Re-land "Clusterfuzz identified overflow check needed in dehoisting."

src/utils.h

Index: src/utils.h
diff --git a/src/utils.h b/src/utils.h
index 5422985bc538c641ac3b5d25a03f4909d390be2a..7c4945e1c25fa5540f6b4eb10dba1f6f7cf8db36 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -16,6 +16,7 @@
 #include "src/list.h"
 #include "src/platform.h"
 #include "src/vector.h"
+#include "src/base/safe_math.h"
 
 namespace v8 {
 namespace internal {
@@ -252,6 +253,20 @@ template<> struct make_unsigned<int64_t> {
 };
 
 
+template<typename T> bool MultiplyOverflows(T x, T y) {

[danno, 2014/06/18 14:55:04]

Do you really need these wrappers? It seems that they make you do the math
twice. Is there really any downside to having the CheckedNumber<T> directly at
the site where it's used... and just using the checked_result.value()?

+  v8::base::internal::CheckedNumeric<T> checked_result = x;
+  checked_result = checked_result * y;
+  return !checked_result.IsValid();
+}
+
+
+template<typename T> bool AdditionOverflows(T x, T y) {
+  v8::base::internal::CheckedNumeric<T> checked_result = x;
+  checked_result = checked_result + y;
+  return !checked_result.IsValid();
+}
+
+
 // ----------------------------------------------------------------------------
 // BitField is a help template for encoding and decode bitfield with
 // unsigned content.