Use address-taken to disambiguate global variable and indirect memops.

 Major steps include:
 1). introduces a not-addr-taken bit-field in GlobalVariable
 2). GlobalOpt pass sets "not-address-taken" if it proves a global varirable 
    dosen't have its address taken.
 3). AA use this info for disambiguation. 


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193251 91177308-0d34-0410-b5e6-96231b3b80d8

9 files changed, 27 insertions, 2 deletions

diff --git a/lib/Analysis/BasicAliasAnalysis.cpp b/lib/Analysis/BasicAliasAnalysis.cpp
index bf92969..4e423a7 100644
--- a/lib/Analysis/BasicAliasAnalysis.cpp
+++ b/lib/Analysis/BasicAliasAnalysis.cpp
@@ -1238,6 +1238,17 @@ BasicAliasAnalysis::aliasCheck(const Value *V1, uint64_t V1Size,
       return NoAlias;
     if (isEscapeSource(O2) && isNonEscapingLocalObject(O1))
       return NoAlias;
+
+    // If one object is a global variable without address taken, the other one
+    // is a different object, they will not alias because the global variable
+    // in question cannot be indirectly accessed.
+    if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(O1))
+      if (!GV->AddressMaybeTaken())
+        return NoAlias;
+
+    if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(O2))
+      if (!GV->AddressMaybeTaken())
+        return NoAlias;
   }
 
   // If the size of one access is larger than the entire object on the other
diff --git a/lib/AsmParser/LLLexer.cpp b/lib/AsmParser/LLLexer.cpp
index 99bff45..6d643b6 100644
--- a/lib/AsmParser/LLLexer.cpp
+++ b/lib/AsmParser/LLLexer.cpp
@@ -504,6 +504,7 @@ lltok::Kind LLLexer::LexIdentifier() {
   KEYWORD(zeroinitializer);
   KEYWORD(undef);
   KEYWORD(null);
+  KEYWORD(notaddrtaken);
   KEYWORD(to);
   KEYWORD(tail);
   KEYWORD(target);
diff --git a/lib/AsmParser/LLParser.cpp b/lib/AsmParser/LLParser.cpp
index 74c0ea4..9b5fb27 100644
--- a/lib/AsmParser/LLParser.cpp
+++ b/lib/AsmParser/LLParser.cpp
@@ -704,7 +704,7 @@ bool LLParser::ParseGlobal(const std::string &Name, LocTy NameLoc,
                            unsigned Linkage, bool HasLinkage,
                            unsigned Visibility) {
   unsigned AddrSpace;
-  bool IsConstant, UnnamedAddr, IsExternallyInitialized;
+  bool IsConstant, UnnamedAddr, IsExternallyInitialized, notAddrTaken;
   GlobalVariable::ThreadLocalMode TLM;
   LocTy UnnamedAddrLoc;
   LocTy IsExternallyInitializedLoc;
@@ -719,6 +719,7 @@ bool LLParser::ParseGlobal(const std::string &Name, LocTy NameLoc,
                          IsExternallyInitialized,
                          &IsExternallyInitializedLoc) ||
       ParseGlobalType(IsConstant) ||
+      ParseOptionalToken(lltok::kw_notaddrtaken, notAddrTaken) ||
       ParseType(Ty, TyLoc))
     return true;
 
@@ -776,6 +777,7 @@ bool LLParser::ParseGlobal(const std::string &Name, LocTy NameLoc,
   GV->setLinkage((GlobalValue::LinkageTypes)Linkage);
   GV->setVisibility((GlobalValue::VisibilityTypes)Visibility);
   GV->setExternallyInitialized(IsExternallyInitialized);
+  GV->setAddressMaybeTaken(!notAddrTaken);
   GV->setThreadLocalMode(TLM);
   GV->setUnnamedAddr(UnnamedAddr);
 
