Changes

[ScheduleDAG] Avoid unnecessary recomputation of topological order.

In some cases ScheduleDAGRRList has to add new nodes to resolve problems
with interfering physical registers. When new nodes are added, it
completely re-computes the topological order, which can take a long
time, but is unnecessary. We only add nodes one by one, and initially
they do not have any predecessors. So we can just insert them at the end
of the vector. Later we add predecessors, but the helper function
properly updates the topological order much more efficiently. With this
change, the compile time for the program below drops from 300s to 30s on
my machine.

    define i11129 @test1() {
      %L1 = load i11129, i11129* undef
      %B30 = ashr i11129 %L1, %L1
      store i11129 %B30, i11129* undef
      ret i11129 %L1
    }

This should be generally beneficial, as we can skip a large amount of
work. Theoretically there are some scenarios where we might not safe
much, e.g. when we add a dependency between the first and last node.
Then we would have to shift all nodes. But we still do not have to spend
the time re-computing the initial order.

Reviewers: MatzeB, atrick, efriedma, niravd, paquette

Reviewed By: paquette

Differential Revision: https://reviews.llvm.org/D59722

[X86][AVX] Pad small shuffle inputs in combineX86ShufflesRecursively

As detailed on PR45974 and D79987, getFauxShuffleMask is creating nodes on the fly to create shuffles with inputs the same size as the result, causing problems for hasOneUse() checks in later simplification stages.

Currently only combineX86ShufflesRecursively benefits from these widened inputs so I've begun moving the functionality there, and out of getFauxShuffleMask. This allows us to remove the widening from VBROADCAST and *EXTEND* faux shuffle cases.

This just leaves the INSERT_SUBVECTOR case in getFauxShuffleMask still creating nodes, which will require more extensive refactoring.

[X86][AVX] getFauxShuffleMask - don't widen shuffle inputs from INSERT_SUBVECTOR(X,SHUFFLE(Y,Z))

Don't create nodes on the fly when decoding INSERT_SUBVECTOR as faux shuffles.

[PhaseOrdering] add scalarization test for PR42174; NFC

Motivating test for vector-combine enhancement in D80885.
Make sure that vectorization and canonicalization are
working together as expected.

[X86][AVX] Add test case described in D79987

[X86] getFauxShuffleMask/getTargetShuffleInputs - make SelectionDAG const (PR45974).

Try to prevent future node creation issues (as detailed in PR45974) by making the SelectionDAG reference const, so it can still be used for analysis, but not node creation.

[VectorCombine] add tests for scalarizing binop-with-constant; NFC

Goes with proposal in D80885.

This is adapted from the InstCombine tests that were added for
D50992

But these should be adjusted further to provide more interesting
scenarios for x86-specific codegen. Eg, vector types/sizes will
have different costs depending on ISA attributes.

We also need to add tests that include a load of the scalar
variable and add tests that include extra uses of the insert
to further exercise the cost model.

[X86][AVX] Add SimplifyMultipleUseDemandedBits VBROADCAST handling to SimplifyDemandedVectorElts.

As suggested on D79987.

[PhaseOrdering] add test for hoisting/CSE (PR46115); NFC

[utils] change update_test_checks.py use of 'TMP' value names

As discussed in PR45951:
https://bugs.llvm.org/show_bug.cgi?id=45951

There's a potential name collision between update_test_checks.py and -instnamer
and/or manually-generated IR test files because all of them try to use the
variable name that should never be used: "tmp".

This patch proposes to reduce the odds of collision and adds a warning if we
detect the problem. This will cause regression test churn when regenerating
CHECK lines on existing files.

Differential Revision: https://reviews.llvm.org/D80584

AArch64/GlobalISel: Fix incorrect ptrmask usage for alignment

I inverted the mask when I ported to the new form of G_PTRMASK in
8bc03d2168241f7b12265e9cd7e4eb7655709f34.

I don't think this really broke anything, since G_VASTART isn't
handled for types with an alignment higher than the stack alignment.

clang-tidy and clang-query wont crash with invalid command line options

Summary: Motivated by [[ https://bugs.llvm.org/show_bug.cgi?id=46141 | clang-tidy crashed for unknown command line argument. ]]

Reviewers: aaron.ballman, alexfh

Reviewed By: aaron.ballman

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D80879

[utils] update expected strings in tests; NFC

The script was changes with:
https://github.com/llvm/llvm-project/commit/bfdc2552664d6f0bb332a9c6a115877020f3c1df