Allow TLS vars in dllimport/export functions; only inline dllimport functions when safe (PR24593)
This patch does two things:
1) Don't error about dllimport/export on thread-local static local variables.
We put those attributes on static locals in dllimport/export functions
implicitly in case the function gets inlined. Now, for TLS variables this
is a problem because we can't import such variables, but it's a benign
problem becase:
2) Make sure we never inline a dllimport function TLS static locals. In fact,
never inline a dllimport function that references a non-imported function
or variable (because these are not defined in the importing library). This
seems to match MSVC's behaviour.
Differential Revision: http://reviews.llvm.org/D12422
llvm-svn: 246338
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 0525869..847cb57 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -1448,6 +1448,35 @@
return true;
}
};
+
+ struct DLLImportFunctionVisitor
+ : public RecursiveASTVisitor<DLLImportFunctionVisitor> {
+ bool SafeToInline = true;
+
+ bool VisitVarDecl(VarDecl *VD) {
+ // A thread-local variable cannot be imported.
+ SafeToInline = !VD->getTLSKind();
+ return SafeToInline;
+ }
+
+ // Make sure we're not referencing non-imported vars or functions.
+ bool VisitDeclRefExpr(DeclRefExpr *E) {
+ ValueDecl *VD = E->getDecl();
+ if (isa<FunctionDecl>(VD))
+ SafeToInline = VD->hasAttr<DLLImportAttr>();
+ else if (VarDecl *V = dyn_cast<VarDecl>(VD))
+ SafeToInline = !V->hasGlobalStorage() || V->hasAttr<DLLImportAttr>();
+ return SafeToInline;
+ }
+ bool VisitCXXDeleteExpr(CXXDeleteExpr *E) {
+ SafeToInline = E->getOperatorDelete()->hasAttr<DLLImportAttr>();
+ return SafeToInline;
+ }
+ bool VisitCXXNewExpr(CXXNewExpr *E) {
+ SafeToInline = E->getOperatorNew()->hasAttr<DLLImportAttr>();
+ return SafeToInline;
+ }
+ };
}
// isTriviallyRecursive - Check if this function calls another
@@ -1478,6 +1507,15 @@
const auto *F = cast<FunctionDecl>(GD.getDecl());
if (CodeGenOpts.OptimizationLevel == 0 && !F->hasAttr<AlwaysInlineAttr>())
return false;
+
+ if (F->hasAttr<DLLImportAttr>()) {
+ // Check whether it would be safe to inline this dllimport function.
+ DLLImportFunctionVisitor Visitor;
+ Visitor.TraverseFunctionDecl(const_cast<FunctionDecl*>(F));
+ if (!Visitor.SafeToInline)
+ return false;
+ }
+
// PR9614. Avoid cases where the source code is lying to us. An available
// externally function should have an equivalent function somewhere else,
// but a function that calls itself is clearly not equivalent to the real