Fix and refactor Objective-C state

Tie the state to an LLVM module/object file instead of having a global
one. And finalize it once per LLVM module instead of once per D module
(previously, as part of ModuleInfo generation).

Fixes issue #2388.

ddmd/gluelayer.d

@@ -32,7 +32,7 @@ version (IN_LLVM)
     {
         Statement asmSemantic(AsmStatement s, Scope* sc);
         RET retStyle(TypeFunction tf);
-        void objc_initSymbols(); // in gen/objcgen.cpp
+        void objc_initSymbols() {}
     }
 }
 else version (NoBackend)

driver/codegenerator.cpp

@@ -247,6 +247,8 @@ void CodeGenerator::finishLLModule(Module *m) {
 }
 
 void CodeGenerator::writeAndFreeLLModule(const char *filename) {
+  ir_->objc.finalize();
+
   // Issue #1829: make sure all replaced global variables are replaced
   // everywhere.
   ir_->replaceGlobals();

gen/irstate.cpp

@@ -35,7 +35,7 @@ IRScope &IRScope::operator=(const IRScope &rhs) {
 
 ////////////////////////////////////////////////////////////////////////////////
 IRState::IRState(const char *name, llvm::LLVMContext &context)
-    : module(name, context), DBuilder(this) {
+    : module(name, context), DBuilder(this), objc(module) {
   ir.state = this;
 }
 

gen/irstate.h

@@ -23,6 +23,7 @@
 #include "aggregate.h"
 #include "root.h"
 #include "gen/dibuilder.h"
+#include "gen/objcgen.h"
 #include "ir/iraggr.h"
 #include "ir/irvar.h"
 #include "llvm/ADT/StringMap.h"
@@ -105,7 +106,7 @@ struct IRAsmBlock {
         retfixup(nullptr) {}
 };
 
-// represents the module
+// represents the LLVM module (object file)
 struct IRState {
 private:
   std::vector<std::pair<llvm::GlobalVariable *, llvm::Constant *>>
@@ -125,6 +126,8 @@ public:
 
   LLStructType *moduleRefType = nullptr;
 
+  ObjCState objc;
+
   // Stack of currently codegen'd functions (more than one for lambdas or other
   // nested functions, inlining-only codegen'ing, etc.), and some convenience
   // accessors for the top-most one.

gen/moduleinfo.cpp

@@ -15,7 +15,6 @@
 #include "gen/llvmhelpers.h"
 #include "gen/logger.h"
 #include "gen/mangling.h"
-#include "gen/objcgen.h"
 #include "gen/rttibuilder.h"
 #include "ir/irfunction.h"
 #include "ir/irmodule.h"
@@ -306,8 +305,6 @@ llvm::GlobalVariable *genModuleInfo(Module *m) {
   const auto at = llvm::ArrayType::get(it, len);
   b.push(toConstantArray(it, at, name, len, false));
 
-  objc_Module_genmoduleinfo_classes();
-
   // Create a global symbol with the above initialiser.
   LLGlobalVariable *moduleInfoSym = getIrModule(m)->moduleInfoSymbol();
   b.finalize(moduleInfoSym->getType()->getPointerElementType(), moduleInfoSym);

gen/objcgen.cpp

@@ -9,89 +9,16 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "gen/objcgen.h"
 #include "mtype.h"
 #include "objc.h"
 #include "gen/irstate.h"
-#include "gen/objcgen.h"
 
 namespace {
-// Were any Objective-C symbols generated?
-bool hasSymbols;
-
-enum ABI {
-  none = 0,
-  fragile = 1,
-  nonFragile = 2
-};
-
+enum ABI { none = 0, fragile = 1, nonFragile = 2 };
 ABI abi = nonFragile;
-
-// symbols that shouldn't be optimized away
-std::vector<LLConstant *> retainedSymbols;
-
-llvm::StringMap<LLGlobalVariable *> methVarNameMap;
-llvm::StringMap<LLGlobalVariable *> methVarRefMap;
-
-void retain(LLConstant *sym) {
-    retainedSymbols.push_back(DtoBitCast(sym, getVoidPtrType()));
 }
 
