[objc-arc] Refactor runtime entrypoint declaration entrypoint creation.

This is the first patch in a series of 3 patches which clean up how we create
runtime function declarations in the ARC optimizer when they do not exist
already in the IR.

Currently we have a bunch of duplicated code in ObjCARCOpts, ObjCARCContract
that does this. This patch refactors that code into a separate class called
ARCRuntimeEntryPoints which lazily creates the declarations for said
entrypoints.

The next two patches will consist of the work of refactoring
ObjCARCContract/ObjCARCOpts to use this new code.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185740 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/ObjCARC/ARCRuntimeEntryPoints.h

@@ -0,0 +1,178 @@
+//===- ARCRuntimeEntryPoints.h - ObjC ARC Optimization --*- mode: c++ -*---===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+/// \file
+/// This file contains a class ARCRuntimeEntryPoints for use in
+/// creating/managing references to entry points to the arc objective c runtime.
+///
+/// WARNING: This file knows about certain library functions. It recognizes them
+/// by name, and hardwires knowledge of their semantics.
+///
+/// WARNING: This file knows about how certain Objective-C library functions are
+/// used. Naive LLVM IR transformations which would otherwise be
+/// behavior-preserving may break these assumptions.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_SCALAR_ARCRUNTIMEENTRYPOINTS_H
+#define LLVM_TRANSFORMS_SCALAR_ARCRUNTIMEENTRYPOINTS_H
+
+#include "ObjCARC.h"
+
+namespace llvm {
+namespace objcarc {
+
+/// Declarations for ObjC runtime functions and constants. These are initialized
+/// lazily to avoid cluttering up the Module with unused declarations.
+class ARCRuntimeEntryPoints {
+public:
+  enum EntryPointType {
+    EPT_AutoreleaseRV,
+    EPT_Release,
+    EPT_Retain,
+    EPT_RetainBlock,
+    EPT_Autorelease,
+    EPT_StoreStrong,
+    EPT_RetainRV,
+    EPT_RetainAutorelease,
+    EPT_RetainAutoreleaseRV
+  };
+
+  ARCRuntimeEntryPoints() : Module(0),
+                            AutoreleaseRV(0),
+                            Release(0),
+                            Retain(0),
+                            RetainBlock(0),
+                            Autorelease(0),
+                            StoreStrong(0),
+                            RetainRV(0),
+                            RetainAutorelease(0),
+                            RetainAutoreleaseRV(0) { }
+
+  ~ARCRuntimeEntryPoints() { }
+
+  void Initialize(Module *M) {
+    Module = M;
+  }
+
+  Constant *get(const EntryPointType entry) {
+    assert(Module != 0 && "Not initialized.");
+
+    switch (entry) {
+    case EPT_AutoreleaseRV:
+      return getI8XRetI8XEntryPoint(AutoreleaseRV,
+                                    "objc_autoreleaseReturnValue", true);
+    case EPT_Release:
+      return getVoidRetI8XEntryPoint(Release, "objc_release");
+    case EPT_Retain:
+      return getI8XRetI8XEntryPoint(Retain, "objc_retain", true);
+    case EPT_RetainBlock:
+      return getI8XRetI8XEntryPoint(RetainBlock, "objc_retainBlock", false);
+    case EPT_Autorelease:
+      return getI8XRetI8XEntryPoint(Autorelease, "objc_autorelease", true);
+    case EPT_StoreStrong:
+      return getI8XRetI8XXI8XEntryPoint(StoreStrong, "objc_storeStrong");
+    case EPT_RetainAutorelease:
+      return getI8XRetI8XEntryPoint(RetainAutorelease, "objc_retainAutorelease",
+                                    true);
+    case EPT_RetainAutoreleaseRV:
