[llvm-commits] [dragonegg] r137606 - /dragonegg/trunk/src/Constants.cpp

[Duncan Sands]

Author: baldrick
Date: Mon Aug 15 03:20:05 2011
New Revision: 137606

URL: http://llvm.org/viewvc/llvm-project?rev=137606&view=rev
Log:
When processing a constructor and default initializing the fields
which did not get an explicit constructor entry, default initialize
in reverse order to ensure that the first field of a union is always
default initialized.  This is a theoretical fix since I failed to
construct a testcase for which this made a difference.

Modified:
    dragonegg/trunk/src/Constants.cpp

Modified: dragonegg/trunk/src/Constants.cpp
URL: http://llvm.org/viewvc/llvm-project/dragonegg/trunk/src/Constants.cpp?rev=137606&r1=137605&r2=137606&view=diff
==============================================================================
--- dragonegg/trunk/src/Constants.cpp (original)
+++ dragonegg/trunk/src/Constants.cpp Mon Aug 15 03:20:05 2011
@@ -1076,9 +1076,18 @@
   // initial value is supplied for a field then the value will overwrite and
   // replace the zero starting value later.
   if (flag_default_initialize_globals) {
+    // Process the fields in reverse order.  This is for the benefit of union
+    // types for which the first field must be default initialized (iterating
+    // in forward order would default initialize the last field).
+    SmallVector<tree, 16> Fields;
     for (tree field = TYPE_FIELDS(TREE_TYPE(exp)); field;
          field = TREE_CHAIN(field)) {
       assert(TREE_CODE(field) == FIELD_DECL && "Lang data not freed?");
+      Fields.push_back(field);
+    }
+    for (SmallVector<tree, 16>::reverse_iterator I = Fields.rbegin(),
+         E = Fields.rend(); I != E; ++I) {
+      tree field = *I;
       // If the field has variable or unknown position then it cannot be default
       // initialized - skip it.
       if (!OffsetIsLLVMCompatible(field))