map previously ignored __attribute((malloc)) to noalias attribute of llvm function's return

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@78541 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/AST/Attr.h

@@ -59,6 +59,7 @@ public:
     FormatArg,
     GNUInline,
     IBOutletKind, // Clang-specific.  Use "Kind" suffix to not conflict with
+    Malloc,
     NoReturn,
     NoThrow,
     Nodebug,
@@ -288,6 +289,7 @@ public:
   static bool classof(const IBOutletAttr *A) { return true; }
 };
 
+DEF_SIMPLE_ATTR(Malloc);
 DEF_SIMPLE_ATTR(NoReturn);
 DEF_SIMPLE_ATTR(AnalyzerNoReturn);  
 DEF_SIMPLE_ATTR(Deprecated);

include/clang/Parse/AttributeList.h

@@ -69,6 +69,7 @@ public:
     AT_format,
     AT_format_arg,
     AT_gnu_inline,
+    AT_malloc,
     AT_mode,
     AT_nodebug,
     AT_noinline,

lib/CodeGen/CGCall.cpp

@@ -385,6 +385,8 @@ void CodeGenModule::ConstructAttributeList(const CGFunctionInfo &FI,
       FuncAttrs |= llvm::Attribute::ReadNone;
     else if (TargetDecl->hasAttr<PureAttr>())
       FuncAttrs |= llvm::Attribute::ReadOnly;
+    if (TargetDecl->hasAttr<MallocAttr>())
+      RetAttrs |= llvm::Attribute::NoAlias;
   }
 
   if (CompileOpts.DisableRedZone)

lib/Frontend/PCHReaderDecl.cpp

@@ -480,6 +480,7 @@ Attr *PCHReader::ReadAttributes() {
       New = ::new (*Context) IBOutletAttr();
       break;
 
+    SIMPLE_ATTR(Malloc);
     SIMPLE_ATTR(NoReturn);
     SIMPLE_ATTR(NoThrow);
     SIMPLE_ATTR(Nodebug);

lib/Frontend/PCHWriter.cpp

@@ -1678,6 +1678,7 @@ void PCHWriter::WriteAttributeRecord(const Attr *Attr) {
         
     case Attr::GNUInline:
     case Attr::IBOutletKind:
+    case Attr::Malloc:
     case Attr::NoReturn:
     case Attr::NoThrow:
     case Attr::Nodebug:

lib/Parse/AttributeList.cpp

@@ -69,7 +69,7 @@ AttributeList::Kind AttributeList::getKind(const IdentifierInfo *Name) {
     break;
   case 6:
     if (!memcmp(Str, "packed", 6)) return AT_packed;
-    if (!memcmp(Str, "malloc", 6)) return IgnoredAttribute; // FIXME: noalias.
+    if (!memcmp(Str, "malloc", 6)) return AT_malloc;
     if (!memcmp(Str, "format", 6)) return AT_format;
     if (!memcmp(Str, "unused", 6)) return AT_unused;
     if (!memcmp(Str, "blocks", 6)) return AT_blocks;

lib/Sema/SemaDeclAttr.cpp

@@ -424,6 +424,22 @@ static void HandleAlwaysInlineAttr(Decl *d, const AttributeList &Attr,
   d->addAttr(::new (S.Context) AlwaysInlineAttr());
 }
 
+static void HandleMallocAttr(Decl *d, const AttributeList &Attr, Sema &S) {
+  // check the attribute arguments.
+  if (Attr.getNumArgs() != 0) {
+    S.Diag(Attr.getLoc(), diag::err_attribute_wrong_number_arguments) << 0;
+    return;
+  }
+
+  if (!isFunctionOrMethod(d)) {
+    S.Diag(Attr.getLoc(), diag::warn_attribute_wrong_decl_type)
+      << Attr.getName() << 0 /*function*/;
+    return;
+  }
+
+  d->addAttr(::new (S.Context) MallocAttr());
+}
+
 static bool HandleCommonNoReturnAttr(Decl *d, const AttributeList &Attr,
                                      Sema &S) {
   // check the attribute arguments.
@@ -1759,6 +1775,7 @@ static void ProcessDeclAttribute(Scope *scope, Decl *D,
   case AttributeList::AT_format_arg:  HandleFormatArgAttr (D, Attr, S); break;
   case AttributeList::AT_gnu_inline:  HandleGNUInlineAttr(D, Attr, S); break;
   case AttributeList::AT_mode:        HandleModeAttr      (D, Attr, S); break;
+  case AttributeList::AT_malloc:      HandleMallocAttr    (D, Attr, S); break;
   case AttributeList::AT_nonnull:     HandleNonNullAttr   (D, Attr, S); break;
   case AttributeList::AT_noreturn:    HandleNoReturnAttr  (D, Attr, S); break;
   case AttributeList::AT_nothrow:     HandleNothrowAttr   (D, Attr, S); break;

test/Sema/attr-malloc.c

@@ -0,0 +1,16 @@
+// RUN: clang-cc -verify -fsyntax-only %s &&
+// RUN: clang-cc -emit-llvm -o %t %s &&
+
+#include <stdlib.h>
+
+int no_vars __attribute((malloc)); // expected-warning {{only applies to function types}}
+
+__attribute((malloc))
+void * xalloc(unsigned n) { return malloc(n); }
+// RUN: grep 'define noalias .* @xalloc(' %t &&
+
+#define __malloc_like __attribute((__malloc__))
+void * xalloc2(unsigned) __malloc_like;
+void * xalloc2(unsigned n) { return malloc(n); }
+// RUN: grep 'define noalias .* @xalloc2(' %t
+