Bug 720753 - hoist EvalCache from JSCompartment into JSRuntime (r=igor)

js/src/jscntxt.h

@@ -204,6 +204,18 @@ class ToSourceCache
     void purge();
 };
 
+class EvalCache
+{
+    static const unsigned SHIFT = 6;
+    static const unsigned LENGTH = 1 << SHIFT;
+    JSScript *table_[LENGTH];
+
+  public:
+    EvalCache() { PodArrayZero(table_); }
+    JSScript **bucket(JSLinearString *str);
+    void purge();
+};
+
 class NativeIterCache
 {
     static const size_t SIZE = size_t(1) << 8;
@@ -755,6 +767,7 @@ struct JSRuntime : js::RuntimeFriendFields
     js::NewObjectCache  newObjectCache;
     js::NativeIterCache nativeIterCache;
     js::ToSourceCache   toSourceCache;
+    js::EvalCache       evalCache;
 
     /* State used by jsdtoa.cpp. */
     DtoaState           *dtoaState;

js/src/jscompartment.cpp

@@ -92,7 +92,6 @@ JSCompartment::JSCompartment(JSRuntime *rt)
     sourceMapMap(NULL),
     debugScriptMap(NULL)
 {
-    PodArrayZero(evalCache);
     setGCMaxMallocBytes(rt->gcMaxMallocBytes * 0.9);
 }
 
@@ -102,11 +101,6 @@ JSCompartment::~JSCompartment()
     Foreground::delete_(scriptCountsMap);
     Foreground::delete_(sourceMapMap);
     Foreground::delete_(debugScriptMap);
-
-#ifdef DEBUG
-    for (size_t i = 0; i < ArrayLength(evalCache); ++i)
-        JS_ASSERT(!evalCache[i]);
-#endif
 }
 
 bool
@@ -536,21 +530,6 @@ void
 JSCompartment::purge()
 {
     dtoaCache.purge();
-
-    /*
-     * Clear the hash and reset all evalHashLink to null before the GC. This
-     * way MarkChildren(trc, JSScript *) can assume that JSScript::u.object is
-     * not null when we have script owned by an object and not from the eval
-     * cache.
-     */
-    for (size_t i = 0; i < ArrayLength(evalCache); ++i) {
-        for (JSScript **listHeadp = &evalCache[i]; *listHeadp; ) {
-            JSScript *script = *listHeadp;
-            JS_ASSERT(GetGCThingTraceKind(script) == JSTRACE_SCRIPT);
-            *listHeadp = NULL;
-            listHeadp = &script->evalHashLink();
-        }
-    }
 }
 
 void

js/src/jscompartment.h

@@ -61,17 +61,6 @@ namespace js {
 /* Defined in jsapi.cpp */
 extern Class dummy_class;
 
-} /* namespace js */
-
-#ifndef JS_EVAL_CACHE_SHIFT
-# define JS_EVAL_CACHE_SHIFT        6
-#endif
-
-/* Number of buckets in the hash of eval scripts. */
-#define JS_EVAL_CACHE_SIZE          JS_BIT(JS_EVAL_CACHE_SHIFT)
-
-namespace js {
-
 /*
  * A single-entry cache for some base-10 double-to-string conversions. This
  * helps date-format-xparb.js.  It also avoids skewing the results for
@@ -207,10 +196,6 @@ struct JSCompartment
     /* Type information about the scripts and objects in this compartment. */
     js::types::TypeCompartment   types;
 
-  public:
-    /* Hashed lists of scripts created by eval to garbage-collect. */
-    JSScript                     *evalCache[JS_EVAL_CACHE_SIZE];
-
     void                         *data;
     bool                         active;  // GC flag, whether there are active frames
     js::WrapperMap               crossCompartmentWrappers;

js/src/jsgc.cpp

@@ -2893,6 +2893,7 @@ PurgeRuntime(JSTracer *trc)
     rt->newObjectCache.purge();
     rt->nativeIterCache.purge();
     rt->toSourceCache.purge();
+    rt->evalCache.purge();
 
     for (ContextIter acx(rt); !acx.done(); acx.next())
         acx->purge();

js/src/jsobj.cpp

@@ -744,8 +744,27 @@ AssertInnerizedScopeChain(JSContext *cx, JSObject &scopeobj)
 # define EVAL_CACHE_CHAIN_LIMIT 4
 #endif
 
-static inline JSScript **
-EvalCacheHash(JSContext *cx, JSLinearString *str)
+void
+EvalCache::purge()
+{
+    /*
+     * Purge all scripts from the eval cache. In addition to removing them from
+     * table_, null out the evalHashLink field of any script removed. Since
+     * evalHashLink is in a union with globalObject, this allows the GC to
+     * indiscriminately use the union as a nullable globalObject pointer.
+     */
+    for (size_t i = 0; i < ArrayLength(table_); ++i) {
+        for (JSScript **listHeadp = &table_[i]; *listHeadp; ) {
+            JSScript *script = *listHeadp;
+            JS_ASSERT(GetGCThingTraceKind(script) == JSTRACE_SCRIPT);
+            *listHeadp = script->evalHashLink();
+            script->evalHashLink() = NULL;
+        }
+    }
+}
+
+inline JSScript **
+EvalCache::bucket(JSLinearString *str)
 {
     const jschar *s = str->chars();
     size_t n = str->length();
@@ -757,8 +776,9 @@ EvalCacheHash(JSContext *cx, JSLinearString *str)
         h = JS_ROTATE_LEFT32(h, 4) ^ *s;
 
     h *= JS_GOLDEN_RATIO;
-    h >>= 32 - JS_EVAL_CACHE_SHIFT;
-    return &cx->compartment->evalCache[h];
+    h >>= 32 - SHIFT;
+    JS_ASSERT(h < ArrayLength(table_));
+    return &table_[h];
 }
 
 static JS_ALWAYS_INLINE JSScript *
@@ -857,7 +877,7 @@ class EvalScriptGuard
       : cx_(cx),
         str_(str),
         script_(cx) {
-        bucket_ = EvalCacheHash(cx, str);
+        bucket_ = cx->runtime->evalCache.bucket(str);
     }
 
     ~EvalScriptGuard() {