da9c513c87
This implements the lowering of static local variables with the Itanium C++ ABI guard variable pattern in LoweringPrepare. This is initial support, errorNYI covering all that hasn't been added just yet. When a GlobalOp has the static_local attribute and a ctor region, this pass: 1. Creates a guard variable global (mangled name from AST) 2. Inserts the guard check pattern at each GetGlobalOp use site: - Load guard byte with acquire ordering - If zero, call __cxa_guard_acquire - If acquire returns non-zero, inline the ctor region code - Call __cxa_guard_release 3. Clears the static_local attribute and ctor region from the GlobalOp Once the new design doc lands I'll add more information over there.
62 lines
2.5 KiB
C++
62 lines
2.5 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This contains code dealing with code generation of C++ declarations
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//
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//===----------------------------------------------------------------------===//
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#include "CIRGenCXXABI.h"
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#include "CIRGenFunction.h"
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#include "CIRGenModule.h"
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#include "clang/AST/Attr.h"
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#include "clang/AST/Mangle.h"
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#include "clang/Basic/LangOptions.h"
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#include "clang/CIR/Dialect/IR/CIRAttrs.h"
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using namespace clang;
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using namespace clang::CIRGen;
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void CIRGenFunction::emitCXXGuardedInit(const VarDecl &varDecl,
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cir::GlobalOp globalOp,
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bool performInit) {
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// If we've been asked to forbid guard variables, emit an error now.
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// This diagnostic is hard-coded for Darwin's use case; we can find
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// better phrasing if someone else needs it.
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if (cgm.getCodeGenOpts().ForbidGuardVariables)
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cgm.error(varDecl.getLocation(), "guard variables are forbidden");
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// Compute the mangled guard variable name and set the static_local attribute
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// BEFORE emitting initialization. This ensures that GetGlobalOps created
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// during initialization (e.g., in the ctor region) will see the attribute
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// and be marked with static_local accordingly.
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llvm::SmallString<256> guardName;
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{
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llvm::raw_svector_ostream out(guardName);
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cgm.getCXXABI().getMangleContext().mangleStaticGuardVariable(&varDecl, out);
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}
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// Mark the global as static local with the guard name. The emission of the
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// guard/acquire is done during LoweringPrepare.
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auto guardAttr = mlir::StringAttr::get(&cgm.getMLIRContext(), guardName);
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globalOp.setStaticLocalGuardAttr(
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cir::StaticLocalGuardAttr::get(&cgm.getMLIRContext(), guardAttr));
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// Emit the initializer and add a global destructor if appropriate.
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cgm.emitCXXGlobalVarDeclInit(&varDecl, globalOp, performInit);
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}
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void CIRGenModule::emitCXXGlobalVarDeclInitFunc(const VarDecl *vd,
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cir::GlobalOp addr,
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bool performInit) {
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assert(!cir::MissingFeatures::cudaSupport());
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assert(!cir::MissingFeatures::deferredCXXGlobalInit());
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emitCXXGlobalVarDeclInit(vd, addr, performInit);
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}
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