[PATCH] D99517: Implemented [[clang::musttail]] attribute for guaranteed tail calls.

[Josh Haberman via Phabricator via cfe-commits]

haberman created this revision.
haberman added reviewers: rsmith, aaron.ballman.
haberman requested review of this revision.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.

This is a Clang-only change and depends on the existing "musttail"
support already implemented in LLVM.

The [[clang::musttail]] attribute goes on a return statement, not
a function definition. There are several constraints that the user
must follow when using [[clang::musttail]], and these constraints
are verified by Sema.

Tail calls are supported on regular function calls, calls through a
function pointer, member function calls, and even pointer to member.

Future work would be to throw a warning if a users tries to pass
a pointer or reference to a local variable through a musttail call.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D99517

Files:
  clang/include/clang/Basic/Attr.td
  clang/include/clang/Basic/AttrDocs.td
  clang/include/clang/Basic/DiagnosticSemaKinds.td
  clang/include/clang/Sema/ScopeInfo.h
  clang/include/clang/Sema/Sema.h
  clang/lib/CodeGen/CGCall.cpp
  clang/lib/CodeGen/CGExpr.cpp
  clang/lib/CodeGen/CGStmt.cpp
  clang/lib/CodeGen/CodeGenFunction.h
  clang/lib/Sema/JumpDiagnostics.cpp
  clang/lib/Sema/Sema.cpp
  clang/lib/Sema/SemaStmt.cpp
  clang/lib/Sema/SemaStmtAttr.cpp
  clang/test/CodeGen/attr-musttail.cpp
  clang/test/Sema/attr-musttail.cpp

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