CIRGenDeclCXX.cpp

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//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This contains code dealing with code generation of C++ declarations
//
//===----------------------------------------------------------------------===//
 
#include "CIRGenCXXABI.h"
#include "CIRGenFunction.h"
#include "CIRGenModule.h"
#include "clang/AST/Attr.h"
#include "clang/AST/Mangle.h"
#include "clang/Basic/LangOptions.h"
#include "clang/CIR/Dialect/IR/CIRAttrs.h"
 
using namespace clang;
using namespace clang::CIRGen;
 
void CIRGenFunction::emitCXXGuardedInit(const VarDecl &varDecl,
                                        cir::GlobalOp globalOp,
                                        bool performInit) {
  // If we've been asked to forbid guard variables, emit an error now.
  // This diagnostic is hard-coded for Darwin's use case; we can find
  // better phrasing if someone else needs it.
  if (cgm.getCodeGenOpts().ForbidGuardVariables)
    cgm.error(varDecl.getLocation(), "guard variables are forbidden");
 
  // Compute the mangled guard variable name and set the static_local attribute
  // BEFORE emitting initialization. This ensures that GetGlobalOps created
  // during initialization (e.g., in the ctor region) will see the attribute
  // and be marked with static_local accordingly.
  llvm::SmallString<256> guardName;
  {
    llvm::raw_svector_ostream out(guardName);
    cgm.getCXXABI().getMangleContext().mangleStaticGuardVariable(&varDecl, out);
  }
 
  // Mark the global as static local with the guard name. The emission of the
  // guard/acquire is done during LoweringPrepare.
  auto guardAttr = mlir::StringAttr::get(&cgm.getMLIRContext(), guardName);
  if (!varDecl.isStaticLocal())
    cgm.errorNYI(
        varDecl.getSourceRange(),
        "Static local guard attr only valid on static local variables");
  globalOp.setStaticLocalGuardAttr(
      cir::StaticLocalGuardAttr::get(&cgm.getMLIRContext(), guardAttr));
 
  // Emit the initializer and add a global destructor if appropriate.
  // TODO(cir): classic codegen calls emitCXXGlobalVarDeclInit for this as well,
  // and this is meant to handle cases with weak linkage (see comment in
  // emitCXXGlobalVarDeclInitFunc). At one point we'll have to do some level of
  // split here depending on whether this is a global (which should/can have
  // ctor/dtor regions), or should have in-function initialization.
  cgm.emitCXXStaticLocalVarDeclInit(&varDecl, globalOp, performInit);
}
 
void CIRGenModule::setGlobalTlsReferences(const VarDecl &vd,
                                          cir::GlobalOp globalOp) {
  assert(!vd.isStaticLocal() && vd.getTLSKind());
 
  // C doesn't need guarded thread-local init, because it can't have
  // non-constant init.
  if (!getLangOpts().CPlusPlus)
    return;
 
  if (globalOp.getTlsModel() != cir::TLS_Model::GeneralDynamic)
    return;
 
  llvm::SmallString<256> wrapperFuncName;
  llvm::SmallString<256> initFuncName;
  llvm::SmallString<256> guardName;
 
  if (getCXXABI().getMangleContext().getKind() == MangleContext::MK_Itanium) {
    llvm::raw_svector_ostream wrapperOut(wrapperFuncName);
    llvm::raw_svector_ostream initOut(initFuncName);
    llvm::raw_svector_ostream guardStream(guardName);
 
    auto &mc = cast<ItaniumMangleContext>(getCXXABI().getMangleContext());
    mc.mangleItaniumThreadLocalWrapper(&vd, wrapperOut);
    mc.mangleItaniumThreadLocalInit(&vd, initOut);
    if (globalOp.hasWeakLinkage() || globalOp.hasLinkOnceLinkage() ||
        isTemplateInstantiation(vd.getTemplateSpecializationKind())) {
      getCXXABI().getMangleContext().mangleStaticGuardVariable(&vd,
                                                               guardStream);
    }
 
  } else {
    errorNYI(vd.getSourceRange(),
             "setGlobalTlsReferences: non-itanium mangler");
    return;
  }
  globalOp.setDynTlsRefsAttr(cir::ThreadLocalGlobalWrapperInitAttr::get(
      &getMLIRContext(), wrapperFuncName, initFuncName, guardName));
}
 
void CIRGenModule::emitCXXGlobalVarDeclInitFunc(const VarDecl *vd,
                                                cir::GlobalOp addr,
                                                bool performInit) {
  assert(!cir::MissingFeatures::cudaSupport());
 
  assert(!cir::MissingFeatures::deferredCXXGlobalInit());
 
  // TODO(cir): Classic codegen calls emitCXXGuardedInit in the following case:
  // template<typename T> struct Templ {
  //   static T f;
  // };
  // template<typename T> T Templ<T>::f = get_i();
  // auto func() {
  //   Templ<int> t;
  //   return decltype(t)::f;
  // }
  //
  // However, at the moment it is only suitable for static-local variables, so
  // we will have to modify it to work for this case as well.
  emitCXXGlobalVarDeclInit(vd, addr, performInit);
}