From 335c2b44df6d1e379d2bd8e5cbba47a6fbb92a67 Mon Sep 17 00:00:00 2001
From: Jan De Mooij <jandemooij@gmail.com>
Date: Thu, 5 Aug 2010 16:09:47 -0700
Subject: [PATCH] [JAEGER] Constant fold neg on ints better (bug 584838,
 r=dvander).

---
 js/src/methodjit/Compiler.cpp | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/js/src/methodjit/Compiler.cpp b/js/src/methodjit/Compiler.cpp
index 070b00174d6..3a141f759fd 100644
--- a/js/src/methodjit/Compiler.cpp
+++ b/js/src/methodjit/Compiler.cpp
@@ -703,11 +703,21 @@ mjit::Compiler::generateMethod()
           {
             FrameEntry *top = frame.peek(-1);
             if (top->isConstant() && top->getValue().isPrimitive()) {
-                double d;
-                ValueToNumber(cx, top->getValue(), &d);
-                d = -d;
-                frame.pop();
-                frame.push(DoubleValue(d));
+                if (top->isType(JSVAL_TYPE_INT32) && 
+                    top->getValue().toInt32() != 0 &&
+                    top->getValue().toInt32() != (1 << 31))
+                {
+                    int32 value = top->getValue().toInt32();
+                    value = -value;
+                    frame.pop();
+                    frame.push(Int32Value(value));
+                } else {
+                    double d;
+                    ValueToNumber(cx, top->getValue(), &d);
+                    d = -d;
+                    frame.pop();
+                    frame.push(DoubleValue(d));
+                }
             } else {
                 jsop_neg();
             }