Package org.jruby.ir.operands

Class ImmutableLiteral<T>

java.lang.Object
org.jruby.ir.operands.Operand
org.jruby.ir.operands.ImmutableLiteral<T>
Type Parameters:
T - type of immutable literal
Direct Known Subclasses:
Bignum, Boolean, Complex, Fixnum, Float, FrozenString, Integer, Nil, NullBlock, Range, Rational, Regexp, Symbol, SymbolProc, UnboxedBoolean, UnboxedFixnum, UnboxedFloat
public abstract class ImmutableLiteral<T> extends Operand
Operands extending this type can make a reasonable assumption of immutability. In Ruby, almost nothing is truly immutable (set_instance_var) but for the sake of our compiler, we can assume the basic behavior will continue to work unchanged (the value of an instance of fixnum 3 will remain 3). Knowing that we have a literal which will not change can be used for optimizations like constant propagation. ENEBO: This cachedObject thing obviously cannot be used from multiple threads without some safety being added. This probably also is not the fastest code, but it is very simple. It would be really nice to make this side-effect free as well, but this is difficult without adding a level of indirection or pre-caching each value we encounter during construction.

  • Constructor Details

    • ImmutableLiteral

      public ImmutableLiteral()

  • Method Details

    • hasKnownValue

      public boolean hasKnownValue()
      Description copied from class: Operand
      Do we know the value of this operand at compile-time? If we do then it may be possible to constant propagate (one case: We also know it is also an ImmutableLiteral).
      Overrides:
      hasKnownValue in class Operand
      Returns:
      true if a known compile-time value.

    • canCopyPropagate

      public boolean canCopyPropagate()
      Description copied from class: Operand
      Can we replace every use of a variable 'v' that contains the value of this operand with the operand itself? This takes importance when there are at least two uses of 'v' within this scope. Ex: v = [1,2,3]; x = v; y = v In this case, we cannot replace the occurrences of 'v' because we would then get x = [1,2,3]; y = [1,2,3] which would then result in two different array objects being constructed instead of a single one.
      Overrides:
      canCopyPropagate in class Operand
      Returns:
      true if it is safe to copy-propagate the operand.

    • addUsedVariables

      public void addUsedVariables(List<Variable> l)
      Description copied from class: Operand
      Append the list of variables used in this operand to the input list -- force every operand to implement this because a missing implementation can cause bad failures.
      Specified by:
      addUsedVariables in class Operand

    • cloneForInlining

      public Operand cloneForInlining(CloneInfo ii)
      Specified by:
      cloneForInlining in class Operand

    • createCacheObject

      public abstract T createCacheObject(ThreadContext context)
      Implementing class is responsible for constructing the cached value.

    • cachedObject

      public T cachedObject(ThreadContext context)
      Returns the cached object. If not then it asks class to create an object to cache.

    • isCached

      public boolean isCached()
      Has this object already been cached?

    • retrieve

      public T retrieve(ThreadContext context, IRubyObject self, StaticScope currScope, DynamicScope currDynScope, Object[] temp)
      retrieve the live value represented by this immutable literal. An interesting property of knowing something cannot change at compile time is that all information necessary to construct it is also known at compile time. We don't pre-create these since we don't want to assume the cost of constructing literals which may never be used.
      Overrides:
      retrieve in class Operand