llvm/llvm-project

[Clang] VectorExprEvaluator::VisitCallExpr / InterpretBuiltin - allow SSE/AVX/AVX512 square root intrinsics to be used in constexpr

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#160,516 opened on Sep 24, 2025

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 (13 comments) (0 reactions) (1 assignee)C++ (10,782 forks)batch import
backend:X86clang:bytecodeclang:headersconstexprgood first issue

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Description

_mm_sqrt_pd / _mm_mask_sqrt_pd / _mm_maskz_sqrt_pd
_mm_sqrt_ps / _mm_mask_sqrt_ps / _mm_maskz_sqrt_ps
_mm256_sqrt_pd /_mm256_mask_sqrt_pd / _mm256_maskz_sqrt_pd
_mm256_sqrt_ps /_mm256_mask_sqrt_ps / _mm256_maskz_sqrt_ps
_mm512_sqrt_pd / _mm512_mask_sqrt_pd / _mm512_maskz_sqrt_pd
_mm512_sqrt_ps / _mm512_mask_sqrt_ps / _mm512_maskz_sqrt_ps

These should probably be limited to non-constrained fp cases

NOTE: We are NOT intending to handle the related rcp and rsqrt estimate intrinsics

Contributor guide

Research direction
Examine VectorExprEvaluator::VisitCallExpr and InterpretBuiltin functions to understand how other builtins are handled in constexpr. Implement support for the listed SSE/AVX/AVX512 square root intrinsics, restricting to non constrained floating point contexts.
Tech stack
None
Domain
backend
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
3-5 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
C++
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30