Changeset 167405 in webkit for trunk/Source/JavaScriptCore/runtime/JSCJSValueInlines.h

Timestamp:

Apr 16, 2014, 5:40:36 PM (11 years ago)

Author:

Brent Fulgham

Message:

[Win] Unreviewed Windows gardening. Restrict our new 'isinf' check
to 32-bit builds, and revise the comment to explain what we are
doing.

• runtime/JSCJSValueInlines.h:

(JSC::JSValue::isMachineInt): Provide motivation for the new
'isinf' check for our 32-bit code path.

File:

• trunk/Source/JavaScriptCore/runtime/JSCJSValueInlines.h (modified) (1 diff)

trunk/Source/JavaScriptCore/runtime/JSCJSValueInlines.h

@@ -507 +507 @@
     if (number != number)
         return false;
-#if OS(WINDOWS)
-    // Need to check for infinity on Windows to avoid floating point error on following cast, see bug 131182.
+#if OS(WINDOWS) && CPU(X86)
+    // The VS Compiler for 32-bit builds generates a floating point error when attempting to cast
+    // from an infinity to a 64-bit integer. We leave this routine with the floating point error
+    // left in a register, causing undefined behavior in later floating point operations.
+    //
+    // To avoid this issue, we check for infinity here, and return false in that case.
     if (std::isinf(number))
         return false;