[all-commits] [llvm/llvm-project] 1132c7: Remove vptr dispatch from FoldingSet.

[Richard Smith via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 1132c75bd77a4ae5e4634e22ac693128e3f39e5c
      https://github.com/llvm/llvm-project/commit/1132c75bd77a4ae5e4634e22ac693128e3f39e5c
  Author: Richard Smith <richard at metafoo.co.uk>
  Date:   2020-04-15 (Wed, 15 Apr 2020)

  Changed paths:
    M llvm/include/llvm/ADT/FoldingSet.h
    M llvm/lib/Support/FoldingSet.cpp

  Log Message:
  -----------
  Remove vptr dispatch from FoldingSet.

Summary:
Instead of storing a vptr in each FoldingSet instance, form an
equivalent struct and pass it implicitly from FoldingSet into the
various FoldingSetBase methods.

This has three benefits:
 * FoldingSet becomes one pointer smaller.
 * Under LTO, the "virtual" functions are much easier to inline.
 * The element type no longer needs to be complete when instantiating
   FoldingSet<T>, only when instantiating an insert / lookup member.

Reviewers: rnk

Subscribers: hiraditya, dexonsmith, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D78247