--- a/js/src/jit/LIR.h
+++ b/js/src/jit/LIR.h
@@ -76,26 +76,26 @@ class LAllocation : public TempObject
         USE,            // Use of a virtual register, with physical allocation policy.
         GPR,            // General purpose register.
         FPU,            // Floating-point register.
         STACK_SLOT,     // Stack slot.
         ARGUMENT_SLOT   // Argument slot.
     };
 
   protected:
-    int32_t data() const {
-        return int32_t(bits_) >> DATA_SHIFT;
+    uint32_t data() const {
+        return uint32_t(bits_) >> DATA_SHIFT;
     }
-    void setData(int32_t data) {
-        JS_ASSERT(int32_t(data) <= int32_t(DATA_MASK));
+    void setData(uint32_t data) {
+        JS_ASSERT(data <= DATA_MASK);
         bits_ &= ~(DATA_MASK << DATA_SHIFT);
         bits_ |= (data << DATA_SHIFT);
     }
     void setKindAndData(Kind kind, uint32_t data) {
-        JS_ASSERT(int32_t(data) <= int32_t(DATA_MASK));
+        JS_ASSERT(data <= DATA_MASK);
         bits_ = (uint32_t(kind) << KIND_SHIFT) | data << DATA_SHIFT;
     }
 
     LAllocation(Kind kind, uint32_t data) {
         setKindAndData(kind, data);
     }
     explicit LAllocation(Kind kind) {
         setKindAndData(kind, 0);