Simplify representation of forward value references in bitcode.

Simplify instruction records by adding concept of a forward type reference
map that maps ValueID's to types. Used to generate forward reference types
for instruction arguments that need a type because the forward reference
has not yet been generated.

BUG= https://code.google.com/p/nativeclient/issues/detail?id=3507
R=jvoung@chromium.org, mseaborn@chromium.org

Review URL: https://codereview.chromium.org/16963004

1 files changed, 4 insertions, 0 deletions

diff --git a/lib/Bitcode/NaCl/Writer/NaClValueEnumerator.cpp b/lib/Bitcode/NaCl/Writer/NaClValueEnumerator.cpp
index 845a608255..4ff9b47bcc 100644
--- a/lib/Bitcode/NaCl/Writer/NaClValueEnumerator.cpp
+++ b/lib/Bitcode/NaCl/Writer/NaClValueEnumerator.cpp
@@ -497,6 +497,9 @@ void NaClValueEnumerator::incorporateFunction(const Function &F) {
   NumModuleValues = Values.size();
   NumModuleMDValues = MDValues.size();
 
+  // Make sure no insertions outside of a function.
+  assert(FnForwardTypeRefs.empty());
+
   // Adding function arguments to the value table.
   for (Function::const_arg_iterator I = F.arg_begin(), E = F.arg_end();
        I != E; ++I)
@@ -565,6 +568,7 @@ void NaClValueEnumerator::purgeFunction() {
   MDValues.resize(NumModuleMDValues);
   BasicBlocks.clear();
   FunctionLocalMDs.clear();
+  FnForwardTypeRefs.clear();
 }
 
 static void IncorporateFunctionInfoGlobalBBIDs(const Function *F,