-void retainSymbols() {
-  // put all objc symbols in the llvm.compiler.used array so optimizer won't
-  // remove.  Should do just once per module.
-  auto arrayType = LLArrayType::get(getVoidPtrType(), retainedSymbols.size());
-  auto usedArray = LLConstantArray::get(arrayType, retainedSymbols);
-  auto var = new LLGlobalVariable
-    (gIR->module, usedArray->getType(), false,
-     LLGlobalValue::AppendingLinkage,
-     usedArray,
-     "llvm.compiler.used");
-  var->setSection("llvm.metadata");
-}
-
-void genImageInfo() {
-  // Use LLVM to generate image info
-  const char *section = (abi == nonFragile ?
-                         "__DATA,__objc_imageinfo,regular,no_dead_strip" :
-                         "__OBJC,__image_info");
-  gIR->module.addModuleFlag(llvm::Module::Error,
-                            "Objective-C Version", abi); //  unused?
-  gIR->module.addModuleFlag(llvm::Module::Error,
-                            "Objective-C Image Info Version", 0u); // version
-  gIR->module.addModuleFlag(llvm::Module::Error,
-                            "Objective-C Image Info Section",
-                            llvm::MDString::get(gIR->context(), section));
-  gIR->module.addModuleFlag(llvm::Module::Override,
-                            "Objective-C Garbage Collection", 0u); // flags
-}
-
-LLGlobalVariable *getCStringVar(const char *symbol,
-                                const llvm::StringRef &str,
-                                const char *section) {
-  auto init = llvm::ConstantDataArray::getString(gIR->context(), str);
-  auto var = new LLGlobalVariable
-    (gIR->module, init->getType(), false,
-     LLGlobalValue::PrivateLinkage, init, symbol);
-    var->setSection(section);
-    return var;
-}
-
-LLGlobalVariable *getMethVarName(const llvm::StringRef &name) {
-  auto it = methVarNameMap.find(name);
-  if (it != methVarNameMap.end()) {
-    return it->second;
-  }
-
-  auto var = getCStringVar("OBJC_METH_VAR_NAME_", name,
-                           abi == nonFragile ?
-                           "__TEXT,__objc_methname,cstring_literals" :
-                           "__TEXT,__cstring,cstring_literals");
-  methVarNameMap[name] = var;
-  retain(var);
-  return var;
-}
-} // end local stuff
-
 bool objc_isSupported(const llvm::Triple &triple) {
   if (triple.isOSDarwin()) {
     // Objective-C only supported on Darwin at this time
@@ -112,15 +39,32 @@ bool objc_isSupported(const llvm::Triple &triple) {
   return false;
 }
 
-// called by the ddmd.objc.Supported ctor
-void objc_initSymbols() {
-  hasSymbols = false;
-  retainedSymbols.clear();
-  methVarNameMap.clear();
-  methVarRefMap.clear();
+LLGlobalVariable *ObjCState::getCStringVar(const char *symbol,
+                                           const llvm::StringRef &str,
+                                           const char *section) {
+  auto init = llvm::ConstantDataArray::getString(module.getContext(), str);
+  auto var = new LLGlobalVariable(module, init->getType(), false,
+                                  LLGlobalValue::PrivateLinkage, init, symbol);
+  var->setSection(section);
+  return var;
 }
 
-LLGlobalVariable *objc_getMethVarRef(const ObjcSelector &sel) {
+LLGlobalVariable *ObjCState::getMethVarName(const llvm::StringRef &name) {
+  auto it = methVarNameMap.find(name);
+  if (it != methVarNameMap.end()) {
+    return it->second;
+  }
+
+  auto var = getCStringVar("OBJC_METH_VAR_NAME_", name,
+                           abi == nonFragile
+                               ? "__TEXT,__objc_methname,cstring_literals"
+                               : "__TEXT,__cstring,cstring_literals");
+  methVarNameMap[name] = var;
+  retain(var);
+  return var;
+}
+
+LLGlobalVariable *ObjCState::getMethVarRef(const ObjcSelector &sel) {
   llvm::StringRef s(sel.stringvalue, sel.stringlen);
   auto it = methVarRefMap.find(s);
   if (it != methVarRefMap.end()) {
@@ -128,30 +72,59 @@ LLGlobalVariable *objc_getMethVarRef(const ObjcSelector &sel) {
   }
 
   auto gvar = getMethVarName(s);
-  auto selref = new LLGlobalVariable
-    (gIR->module, gvar->getType(),
+  auto selref = new LLGlobalVariable(
+      module, gvar->getType(),
       false, // prevent const elimination optimization
-     LLGlobalValue::PrivateLinkage,
-     gvar,
-     "OBJC_SELECTOR_REFERENCES_",
-     nullptr, LLGlobalVariable::NotThreadLocal, 0,
+      LLGlobalValue::PrivateLinkage, gvar, "OBJC_SELECTOR_REFERENCES_", nullptr,
+      LLGlobalVariable::NotThreadLocal, 0,
       true); // externally initialized
-  selref->setSection(abi == nonFragile ?
-                     "__DATA,__objc_selrefs,literal_pointers,no_dead_strip" :
-                     "__OBJC,__message_refs,literal_pointers,no_dead_strip");
+  selref->setSection(
+      abi == nonFragile
+          ? "__DATA,__objc_selrefs,literal_pointers,no_dead_strip"
+          : "__OBJC,__message_refs,literal_pointers,no_dead_strip");
 
