IndVarSimplify: Don't let LFTR compare against a poison value

[oota-llvm.git] / lib / Transforms / ObjCARC / ObjCARCAPElim.cpp

diff --git a/lib/Transforms/ObjCARC/ObjCARCAPElim.cpp b/lib/Transforms/ObjCARC/ObjCARCAPElim.cpp
index 36cf4e54d5cf0daeecf02b98f34738f27bd636ca..1a253916d7ca08fd66d42ff73356e42aa837788e 100644 (file)
--- a/lib/Transforms/ObjCARC/ObjCARCAPElim.cpp
+++ b/lib/Transforms/ObjCARC/ObjCARCAPElim.cpp
@@ -1,4 +1,4 @@
-//===- ObjCARCOpts.cpp - ObjC ARC Optimization ----------------------------===//
+//===- ObjCARCAPElim.cpp - ObjC ARC Optimization --------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
@@ -7,17 +7,13 @@
 //
 //===----------------------------------------------------------------------===//
 /// \file
+///
 /// This file defines ObjC ARC optimizations. ARC stands for Automatic
 /// Reference Counting and is a system for managing reference counts for objects
 /// in Objective C.
 ///
-/// The optimizations performed include elimination of redundant, partially
-/// redundant, and inconsequential reference count operations, elimination of
-/// redundant weak pointer operations, pattern-matching and replacement of
-/// low-level operations into higher-level operations, and numerous minor
-/// simplifications.
-///
-/// This file also defines a simple ARC-aware AliasAnalysis.
+/// This specific file implements optimizations which remove extraneous
+/// autorelease pools.
 ///
 /// WARNING: This file knows about certain library functions. It recognizes them
 /// by name, and hardwires knowledge of their semantics.
@@ -28,20 +24,22 @@
 ///
 //===----------------------------------------------------------------------===//
 
-#define DEBUG_TYPE "objc-arc-ap-elim"
 #include "ObjCARC.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
 
 using namespace llvm;
 using namespace llvm::objcarc;
 
+#define DEBUG_TYPE "objc-arc-ap-elim"
+
 namespace {
   /// \brief Autorelease pool elimination.
   class ObjCARCAPElim : public ModulePass {
-    virtual void getAnalysisUsage(AnalysisUsage &AU) const;
-    virtual bool runOnModule(Module &M);
+    void getAnalysisUsage(AnalysisUsage &AU) const override;
+    bool runOnModule(Module &M) override;
 
     static bool MayAutorelease(ImmutableCallSite CS, unsigned Depth = 0);
     static bool OptimizeBB(BasicBlock *BB);
@@ -96,7 +94,7 @@ bool ObjCARCAPElim::MayAutorelease(ImmutableCallSite CS, unsigned Depth) {
 bool ObjCARCAPElim::OptimizeBB(BasicBlock *BB) {
   bool Changed = false;
 
-  Instruction *Push = 0;
+  Instruction *Push = nullptr;
   for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ) {
     Instruction *Inst = I++;
     switch (GetBasicInstructionClass(Inst)) {
@@ -115,11 +113,11 @@ bool ObjCARCAPElim::OptimizeBB(BasicBlock *BB) {
         Inst->eraseFromParent();
         Push->eraseFromParent();
       }
-      Push = 0;
+      Push = nullptr;
       break;
     case IC_CallOrUser:
       if (MayAutorelease(ImmutableCallSite(Inst)))
-        Push = 0;
+        Push = nullptr;
       break;
     default:
       break;
@@ -157,8 +155,8 @@ bool ObjCARCAPElim::runOnModule(Module &M) {
   for (User::op_iterator OI = Init->op_begin(), OE = Init->op_end();
        OI != OE; ++OI) {
     Value *Op = *OI;
-    // llvm.global_ctors is an array of pairs where the second members
-    // are constructor functions.
+    // llvm.global_ctors is an array of three-field structs where the second
+    // members are constructor functions.
     Function *F = dyn_cast<Function>(cast<ConstantStruct>(Op)->getOperand(1));
     // If the user used a constructor function with the wrong signature and
     // it got bitcasted or whatever, look the other way.
@@ -168,7 +166,7 @@ bool ObjCARCAPElim::runOnModule(Module &M) {
     if (F->isDeclaration())
       continue;
     // Only look at functions with one basic block.
-    if (llvm::next(F->begin()) != F->end())
+    if (std::next(F->begin()) != F->end())
       continue;
     // Ok, a single-block constructor function definition. Try to optimize it.
     Changed |= OptimizeBB(F->begin());