LLVM Error: Can't Get Available Size? Causes & Solutions

by Alex Johnson 57 views

Have you encountered the frustrating “LLVM ERROR: Can't get available size” when launching OpenCL applications, especially after a Windows Adrenalin update? This cryptic error message, stemming from deep within the LLVM libraries, can halt your workflow and leave you scratching your head. But don't worry, we're here to dissect this issue, understand its root causes, and explore potential solutions. In this comprehensive guide, we'll walk you through the technical details, potential culprits, and troubleshooting steps to get your OpenCL apps running smoothly again.

Understanding the LLVM Error

To effectively tackle the “LLVM ERROR: Can't get available size”, it’s crucial to first understand where this error originates. The message arises from the CachePruning.cpp file within the LLVM project, specifically during the process of determining the available disk space for caching compiled code. This caching mechanism is designed to speed up subsequent application launches by reusing previously compiled kernels. However, when the system fails to accurately retrieve the available disk space, this error surfaces.

Specifically, the error occurs in this part of the LLVM source code:

// From CachePruning.cpp
// ...
if (sys::fs::space_available(CacheDir, AvailableSpace)) {
  // Handle error
  return;
}

This code snippet attempts to get the available space on the disk where the cache directory is located. If sys::fs::space_available returns an error, the “LLVM ERROR: Can't get available size” is triggered. Delving deeper, the error often traces back to issues within the Windows path handling in LLVM, particularly in the Path.inc file. This is where the interaction with the Windows API to retrieve disk space information takes place. The error usually manifests due to complications with character encoding or path interpretation, especially when non-ASCII characters are present in the user's path.

Digging Deeper into the Code

The specific line of code in Path.inc that often triggers this error looks something like this:

// From Windows/Path.inc
// ...
DWORD sectorsPerCluster, bytesPerSector, numberOfFreeClusters, totalNumberOfClusters;
if (!GetDiskFreeSpaceW(wPath.c_str(), &sectorsPerCluster, &bytesPerSector, &numberOfFreeClusters, &totalNumberOfClusters)) {
  // Handle error
  return std::error_code(GetLastError(), std::system_category());
}

Here, the GetDiskFreeSpaceW function, a Windows API call, is used to retrieve disk space information. The “W” suffix in the function name indicates that it’s the wide character version, designed to handle Unicode paths. However, if the path passed to this function contains characters that are not correctly encoded or interpreted, the function can fail, leading to the LLVM error. This is a critical piece of information because it suggests that the error is not necessarily about running out of disk space, but about the system's ability to correctly interpret the path to the cache directory.

Potential Causes and Scenarios

The error message **