[llvm-commits] [llvm-gcc-4.2] r53624 - /llvm-gcc-4.2/trunk/gcc/llvm-convert.cpp

[Dale Johannesen]

Author: johannes
Date: Tue Jul 15 12:57:24 2008
New Revision: 53624

URL: http://llvm.org/viewvc/llvm-project?rev=53624&view=rev
Log:
Improve comment on my last checkin.


Modified:
    llvm-gcc-4.2/trunk/gcc/llvm-convert.cpp

Modified: llvm-gcc-4.2/trunk/gcc/llvm-convert.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm-gcc-4.2/trunk/gcc/llvm-convert.cpp?rev=53624&r1=53623&r2=53624&view=diff

==============================================================================
--- llvm-gcc-4.2/trunk/gcc/llvm-convert.cpp (original)
+++ llvm-gcc-4.2/trunk/gcc/llvm-convert.cpp Tue Jul 15 12:57:24 2008
@@ -5753,8 +5753,11 @@
   } else {
     Value *Offset = Emit(field_offset, 0);
 
-    // For ObjC2, we may have a base class field that should not be taken into
-    // account here, as it is already in Offset.  The ObjC FE figures this out.
+    // For ObjC2, the offset of the field is loaded from memory (it can
+    // change at runtime), and the initial value in memory includes the
+    // value that would normally be computed at compile time; we don't
+    // want to add this in twice.  The ObjC FE figures out the value we
+    // actually should add at compile time (usually 0).
     tree field_bit_offset = objc_v2_bitfield_ivar_bitpos(exp);
     if (field_bit_offset) {
       BitStart = (unsigned)getINTEGER_CSTVal(field_bit_offset);