   // Save for later lookup and prevent optimizer elimination
   methVarRefMap[s] = selref;
   retain(selref);
-  hasSymbols = true;
 
   return selref;
 }
 
-void objc_Module_genmoduleinfo_classes() {
-  if (hasSymbols) {
+void ObjCState::retain(LLConstant *sym) {
+  retainedSymbols.push_back(DtoBitCast(sym, getVoidPtrType()));
+}
+
+void ObjCState::finalize() {
+  if (!retainedSymbols.empty()) {
     genImageInfo();
     // add in references so optimizer won't remove symbols.
     retainSymbols();
   }
 }
+
+void ObjCState::genImageInfo() {
+  // Use LLVM to generate image info
+  const char *section =
+      (abi == nonFragile ? "__DATA,__objc_imageinfo,regular,no_dead_strip"
+                         : "__OBJC,__image_info");
+  module.addModuleFlag(llvm::Module::Error, "Objective-C Version",
+                       abi); //  unused?
+  module.addModuleFlag(llvm::Module::Error, "Objective-C Image Info Version",
+                       0u); // version
+  module.addModuleFlag(llvm::Module::Error, "Objective-C Image Info Section",
+                       llvm::MDString::get(module.getContext(), section));
+  module.addModuleFlag(llvm::Module::Override, "Objective-C Garbage Collection",
+                       0u); // flags
+}
+
+void ObjCState::retainSymbols() {
+  // put all objc symbols in the llvm.compiler.used array so optimizer won't
+  // remove.
+  auto arrayType = LLArrayType::get(retainedSymbols.front()->getType(),
+                                    retainedSymbols.size());
+  auto usedArray = LLConstantArray::get(arrayType, retainedSymbols);
+  auto var = new LLGlobalVariable(module, arrayType, false,
+                                  LLGlobalValue::AppendingLinkage, usedArray,
+                                  "llvm.compiler.used");
+  var->setSection("llvm.metadata");
+}

gen/objcgen.h

@@ -14,15 +14,44 @@
 #ifndef LDC_GEN_OBJCGEN_H
 #define LDC_GEN_OBJCGEN_H
 
+#include <vector>
+#include "llvm/ADT/StringMap.h"
+
 struct ObjcSelector;
 namespace llvm {
+class Constant;
 class GlobalVariable;
+class Module;
 class Triple;
 }
 
 bool objc_isSupported(const llvm::Triple &triple);
-void objc_initSymbols();
-void objc_Module_genmoduleinfo_classes();
-llvm::GlobalVariable *objc_getMethVarRef(const ObjcSelector &sel);
+
+// Objective-C state tied to an LLVM module (object file).
+class ObjCState {
+public:
+  ObjCState(llvm::Module &module) : module(module) {}
+
+  llvm::GlobalVariable *getMethVarRef(const ObjcSelector &sel);
+  void finalize();
+
+private:
+  llvm::Module &module;
+
+  // symbols that shouldn't be optimized away
+  std::vector<llvm::Constant *> retainedSymbols;
+
+  llvm::StringMap<llvm::GlobalVariable *> methVarNameMap;
+  llvm::StringMap<llvm::GlobalVariable *> methVarRefMap;
+
+  llvm::GlobalVariable *getCStringVar(const char *symbol,
+                                      const llvm::StringRef &str,
+                                      const char *section);
+  llvm::GlobalVariable *getMethVarName(const llvm::StringRef &name);
+  void retain(llvm::Constant *sym);
+
+  void genImageInfo();
+  void retainSymbols();
+};
 
 #endif // LDC_GEN_OBJCGEN_H

gen/tocall.cpp

@@ -22,7 +22,6 @@
 #include "gen/llvmhelpers.h"
 #include "gen/logger.h"
 #include "gen/nested.h"
-#include "gen/objcgen.h"
 #include "gen/tollvm.h"
 #include "gen/runtime.h"
 #include "ir/irfunction.h"
@@ -774,7 +773,7 @@ private:
       assert(dfnval);
       const auto selector = dfnval->func->selector;
       assert(selector);
-      LLGlobalVariable *selptr = objc_getMethVarRef(*selector);
+      LLGlobalVariable *selptr = gIR->objc.getMethVarRef(*selector);
       args.push_back(DtoBitCast(DtoLoad(selptr), getVoidPtrType()));
     }
   }

tests/compilable/objc_gh2388.d

@@ -0,0 +1,15 @@
+// REQUIRES: Darwin
+// RUN: %ldc -c -singleobj %s %S/objc_gh2387.d
+
+void alloc()
+{
+    NSObject o;
+    o.alloc();
+}
+
+extern (Objective-C):
+
+interface NSObject
+{
+    NSObject alloc() @selector("alloc");
+}