[cfe-commits] r121477 - /cfe/trunk/include/clang/AST/Type.h

[Douglas Gregor]

Author: dgregor
Date: Fri Dec 10 04:08:30 2010
New Revision: 121477

URL: http://llvm.org/viewvc/llvm-project?rev=121477&view=rev
Log:
Update ExtQuals comment to reflect the expansion of the fast qualifiers

Modified:
    cfe/trunk/include/clang/AST/Type.h

Modified: cfe/trunk/include/clang/AST/Type.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/AST/Type.h?rev=121477&r1=121476&r2=121477&view=diff
==============================================================================
--- cfe/trunk/include/clang/AST/Type.h (original)
+++ cfe/trunk/include/clang/AST/Type.h Fri Dec 10 04:08:30 2010
@@ -327,20 +327,16 @@
 };
 
 
-/// ExtQuals - We can encode up to three bits in the low bits of a
+/// ExtQuals - We can encode up to four bits in the low bits of a
 /// type pointer, but there are many more type qualifiers that we want
 /// to be able to apply to an arbitrary type.  Therefore we have this
 /// struct, intended to be heap-allocated and used by QualType to
 /// store qualifiers.
 ///
-/// The current design tags the 'const' and 'restrict' qualifiers in
-/// two low bits on the QualType pointer; a third bit records whether
-/// the pointer is an ExtQuals node.  'const' was chosen because it is
-/// orders of magnitude more common than the other two qualifiers, in
-/// both library and user code.  It's relatively rare to see
-/// 'restrict' in user code, but many standard C headers are saturated
-/// with 'restrict' declarations, so that representing them efficiently
-/// is a critical goal of this representation.
+/// The current design tags the 'const', 'restrict', and 'volatile' qualifiers 
+/// in three low bits on the QualType pointer; a fourth bit records whether
+/// the pointer is an ExtQuals node. The extended qualifiers (address spaces,
+/// Objective-C GC attributes) are much more rare.
 class ExtQuals : public llvm::FoldingSetNode {
   // NOTE: changing the fast qualifiers should be straightforward as
   // long as you don't make 'const' non-fast.