jgs Compilers Lecture 23: Intermediate Code III Dr. Javier Gonzalez-Sanchez jgonzalezs@up.edu.mx

Dr. Javier Gonzalez-Sanchez | Compilers | 2 jgs Video

jgs Previously …

Dr. Javier Gonzalez-Sanchez | Compilers | 4 jgs Translate Source to Object { int a; int b; int c; int d; if (a != 5) { b = c + d; } print (a); } a,int,global 0 b,int,global 0 c,int,global 0 d,int,global 0 #E1,int,label,9 #P,int,label,1 @ lod , 0 lit 5, 0 opr 14, 0 jmc #e1, false lod c, 0 lod d, 0 opr 2, 0 sto b, 0 lod a, 0 opr 21, 0 opr 1, 0

Dr. Javier Gonzalez-Sanchez | Compilers | 5 jgs Your Code Should be

Dr. Javier Gonzalez-Sanchez | Compilers | 6 jgs

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Dr. Javier Gonzalez-Sanchez | Compilers | 8 jgs Review Programming Assignment 4 Level 1 LIT, LOD, STO, OPR

Dr. Javier Gonzalez-Sanchez | Compilers | 9 jgs Code PROGRAM OPR 0, 0

Dr. Javier Gonzalez-Sanchez | Compilers | 10 jgs Code BODY

Dr. Javier Gonzalez-Sanchez | Compilers | 11 jgs Code PRINT OPR 21, 0

Dr. Javier Gonzalez-Sanchez | Compilers | 12 jgs Code ASSIGNMENT STO identifier, 0

Dr. Javier Gonzalez-Sanchez | Compilers | 13 jgs Code VARIABLE identifier,

Dr. Javier Gonzalez-Sanchez | Compilers | 14 jgs Code RETURN OPR 1, 0

Dr. Javier Gonzalez-Sanchez | Compilers | 15 jgs Parser EXPRESSION if (twice) { OPR 8, 0 }

Dr. Javier Gonzalez-Sanchez | Compilers | 16 jgs Parser X if (twice) { OPR 9, 0 }

Dr. Javier Gonzalez-Sanchez | Compilers | 17 jgs Parser Y if (operatorUsed) { OPR 10, 0 }

Dr. Javier Gonzalez-Sanchez | Compilers | 18 jgs Parser R if (twice) { OPR , 0 }

Dr. Javier Gonzalez-Sanchez | Compilers | 19 jgs Parser E if (twice) { OPR , 0 }

Dr. Javier Gonzalez-Sanchez | Compilers | 20 jgs Parser A if (twice) { OPR , 0 }

Dr. Javier Gonzalez-Sanchez | Compilers | 21 jgs Parser B if (operatorUsed) { OPR 3, 0 } LIT 0, 0

Dr. Javier Gonzalez-Sanchez | Compilers | 22 jgs Assignment 2 | Code C LIT , 0 LOD identifier, 0

Dr. Javier Gonzalez-Sanchez | Compilers | 23 jgs Review Programming Assignment 4 Level 2 JMP, JMC

Dr. Javier Gonzalez-Sanchez | Compilers | 24 jgs Instructions § JMP , 0 Put the value in the program counter; thus, the next line to be executed will be Examples: JMP 1, 0 JMP 14, 0 JMP 75, 0

Dr. Javier Gonzalez-Sanchez | Compilers | 25 jgs Instructions § JMC , Read one value from the CPU register If the value is equal to , put the value in the program counter; thus, the next line to be executed will be Examples: JMC 1, true JMC 14, false JMC 75, true

Dr. Javier Gonzalez-Sanchez | Compilers | 26 jgs Example { int a; int b; a = 10; while (a>1){ print (a); } return; } int a global 0 int b global 0 @ LIT 10, 0 STO a, 0 LOD a, 0 LIT 1, 0 OPR 11, 0 ; > JMC #e1, false LOD a, 0 OPR 20, 0 ; print JMP #e2, 0 OPR 1, 0 OPR 0, 0

Dr. Javier Gonzalez-Sanchez | Compilers | 27 jgs Labels § The compiler creates variables and adds them to the symbol table to remember positions in the code. § This is useful for loops and conditions.

