[PATCH] D132848: [clang] Fix checking for emulated TLS in shouldAssumeDSOLocal in CodeGen

[Martin Storsjö via Phabricator via cfe-commits]

mstorsjo created this revision.
mstorsjo added a reviewer: aaron.ballman.
Herald added a project: All.
mstorsjo requested review of this revision.
Herald added a project: clang.

We shouldn't just check the clang options, we also should check
`Triple::hasDefaultEmulatedTLS()`.

This doesn't make any testable difference in this commit, because
the check for emulated TLS is within a block for
`TT.isWindowsGNUEnvironment()`, and `hasDefaultEmulatedTLS()` returns
false for any such environment - but it makes the code from
0e4cf807aeaf54a10e02176498a7df13ac722b37 <https://reviews.llvm.org/rG0e4cf807aeaf54a10e02176498a7df13ac722b37> / D102970 <https://reviews.llvm.org/D102970> more correct and
generic.

Some mingw distributions carry a downstream patch, that enables
emulated TLS by default for mingw targets in `hasDefaultEmulatedTLS()`

- and for such cases, this patch does make a difference and fixes the

detection of emulated TLS, if it is implicitly enabled.

I'm open for better suggestions on where to place the `useEmulatedTLS()`
helper function; it's a parallel to the preexisting
`TargetMachine::useEmulatedTLS()` which does the same, within llvm.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D132848

Files:
  clang/lib/CodeGen/CodeGenModule.cpp
  clang/lib/CodeGen/CodeGenModule.h


Index: clang/lib/CodeGen/CodeGenModule.h
===================================================================
--- clang/lib/CodeGen/CodeGenModule.h
+++ clang/lib/CodeGen/CodeGenModule.h
@@ -746,6 +746,12 @@
 
   const TargetCodeGenInfo &getTargetCodeGenInfo();
 
+  bool useEmulatedTLS() const {
+    if (CodeGenOpts.ExplicitEmulatedTLS)
+      return CodeGenOpts.EmulatedTLS;
+    return getTriple().hasDefaultEmulatedTLS();
+  }
+
   CodeGenTypes &getTypes() { return Types; }
 
   CodeGenVTables &getVTables() { return VTables; }
Index: clang/lib/CodeGen/CodeGenModule.cpp
===================================================================
--- clang/lib/CodeGen/CodeGenModule.cpp
+++ clang/lib/CodeGen/CodeGenModule.cpp
@@ -1154,7 +1154,7 @@
     // such variables can't be marked as DSO local. (Native TLS variables
     // can't be dllimported at all, though.)
     if (GV->isDeclarationForLinker() && isa<llvm::GlobalVariable>(GV) &&
-        (!GV->isThreadLocal() || CGM.getCodeGenOpts().EmulatedTLS))
+        (!GV->isThreadLocal() || CGM.useEmulatedTLS()))
       return false;
   }
 


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