The thing that does CodeGeneration.

Referred to from several places, the "Code Generator" is a piece of software which, when given appropriate inputs, generates code (Duh!) that can then be compiled. ... Though, technically, a compiler is a CodeGenerator, too.  

Alternatively, it's the software that takes an internal representation of source code and generates AssemblyLanguage or MachineCode.

These pages might be of interest:

* AutomatedCodeGeneration
* CodeGeneration
** ActiveCodeGeneration
** PassiveCodeGeneration
* CodeGenerationIsSmell
* CodeGenerationIsaDesignSmell
* EffectiveCodeGeneration
* HowToDoCodeGenerationWell
* InstallableCodeGenerators
* IntroduceCodeGenerator
* MixedCodeGeneration
* ReflectionVsCodeGenerationArticle