Dr. Javier Gonzalez-Sanchez | Compilers | 28 jgs Labels | how while works while (a < b) { //code } label#1 if (a < b) { //code } else goto label#2 } goto label#1 label #2

Dr. Javier Gonzalez-Sanchez | Compilers | 29 jgs Labels | how if works if (a < b) { //code1 } else { // code2 } if (a < b) { if (a>b) goto label #1 //code1 } else goto label#2 label #1 // code2 } label #2

Dr. Javier Gonzalez-Sanchez | Compilers | 30 jgs Example | while { int a; int b; a = 10; while (a>1){ print (a); } return; } int a global 0 int b global 0 int #e1 global 10 int #e2 global 3 LIT 10, 0 STO a, 0 LOD a, 0 LIT 1, 0 OPR 11, 0 ; > JMC #e1, false LOD a, 0 OPR 20, 0 ;print JMP #e2, 0 OPR 1, 0 OPR 0, 0

Dr. Javier Gonzalez-Sanchez | Compilers | 31 jgs Example | if { int a; int b; a = 10; if (a>1) { print (a); } else { print (b); } return; } int a global 0 int b global 0 int #e1 global 10 int #e2 global 12 LIT 10, 0 STO a, 0 LOD a, 0 LIT 1, 0 OPR 11, 0 ; > JMC #e1, false LOD a, 0 OPR 20, 0 ;print JMP #e2, 0 LOD b, 0 OPR 20, 0 ;print OPR 1, 0 OPR 0, 0

Dr. Javier Gonzalez-Sanchez | Compilers | 32 jgs Exercise { int a; int b; a = 10; while (a>1) { if (a != 0) { print (a); } else { print (b); } a = a -1; } }

Dr. Javier Gonzalez-Sanchez | Compilers | 33 jgs Handwritten notes

Dr. Javier Gonzalez-Sanchez | Compilers | 34 jgs Code WHILE

Dr. Javier Gonzalez-Sanchez | Compilers | 35 jgs Code

Dr. Javier Gonzalez-Sanchez | Compilers | 36 jgs Code IF

Dr. Javier Gonzalez-Sanchez | Compilers | 37 jgs Code

Dr. Javier Gonzalez-Sanchez | Compilers | 38 jgs Review Programming Assignment 4 Level 3 Bonus Points: SWITCH

Dr. Javier Gonzalez-Sanchez | Compilers | 39 jgs Homework Translate this source code to intermediate code: int a; switch (a) { case 1: { print("hi”); break;} case 2: { print("world"); break;} default: { print(”end"); break;} }

Dr. Javier Gonzalez-Sanchez | Compilers | 40 jgs Handwritten notes Add the symbol table here…

Dr. Javier Gonzalez-Sanchez | Compilers | 41 jgs Homework Assignment #4

Dr. Javier Gonzalez-Sanchez | Compilers | 42 jgs High-Level Languages X,E,G,O,O #e1,I,I,0,7 @ OPR 19, AX STO x, AX LIT 5, AX OPR 21, AX LOD #e1,AX CAL 1, AX OPR 0, AX 5 Virtual Machine (interpreter) // sorce code int x; int foo () { read (x); print (5); } main () { foo (); } Lexer Parser Semantic Analyzer Code Generation 01001010101000010 01010100101010010 10100100000011011 11010010110101111 00010010101010010 10101001010101011 Assembler compilation execution

Dr. Javier Gonzalez-Sanchez | Compilers | 43 jgs Questions

jgs Compilers Javier Gonzalez-Sanchez, Ph.D. jgonzalezs@up.edu.mx Spring 2024 Copyright. These slides can only be used as study material for the Compilers course at Universidad Panamericana. They cannot be distributed or used for another purpose.