Removed definitions of vectorizeBasicBlock and VectorizeConfig
(possibly a remnant from the BBVectorize pass that was removed
way back in 2017).

Also reduced amount of include dependencies to Transforms/Vectorize.h.

Remove C APIs for interacting with PassRegistry and pass
initialization. These are legacy PM concepts, and are no longer
relevant for the new pass manager.

Calls to these initialization functions can simply be dropped.

Differential Revision: https://reviews.llvm.org/D145043

No need to include CallGraphSCCPass.h from the IPO/Inliner.

Also removed the include of LegacyPassManager.h in a couple of files
that do not really depend on that header file.

Differential Revision: https://reviews.llvm.org/D148083

DFAJumpThreading
JumpThreading
LibCallsShrink
LoopVectorize
SLPVectorizer
DeadStoreElimination
AggressiveDCE
CorrelatedValuePropagation
IndVarSimplify

These are part of the optimization pipeline, of which the legacy version is deprecated and being removed.

Legacy passes are only supported for codegen, and I don't believe
it's possible to write backends using the C API, so we should drop
all of those. Reduces the number of places that need to be modified
when removing legacy passes.

Differential Revision: https://reviews.llvm.org/D144970

These are part of the optimization pipeline, of which the legacy pass manager version is deprecated.

Namely
* Internalize
* StripSymbols
* StripNonDebugSymbols
* StripDeadDebugInfo
* StripDeadPrototypes
* VectorCombine
* WarnMissedTransformations

Fixed previously failing ocaml tests (one of them seems to already be failing?)

This reverts commit a4b4f62beb0bf40123181e5f5bdf32ef54f87166.

Ocaml bindings tests failing.

These are part of the optimization pipeline, of which the legacy pass manager version is deprecated.

Namely
* Internalize
* StripSymbols
* StripNonDebugSymbols
* StripDeadDebugInfo
* StripDeadPrototypes
* VectorCombine
* WarnMissedTransformations

Discourse thread: https://discourse.llvm.org/t/include-what-you-use-include-cleanup
Differential Revision: https://reviews.llvm.org/D121332

Based on the output of include-what-you-use.

This is a big chunk of changes. It is very likely to break downstream code
unless they took a lot of care in avoiding hidden ehader dependencies, something
the LLVM codebase doesn't do that well :-/

I've tried to summarize the biggest change below:

- llvm/include/llvm-c/Core.h: no longer includes llvm-c/ErrorHandling.h
- llvm/IR/DIBuilder.h no longer includes llvm/IR/DebugInfo.h
- llvm/IR/IRBuilder.h no longer includes llvm/IR/IntrinsicInst.h
- llvm/IR/LLVMRemarkStreamer.h no longer includes llvm/Support/ToolOutputFile.h
- llvm/IR/LegacyPassManager.h no longer include llvm/Pass.h
- llvm/IR/Type.h no longer includes llvm/ADT/SmallPtrSet.h
- llvm/IR/PassManager.h no longer includes llvm/Pass.h nor llvm/Support/Debug.h

And the usual count of preprocessed lines:
$ clang++ -E  -Iinclude -I../llvm/include ../llvm/lib/IR/*.cpp -std=c++14 -fno-rtti -fno-exceptions | wc -l
before: 6400831
after:  6189948

200k lines less to process is no that bad ;-)

Discourse thread on the topic: https://llvm.discourse.group/t/include-what-you-use-include-cleanup

Differential Revision: https://reviews.llvm.org/D118652