Removed incorrect optimization

src/build/core/CompileDefinition.go

@@ -38,15 +38,6 @@ func (f *Function) CompileDefinition(node *ast.Define) error {
 		return err
 	}
 
-	if uses == 1 {
-		f.definitions[name] = &Definition{
-			Name:  name,
-			Value: value,
-		}
-
-		return nil
-	}
-
 	return f.storeVariableInRegister(name, value, uses)
 }
 
@@ -83,12 +74,6 @@ func (f *Function) identifierExists(name string) bool {
 		return true
 	}
 
-	_, exists = f.definitions[name]
-
-	if exists {
-		return true
-	}
-
 	_, exists = f.functions[name]
 	return exists
 }

src/build/core/Function.go

@@ -36,7 +36,6 @@ func NewFunction(name string, file *fs.File, body token.List) *Function {
 				Syscall: x64.SyscallRegisters,
 				Output:  x64.ReturnValueRegisters,
 			},
-			definitions: map[string]*Definition{},
 			variables: map[string]*Variable{},
 			finished:  make(chan struct{}),
 		},

src/build/core/TokenToRegister.go

@@ -15,12 +15,6 @@ func (f *Function) TokenToRegister(t token.Token, register cpu.Register) error {
 	switch t.Kind {
 	case token.Identifier:
 		name := t.Text()
-		constant, exists := f.definitions[name]
-
-		if exists {
-			return f.ExpressionToRegister(constant.Value, register)
-		}
-
 		variable, exists := f.variables[name]
 
 		if !exists {

src/build/core/Variable.go

@@ -12,9 +12,3 @@ type Variable struct {
 	Register cpu.Register
 	Alive    int
 }
-
-// Definitions are single use expressions that don't reside in a register yet.
-type Definition struct {
-	Value *expression.Expression
-	Name  string
-}

src/build/core/state.go

@@ -11,7 +11,6 @@ import (
 // state is the data structure we embed in each function to preserve compilation state.
 type state struct {
 	err       error
-	definitions map[string]*Definition
 	variables map[string]*Variable
 	functions map[string]*Function
 	finished  chan struct{}

tests/programs/reassign.q

@@ -0,0 +1,6 @@
+main() {
+	x := 1
+	y := x + 1
+	x = 2
+	syscall(60, y)
+}

tests/programs_test.go

@@ -22,6 +22,7 @@ var programs = []struct {
 	{"chained-calls.q", "", 9},
 	{"nested-calls.q", "", 4},
 	{"return.q", "", 6},
+	{"reassign.q", "", 2},
 }
 
 func TestPrograms(t *testing.T) {