diff --git a/js/src/jit/MIRGraph.cpp b/js/src/jit/MIRGraph.cpp
index 9d93b7f11cc..56501a47dc6 100644
--- a/js/src/jit/MIRGraph.cpp
+++ b/js/src/jit/MIRGraph.cpp
@@ -758,16 +758,6 @@ MBasicBlock::moveBefore(MInstruction *at, MInstruction *ins)
     ins->setTrackedSite(at->trackedSite());
 }
 
-static inline void
-AssertSafelyDiscardable(MDefinition *def)
-{
-#ifdef DEBUG
-    // Instructions captured by resume points cannot be safely discarded, since
-    // they are necessary for interpreter frame reconstruction in case of bailout.
-    JS_ASSERT(!def->hasUses());
-#endif
-}
-
 void
 MBasicBlock::discardResumePoint(MResumePoint *rp, ReferencesType refType /* = RefType_Default */)
 {
@@ -800,9 +790,11 @@ MBasicBlock::prepareForDiscard(MInstruction *ins, ReferencesType refType /* = Re
     // point.
     MOZ_ASSERT_IF(refType & RefType_AssertNoUses, !ins->hasUses());
 
-    MOZ_ASSERT(refType & RefType_DiscardOperands);
-    for (size_t i = 0, e = ins->numOperands(); i < e; i++)
-        ins->discardOperand(i);
+    const uint32_t InstructionOperands = RefType_DiscardOperands | RefType_DiscardInstruction;
+    if ((refType & InstructionOperands) == InstructionOperands) {
+        for (size_t i = 0, e = ins->numOperands(); i < e; i++)
+            ins->discardOperand(i);
+    }
 
     ins->setDiscarded();
 }
@@ -817,12 +809,12 @@ MBasicBlock::discard(MInstruction *ins)
 void
 MBasicBlock::discardIgnoreOperands(MInstruction *ins)
 {
-    AssertSafelyDiscardable(ins);
 #ifdef DEBUG
     for (size_t i = 0, e = ins->numOperands(); i < e; i++)
         JS_ASSERT(ins->operandDiscarded(i));
 #endif
 
+    prepareForDiscard(ins, RefType_IgnoreOperands);
     instructions_.remove(ins);
 }
 
diff --git a/js/src/jit/MIRGraph.h b/js/src/jit/MIRGraph.h
index e37dc680492..d1745e65521 100644
--- a/js/src/jit/MIRGraph.h
+++ b/js/src/jit/MIRGraph.h
@@ -66,11 +66,29 @@ class MBasicBlock : public TempObject, public InlineListNode<MBasicBlock>
 
     enum ReferencesType {
         RefType_None = 0,
+
+        // Assert that the instruction is unused.
         RefType_AssertNoUses = 1 << 0,
+
+        // Discard the operands of the resume point / instructions if the
+        // following flag are given too.
         RefType_DiscardOperands = 1 << 1,
         RefType_DiscardResumePoint = 1 << 2,
-        RefType_DefaultNoAssert = RefType_DiscardOperands | RefType_DiscardResumePoint,
-        RefType_Default = RefType_AssertNoUses | RefType_DiscardOperands | RefType_DiscardResumePoint
+        RefType_DiscardInstruction = 1 << 3,
+
+        // Discard operands of the instruction and its resume point.
+        RefType_DefaultNoAssert = RefType_DiscardOperands |
+                                  RefType_DiscardResumePoint |
+                                  RefType_DiscardInstruction,
+
+        // Discard everything and assert that the instruction is not used.
+        RefType_Default = RefType_AssertNoUses | RefType_DefaultNoAssert,
+
+        // Discard resume point operands only, without discarding the operands
+        // of the current instruction.  Asserts that the instruction is unused.
+        RefType_IgnoreOperands = RefType_AssertNoUses |
+                                 RefType_DiscardOperands |
+                                 RefType_DiscardResumePoint
     };
 
     void discardResumePoint(MResumePoint *rp, ReferencesType refType = RefType_Default);