enumerate the operands of a constant before we enumerate the constant itself
This avoids fwd references in the reader.
llvm-svn: 36822
diff --git a/llvm/lib/Bitcode/Writer/ValueEnumerator.cpp b/llvm/lib/Bitcode/Writer/ValueEnumerator.cpp
index ae9e67c..f5224d2 100644
--- a/llvm/lib/Bitcode/Writer/ValueEnumerator.cpp
+++ b/llvm/lib/Bitcode/Writer/ValueEnumerator.cpp
@@ -165,11 +165,10 @@
Values[ValueID-1].second++;
return;
}
-
- // Add the value.
- Values.push_back(std::make_pair(V, 1U));
- ValueID = Values.size();
+ // Enumerate the type of this value.
+ EnumerateType(V->getType());
+
if (const Constant *C = dyn_cast<Constant>(V)) {
if (isa<GlobalValue>(C)) {
// Initializers for globals are handled explicitly elsewhere.
@@ -177,16 +176,30 @@
// Do not enumerate the initializers for an array of simple characters.
// The initializers just polute the value table, and we emit the strings
// specially.
- } else {
- // This makes sure that if a constant has uses (for example an array of
- // const ints), that they are inserted also.
+ } else if (C->getNumOperands()) {
+ // If a constant has operands, enumerate them. This makes sure that if a
+ // constant has uses (for example an array of const ints), that they are
+ // inserted also.
+
+ // We prefer to enumerate them with values before we enumerate the user
+ // itself. This makes it more likely that we can avoid forward references
+ // in the reader. We know that there can be no cycles in the constants
+ // graph that don't go through a global variable.
for (User::const_op_iterator I = C->op_begin(), E = C->op_end();
I != E; ++I)
EnumerateValue(*I);
+
+ // Finally, add the value. Doing this could make the ValueID reference be
+ // dangling, don't reuse it.
+ Values.push_back(std::make_pair(V, 1U));
+ ValueMap[V] = Values.size();
+ return;
}
}
-
- EnumerateType(V->getType());
+
+ // Add the value.
+ Values.push_back(std::make_pair(V, 1U));
+ ValueID = Values.size();
}