Lecture Notes: MIPS Case Study (Control Flow Instruction) PDF

ISA : MIPS Case Study (Control Flow Instruction) 471029: Introduction to Computer Architecture 11th Lecture Disclaimer: Slides are mainly based on COD 5th textbook and also developed in part by Profs. Dohyung Kim @ KNU and Computer architecture course @ KAIST and SKKU...

ISA : MIPS Case Study (Control Flow Instruction) 471029: Introduction to Computer Architecture 11th Lecture Disclaimer: Slides are mainly based on COD 5th textbook and also developed in part by Profs. Dohyung Kim @ KNU and Computer architecture course @ KAIST and SKKU 1 MIPS Control Flow Instructions  Conditional operations  Branch to a labeled instruction if a condition is true  Otherwise, continue sequentially beq rs, rt, L1  if (rs == rt) branch to instruction labeled L1; bne rs, rt, L1  if (rs != rt) branch to instruction labeled L1; J L1  unconditional jump to instruction labeled L1; 2  MIPS Control Flow Instructions (cont’d)  Compiling If statements  C code: if (i == j) f = g + h; else f = g – h;  Assume f, g, h, I, and j in $s0, $s1, $s2, $s3, and $s4, respectively  Compiled MIPS code: bne $s3, $s4, Else Assembler calculates addresses add $s0, $s1, $s2 j Exit Else: sub $s0, $s1, $s2 Exit:... 3 MIPS Control Flow Instructions (cont’d)  Compiling loop statements  C code: while (save[i] == k) i += 1; i in $s3, k in $s5, address of save in $s6  Suppose the data type of the save array is word  Compiled MIPS code: Loop: sll $t1, $s3, 2 add $t1, $t1, $s6 lw $t0, 0($t1) bne $t0, $s5, Exit addi $s3, $s3, 1 j Loop Exit:... 4 MIPS Control Flow Instructions (cont’d)  More conditional operations  Set result to 1 if a condition is true (slt: set less than)  Otherwise, set to 0  if (rs