ISPC Lit Test Best Practices FAQs

Question 1

How do I make ISPC lit tests portable across different architectures?

Accepted Answer

Avoid hardcoding vector widths or variable names. Instead, use named patterns like [[WIDTH]] and [[TYPE]] in your CHECK statements to match flexible LLVM IR outputs.

Question 2

What is the standard naming convention for ISPC regression tests?

Accepted Answer

Regression tests should be named after their GitHub issue number (e.g., 1234.ispc) to provide clear context and link the test directly to the fixed bug.

Question 3

Why should I use --nowrap in ISPC lit tests?

Accepted Answer

Using --nowrap prevents line wrapping in the compiler output, which ensures that FileCheck matches remain consistent and reliable across different environments.

Question 4

How can I test specific optimization passes in ISPC?

Accepted Answer

You can use the --debug-phase flag to capture the output of a specific optimization pass and then run FileCheck against the resulting dumped IR file.

Question 5

When should I use the 'export' keyword in a test file?

Accepted Answer

Avoid using 'export' unless you are explicitly testing export behavior. Exported functions generate both masked and unmasked IR, which doubles the maintenance effort for the test.

ISPC Lit Test Best Practices

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Key Features

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ISPC Lit Test Best Practices

About

Key Features

Use Cases