Increase precision when finding the remainder after division by pi/2.

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index 213166a92d48f212d89ad23589505efd7e6a1eea..7a70e825a97e494d0f7bde5297c362ca285ff543 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -6874,6 +6874,31 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_AllocateHeapNumber) {
 }
 
 
+static int HexToInt(uint16_t c) {
+  if (c >= '0' && c <= '9') return c - '0';
+  ASSERT(c >= 'a' && c <= 'f');
+  return c - 'a' + 10;
+}
+
+
+RUNTIME_FUNCTION(MaybeObject*, Runtime_HeapNumberFromHex) {
+  SealHandleScope shs(isolate);
+  ASSERT(args.length() == 1);
+  CONVERT_ARG_CHECKED(String, input, 0);
+  RUNTIME_ASSERT(input->length() == 16);
+  // Only used during bootstrapping.
+  RUNTIME_ASSERT(isolate->bootstrapper()->IsActive());
+  double result = 0;
+  uint8_t* bytes = reinterpret_cast<uint8_t*>(&result);

[Jakob Kummerow, 2013/11/19 17:49:54]

Are you sure this compiles? AFAIK this is what we have BitCast for. (You'll
probably want to start with an uint8_t[8] and then BitCast to double.)

+  // Input string is a little-endian hex representation of the double value.
+  for (int i = 0; i < 8; i++) {
+    bytes[i] = HexToInt(input->Get(2 * i)) * 16 +
+               HexToInt(input->Get(2 * i + 1));
+  }
+  return isolate->heap()->AllocateHeapNumber(result);
+}
+
+
 RUNTIME_FUNCTION(MaybeObject*, Runtime_NumberAdd) {
   SealHandleScope shs(isolate);
   ASSERT(args.length() == 2);