In this lab, you are expected to compare the source code and assembly code for t

Question

In this lab, you are expected to compare the source code and assembly code for the following C code. (you can get the assembly code with usually –s flag). Can you see any optimizations that can be done on the assembly code?

int a=1, b=2, c=3;

int proc1 (int a, int b, int c)

{ If (a>0) return b – c;

else return b + c; }

int main()

{ int w, x, y; w = proc1 (a, b, c);

switch (w)

{ case 0: x=3; break;

case 1: x=4; break;

case 2: x=7; break;

default: x=9; break; }

y= w + x; return 0; }

what this program does and how assembly code can be optimized.

Explanation / Answer

step 1: starting with main

step 2: will call function proc1(1,2,3)

step 3: in proc1 condition check a=1,a>1yes so b-c=(2-3) = -1

step 4: w having value -1 case value{0,1,2} so default case will run

step 5: x=9,and w=-1 so y=w+x (9-1) answerrrrrr: y=8

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