[PATCH] D61615: [COFF] Use COFF stubs for extern_weak functions

[Reid Kleckner via Phabricator via cfe-commits]

rnk created this revision.
rnk added reviewers: smeenai, mstorsjo.
Herald added subscribers: cfe-commits, hiraditya.
Herald added projects: clang, LLVM.

A COFF stub indirects the reference to a symbol through memory. A
.refptr.$sym global variable pointer is created to refer to $sym.
Typically mingw uses these for external global variable declarations,
but we can use them for weak function declarations as well.

Updates the dso_local classification to add a special case for
extern_weak symbols on COFF in both clang and LLVM.

Fixes PR37598


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D61615

Files:
  clang/lib/CodeGen/CodeGenModule.cpp
  clang/test/CodeGen/dso-local-executable.c
  llvm/lib/Target/TargetMachine.cpp
  llvm/lib/Target/X86/X86FastISel.cpp
  llvm/lib/Target/X86/X86ISelLowering.cpp
  llvm/lib/Target/X86/X86Subtarget.cpp
  llvm/test/CodeGen/X86/extern_weak.ll

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