+      return getI8XRetI8XEntryPoint(RetainAutoreleaseRV,
+                                    "objc_retainAutoreleaseReturnValue", true);
+    case EPT_RetainRV:
+      return getI8XRetI8XEntryPoint(RetainRV,
+                                    "objc_retainAutoreleasedReturnValue", true);
+    }
+  }
+
+private:
+  /// Cached reference to the module which we will insert declarations into.
+  Module *Module;
+
+  /// Declaration for ObjC runtime function objc_autoreleaseReturnValue.
+  Constant *AutoreleaseRV;
+  /// Declaration for ObjC runtime function objc_release.
+  Constant *Release;
+  /// Declaration for ObjC runtime function objc_retain.
+  Constant *Retain;
+  /// Declaration for ObjC runtime function objc_retainBlock.
+  Constant *RetainBlock;
+  /// Declaration for ObjC runtime function objc_autorelease.
+  Constant *Autorelease;
+  /// Declaration for objc_storeStrong().
+  Constant *StoreStrong;
+  /// Declaration for objc_retainAutoreleasedReturnValue().
+  Constant *RetainRV;
+  /// Declaration for objc_retainAutorelease().
+  Constant *RetainAutorelease;
+  /// Declaration for objc_retainAutoreleaseReturnValue().
+  Constant *RetainAutoreleaseRV;
+
+  Constant *getVoidRetI8XEntryPoint(Constant *&Decl,
+                                    const char *Name) {
+    if (Decl)
+      return Decl;
+
+    LLVMContext &C = Module->getContext();
+    Type *Params[] = { PointerType::getUnqual(Type::getInt8Ty(C)) };
+    AttributeSet Attr =
+      AttributeSet().addAttribute(Module->getContext(),
+                                  AttributeSet::FunctionIndex,
+                                  Attribute::NoUnwind);
+    FunctionType *Fty = FunctionType::get(Type::getVoidTy(C), Params,
+                                          /*isVarArg=*/false);
+    return Decl = Module->getOrInsertFunction(Name, Fty, Attr);
+  }
+
+  Constant *getI8XRetI8XEntryPoint(Constant *& Decl,
+                                   const char *Name,
+                                   bool NoUnwind = false) {
+    if (Decl)
+      return Decl;
+
+    LLVMContext &C = Module->getContext();
+    Type *I8X = PointerType::getUnqual(Type::getInt8Ty(C));
+    Type *Params[] = { I8X };
+    FunctionType *Fty = FunctionType::get(I8X, Params, /*isVarArg=*/false);
+    AttributeSet Attr = AttributeSet();
+
+    if (NoUnwind)
+      Attr = Attr.addAttribute(Module->getContext(),
+                               AttributeSet::FunctionIndex,
+                               Attribute::NoUnwind);
+
+    return Decl = Module->getOrInsertFunction(Name, Fty, Attr);
+  }
+
+  Constant *getI8XRetI8XXI8XEntryPoint(Constant *&Decl,
+                                       const char *Name) {
+    if (Decl)
+      return Decl;
+
+    LLVMContext &C = Module->getContext();
+    Type *I8X = PointerType::getUnqual(Type::getInt8Ty(C));
+    Type *I8XX = PointerType::getUnqual(I8X);
+    Type *Params[] = { I8XX, I8X };
+
+    AttributeSet Attr =
+      AttributeSet().addAttribute(Module->getContext(),
+                                  AttributeSet::FunctionIndex,
+                                  Attribute::NoUnwind);
+    Attr = Attr.addAttribute(Module->getContext(), 1, Attribute::NoCapture);
+
+    FunctionType *Fty = FunctionType::get(Type::getVoidTy(C), Params,
+                                          /*isVarArg=*/false);
+
+    return Decl = Module->getOrInsertFunction(Name, Fty, Attr);
+  }
+
+}; // class ARCRuntimeEntryPoints
+
+} // namespace objcarc
+} // namespace llvm
+
+#endif // LLVM_TRANSFORMS_SCALAR_ARCRUNTIMEENTRYPOINTS_H