Homework
ICS 232 Computer Organization & Architecture
Project XXXXXXXXXXpoints + 20 Bonus Points
Due Date: 4/24/2023
Name:
Note: Post your submission to ICS232 D2L site on or before the due date.
Programming Assignment 2:
The purpose of this project is to gain a greater understanding of the Intel 32-bit instruction set and understand how a compiler translates C code into assembly language. By compiling the program in unoptimized mode you will hopefully see a fairly clear translation. When running in optimization mode, you will see how well compilers can optimize your code.
To compile an unoptimized version use:
gcc -Wa,-adhln -g -masm=intel -m32 "Project 2.c" > "Project 2-g.asm"
This will write the unoptimized inter-mixed source and assembly code Project 2-g.asm.
To compile an optimized version use:
gcc -Wa,-adhln -O -masm=intel -m32 "Project 2.c" > "Project 2-o.asm"
This will write the optimized inter-mixed source and assembly code Project 2-o.asm.
The -Wa,-adhln option causes gcc to generate intermixed source and assembly code.
The -masm=intel option causes gcc to generate assembly code in intel format.
The -m32 generates 32-bit code.
The -g option generates unoptimized code while -O generates optimized code.
The web site Godbolt.org can also be used to compile the program.
The generated code includes quite a few directives that can be ignored. Most of the directives begin with a period (.). There are also a few call instructions to procedures that you may not know what they mean that can be ignored. For example:
call __x86.get_pc_thunk.bx
add ebx, OFFSET FLAT:_GLOBAL_OFFSET_TABLE_
In all of the following questions, the line numbers refer the line numbers in the C code.
The following questions should be answered using the unoptimized code.
1. Describe the stack at line 25 (return (sum);). The bottom of the stack is the first row below. The top of the stack will be the last item. The first few items are provided. You will probably need to add some additional rows to the table below.
Description
Value
First argument to main
argv
Second argument to main
argc
Return address of main
Caller’s return address
C runtime value of bp
Caller’s bp registe
Local variable i in main [bp-12]
5
2. In detail explain the code generated for line 105 (k = function1(i, j);). For this and all further questions in which you are asked to explain the code generated in detail, I expect you to copy the generated code and add a comment for each line. For example:
006e C745FC00 mov DWORD PTR -4[ebp], 0 ; initialize i
You can also refer to Week9-CAssembly-g.asm for examples of what you should submit.
3. In detail explain the code generated for function2 (line 29 through 49).
4. In detail explain the code generated for function5 (line 80 through 93).
The following questions should be answered using the optimized code.
5. In detail explain the code generated for function1 (line 12 through 27).
6. How are function calls optimized? For example, see lines 114 and 117.
The following questions should be answered using by comparing the unoptimized code and the optimized code.
7. Compare the code generated by function4 in the unoptimized and optimized versions. Explain the optimizations.
Bonus – 10 points
In detail explain the code generated for function3. This a hard. Try your best. Why is the compiler doing this? You need to explain the purpose of each line of the generated assembly code.
Bonus – 10 points
The file strlen.asm contains the Microsoft Visual Studio source code for the strlen() function. You need to explain the purpose of each line of the assembly code particularly lines 81 through 88.
Grading Criteria By Project Items:
1. Stack contents not defined well enough (-5 -> -10 points).
2. Call functon1 description (-5 -> -10 points).
3. Code description for function2 not complete enough (-5 -> -10 points).
4. Code description for function5 not complete enough (-5 -> -10 points).
5. Optimized function1 description incomplete (-5 -> -10 points).
6. Optimized function call description incomplete (-5 -> -10 points).
7. Function4 optimized description incomplete (-5 -> -10 points).
Late Submission Policy:
-10 points if submitted after the due date and an extension has been granted.
-20 points if submitted after the due date and an extension has not been granted.