Promote ConstantInitBuilder to be a public CodeGen API; it's
a generally useful utility for other frontends. NFC.
llvm-svn: 296806
diff --git a/clang/lib/CodeGen/ConstantInitBuilder.cpp b/clang/lib/CodeGen/ConstantInitBuilder.cpp
new file mode 100644
index 0000000..772391e
--- /dev/null
+++ b/clang/lib/CodeGen/ConstantInitBuilder.cpp
@@ -0,0 +1,131 @@
+//===--- ConstantInitBuilder.cpp - Global initializer builder -------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines out-of-line routines for building initializers for
+// global variables, in particular the kind of globals that are implicitly
+// introduced by various language ABIs.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/CodeGen/ConstantInitBuilder.h"
+#include "CodeGenModule.h"
+
+using namespace clang;
+using namespace CodeGen;
+
+llvm::GlobalVariable *
+ConstantInitBuilder::createGlobal(llvm::Constant *initializer,
+ const llvm::Twine &name,
+ CharUnits alignment,
+ bool constant,
+ llvm::GlobalValue::LinkageTypes linkage,
+ unsigned addressSpace) {
+ auto GV = new llvm::GlobalVariable(CGM.getModule(),
+ initializer->getType(),
+ constant,
+ linkage,
+ initializer,
+ name,
+ /*insert before*/ nullptr,
+ llvm::GlobalValue::NotThreadLocal,
+ addressSpace);
+ GV->setAlignment(alignment.getQuantity());
+ resolveSelfReferences(GV);
+ return GV;
+}
+
+void ConstantInitBuilder::setGlobalInitializer(llvm::GlobalVariable *GV,
+ llvm::Constant *initializer) {
+ GV->setInitializer(initializer);
+
+ if (!SelfReferences.empty())
+ resolveSelfReferences(GV);
+}
+
+void ConstantInitBuilder::resolveSelfReferences(llvm::GlobalVariable *GV) {
+ for (auto &entry : SelfReferences) {
+ llvm::Constant *resolvedReference =
+ llvm::ConstantExpr::getInBoundsGetElementPtr(
+ GV->getValueType(), GV, entry.Indices);
+ entry.Dummy->replaceAllUsesWith(resolvedReference);
+ entry.Dummy->eraseFromParent();
+ }
+}
+
+void ConstantInitBuilder::AggregateBuilderBase::addSize(CharUnits size) {
+ add(Builder.CGM.getSize(size));
+}
+
+llvm::Constant *
+ConstantInitBuilder::AggregateBuilderBase::getAddrOfCurrentPosition(
+ llvm::Type *type) {
+ // Make a global variable. We will replace this with a GEP to this
+ // position after installing the initializer.
+ auto dummy =
+ new llvm::GlobalVariable(Builder.CGM.getModule(), type, true,
+ llvm::GlobalVariable::PrivateLinkage,
+ nullptr, "");
+ Builder.SelfReferences.emplace_back(dummy);
+ auto &entry = Builder.SelfReferences.back();
+ (void) getGEPIndicesToCurrentPosition(entry.Indices);
+ return dummy;
+}
+
+void ConstantInitBuilder::AggregateBuilderBase::getGEPIndicesTo(
+ llvm::SmallVectorImpl<llvm::Constant*> &indices,
+ size_t position) const {
+ // Recurse on the parent builder if present.
+ if (Parent) {
+ Parent->getGEPIndicesTo(indices, Begin);
+
+ // Otherwise, add an index to drill into the first level of pointer.
+ } else {
+ assert(indices.empty());
+ indices.push_back(llvm::ConstantInt::get(Builder.CGM.Int32Ty, 0));
+ }
+
+ assert(position >= Begin);
+ // We have to use i32 here because struct GEPs demand i32 indices.
+ // It's rather unlikely to matter in practice.
+ indices.push_back(llvm::ConstantInt::get(Builder.CGM.Int32Ty,
+ position - Begin));
+}
+
+llvm::Constant *ConstantArrayBuilder::finishImpl() {
+ markFinished();
+
+ auto &buffer = getBuffer();
+ assert((Begin < buffer.size() ||
+ (Begin == buffer.size() && EltTy))
+ && "didn't add any array elements without element type");
+ auto elts = llvm::makeArrayRef(buffer).slice(Begin);
+ auto eltTy = EltTy ? EltTy : elts[0]->getType();
+ auto type = llvm::ArrayType::get(eltTy, elts.size());
+ auto constant = llvm::ConstantArray::get(type, elts);
+ buffer.erase(buffer.begin() + Begin, buffer.end());
+ return constant;
+}
+
+llvm::Constant *ConstantStructBuilder::finishImpl() {
+ markFinished();
+
+ auto &buffer = getBuffer();
+ assert(Begin < buffer.size() && "didn't add any struct elements?");
+ auto elts = llvm::makeArrayRef(buffer).slice(Begin);
+
+ llvm::Constant *constant;
+ if (Ty) {
+ constant = llvm::ConstantStruct::get(Ty, elts);
+ } else {
+ constant = llvm::ConstantStruct::getAnon(elts, /*packed*/ false);
+ }
+
+ buffer.erase(buffer.begin() + Begin, buffer.end());
+ return constant;
+}