Store RNG state on function context.

R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/1425693006

Cr-Commit-Position: refs/heads/master@{#31712}

src/bootstrapper.cc

@@ -6,7 +6,6 @@
 
 #include "src/accessors.h"
 #include "src/api-natives.h"
-#include "src/base/utils/random-number-generator.h"
 #include "src/code-stubs.h"
 #include "src/extensions/externalize-string-extension.h"
 #include "src/extensions/free-buffer-extension.h"
@@ -1792,28 +1791,11 @@ Handle<JSTypedArray> CreateTypedArray(Isolate* isolate, ExternalArrayType type,
 
 bool Genesis::InitializeBuiltinTypedArrays() {
   HandleScope scope(isolate());
-  Handle<JSTypedArray> rng_state;
-  Handle<JSTypedArray> rempio2result;
-
-  {
-    // Seed the per-context RNG using the per-isolate RNG.
-    const size_t num_elements = 2;
-    const size_t num_bytes = num_elements * sizeof(uint32_t);
-    uint32_t* state = NULL;
-    rng_state =
-        CreateTypedArray(isolate(), kExternalUint32Array, num_elements, &state);
-    do {
-      isolate()->random_number_generator()->NextBytes(state, num_bytes);
-    } while (state[0] == 0 || state[1] == 0);
-  }
-
-  {  // Initialize a result array for rempio2 calculation
-    const size_t num_elements = 2;
-    double* data = NULL;
-    rempio2result =
-        CreateTypedArray(isolate(), kExternalFloat64Array, num_elements, &data);
-    for (size_t i = 0; i < num_elements; i++) data[i] = 0;
-  }
+  const size_t num_elements = 2;
+  double* data = NULL;
+  Handle<JSTypedArray> rempio2result =
+      CreateTypedArray(isolate(), kExternalFloat64Array, num_elements, &data);
+  for (size_t i = 0; i < num_elements; i++) data[i] = 0;
 
   Handle<JSObject> utils =
       Handle<JSObject>::cast(isolate()->natives_utils_object());
@@ -1821,7 +1803,7 @@ bool Genesis::InitializeBuiltinTypedArrays() {
       "InitializeBuiltinTypedArrays");
   Handle<Object> fun = JSObject::GetDataProperty(utils, name_string);
   Handle<Object> receiver = isolate()->factory()->undefined_value();
-  Handle<Object> args[] = {utils, rng_state, rempio2result};
+  Handle<Object> args[] = {utils, rempio2result};
   return !Execution::Call(isolate(), fun, receiver, arraysize(args), args)
               .is_null();
 }

src/js/math.js

@@ -14,12 +14,19 @@ var GlobalMath = global.Math;
 var GlobalObject = global.Object;
 var InternalArray = utils.InternalArray;
 var NaN = %GetRootNaN();
-var rngstate;
+var rngstate_0;
+var rngstate_1;
+var rngstate_2;
+var rngstate_3;
 var toStringTagSymbol = utils.ImportNow("to_string_tag_symbol");
 
-utils.SetupTypedArray(function(arg1, arg2, arg3) {
-  rngstate = arg1;
-});
+utils.InitializeRNG = function() {
+  var rngstate = %InitializeRNG();
+  rngstate_0 = rngstate[0];
+  rngstate_1 = rngstate[1];
+  rngstate_2 = rngstate[2];
+  rngstate_3 = rngstate[3];
+};
 
 //-------------------------------------------------------------------
 
@@ -134,22 +141,25 @@ function MathPowJS(x, y) {
 
 // ECMA 262 - 15.8.2.14
 function MathRandom() {
-  var r0 = (MathImul(18030, rngstate[0] & 0xFFFF) + (rngstate[0] >>> 16)) | 0;
-  rngstate[0] = r0;
-  var r1 = (MathImul(36969, rngstate[1] & 0xFFFF) + (rngstate[1] >>> 16)) | 0;
-  rngstate[1] = r1;
-  var x = ((r0 << 16) + (r1 & 0xFFFF)) | 0;
-  // Division by 0x100000000 through multiplication by reciprocal.
-  return (x < 0 ? (x + 0x100000000) : x) * 2.3283064365386962890625e-10;
+  var r0 = (MathImul(18030, rngstate_0) + rngstate_1) | 0;
+  var r1 = (MathImul(36969, rngstate_2) + rngstate_3) | 0;
+  rngstate_0 = r0 & 0xFFFF;
+  rngstate_1 = r0 >>> 16;
+  rngstate_2 = r1 & 0xFFFF;
+  rngstate_3 = r1 >>> 16;
+  // Construct a double number 1.<32-bits of randomness> and subtract 1.
+  return %_ConstructDouble(0x3FF00000 | (r0 & 0x000FFFFF), r1 & 0xFFF00000) - 1;
 }
 
