[LLVM][IR] Use splat syntax when printing ConstantExpr based splats. (#116856)

This brings the printing of scalable vector constant splats inline with
their fixed length counterparts.

[LLVM][IR] Teach constant integer binop folds about vector ConstantInts. (#115739)

The existing logic mostly works with the main changes being:
* Use getScalarSizeInBits instead of IntegerType::ge

[LLVM][IR] Teach constant integer binop folds about vector ConstantInts. (#115739)

The existing logic mostly works with the main changes being:
* Use getScalarSizeInBits instead of IntegerType::getBitWidth
* Use ConstantInt::get(Type* instead of ConstantInt::get(LLVMContext

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

[InstSimplify][InstCombine][ConstantFold] Move vector div/rem by zero fold to InstCombine (#114280)

Previously we fold `div/rem X, C` into `poison` if any element of the
constant divisor `C` is zer

[InstSimplify][InstCombine][ConstantFold] Move vector div/rem by zero fold to InstCombine (#114280)

Previously we fold `div/rem X, C` into `poison` if any element of the
constant divisor `C` is zero or undef. However, it is incorrect when
threading udiv over an vector select:
https://alive2.llvm.org/ce/z/3Ninx5
```
define <2 x i32> @vec_select_udiv_poison(<2 x i1> %x) {
%sel = select <2 x i1> %x, <2 x i32> <i32 -1, i32 -1>, <2 x i32> <i32 0, i32 1>
%div = udiv <2 x i32> <i32 42, i32 -7>, %sel
ret <2 x i32> %div
}
```
In this case, `threadBinOpOverSelect` folds `udiv <i32 42, i32 -7>, <i32
-1, i32 -1>` and `udiv <i32 42, i32 -7>, <i32 0, i32 1>` into
`zeroinitializer` and `poison`, respectively. One solution is to
introduce a new flag indicating that we are threading over a vector
select. But it requires to modify both `InstSimplify` and
`ConstantFold`.

However, this optimization doesn't provide benefits to real-world
programs:

https://dtcxzyw.github.io/llvm-opt-benchmark/coverage/data/zyw/opt-ci/actions-runner/_work/llvm-opt-benchmark/llvm-opt-benchmark/llvm/llvm-project/llvm/lib/IR/ConstantFold.cpp.html#L908

https://dtcxzyw.github.io/llvm-opt-benchmark/coverage/data/zyw/opt-ci/actions-runner/_work/llvm-opt-benchmark/llvm-opt-benchmark/llvm/llvm-project/llvm/lib/Analysis/InstructionSimplify.cpp.html#L1107

This patch moves the fold into InstCombine to avoid breaking numerous
existing tests.

Fixes #114191 and #113866 (only poison-safety issue).

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[InstCombine] Teach takeLog2 about right shifts, truncation and bitwise-and

We left some easy opportunities for further simplifications.

log2(trunc(x)) is simply trunc(log2(x)). This is safe if we

[InstCombine] Teach takeLog2 about right shifts, truncation and bitwise-and

We left some easy opportunities for further simplifications.

log2(trunc(x)) is simply trunc(log2(x)). This is safe if we know that
trunc is NUW because it means that the truncation didn't drop any bits.
It is also safe if the caller is OK with zero as a possible answer.

log2(x >>u y) is simply `log2(x) - y`.

log2(x & y) is a funny one. It comes up when doing something like:
```
unsigned int f(unsigned int x, unsigned int y) {
unsigned char a = 1u << x;
return y / a;
}
```

LLVM would canonicalize this to:
```
%shl = shl nuw i32 1, %x
%conv1 = and i32 %shl, 255
%div = udiv i32 %y, %conv1
```

In cases like these, we can ignore the mask entirely.
This is equivalent to `y >> x`.

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[InstCombine] integrate `N{U,S}WAddLike` into existing folds

Just went a quick replacement of `N{U,S}WAdd` with the `Like` variant
that old matches `or disjoint`

Closes #86082

[InstCombine] Add tests for integrating `N{U,S}WAddLike`; NFC

[LLVM][tests/Transforms/InstCombine] Convert instances of ConstantExpr based splats to use splat().

This is mostly NFC but some output does change due to consistently
inserting into poison rather th

[LLVM][tests/Transforms/InstCombine] Convert instances of ConstantExpr based splats to use splat().

This is mostly NFC but some output does change due to consistently
inserting into poison rather than undef and using i64 as the index
type for inserts.

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[InstCombine] simplify `(X * C0) / (X * C1)` into `C0 / C1`. (#73204)

fix #72114
proof: https://alive2.llvm.org/ce/z/xqprFm

[InstCombine] Preserve NSW flags for neg instructions (#72548)

Alive2: https://alive2.llvm.org/ce/z/F9HG3M

This missed optimization is discovered with the help of
https://github.com/AliveToolkit

[InstCombine] Preserve NSW flags for neg instructions (#72548)

Alive2: https://alive2.llvm.org/ce/z/F9HG3M

This missed optimization is discovered with the help of
https://github.com/AliveToolkit/alive2/pull/962.

