| [2] | 1 | = INTRODUCTION =
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| 2 |
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| 3 | Welcome reader,
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| 4 |
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| 5 | You will find our solution on assignment 5 of Compiler Constructions 2008
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| 6 | giving at LIACS University. First we will you a grand overview of the files
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| 7 | altered, next we will bullet point the most important design decisions.
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| 8 |
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| 9 | And the grand finale will show the usage of the program.
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| 10 |
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| 11 | Enjoy!
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| 12 | Johan and Rick <hvdzwet@liacs.nl>
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| 13 |
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| 14 |
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| 15 | = FILES EDITED/ADDED =
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| 16 | E ICGenerator.cc = Intermidiate code generator C++ source
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| 17 | E ICGenerator.h = Intermidiate code generator C++ source
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| 18 | E main.cc = Main program function, argument parsing
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| 19 |
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| 20 | = DESIGN DECISIONS =
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| 21 | * Constants are evaluated upfront, also nested ones. Optimalisations are
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| 22 | included into the tree and generated on the fly
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| 23 |
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| 24 | * In order to keep the code readable human-readable tests are defined like
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| 25 | IsZero, IsConstant.
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| 26 |
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| 27 | * Made icode, symtab global to avoid calling the Treewalk with a whole lot of
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| 28 | arguments every time.
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| 29 |
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| 30 | * Recursive walking of Tree using Treewalk allowing us to generate code on the
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| 31 | fly on three different 'location' e.g. first encounter, midle pass, last visit.
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| 32 |
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| 33 | * Tried various optimatisations on PostProcess, by changing variable names,
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| 34 | removing assignments, but yet all led to race conditions.
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| 35 |
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| 36 | * Wrote some theoritical tests PostProcess which could be implemented.
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| 37 |
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| 38 | * Constants in multiple additions (e.g. 10 + a + 20 + b) will be simplified 30 + a + b
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| 39 |
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| 40 | * Constants in multiple combinations of additions and substractions will be
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| 41 | simplyfied (e.g. 10 + a - 20 + b) will be simplified -10 + a + b
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| 42 |
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| 43 | * In order to allow the full folding, NODE_ADD and NODE_SUB are evaluated
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| 44 | differently, Like first right child, then left child.
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| 45 |
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| 46 | * Full constant folding on NODE_MUL has not been implemented, but will goes
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| 47 | more and less the same as the code at NODE_ADD
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| 48 |
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| 49 | = SAMPLE GENERATED CODE =
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| 50 | C01) program example;
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| 51 | C02)
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| 52 | C03) var x, y, z: integer;
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| 53 | C04) function foo(a,b: integer): integer;
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| 54 | C05) begin
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| 55 | C06) foo := 1
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| 56 | C07) end;
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| 57 | C08)
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| 58 | C09) begin
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| 59 | C10) x := readinteger;
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| 60 | C11) y := 20;
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| 61 | C12) z := x + 20;
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| 62 | C13) z := z + foo(0,0)
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| 63 | C14) end.
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| 64 |
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| 65 | Program: example
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| 66 | # operator | operand1 | operand2 | result
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| 67 | ------------------+-------------------+-------------------+-------------------
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| 68 | 0: CALL FUNC | sym: readinteger | | sym: t1
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| 69 | 1: ASSIGN_I | sym: t1 | | sym: x
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| 70 | 2: ASSIGN_I | int: 20 | | sym: y
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| 71 | 3: ADD_I | sym: x | int: 20 | sym: t2
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| 72 | 4: ASSIGN_I | sym: t2 | | sym: z
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| 73 | 5: PARAM_I | int: 0 | |
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| 74 | 6: PARAM_I | int: 0 | |
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| 75 | 7: CALL FUNC | sym: foo | | sym: t3
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| 76 | 8: ADD_I | sym: z | sym: t3 | sym: t4
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| 77 | 9: ASSIGN_I | sym: t4 | | sym: z
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| 78 | 10: RETURN | | |
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| 79 |
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| 80 | 11: SUBPROG | sym: foo | |
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| 81 | 12: ASSIGN_I | int: 1 | | sym: foo
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| 82 | 13: RETURN_I | sym: foo | |
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| 83 |
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| 84 | ------------------+-------------------+-------------------+-------------------
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| 85 |
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| 86 | Line 0,1 will be line C10. Direct assignments like line C11 will only use one
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| 87 | line 3. When calling functions (C13), first the parameters will be set on
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| 88 | place at line 5,6 then the function itself will be caled at line 7.
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| 89 |
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| 90 | Some book keeping could be found at line 13 (return)
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| 91 |
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| 92 | = USAGE =
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| 93 | # Compile
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| 94 | $ make dirs
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| 95 | $ make
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| 96 | # Call without optimalisation
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| 97 | $ ./comp -w -00 <testfile
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| 98 | # Call with optimalisation
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| 99 | $ ./comp -w -01 <testfile
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