 function MathRandomRaw() {
-  var r0 = (MathImul(18030, rngstate[0] & 0xFFFF) + (rngstate[0] >>> 16)) | 0;
-  rngstate[0] = r0;
-  var r1 = (MathImul(36969, rngstate[1] & 0xFFFF) + (rngstate[1] >>> 16)) | 0;
-  rngstate[1] = r1;
+  var r0 = (MathImul(18030, rngstate_0) + rngstate_1) | 0;
+  var r1 = (MathImul(36969, rngstate_2) + rngstate_3) | 0;
+  rngstate_0 = r0 & 0xFFFF;
+  rngstate_1 = r0 >>> 16;
+  rngstate_2 = r1 & 0xFFFF;
+  rngstate_3 = r1 >>> 16;
   var x = ((r0 << 16) + (r1 & 0xFFFF)) | 0;
-  return x & 0x3fffffff;
+  return x & 0x3FFFFFFF;
 }
 
 // ECMA 262 - 15.8.2.15

src/js/prologue.js

@@ -245,6 +245,9 @@ function PostExperimentals(utils) {
     imports_from_experimental(exports_container);
   }
 
+  utils.InitializeRNG();
+  utils.InitializeRNG = UNDEFINED;
+
   utils.Export = UNDEFINED;
   utils.PostDebug = UNDEFINED;
   utils.PostExperimentals = UNDEFINED;
@@ -259,6 +262,9 @@ function PostDebug(utils) {
     imports(exports_container);
   }
 
+  utils.InitializeRNG();
+  utils.InitializeRNG = UNDEFINED;
+
   exports_container = UNDEFINED;
 
   utils.Export = UNDEFINED;

src/runtime/runtime-maths.cc

@@ -6,6 +6,7 @@
 
 #include "src/arguments.h"
 #include "src/assembler.h"
+#include "src/base/utils/random-number-generator.h"
 #include "src/codegen.h"
 #include "src/third_party/fdlibm/fdlibm.h"
 
@@ -244,5 +245,20 @@ RUNTIME_FUNCTION(Runtime_IsMinusZero) {
   HeapNumber* number = HeapNumber::cast(obj);
   return isolate->heap()->ToBoolean(IsMinusZero(number->value()));
 }
+
+
+RUNTIME_FUNCTION(Runtime_InitializeRNG) {
+  HandleScope scope(isolate);
+  DCHECK(args.length() == 0);
+  static const int kSize = 4;
+  Handle<FixedArray> array = isolate->factory()->NewFixedArray(kSize);
+  uint16_t seeds[kSize];
+  do {
+    isolate->random_number_generator()->NextBytes(seeds,
+                                                  kSize * sizeof(*seeds));
+  } while (!(seeds[0] && seeds[1] && seeds[2] && seeds[3]));
+  for (int i = 0; i < kSize; i++) array->set(i, Smi::FromInt(seeds[i]));
+  return *isolate->factory()->NewJSArrayWithElements(array);
+}
 }  // namespace internal
 }  // namespace v8

src/runtime/runtime.h

@@ -404,7 +404,8 @@ namespace internal {
   F(RoundNumber, 1, 1)              \
   F(MathSqrt, 1, 1)                 \
   F(MathFround, 1, 1)               \
-  F(IsMinusZero, 1, 1)
+  F(IsMinusZero, 1, 1)              \
+  F(InitializeRNG, 0, 1)
 
 
 #define FOR_EACH_INTRINSIC_NUMBERS(F)  \

src/third_party/fdlibm/fdlibm.js

@@ -39,8 +39,8 @@ utils.Import(function(from) {
   MathExp = from.MathExp;
 });
 
-utils.SetupTypedArray(function(arg1, arg2) {
-  rempio2result = arg2;
+utils.SetupTypedArray(function(arg) {
+  rempio2result = arg;
 });
 
 // -------------------------------------------------------------------