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[InstCombine] Simplifiy `sdiv -X, X` into `X == INT_MIN ? 1 : -1` (#71768)

Alive2: https://alive2.llvm.org/ce/z/dHddwH
Fixes #69574

[InstCombine] Canonicalize icmp eq pow2 more thoroughly

We currently already canonicalize icmp eq (%x & Pow2), Pow2 to
icmp ne (%x & Pow2), 0. This patch generalizes the fold based on
known bits.

I

[InstCombine] Canonicalize icmp eq pow2 more thoroughly

We currently already canonicalize icmp eq (%x & Pow2), Pow2 to
icmp ne (%x & Pow2), 0. This patch generalizes the fold based on
known bits.

In particular, this allows us to handle comparisons against
!range !{i64 0, i64 2} loads, which addresses an optimization
regression in Rust caused by 8df376db7282b955e7990cb8887ee9dcd3565040.

Differential Revision: https://reviews.llvm.org/D146149

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[InstCombine] relax constraint on udiv fold

The pair of div folds was just added with:
4966d8ebe1bbe5bd6a4d28

But as noted in the post-commit review, we don't actually need
the no-remainder require

[InstCombine] relax constraint on udiv fold

The pair of div folds was just added with:
4966d8ebe1bbe5bd6a4d28

But as noted in the post-commit review, we don't actually need
the no-remainder requirement for an unsigned division (still
need the no-unsigned-wrap though):
https://alive2.llvm.org/ce/z/qHjK3Q

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[InstCombine] distribute div over add with matching mul-by-constant

((X * C2) + C1) / C2 --> X + C1/C2
https://alive2.llvm.org/ce/z/P66io8
https://alive2.llvm.org/ce/z/vghegw

This could be made mor

[InstCombine] distribute div over add with matching mul-by-constant

((X * C2) + C1) / C2 --> X + C1/C2
https://alive2.llvm.org/ce/z/P66io8
https://alive2.llvm.org/ce/z/vghegw

This could be made more general -- the multiplier could be a
multiple of the divisor -- but this is the pattern from
issue #60754.

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[InstCombine] add tests for div with muladd operand; NFC

issue #60754

[IRBuilder] Use canonical i64 type for insertelement index used by vector splats.

Instcombine prefers this canonical form (see getPreferredVectorIndex),
as does IRBuilder when passing the index as a

[IRBuilder] Use canonical i64 type for insertelement index used by vector splats.

Instcombine prefers this canonical form (see getPreferredVectorIndex),
as does IRBuilder when passing the index as an integer so we may as
well use the prefered form from creation.

NOTE: All test changes are mechanical with nothing else expected
beyond a change of index type from i32 to i64.

Differential Revision: https://reviews.llvm.org/D140983

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[InstCombine] try harder to cancel out mul/div

((Op1 * X) / Y) / Op1 --> X / Y
https://alive2.llvm.org/ce/z/JYxWjA

InstSimplify handles the more basic mul+div pattern with
shared operand, but we do

[InstCombine] try harder to cancel out mul/div

((Op1 * X) / Y) / Op1 --> X / Y
https://alive2.llvm.org/ce/z/JYxWjA

InstSimplify handles the more basic mul+div pattern with
shared operand, but we don't seem to have any reassociation
folds to handle cases where the common op is further away.

This is a generalization of 9cff4711ac72 and another
transform derived from issue #58137.

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[InstCombine] add tests for div with common mul operand; NFC

[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

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[NFC] remove 'br undef' from InstCombine test cases
This is UB and allows the compiler to give any result, so these tests weren't meaningful
InstCombine tests are now clean of 'br undef'

[InstCombine] freeze operand in sdiv expansion

As discussed in issue #37809, this transform is not safe
if the input is an undefined value.

This is similar to a recent change for urem:
d428f09b2c9d

[InstCombine] freeze operand in sdiv expansion

As discussed in issue #37809, this transform is not safe
if the input is an undefined value.

This is similar to a recent change for urem:
d428f09b2c9d

There is no difference in codegen on the basic examples,
but this could lead to regressions. We may need to
improve freeze analysis or lowering if that happens.

Presumably, in real cases that are similar to the tests
where a subsequent transform removes the select, we
will also be able to remove the freeze by seeing that
the parameter has 'noundef'.

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[InstCombine] update auto-generated CHECK lines in test file; NFC

These are all cosmetic (value naming) diffs that would distract from
real changes in this file.

[InstCombine] fold more constant divisor to select-of-constants divisor

By adding a parameter to function FoldOpIntoSelect， we can fold more Ops to Select.
For this example, we tend to fold the divi

[InstCombine] fold more constant divisor to select-of-constants divisor

By adding a parameter to function FoldOpIntoSelect， we can fold more Ops to Select.
For this example, we tend to fold the division instruction,
so we no longer care whether SelectInst is one use.

This patch slove TODO left in InstCombine/div.ll.

Reviewed By: RKSimon

Differential Revision: https://reviews.llvm.org/D122967

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[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

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[InstCombine] Add PR34063 test coverage