[llvm-branch-commits] [cfe-branch] r309135 - Merging r309058:

[Hans Wennborg via llvm-branch-commits]

Author: hans
Date: Wed Jul 26 09:35:53 2017
New Revision: 309135

URL: http://llvm.org/viewvc/llvm-project?rev=309135&view=rev
Log:
Merging r309058:
------------------------------------------------------------------------
r309058 | majnemer | 2017-07-25 16:33:58 -0700 (Tue, 25 Jul 2017) | 9 lines

[CodeGen] Correctly model std::byte's aliasing properties

std::byte, when defined as an enum, needs to be given special treatment
with regards to its aliasing properties. An array of std::byte is
allowed to be used as storage for other types.

This fixes PR33916.

Differential Revision: https://reviews.llvm.org/D35824
------------------------------------------------------------------------

Added:
    cfe/branches/release_50/test/CodeGenCXX/std-byte.cpp
      - copied unchanged from r309058, cfe/trunk/test/CodeGenCXX/std-byte.cpp
Modified:
    cfe/branches/release_50/   (props changed)
    cfe/branches/release_50/include/clang/AST/Type.h
    cfe/branches/release_50/lib/AST/Type.cpp
    cfe/branches/release_50/lib/CodeGen/CodeGenTBAA.cpp

Propchange: cfe/branches/release_50/
------------------------------------------------------------------------------
--- svn:mergeinfo (original)
+++ svn:mergeinfo Wed Jul 26 09:35:53 2017
@@ -1,4 +1,4 @@
 /cfe/branches/type-system-rewrite:134693-134817
-/cfe/trunk:308455,308824,308897
+/cfe/trunk:308455,308824,308897,309058
 /cfe/trunk/test:170344
 /cfe/trunk/test/SemaTemplate:126920

Modified: cfe/branches/release_50/include/clang/AST/Type.h
URL: http://llvm.org/viewvc/llvm-project/cfe/branches/release_50/include/clang/AST/Type.h?rev=309135&r1=309134&r2=309135&view=diff
==============================================================================
--- cfe/branches/release_50/include/clang/AST/Type.h (original)
+++ cfe/branches/release_50/include/clang/AST/Type.h Wed Jul 26 09:35:53 2017
@@ -1752,6 +1752,7 @@ public:
   bool isTemplateTypeParmType() const;          // C++ template type parameter
   bool isNullPtrType() const;                   // C++11 std::nullptr_t
   bool isAlignValT() const;                     // C++17 std::align_val_t
+  bool isStdByteType() const;                   // C++17 std::byte
   bool isAtomicType() const;                    // C11 _Atomic()
 
 #define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) \

Modified: cfe/branches/release_50/lib/AST/Type.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/branches/release_50/lib/AST/Type.cpp?rev=309135&r1=309134&r2=309135&view=diff
==============================================================================
--- cfe/branches/release_50/lib/AST/Type.cpp (original)
+++ cfe/branches/release_50/lib/AST/Type.cpp Wed Jul 26 09:35:53 2017
@@ -2313,6 +2313,15 @@ bool Type::isAlignValT() const {
   return false;
 }
 
+bool Type::isStdByteType() const {
+  if (auto *ET = getAs<EnumType>()) {
+    auto *II = ET->getDecl()->getIdentifier();
+    if (II && II->isStr("byte") && ET->getDecl()->isInStdNamespace())
+      return true;
+  }
+  return false;
+}
+
 bool Type::isPromotableIntegerType() const {
   if (const BuiltinType *BT = getAs<BuiltinType>())
     switch (BT->getKind()) {

Modified: cfe/branches/release_50/lib/CodeGen/CodeGenTBAA.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/branches/release_50/lib/CodeGen/CodeGenTBAA.cpp?rev=309135&r1=309134&r2=309135&view=diff
==============================================================================
--- cfe/branches/release_50/lib/CodeGen/CodeGenTBAA.cpp (original)
+++ cfe/branches/release_50/lib/CodeGen/CodeGenTBAA.cpp Wed Jul 26 09:35:53 2017
@@ -139,6 +139,12 @@ CodeGenTBAA::getTBAAInfo(QualType QTy) {
     }
   }
 
+  // C++1z [basic.lval]p10: "If a program attempts to access the stored value of
+  // an object through a glvalue of other than one of the following types the
+  // behavior is undefined: [...] a char, unsigned char, or std::byte type."
+  if (Ty->isStdByteType())
+    return MetadataCache[Ty] = getChar();
+
   // Handle pointers.
   // TODO: Implement C++'s type "similarity" and consider dis-"similar"
   // pointers distinct.