cs441f10-ex2-key

cs441f10-ex2-key - Exam 2 Tuesday, November 23, 2010 at...

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Exam 2 Tuesday, November 23, 2010 at 11:00AM CS 441 Fall 2010 – Sample exam Key Solutions (AW) (For CS 441 use only – do not distribute) A. Run-time storage management Consider the following proc_block program BLOCK START MAIN var x,y,z; procedure A; BLOCK START A var x; { x:=1; y:= x*2 +1 } BLOCK END A procedure B; BLOCK START B var y; procedure C; BLOCK START C var z; procedure D; BLOCK START D var y; { x:= 1.25*z; call A; writeln(x) }; BLOCK END D { z:=1; call A; call D }; BLOCK END C { call C; writeln(x) }; BLOCK END B { x:=0; call B; write(x) }; BLOCK END MAIN Questions a) draw blocks around procedures to indicate the block structure of the program. b) what is the nesting level (largest block number)? c) write the executin history for this program in the form: d) draw the call graph for this program (a tree of calls). e) draw the stack of activation records for two cases: (i) directly after C calls A (ii) directly after D calls A f) what is the output (writeln) from the program assuming the static scoping? What is the output assuming dynamic scoping? Assume that the execution starts at location 900, the end of code
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for main is at 200, for A at 300, for B at 400, for C at 500 and for D at 600. Answer: solutions to problem A are in http://www.cs.uky.edu/~jurek/cs441/cs441f10/hw/hw7help.pdf B. Code Generation Write (by hand) P-stack code for the following program: { int i; procedure proc1(){ int a,b; { i:= 12; a:=10; if (a < i ) { b:= a+i}; b:= i + a; i:= i + a * b; }; } { call proc1(); write(i);}; } ANSWER: 001 Prog 1 073 004 Proc 2 007 ; #local var and the beginning of the proc 007 I_Variable 1 3 ; @i (i is non-local, REL_BLK_LEV = 1, OFF = 3) 010 I_Variable 0 3
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cs441f10-ex2-key - Exam 2 Tuesday, November 23, 2010 at...

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