# [Use LLVM Machine Code Analyzer to analyze assembly performance on Arm](https://learn.arm.com/learning-paths/cross-platform/mca-godbolt/)

## In this learning path

- [Introduction](https://learn.arm.com/learning-paths/cross-platform/mca-godbolt/)
- [Background](https://learn.arm.com/learning-paths/cross-platform/mca-godbolt/background/)
- [Run MCA with Arm assembly](https://learn.arm.com/learning-paths/cross-platform/mca-godbolt/running_mca/)
- [Use MCA with Compiler Explorer](https://learn.arm.com/learning-paths/cross-platform/mca-godbolt/mca_on_godbolt/)
- [Next Steps](https://learn.arm.com/learning-paths/cross-platform/mca-godbolt/_next-steps/)

## About this Learning Path

| Skill level:       | Introductory                |
|--------------------|-----------------------------|
| Reading time:      | 1 hr                        |
| Last updated:      | 03 Aug 2026                 |

| Author:            | Asher Dobrescu, Arm         |
|--------------------|-----------------------------|
| Arm IP:            | [Cortex-A](https://support.arm.com/?tab=compute-ip&Product%20Type=Application%20Processors) [Neoverse](https://support.arm.com/?tab=compute-ip&Product%20Type=Infrastructure%20Processors) |
| Tags:              | [Performance and Architecture](https://learn.arm.com/tag/performance-and-architecture) [Linux](https://learn.arm.com/tag/linux) [Windows](https://learn.arm.com/tag/windows) [macOS](https://learn.arm.com/tag/macos) [Assembly](https://learn.arm.com/tag/assembly) [llvm-mca](https://learn.arm.com/tag/llvm-mca) [Runbook](https://learn.arm.com/tag/runbook) |

### Who is this for?
This is an introductory topic for developers who want to diagnose performance issues of Arm programs using LLVM Machine Code Analyzer (MCA) and Compiler Explorer.

### What will you learn?
Upon completion of this Learning Path, you will be able to:
- Estimate the hardware resource pressure and the number of cycles taken to execute your code snippet using llvm-mca.
- Describe how this estimate can help diagnose possible performance issues.
- Use Compiler Explorer to run llvm-mca.

### Prerequisites
Before starting, you will need the following:
- Familiarity with Arm assembly.
- LLVM version 16 or newer, which includes support for Neoverse V2.

### Summary
You’ll use LLVM Machine Code Analyzer (`llvm-mca`) to reason about Arm assembly performance. You’ll analyze a short six-value sum to estimate cycles and resource pressure, identify bottlenecks, and relate the report to pipeline behavior. You’ll also run `llvm-mca` in Compiler Explorer to compare compiler versions and apply the workflow to other Arm assembly fragments.

### Frequently asked questions

<details>
<summary>What result should I expect when I run `llvm-mca` on the `sum_test1.s` example?</summary>
`llvm-mca` prints estimated cycles and hardware resource pressure for the add instructions. Use those metrics to identify possible stalls and the most stressed resources.
</details>

<details>
<summary>How do I run `llvm-mca` inside Compiler Explorer?</summary>
Open [Compiler Explorer](https://godbolt.org), then select the `llvm-mca` tool integration to analyze your code. You can choose compilers and tools without installing them locally.
</details>

<details>
<summary>How do I know `llvm-mca` executed correctly on my snippet?</summary>
The report includes an estimated cycle count and a resource-usage breakdown without errors. If it’s missing or incomplete, verify that the input matches the example and rerun the analysis.
</details>

<details>
<summary>What should I check before analyzing the Arm assembly example?</summary>
Save the provided instructions exactly as shown in `sum_test1.s`. Make sure the registers match the example so the analysis reflects the intended sequence.
</details>

<details>
<summary>Can I follow this path without installing LLVM locally?</summary>
Yes. Compiler Explorer includes `llvm-mca` and lets you try compiler versions in the browser. For Neoverse V2 support, use LLVM 16 or later.
</details>