Updating branches/google/stable to r176857

git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/google/stable@177040 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 241 insertions, 0 deletions

diff --git a/lib/Transforms/ObjCARC/ObjCARCUtil.cpp b/lib/Transforms/ObjCARC/ObjCARCUtil.cpp
new file mode 100644
index 0000000000..a841c64a9f
--- /dev/null
+++ b/lib/Transforms/ObjCARC/ObjCARCUtil.cpp
@@ -0,0 +1,241 @@
+//===- ObjCARCUtil.cpp - 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 defines several utility functions used by various ARC
+/// optimizations which are IMHO too big to be in a header file.
+///
+/// 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.
+///
+//===----------------------------------------------------------------------===//
+
+#include "ObjCARC.h"
+#include "llvm/IR/Intrinsics.h"
+
+using namespace llvm;
+using namespace llvm::objcarc;
+
+raw_ostream &llvm::objcarc::operator<<(raw_ostream &OS,
+                                       const InstructionClass Class) {
+  switch (Class) {
+  case IC_Retain:
+    return OS << "IC_Retain";
+  case IC_RetainRV:
+    return OS << "IC_RetainRV";
+  case IC_RetainBlock:
+    return OS << "IC_RetainBlock";
+  case IC_Release:
+    return OS << "IC_Release";
+  case IC_Autorelease:
+    return OS << "IC_Autorelease";
+  case IC_AutoreleaseRV:
+    return OS << "IC_AutoreleaseRV";
+  case IC_AutoreleasepoolPush:
+    return OS << "IC_AutoreleasepoolPush";
+  case IC_AutoreleasepoolPop:
+    return OS << "IC_AutoreleasepoolPop";
+  case IC_NoopCast:
+    return OS << "IC_NoopCast";
+  case IC_FusedRetainAutorelease:
+    return OS << "IC_FusedRetainAutorelease";
+  case IC_FusedRetainAutoreleaseRV:
+    return OS << "IC_FusedRetainAutoreleaseRV";
+  case IC_LoadWeakRetained:
+    return OS << "IC_LoadWeakRetained";
+  case IC_StoreWeak:
+    return OS << "IC_StoreWeak";
+  case IC_InitWeak:
+    return OS << "IC_InitWeak";
+  case IC_LoadWeak:
+    return OS << "IC_LoadWeak";
+  case IC_MoveWeak:
+    return OS << "IC_MoveWeak";
+  case IC_CopyWeak:
+    return OS << "IC_CopyWeak";
+  case IC_DestroyWeak:
+    return OS << "IC_DestroyWeak";
+  case IC_StoreStrong:
+    return OS << "IC_StoreStrong";
+  case IC_CallOrUser:
+    return OS << "IC_CallOrUser";
+  case IC_Call:
+    return OS << "IC_Call";
+  case IC_User:
+    return OS << "IC_User";
+  case IC_None:
+    return OS << "IC_None";
+  }
+  llvm_unreachable("Unknown instruction class!");
+}
+
+InstructionClass llvm::objcarc::GetFunctionClass(const Function *F) {
+  Function::const_arg_iterator AI = F->arg_begin(), AE = F->arg_end();
+
+  // No arguments.
+  if (AI == AE)
+    return StringSwitch<InstructionClass>(F->getName())
+      .Case("objc_autoreleasePoolPush",  IC_AutoreleasepoolPush)
+      .Default(IC_CallOrUser);
+
+  // One argument.
+  const Argument *A0 = AI++;
+  if (AI == AE)
+    // Argument is a pointer.
+    if (PointerType *PTy = dyn_cast<PointerType>(A0->getType())) {
+      Type *ETy = PTy->getElementType();
+      // Argument is i8*.
+      if (ETy->isIntegerTy(8))
+        return StringSwitch<InstructionClass>(F->getName())
+          .Case("objc_retain",                IC_Retain)
+          .Case("objc_retainAutoreleasedReturnValue", IC_RetainRV)
+          .Case("objc_retainBlock",           IC_RetainBlock)
+          .Case("objc_release",               IC_Release)
+          .Case("objc_autorelease",           IC_Autorelease)
+          .Case("objc_autoreleaseReturnValue", IC_AutoreleaseRV)
+          .Case("objc_autoreleasePoolPop",    IC_AutoreleasepoolPop)
+          .Case("objc_retainedObject",        IC_NoopCast)
+          .Case("objc_unretainedObject",      IC_NoopCast)
+          .Case("objc_unretainedPointer",     IC_NoopCast)
+          .Case("objc_retain_autorelease",    IC_FusedRetainAutorelease)
+          .Case("objc_retainAutorelease",     IC_FusedRetainAutorelease)
+          .Case("objc_retainAutoreleaseReturnValue",IC_FusedRetainAutoreleaseRV)
+          .Default(IC_CallOrUser);
+
+      // Argument is i8**
+      if (PointerType *Pte = dyn_cast<PointerType>(ETy))
+        if (Pte->getElementType()->isIntegerTy(8))
+          return StringSwitch<InstructionClass>(F->getName())
+            .Case("objc_loadWeakRetained",      IC_LoadWeakRetained)
+            .Case("objc_loadWeak",              IC_LoadWeak)
+            .Case("objc_destroyWeak",           IC_DestroyWeak)
+            .Default(IC_CallOrUser);
+    }
+
+  // Two arguments, first is i8**.
