Support LLVM 22 and fix diagnostics lifetime

[shi-eric]

Description

Make warp-clang compatible with externally supplied LLVM 22 installations while keeping Warp's source-build default at LLVM 21.1.0. This also fixes a latent diagnostic-consumer use-after-free in the shared LLVM 21+ path.

LLVM 22 removed the ORC debug-object APIs Warp used, and LLVM 19 changed the host CPU feature query to return its map by value. On LLVM 21+, the diagnostics setup also deleted its owned TextDiagnosticPrinter before retaining the same pointer as a non-owned client. LLVM 22 on Windows made that dangling pointer reliably visible as a crash during CPU kernel compilation.

Changes

• Select the compatible host CPU feature API for LLVM 19+ and ORC debug plugin for LLVM 22+.
• Transfer diagnostic-consumer ownership with takeClient() and bind its options to the compiler invocation for the required lifetime.
• Filter Windows LLVM link-directory contents to .lib files so package metadata such as Conan's components.json is not passed to link.exe.

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.
• CHANGELOG.md is updated for any user-facing changes under the Unreleased section.

Validation summary

• Verified a focused Windows-link-input test fails before the change because components.json reaches the linker inputs, then passes after the .lib filter is applied.
• Rebuilt warp.so and warp-clang.so from clean native sources with the bundled LLVM 18.1.3 toolchain and CUDA 13.0.
• Ran a CPU JIT smoke kernel through the rebuilt library and verified its output.
• Ran test_modules_lite (6 tests) and the full autodetected Warp suite (14,769 tests, 21 skipped); both passed.
• Ran all configured pre-commit hooks on the changed files.
• The originating private patch was also validated on Windows x86-64 with LLVM 22.1.8 and LLVM 21.1.8, including warp-clang compilation, linking, and a CPU JIT smoke kernel.

Bug fix

With warp-clang built against externally supplied LLVM 22 libraries, a CPU kernel compile exercised the dangling diagnostic consumer and crashed before this change. The equivalent smoke kernel now compiles and runs:

import warp as wp


@wp.kernel
def increment(values: wp.array(dtype=wp.int32)):
    i = wp.tid()
    values[i] += 1


values = wp.array([1, 2, 3], dtype=wp.int32, device="cpu")
wp.launch(increment, dim=values.size, inputs=[values], device="cpu")
assert values.numpy().tolist() == [2, 3, 4]

Summary by CodeRabbit

• Bug Fixes
  • Improved Windows builds by excluding non-library files from the linking process.
  • Updated compatibility for newer LLVM versions, improving compiler integration and reducing build failures.
  • Improved diagnostic handling to provide more reliable compiler error and warning reporting.
  • Enhanced debug information support for JIT-compiled code on recent LLVM releases.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yml

Review profile: CHILL

Plan: Enterprise

Run ID: bf1234e9-98bf-49c7-96ce-258ad381bce7

📥 Commits

Reviewing files that changed from the base of the PR and between 5498fff and d4974dc.

📒 Files selected for processing (2)

• build_llvm.py
• warp/native/clang/clang.cpp

✅ Files skipped from review due to trivial changes (1)

• build_llvm.py

🚧 Files skipped from review as they are similar to previous changes (1)

• warp/native/clang/clang.cpp

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📝 Walkthrough

Walkthrough

The change filters Windows linker inputs to .lib files and updates clang’s LLVM-version-specific CPU, diagnostics, and JIT debug-object integration for newer LLVM APIs.

Changes

LLVM compatibility and linking

Layer / File(s)	Summary
Windows library input filtering build_llvm.py	The Windows clang build path retains only .lib entries from collected linker inputs.
LLVM compiler and diagnostics API compatibility warp/native/clang/clang.cpp	CPU feature discovery, diagnostic option lifetime, and diagnostic consumer ownership are adjusted for LLVM version-specific APIs.
JIT debug-object plugin integration warp/native/clang/clang.cpp	LLVM 22 and newer use ELFDebugObjectPlugin, with conditional error handling and version-specific debug headers; older versions retain the legacy path.

Estimated code review effort: 3 (Moderate) | ~20 minutes

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title matches the main changes: LLVM 22 support and the diagnostics lifetime fix.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

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[greptile-apps]

Greptile Summary

This PR updates Warp's LLVM integration for newer external LLVM installs. The main changes are:

• LLVM 22 ORC debug plugin support for JITLink.
• LLVM 19+ host CPU feature API compatibility.
• Safer diagnostic consumer ownership for LLVM 21+.
• Windows LLVM link input filtering for .lib files.

Confidence Score: 5/5

This looks safe to merge.

• No blocking issues found in the changed code.

Important Files Changed

Filename	Overview
build_llvm.py	Filters Windows LLVM link inputs to case-insensitive .lib files before adding required system libraries.
warp/native/clang/clang.cpp	Adds LLVM-version-specific handling for CPU features, diagnostics ownership, and LLVM 22 debug plugin setup.

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