Welcome to My SPO600 Journey

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Welcome to My SPO600 Journey

Hello and welcome to my first blog post! This space will document my journey through SPO600: Software Portability and Optimization, a course taught by Chris Tyler focused on understanding how software can be optimized for different hardware architectures.

Throughout the course, I will be exploring low-level programming concepts, performance analysis techniques, and optimization strategies, starting with the 6502 microprocessor and advancing towards modern architectures like x86_64 and AArch64.

About Me

Hi everyone! My name is Haroon bajwa and I am currently studying Computer Programming and Analysis at Seneca College Newnham Campus, with a keen interest in system-level programming and performance optimization. This course presents an exciting opportunity to dive deep into assembly language and understand how code interacts with hardware. Through this blog, I aim to track my learning, share insights, and explore different optimization techniques.

What to Expect from This Blog

This blog will serve as a record of my progress in SPO600, covering topics such as:

  • Lab Reports: Step by step documentation of labs, starting with 6502 assembly language and later expanding to more complex architectures.

  • Performance Analysis: Understanding how execution time and memory usage impact software efficiency.

  • Optimization Techniques: Exploring ways to make code run faster and more efficiently on different hardware platforms.

  • Reflections and Challenges: My thoughts on assembly programming, debugging experiences, and lessons learned throughout the course labs and projects!

Looking Ahead

My next post will cover Lab 1, where I will experiment with 6502 assembly language by writing and optimizing bitmap display code. This will be my first hands-on experience with assembly programming, and I look forward to sharing my findings!

Stay tuned for upcoming posts, and feel free to follow along and comment as I explore the world of software portability and optimization!

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Project Stage 2.A

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Project Stage 2 – Part A: Finding Cloned Functions For Stage 2 of my SPO600 project, I’m taking the basic GCC analysis pass I built in Stage 1 and evolving it into something a bit more interesting—analyzing cloned functions. The end goal? Build a Clone-Pruning Analysis Pass that checks if functions in a compiled program are just duplicates and, if they are, recommends pruning them to save space and avoid redundancy. But before we can make any pruning decisions, we first need to find these clones. That’s what this blog is all about: detecting cloned functions in the compiled code. What Is a Cloned Function? When GCC optimizes code, it often makes slightly modified copies of functions—these are called clones . You’ll see them with names like: scale_samples.constprop.0 scale_samples.Mrng scale_samples.resolver These cloned functions usually come from optimizations like constant propagation , inlining , or architecture-specific tuning . For example, if the compiler notices that a functio...
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Project Stage 3

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  Project Stage 3: Tidy & Wrap – Clone-Prune Analysis at Scale Welcome to the final part of my SPO600 project! In the previous stage, I built a GCC pass that could compare a cloned function to its original version by checking the number of basic blocks and the GIMPLE statements inside them. The pass would then decide whether the cloned function was identical and could be safely pruned. That version worked well when there was only one cloned function to analyze. But in this stage I wanted to scale things up. What’s New in Stage 3? The goal for Stage 3 was to make the Clone-Prune Analysis Pass more complete and scalable . Here's what I aimed to do: Handle multiple cloned functions , not just one. Automatically skip resolver functions , which are internal compiler helpers we don’t want to compare. Make the output more clear and architecture-independent (i.e., it works the same on both x86_64 and aarch64). Improve diagnostic logging to make testing and verification easier. This m...
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Project Stage 2.C

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  Project Stage 2 – Part C: Clone-Pruning in Action This is it the final part of my Clone-Pruning Analysis Pass series! So far, I’ve: Found cloned functions using name patterns and suffixes (Part A) Extracted and compared their GIMPLE to check for similarity (Part B) Now, in this post, I’ll show the analysis in action—specifically how my pass performs on two test cases provided in the course: clone-test-prune and clone-test-noprune . This is where all the logic from earlier pays off! Clone-Prune Test Files These test files contain three functions: scale_samples.default scale_samples.Mrng scale_samples.resolver My goal here: identify whether scale_samples.Mrng is identical to scale_samples.default —and if so, recommend pruning . Let’s look at them. scale_samples.default // Simplified view of instructions... vscale = 2; for (...) {     result[i] = input[i] * vscale; } scale_samples.Mrng // Basically the same logic, just cloned for target Mrng vscale = 2; for ...
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Stage 1 Completed

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Project Stage 1 Completed! For the first stage of my SPO600 project, I created a custom GCC pass that prints out the name of each function being compiled, along with the number of basic blocks and GIMPLE statements in that function. This gave me a deeper look into how the compiler breaks down high-level code during the compilation process. Setting Up My Environment I used the recommended three-directory setup: ~/git/gcc/         # GCC source directory ~/gcc-build-001/   # Build directory ~/gcc-test-001/    # Install/test directory I followed the official GCC documentation to configure the build: ../git/gcc/configure --prefix=$HOME/gcc-test-001 --enable-languages=c --disable-bootstrap --disable-multilib time make -j$(nproc) |& tee build.log The build process took a while at first, but using make for incremental rebuilds really saved time later. I made sure to always build inside a screen session so I wouldn't lose progress if my SSH connection dro...
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Lab1 6502 Assembly Language

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  Optimizing Assembly: Insights from Lab 1 Introduction Lab 1 introduced me to the fundamentals of 6502 Assembly programming. It was my first real experience diving into low-level code, and honestly, it was a mix of confusion and excitement. The goal of the lab was to analyze an existing assembly program, understand how it works, and then try making changes to improve or modify what it does. This blog post walks through my personal journey with the lab—from running the original code to experimenting with new instructions—and what I learned along the way. Running the Bitmap Code We kicked things off with a basic assembly program designed to fill the emulator’s display with a single solid color. The code sets a pointer in memory to start writing pixel data and loops through, placing the same color on each pixel. Here’s a quick breakdown of what happens: The program sets up a pointer to location $0200 (the start of the bitmap). It sets the color to yellow with LDA #$07 . Then it uses...
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Project Stage 2.B

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Project Stage 2 – Part B: Comparing GIMPLE of Cloned Functions In the previous post , I wrote about how I detected cloned functions in the compiled program. I used naming conventions (like .constprop , .variant , and .resolver ) to group clones by their original function name. Now that I’ve found these cloned functions, it’s time to look inside them —into their GIMPLE representation —and figure out if they’re actually doing the same thing. This blog is all about how I accessed, compared, and analyzed the internal structure of these functions. Wait, What Is GIMPLE Again? GIMPLE is a simplified version of C/C++ code that GCC uses for optimization. It’s kind of like a low-level, easy-to-analyze form of your code, broken down into really basic steps (like x = y + 1 ). Each function is made up of: Basic Blocks : These are sequences of instructions with no jumps except at the end. GIMPLE Statements : Individual operations or assignments. In this part, I extracted GIMPLE from each clone and i...
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Lab 4 Building GCC on My Linux VM

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Project Stage 1 Diving In!

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Lab 2 Adventures in 6502 Assembly

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