+  const Argument *A1 = AI++;
+  if (AI == AE)
+    if (PointerType *PTy = dyn_cast<PointerType>(A0->getType()))
+      if (PointerType *Pte = dyn_cast<PointerType>(PTy->getElementType()))
+        if (Pte->getElementType()->isIntegerTy(8))
+          if (PointerType *PTy1 = dyn_cast<PointerType>(A1->getType())) {
+            Type *ETy1 = PTy1->getElementType();
+            // Second argument is i8*
+            if (ETy1->isIntegerTy(8))
+              return StringSwitch<InstructionClass>(F->getName())
+                .Case("objc_storeWeak",             IC_StoreWeak)
+                .Case("objc_initWeak",              IC_InitWeak)
+                .Case("objc_storeStrong",           IC_StoreStrong)
+                .Default(IC_CallOrUser);
+            // Second argument is i8**.
+            if (PointerType *Pte1 = dyn_cast<PointerType>(ETy1))
+              if (Pte1->getElementType()->isIntegerTy(8))
+                return StringSwitch<InstructionClass>(F->getName())
+                  .Case("objc_moveWeak",              IC_MoveWeak)
+                  .Case("objc_copyWeak",              IC_CopyWeak)
+                  .Default(IC_CallOrUser);
+          }
+
+  // Anything else.
+  return IC_CallOrUser;
+}
+
+/// \brief Determine what kind of construct V is.
+InstructionClass
+llvm::objcarc::GetInstructionClass(const Value *V) {
+  if (const Instruction *I = dyn_cast<Instruction>(V)) {
+    // Any instruction other than bitcast and gep with a pointer operand have a
+    // use of an objc pointer. Bitcasts, GEPs, Selects, PHIs transfer a pointer
+    // to a subsequent use, rather than using it themselves, in this sense.
+    // As a short cut, several other opcodes are known to have no pointer
+    // operands of interest. And ret is never followed by a release, so it's
+    // not interesting to examine.
+    switch (I->getOpcode()) {
+    case Instruction::Call: {
+      const CallInst *CI = cast<CallInst>(I);
+      // Check for calls to special functions.
+      if (const Function *F = CI->getCalledFunction()) {
+        InstructionClass Class = GetFunctionClass(F);
+        if (Class != IC_CallOrUser)
+          return Class;
+
+        // None of the intrinsic functions do objc_release. For intrinsics, the
+        // only question is whether or not they may be users.
+        switch (F->getIntrinsicID()) {
+        case Intrinsic::returnaddress: case Intrinsic::frameaddress:
+        case Intrinsic::stacksave: case Intrinsic::stackrestore:
+        case Intrinsic::vastart: case Intrinsic::vacopy: case Intrinsic::vaend:
+        case Intrinsic::objectsize: case Intrinsic::prefetch:
+        case Intrinsic::stackprotector:
+        case Intrinsic::eh_return_i32: case Intrinsic::eh_return_i64:
+        case Intrinsic::eh_typeid_for: case Intrinsic::eh_dwarf_cfa:
+        case Intrinsic::eh_sjlj_lsda: case Intrinsic::eh_sjlj_functioncontext:
+        case Intrinsic::init_trampoline: case Intrinsic::adjust_trampoline:
+        case Intrinsic::lifetime_start: case Intrinsic::lifetime_end:
+        case Intrinsic::invariant_start: case Intrinsic::invariant_end:
+        // Don't let dbg info affect our results.
+        case Intrinsic::dbg_declare: case Intrinsic::dbg_value:
+          // Short cut: Some intrinsics obviously don't use ObjC pointers.
+          return IC_None;
+        default:
+          break;
+        }
+      }
+      return GetCallSiteClass(CI);
+    }
+    case Instruction::Invoke:
+      return GetCallSiteClass(cast<InvokeInst>(I));
+    case Instruction::BitCast:
+    case Instruction::GetElementPtr:
+    case Instruction::Select: case Instruction::PHI:
+    case Instruction::Ret: case Instruction::Br:
+    case Instruction::Switch: case Instruction::IndirectBr:
+    case Instruction::Alloca: case Instruction::VAArg:
+    case Instruction::Add: case Instruction::FAdd:
+    case Instruction::Sub: case Instruction::FSub:
+    case Instruction::Mul: case Instruction::FMul:
+    case Instruction::SDiv: case Instruction::UDiv: case Instruction::FDiv:
+    case Instruction::SRem: case Instruction::URem: case Instruction::FRem:
+    case Instruction::Shl: case Instruction::LShr: case Instruction::AShr:
+    case Instruction::And: case Instruction::Or: case Instruction::Xor:
+    case Instruction::SExt: case Instruction::ZExt: case Instruction::Trunc:
+    case Instruction::IntToPtr: case Instruction::FCmp:
+    case Instruction::FPTrunc: case Instruction::FPExt:
+    case Instruction::FPToUI: case Instruction::FPToSI:
+    case Instruction::UIToFP: case Instruction::SIToFP:
+    case Instruction::InsertElement: case Instruction::ExtractElement:
+    case Instruction::ShuffleVector:
+    case Instruction::ExtractValue:
+      break;
+    case Instruction::ICmp:
+      // Comparing a pointer with null, or any other constant, isn't an
+      // interesting use, because we don't care what the pointer points to, or
+      // about the values of any other dynamic reference-counted pointers.
+      if (IsPotentialRetainableObjPtr(I->getOperand(1)))
+        return IC_User;
+      break;
+    default:
+      // For anything else, check all the operands.
+      // Note that this includes both operands of a Store: while the first
+      // operand isn't actually being dereferenced, it is being stored to
+      // memory where we can no longer track who might read it and dereference
+      // it, so we have to consider it potentially used.
+      for (User::const_op_iterator OI = I->op_begin(), OE = I->op_end();
+           OI != OE; ++OI)
+        if (IsPotentialRetainableObjPtr(*OI))
+          return IC_User;
+    }
+  }
+
+  // Otherwise, it's totally inert for ARC purposes.
+  return IC_None;
+}