Bug 1302645 - Only relazify functions on shrinking GCs to avoid reparsing too much. r=terrence

js/src/builtin/TestingFunctions.cpp

@@ -479,10 +479,15 @@ RelazifyFunctions(JSContext* cx, unsigned argc, Value* vp)
     // not active. To aid fuzzing, this testing function allows us to relazify
     // even if the compartment is active.
 
+    CallArgs args = CallArgsFromVp(argc, vp);
     SetAllowRelazification(cx, true);
-    bool res = GC(cx, argc, vp);
+
+    JS::PrepareForFullGC(cx);
+    JS::GCForReason(cx, GC_SHRINK, JS::gcreason::API);
+
     SetAllowRelazification(cx, false);
-    return res;
+    args.rval().setUndefined();
+    return true;
 }
 
 static bool

js/src/jit-test/tests/xdr/lazy.js

@@ -111,7 +111,7 @@ test = "function f() { }; f();"
      + "assertEq(isLazyFunction(f), false);"
      + "var expect = isRelazifiableFunction(f);";
 checkAfter = function (ctx) {
-  gc(ctx.global.f); // relazify f, if possible.
+  gc(ctx.global.f, "shrinking"); // relazify f, if possible.
   evaluate("assertEq(isLazyFunction(f), expect);", ctx);
 };
 evalWithCache(test, {
@@ -128,7 +128,7 @@ test = "function f() { return isRelazifiableFunction(f) }; var expect = f();"
      + "assertEq(isLazyFunction(f), false);"
      + "expect";
 checkAfter = function (ctx) {
-  gc(ctx.global.f); // relazify f, if possible.
+  gc(ctx.global.f, "shrinking"); // relazify f, if possible.
   evaluate("assertEq(isLazyFunction(f), expect);", ctx);
 };
 evalWithCache(test, {

js/src/jsgc.cpp

@@ -3841,11 +3841,16 @@ GCRuntime::beginMarkPhase(JS::gcreason::Reason reason, AutoLockForExclusiveAcces
      * Relazify functions after discarding JIT code (we can't relazify
      * functions with JIT code) and before the actual mark phase, so that
      * the current GC can collect the JSScripts we're unlinking here.
+     * We do this only when we're performing a shrinking GC, as too much
+     * relazification can cause performance issues when we have to reparse
+     * the same functions over and over.
      */
-    for (GCZonesIter zone(rt); !zone.done(); zone.next()) {
+    if (invocationKind == GC_SHRINK) {
         gcstats::AutoPhase ap(stats, gcstats::PHASE_RELAZIFY_FUNCTIONS);
-        RelazifyFunctions(zone, AllocKind::FUNCTION);
-        RelazifyFunctions(zone, AllocKind::FUNCTION_EXTENDED);
+        for (GCZonesIter zone(rt); !zone.done(); zone.next()) {
+            RelazifyFunctions(zone, AllocKind::FUNCTION);
+            RelazifyFunctions(zone, AllocKind::FUNCTION_EXTENDED);
+        }
     }
 
     startNumber = number;