In-Class

Compiler generated assembly 1
Let us get some experience reading assembly code generated by the compiler.

• Write a C program that swaps two integers.
• Save, Compile, and Run the program to verify it works.
• Output the assembly from that program (Save it as sample_int.s).
• Use: clang sample_int.c -S -o sample_int.s
• Now modify your program to swap to long's.
• Save, Compile, and Run the program to verify it works.
• Output the assembly from that program (Save it as sample_long.s).
• Compare each of the two assembly files using diff. See what changed.
  • diff syntax
  • diff -y sample_int.s sample_long.s

Compiler generated assembly 2
Let us get more experience an infer some assembly code generated by the compiler.

• Write a C program that swaps two integers in a function (You may use today's slide as a reference).
• Save, Compile, and Run the program to verify it works.
• Output the assembly from that program (Save it as sample_int.s).
• Do the instructions use memory/registers in a different way?

Compiler generated assembly 3
Let us get more experience an infer some assembly code generated by the compiler.

• Write a C program that has an array of 4 integers.
• Set each value to something (do not use a loop) (e.g. myArray[0]=1; myArray[1]=2; etc)
• Save, Compile, and Run the program to verify it works.
• Output the assembly from that program (Save it as sample_int.s).
• How much are the offsets from the address?

Grading

Note that in-class activities are part of your participation grade, and participating will help you perform well on your assignments. You do not have to formally submit anything.