[PATCH] D138792: [AArch64] Improve TargetParser API

[Tomas Matheson via Phabricator via llvm-commits]

tmatheson created this revision.
tmatheson added reviewers: lenary, pratlucas, dmgreen, tschuett, DavidSpickett, danielkiss.
Herald added subscribers: hiraditya, kristof.beyls.
Herald added a project: All.
tmatheson requested review of this revision.
Herald added subscribers: llvm-commits, cfe-commits, MaskRay.
Herald added projects: clang, LLVM.

The TargetParser depends heavily on a collection of macros and enums to tie
together information about architectures, CPUs and extensions. Over time this
has led to some pretty awkward API choices. For example, recently a custom
operator-- has been added to the enum, which effectively turns iteration into
a graph traversal and makes the ordering of the macro calls in the header
significant. More generally there is a lot of string <-> enum conversion
going on. I think this shows the extent to which the current data structures
are constraining us, and the need for a rethink.

I tried to split this into smaller commits, but couldn't find a way to do it
without requiring people to review a lot of code that would be deleted in the
next patch.

AArch64 only for now, but if it is accepted I will work on the same for ARM.

Key changes:

- Get rid of Arch enum, which is used to bind fields together. Instead of passing around ArchKind, use the named ArchInfo objects directly or via references.
- The list of all known ArchInfo becomes an array of pointers.
- ArchKind::operator-- is replaced with ArchInfo::operator< etc, which defines which architectures are predecessors to each other. This allows features from predecessor architectures to be added in a more intuitive way.
- Free functions of the form f(ArchKind) are converted to ArchInfo::f(). Some functions become unnecessary and are deleted.
- Version number and profile are added to the ArchInfo. This makes comparison of architectures easier and moves a couple of functions out of clang and into AArch64TargetParser.
- clang::AArch64TargetInfo ArchInfo is initialised to Armv8a not INVALID.
- AArch64::ArchProfile which is distinct from ARM::ArchProfile
- Give things sensible names and add some comments.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D138792

Files:
  clang/lib/Basic/Targets/AArch64.cpp
  clang/lib/Basic/Targets/AArch64.h
  clang/lib/Driver/ToolChains/Arch/AArch64.cpp
  llvm/include/llvm/Support/AArch64TargetParser.def
  llvm/include/llvm/Support/AArch64TargetParser.h
  llvm/include/llvm/Support/VersionTuple.h
  llvm/lib/Support/AArch64TargetParser.cpp
  llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp
  llvm/unittests/Support/TargetParserTest.cpp

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