$OpenBSD$

index d2ed077..9d6fd5d 100644
--- js/src/jit/IonAnalysis.cpp.orig	Fri Feb 20 15:40:37 2015
+++ js/src/jit/IonAnalysis.cpp	Fri Feb 20 15:40:37 2015
@@ -137,6 +137,14 @@ jit::EliminateDeadResumePointOperands(MIRGenerator *mir, MIRGraph &graph)
                     continue;
                 }
 
+                // The operand is an uneliminable slot. This currently
+                // includes argument slots in non-strict scripts (due to being
+                // observable via Function.arguments).
+                if (!block->info().canOptimizeOutSlot(uses->index())) {
+                    uses++;
+                    continue;
+                }
+
                 // Store an optimized out magic value in place of all dead
                 // resume point operands. Making any such substitution can in
                 // general alter the interpreter's behavior, even though the
@@ -233,18 +241,11 @@ IsPhiObservable(MPhi *phi, Observability observe)
         return true;
     }
 
-    // If the Phi is one of the formal argument, and we are using an argument
-    // object in the function. The phi might be observable after a bailout.
-    // For inlined frames this is not needed, as they are captured in the inlineResumePoint.
-    if (fun && info.hasArguments()) {
-        uint32_t first = info.firstArgSlot();
-        if (first <= slot && slot - first < info.nargs()) {
-            // If arguments obj aliases formals, then the arg slots will never be used.
-            if (info.argsObjAliasesFormals())
-                return false;
-            return true;
-        }
-    }
+    // The Phi is an uneliminable slot. Currently this includes argument slots
+    // in non-strict scripts (due to being observable via Function.arguments).
+    if (fun && !info.canOptimizeOutSlot(slot))
+        return true;
+
     return false;
 }