From cac8501966fbc8f5b862fbeb38ed0222c3038a28 Mon Sep 17 00:00:00 2001
From: Benjamin Bouvier <benj@benj.me>
Date: Wed, 29 Jan 2014 12:12:03 +0100
Subject: [PATCH] Bug 942550: Take care of all particular cases in ecmaPow
 instead of js_math_pow; r=jandem

---
 js/src/jit-test/tests/ion/bug942550.js |  6 +++++
 js/src/jsmath.cpp                      | 34 +++++++++-----------------
 2 files changed, 18 insertions(+), 22 deletions(-)
 create mode 100644 js/src/jit-test/tests/ion/bug942550.js

diff --git a/js/src/jit-test/tests/ion/bug942550.js b/js/src/jit-test/tests/ion/bug942550.js
new file mode 100644
index 00000000000..16344f08482
--- /dev/null
+++ b/js/src/jit-test/tests/ion/bug942550.js
@@ -0,0 +1,6 @@
+function pow(x,y) {
+    return Math.pow(x,y);
+}
+var x = pow(3, -.5);
+var y = pow(3, -.5);
+assertEq(x, y);
diff --git a/js/src/jsmath.cpp b/js/src/jsmath.cpp
index 10169094b64..e6a1d42eec8 100644
--- a/js/src/jsmath.cpp
+++ b/js/src/jsmath.cpp
@@ -625,9 +625,21 @@ js::ecmaPow(double x, double y)
      */
     if (!IsFinite(y) && (x == 1.0 || x == -1.0))
         return GenericNaN();
+
     /* pow(x, +-0) is always 1, even for x = NaN (MSVC gets this wrong). */
     if (y == 0)
         return 1;
+
+    /*
+     * Special case for square roots. Note that pow(x, 0.5) != sqrt(x)
+     * when x = -0.0, so we have to guard for this.
+     */
+    if (IsFinite(x) && x != 0.0) {
+        if (y == 0.5)
+            return sqrt(x);
+        if (y == -0.5)
+            return 1.0 / sqrt(x);
+    }
     return pow(x, y);
 }
 #if defined(_MSC_VER)
@@ -651,29 +663,7 @@ js_math_pow(JSContext *cx, unsigned argc, Value *vp)
     if (!ToNumber(cx, args.get(1), &y))
         return false;
 
-    /*
-     * Special case for square roots. Note that pow(x, 0.5) != sqrt(x)
-     * when x = -0.0, so we have to guard for this.
-     */
-    if (IsFinite(x) && x != 0.0) {
-        if (y == 0.5) {
-            args.rval().setNumber(sqrt(x));
-            return true;
-        }
-        if (y == -0.5) {
-            args.rval().setNumber(1.0/sqrt(x));
-            return true;
-        }
-    }
-
-    /* pow(x, +-0) is always 1, even for x = NaN. */
-    if (y == 0) {
-        args.rval().setInt32(1);
-        return true;
-    }
-
     double z = ecmaPow(x, y);
-
     args.rval().setNumber(z);
     return true;
 }