Bug 845175 - Lazily allocate the bytecode and srcnote Vectors' storage. r=jorendorff.

--HG--
extra : rebase_source : f39db7bf439b9f86419cb9fdf4f899c052ae7638

js/src/frontend/BytecodeEmitter.cpp

@@ -124,15 +124,15 @@ BytecodeEmitter::init()
     return atomIndices.ensureMap(sc->context);
 }
 
-BytecodeEmitter::~BytecodeEmitter()
-{
-}
-
 static ptrdiff_t
 EmitCheck(JSContext *cx, BytecodeEmitter *bce, ptrdiff_t delta)
 {
     ptrdiff_t offset = bce->code().length();
 
+    // Start it off moderately large to avoid repeated resizings early on.
+    if (bce->code().capacity() == 0 && !bce->code().reserve(1024))
+        return -1;
+
     jsbytecode dummy = 0;
     if (!bce->code().appendN(dummy, delta)) {
         js_ReportOutOfMemory(cx);
@@ -5897,6 +5897,10 @@ frontend::EmitTree(JSContext *cx, BytecodeEmitter *bce, ParseNode *pn)
 static int
 AllocSrcNote(JSContext *cx, SrcNotesVector &notes)
 {
+    // Start it off moderately large to avoid repeated resizings early on.
+    if (notes.capacity() == 0 && !notes.reserve(1024))
+        return -1;
+
     jssrcnote dummy = 0;
     if (!notes.append(dummy)) {
         js_ReportOutOfMemory(cx);

js/src/frontend/BytecodeEmitter.h

@@ -84,12 +84,7 @@ struct BytecodeEmitter
 
         EmitSection(JSContext *cx, unsigned lineno)
           : code(cx), notes(cx), lastNoteOffset(0), currentLine(lineno), lastColumn(0)
-        {
-            // Start them off moderately large, to avoid repeated resizings
-            // early on.
-            code.reserve(1024);
-            notes.reserve(1024);
-        }
+        {}
     };
     EmitSection prolog, main, *current;
 
@@ -149,8 +144,6 @@ struct BytecodeEmitter
                     unsigned lineno, bool selfHostingMode = false);
     bool init();
 
-    ~BytecodeEmitter();
-
     bool isAliasedName(ParseNode *pn);
 
     JS_ALWAYS_INLINE