mxex6V

This is similar to 9d218b61cc50 where we peeked through
another l

[InstCombine] reduce another or-xor bitwise logic pattern

~(A & ?) | (A ^ B) --> ~((A & ?) & B)
https://alive2.llvm.org/ce/z/mxex6V

This is similar to 9d218b61cc50 where we peeked through
another logic op to find a common operand.

show more ...

[InstCombine] add tests for or-xor-nand; NFC

[InstCombine] fold bitwise logic or+or+xor+not

(~A | C) | (A ^ B) --> ~(A & B) | C
https://alive2.llvm.org/ce/z/Qw3aiJ

This extends the existing fold (just above the new match)
to peek through anot

[InstCombine] fold bitwise logic or+or+xor+not

(~A | C) | (A ^ B) --> ~(A & B) | C
https://alive2.llvm.org/ce/z/Qw3aiJ

This extends the existing fold (just above the new match)
to peek through another 'or' instruction.

This should let the motivating case from issue #57174
simplify completely.

show more ...

[InstCombine] add tests for or-xor-not patterns; NFC

[InstCombine] fix "X|(X^Y)" pattern-matching for commuted variants

[InstCombine] add tests for or-xor; NFC

The existing pattern matching fails to handle all commutes.

[InstCombine] reduce or-xor-or patterns

(A | ?) | (A ^ B) --> (A | ?) | B
https://alive2.llvm.org/ce/z/dbNQw4

This extends the existing transform to peek through
another 'or' instruction for the co

[InstCombine] reduce or-xor-or patterns

(A | ?) | (A ^ B) --> (A | ?) | B
https://alive2.llvm.org/ce/z/dbNQw4

This extends the existing transform to peek through
another 'or' instruction for the common operand.

This is the underlying missing fold that should allow
issue #56711 and issue #57120 to reduce even more.

show more ...

[InstCombine] add tests for or-xor-or; NFC

[InstCombine] Fold `(X | C2) ^ C1 --> (X & ~C2) ^ (C1^C2)`

These two are equivalent,
and i *think* the `and` form is more-ish canonical.

General proof: https://alive2.llvm.org/ce/z/RrF5s6

If const

[InstCombine] Fold `(X | C2) ^ C1 --> (X & ~C2) ^ (C1^C2)`

These two are equivalent,
and i *think* the `and` form is more-ish canonical.

General proof: https://alive2.llvm.org/ce/z/RrF5s6

If constant on the (outer) `xor` is an `undef`,
the whole lane is dead: https://alive2.llvm.org/ce/z/mu4Sh2

However, if the constant on the (inner) `or` is an `undef`,
we must sanitize it first: https://alive2.llvm.org/ce/z/MHYJL7
I guess, producing a zero `and`-mask is optimal in that case.

alive-tv is happy about the entirety of `xor-of-or.ll`.

show more ...

[test] Use -passes=instcombine instead of -instcombine in lots of tests. NFC

Another step moving away from the deprecated syntax of specifying
pass pipeline in opt.

Differential Revision: https://r

[test] Use -passes=instcombine instead of -instcombine in lots of tests. NFC

Another step moving away from the deprecated syntax of specifying
pass pipeline in opt.

Differential Revision: https://reviews.llvm.org/D119081

show more ...

[InstCombine] Fold (A^B)|~A-->~(A&B)

https://alive2.llvm.org/ce/z/2v6rhF

Fixes:
https://llvm.org/PR52478

Differential Revision: https://reviews.llvm.org/D113783

[InstCombine] add tests for or-xor logic fold; NFC

Baseline tests for D113783

Differential Revision: https://reviews.llvm.org/D113846

[InstCombine] allow vector splat matching for bitwise logic folds

These transforms are also likely missing a one-use check,
but that's another patch.

[InstCombine] add tests for bitwise logic folds; NFC

[InstCombine] Add PR45977 test coverage

[InstCombine] Hoist xor-by-constant from xor-by-value

This is one of the deficiencies that can be observed in
https://godbolt.org/z/YPczsG after D91038 patch set.

This exposed two missing folds, on

[InstCombine] Hoist xor-by-constant from xor-by-value

This is one of the deficiencies that can be observed in
https://godbolt.org/z/YPczsG after D91038 patch set.

This exposed two missing folds, one was fixed by the previous commit,
another one is `(A ^ B) | ~(A ^ B) --> -1` / `(A ^ B) & ~(A ^ B) --> 0`.

`-early-cse` will catch it: https://godbolt.org/z/4n1T1v,
but isn't meaningful to fix it in InstCombine,
because we'd need to essentially do our own CSE,
and we can't even rely on `Instruction::isIdenticalTo()`,
because there are no guarantees that the order of operands matches.
So let's just accept it as a loss.

show more ...

[InstCombine] prefer xor with -1 because 'not' is easier to understand (PR32706)

This is a retry of rL300977 which was reverted because of infinite loops.
We have fixed all of the known places where

[InstCombine] prefer xor with -1 because 'not' is easier to understand (PR32706)

This is a retry of rL300977 which was reverted because of infinite loops.
We have fixed all of the known places where that would happen, but there's
still a chance that this patch will cause infinite loops.

This matches the demanded bits behavior in the DAG and should fix:
https://bugs.llvm.org/show_bug.cgi?id=32706

Differential Revision: https://reviews.llvm.org/D32255

show more ...