2005 Paper 5 Question 6 Compiler Construction (a) Explain how a parse tree representing an expression can (i) be converted into stack-oriented intermediate code and then (ii) be translated into simple machine code for a register-oriented architecture (e.g. ARM or IA32) on an instruction-by-instruction basis. Also indicate how this code might be improved to remove push–pop pairs introduced by (ii). Your answer need only consider expression forms encountered in the expression: h(a, g(b), c) * 3 + d [12 marks] (b) In Java, expressions are evaluated strictly left-to-right. Consider compiling the function f in the following Java class definition: class A { static int a,b; void f() { … <> … } int g(int x) { … a++; … } }; Indicate what both the intermediate code and (improved as above) target code might be for <> for the cases where <> is: (i) b = g(7) + a; (ii) b = a + g(7); (iii) b = (-g(7)) + a; (iv) b = a – g(7); Comment on any inherent differences in efficiency at both the intermediate code and target code levels. [8 marks]