diff --git a/lib/AsmParser/LLToken.h b/lib/AsmParser/LLToken.h
index e1382fd..7832e81 100644
--- a/lib/AsmParser/LLToken.h
+++ b/lib/AsmParser/LLToken.h
@@ -51,6 +51,7 @@ namespace lltok {
     kw_localdynamic, kw_initialexec, kw_localexec,
     kw_zeroinitializer,
     kw_undef, kw_null,
+    kw_notaddrtaken,
     kw_to,
     kw_tail,
     kw_target,
diff --git a/lib/Bitcode/Reader/BitcodeReader.cpp b/lib/Bitcode/Reader/BitcodeReader.cpp
index e408cd1..3fca4ab 100644
--- a/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -1848,6 +1848,9 @@ bool BitcodeReader::ParseModule(bool Resume) {
         new GlobalVariable(*TheModule, Ty, isConstant, Linkage, 0, "", 0,
                            TLM, AddressSpace, ExternallyInitialized);
       NewGV->setAlignment(Alignment);
+      if (Record.size() > 10)
+        NewGV->setAddressMaybeTaken(Record[10]);
+
       if (!Section.empty())
         NewGV->setSection(Section);
       NewGV->setVisibility(Visibility);
diff --git a/lib/Bitcode/Writer/BitcodeWriter.cpp b/lib/Bitcode/Writer/BitcodeWriter.cpp
index b082ba6..4f631b9 100644
--- a/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -616,11 +616,13 @@ static void WriteModuleInfo(const Module *M, const ValueEnumerator &VE,
     Vals.push_back(GV->hasSection() ? SectionMap[GV->getSection()] : 0);
     if (GV->isThreadLocal() ||
         GV->getVisibility() != GlobalValue::DefaultVisibility ||
-        GV->hasUnnamedAddr() || GV->isExternallyInitialized()) {
+        GV->hasUnnamedAddr() || GV->isExternallyInitialized() ||
+        !GV->AddressMaybeTaken()) {
       Vals.push_back(getEncodedVisibility(GV));
       Vals.push_back(getEncodedThreadLocalMode(GV));
       Vals.push_back(GV->hasUnnamedAddr());
       Vals.push_back(GV->isExternallyInitialized());
+      Vals.push_back(GV->AddressMaybeTaken());
     } else {
       AbbrevToUse = SimpleGVarAbbrev;
     }
diff --git a/lib/IR/AsmWriter.cpp b/lib/IR/AsmWriter.cpp
index 6e3b853..dc337c1 100644
--- a/lib/IR/AsmWriter.cpp
+++ b/lib/IR/AsmWriter.cpp
@@ -1459,6 +1459,7 @@ void AssemblyWriter::printGlobal(const GlobalVariable *GV) {
   if (GV->hasUnnamedAddr()) Out << "unnamed_addr ";
   if (GV->isExternallyInitialized()) Out << "externally_initialized ";
   Out << (GV->isConstant() ? "constant " : "global ");
+  if (!GV->AddressMaybeTaken()) Out << "notaddrtaken ";
   TypePrinter.print(GV->getType()->getElementType(), Out);
 
   if (GV->hasInitializer()) {
diff --git a/lib/IR/Globals.cpp b/lib/IR/Globals.cpp
index da3b02a..8c28ec1 100644
--- a/lib/IR/Globals.cpp
+++ b/lib/IR/Globals.cpp
@@ -99,6 +99,7 @@ GlobalVariable::GlobalVariable(Type *Ty, bool constant, LinkageTypes Link,
   }
 
   LeakDetector::addGarbageObject(this);
+  setAddressMaybeTaken(true);
 }
 
 GlobalVariable::GlobalVariable(Module &M, Type *Ty, bool constant,
@@ -125,6 +126,7 @@ GlobalVariable::GlobalVariable(Module &M, Type *Ty, bool constant,
     Before->getParent()->getGlobalList().insert(Before, this);
   else
     M.getGlobalList().push_back(this);
+  setAddressMaybeTaken(true);
 }
 
 void GlobalVariable::setParent(Module *parent) {
@@ -185,6 +187,7 @@ void GlobalVariable::copyAttributesFrom(const GlobalValue *Src) {
   GlobalValue::copyAttributesFrom(Src);
   const GlobalVariable *SrcVar = cast<GlobalVariable>(Src);
   setThreadLocal(SrcVar->isThreadLocal());
+  setAddressMaybeTaken(SrcVar->AddressMaybeTaken());
 }
 
 
diff --git a/lib/Transforms/IPO/GlobalOpt.cpp b/lib/Transforms/IPO/GlobalOpt.cpp
index 82a59ed..a259b4d 100644
--- a/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/lib/Transforms/IPO/GlobalOpt.cpp
@@ -1723,6 +1723,7 @@ bool GlobalOpt::ProcessGlobal(GlobalVariable *GV,
   if (GlobalStatus::analyzeGlobal(GV, GS))
     return false;
 
+  GV->setAddressMaybeTaken(false);
   if (!GS.IsCompared && !GV->hasUnnamedAddr()) {
     GV->setUnnamedAddr(true);
     NumUnnamed++;