icode: discard unused pure ICode expressions

[nit.git] / src / icode / icode_base.nit

diff --git a/src/icode/icode_base.nit b/src/icode/icode_base.nit
index f46ff5b..6a822e3 100644 (file)
--- a/src/icode/icode_base.nit
+++ b/src/icode/icode_base.nit
@@ -88,6 +88,9 @@ abstract class ICode
 
        # The location of the icode (if any)
        readable writable var _location: nullable Location = null
+
+       # Is the icode side effect free?
+       fun is_pure: Bool do return false
 end
 
 # An icode that uses no registers (no args)
@@ -274,6 +277,8 @@ special ICodeN
                super(e)
                _code = c
        end
+
+       redef readable writable var _is_pure: Bool = false
 end
 
 # A register assigment
@@ -286,6 +291,8 @@ special ICode1
                super(e)
                _result = r
        end
+
+       redef fun is_pure do return true
 end
 
 # An attribute read access
@@ -300,6 +307,8 @@ special ICode1
                super(r)
                _property = p
        end
+
+       redef fun is_pure do return true
 end
 
 # An attribute assignment
@@ -329,6 +338,8 @@ special ICode1
                super(r)
                _property = p
        end
+
+       redef fun is_pure do return true
 end
 
 # A type check
@@ -343,6 +354,8 @@ special ICode1
                super(e)
                _stype = t
        end
+
+       redef fun is_pure do return true
 end
 
 # The 'is' operator
@@ -353,6 +366,8 @@ special ICode2
        do
                super
        end
+
+       redef fun is_pure do return true
 end
 
 # The unary 'not' operation
@@ -363,6 +378,8 @@ special ICode1
        do
                super
        end
+
+       redef fun is_pure do return true
 end
 
 # Evaluate body once them return the same value again and again
@@ -383,6 +400,8 @@ special ICode0
        do
                _closure_decl = c
        end
+
+       redef fun is_pure do return true
 end
 
 #################################################