[CodeGen] Propagate may-alias'ness of lvalues with TBAA info

This patch fixes various places in clang to propagate may-alias
TBAA access descriptors during construction of lvalues, thus
eliminating the need for the LValueBaseInfo::MayAlias flag.

This is part of D38126 reworked to be a separate patch to
simplify review.

Differential Revision: https://reviews.llvm.org/D39008

llvm-svn: 316988

1 files changed, 13 insertions, 4 deletions

diff --git a/clang/lib/CodeGen/CodeGenModule.h b/clang/lib/CodeGen/CodeGenModule.h
index ebc1ec65cfe..21bab6cfa05 100644
--- a/clang/lib/CodeGen/CodeGenModule.h
+++ b/clang/lib/CodeGen/CodeGenModule.h
@@ -673,15 +673,24 @@ public:
   /// getTBAAAccessTagInfo - Get TBAA tag for a given memory access.
   llvm::MDNode *getTBAAAccessTagInfo(TBAAAccessInfo Info);
 
-  /// getTBAAMayAliasAccessInfo - Get TBAA information that represents
-  /// may-alias accesses.
-  TBAAAccessInfo getTBAAMayAliasAccessInfo();
-
   /// mergeTBAAInfoForCast - Get merged TBAA information for the purposes of
   /// type casts.
   TBAAAccessInfo mergeTBAAInfoForCast(TBAAAccessInfo SourceInfo,
                                       TBAAAccessInfo TargetInfo);
 
+  /// mergeTBAAInfoForConditionalOperator - Get merged TBAA information for the
+  /// purposes of conditional operator.
+  TBAAAccessInfo mergeTBAAInfoForConditionalOperator(TBAAAccessInfo InfoA,
+                                                     TBAAAccessInfo InfoB);
+
+  /// getTBAAInfoForSubobject - Get TBAA information for an access with a given
+  /// base lvalue.
+  TBAAAccessInfo getTBAAInfoForSubobject(LValue Base, QualType AccessType) {
+    if (Base.getTBAAInfo().isMayAlias())
+      return TBAAAccessInfo::getMayAliasInfo();
+    return getTBAAAccessInfo(AccessType);
+  }
+
   bool isTypeConstant(QualType QTy, bool ExcludeCtorDtor);
 
   bool isPaddedAtomicType(QualType type);