I like to contribute to open source, here are links to some of my contributions 🙏

LLVM

Repository: llvm/llvm-project
GitHub: @chaitanyav Period: March 2023 - April 2026

1️⃣ C23 Standard Library Builtins

🟢 `__builtin_stdc_*` Bit Manipulation Builtins (April 2026)

PR #185978 | Merged April 16, 2026 | C23 Language Feature

Implemented the C23 bit manipulation builtins following the ISO C23 standard specification:

__builtin_stdc_leading_zeros() / __builtin_stdc_leading_ones()
__builtin_stdc_trailing_zeros() / __builtin_stdc_trailing_ones()
__builtin_stdc_first_leading_zero() / __builtin_stdc_first_leading_one()
__builtin_stdc_first_trailing_zero() / __builtin_stdc_first_trailing_one()
__builtin_stdc_count_zeros() / __builtin_stdc_count_ones()
__builtin_stdc_has_single_bit()
__builtin_stdc_bit_width() / __builtin_stdc_bit_floor() / __builtin_stdc_bit_ceil()

💡 Technical Approach:

✅ Designed for GCC compatibility while leveraging LLVM’s existing intrinsics (ctlz, cttz, ctpop)
✅ Type-generic implementation supporting all unsigned integer types
✅ Integration with Clang’s constant expression evaluator

🎯 Impact: Enables C23-compliant portable bit manipulation without vendor-specific intrinsics.

🟢 Typed Variants for C23 stdbit.h Builtins (April 2026)

PR #192718 | Merged April 21, 2026 | C23 Language Feature Added typed variants of the C23 bit manipulation builtins following the stdbit.h specification: Typed functions for specific unsigned integer types:

stdc_leading_zeros_{uc,us,ui,ul,ull} - Leading zeros for unsigned char, unsigned short, unsigned int, unsigned long, unsigned long long
stdc_leading_ones_{uc,us,ui,ul,ull} - Leading ones
stdc_trailing_zeros_{uc,us,ui,ul,ull} - Trailing zeros
stdc_trailing_ones_{uc,us,ui,ul,ull} - Trailing ones
stdc_first_leading_zero_{uc,us,ui,ul,ull} - First leading zero position
stdc_first_leading_one_{uc,us,ui,ul,ull} - First leading one position
stdc_first_trailing_zero_{uc,us,ui,ul,ull} - First trailing zero position
stdc_first_trailing_one_{uc,us,ui,ul,ull} - First trailing one position
stdc_count_zeros_{uc,us,ui,ul,ull} - Count of zero bits
stdc_count_ones_{uc,us,ui,ul,ull} - Count of one bits
stdc_has_single_bit_{uc,us,ui,ul,ull} - Check if power of two
stdc_bit_width_{uc,us,ui,ul,ull} - Bit width
stdc_bit_floor_{uc,us,ui,ul,ull} - Largest power of 2 ≤ value
stdc_bit_ceil_{uc,us,ui,ul,ull} - Smallest power of 2 ≥ value

💡 Technical Approach:

✅ Complements the type-generic _builtin_stdc* implementations from PR #185978
✅ Provides C23-compliant typed interface matching the standard library specification
✅ Maps to the same underlying intrinsics (ctlz, cttz, ctpop) with type-specific wrappers

🎯 Impact: Completes C23 <stdbit.h> implementation, allowing both type-generic and type-specific bit manipulation functions.

🟢 Rotate Builtins (January 2026)

PR #160259 | Merged January 21, 2026 | C23 Language Feature

Implemented __builtin_stdc_rotate_left() and __builtin_stdc_rotate_right():

Type-generic support for all unsigned integer types including _BitInt(N)
Compile-time evaluation in constexpr contexts
Maps to efficient rotate instructions on target architectures
Handling ARM32 compatibility issues with __int128 types required careful test design and fallback to _BitInt(128).

2️⃣ Constexpr SIMD Intrinsics:

Between October 2025 and February 2026, I systematically enabled compile-time evaluation for X86 SIMD intrinsics across multiple instruction set extensions. This work allows these intrinsics to be used in constexpr contexts, enabling better compile-time optimization and static analysis.

🔵 AVX-512 Advanced Intrinsics

🔵 AVX-512 VPMULTISHIFTQB (November 2025)
PR #168995 | Resolves #167477 | AVX-512 Constexpr
Multi-byte shift operations with compile-time evaluation support.

_mm512_multishift_epi64_epi8, _mm512_mask_multishift_epi64_epi8, _mm512_maskz_multishift_epi64_epi8
_mm256_multishift_epi64_epi8, _mm256_mask_multishift_epi64_epi8, _mm256_maskz_multishift_epi64_epi8
_mm_multishift_epi64_epi8, _mm_mask_multishift_epi64_epi8, _mm_maskz_multishift_epi64_epi8

🔵 AVX-512 VPSHUFBITQMB (November 2025)
PR #168100 | Resolves #161337 | AVX-512 Constexpr Cryptographic
Bit shuffle operations for cryptographic and data manipulation workloads.

_mm512_bitshuffle_epi64_mask, _mm512_mask_bitshuffle_epi64_mask
_mm256_bitshuffle_epi64_mask, _mm256_mask_bitshuffle_epi64_mask
_mm_bitshuffle_epi64_mask, _mm_mask_bitshuffle_epi64_mask

🔵 AVX-512 Conflict Detection (October 2025)
PR #163293 | Resolves #160524 | AVX-512 Constexpr
Enables conflict detection intrinsics in constexpr contexts for identifying duplicate elements.

_mm512_conflict_epi32, _mm512_mask_conflict_epi32, _mm512_maskz_conflict_epi32
_mm512_conflict_epi64, _mm512_mask_conflict_epi64, _mm512_maskz_conflict_epi64

🔵 AVX-512 IFMA (October 2025)
PR #161056 | Resolves #160498 | AVX-512 AVX-IFMA Constexpr
Integer fused multiply-add (madd52) support for large integer arithmetic.

AVX-512: _mm512_madd52hi_epu64, _mm512_madd52lo_epu64 (and mask/maskz variants)
AVX-IFMA: _mm256_madd52hi_epu64, _mm256_madd52lo_epu64, _mm_madd52hi_epu64, _mm_madd52lo_epu64 (and mask/maskz variants)

🟣 AVX-512 Permutation & Shuffle Operations

🟣 Permutexvar Intrinsics (November 2025)
PR #167802 | Resolves #167476 | AVX-512 Permutation Constexpr
Variable permutation operations across vector lanes.

_mm512_permutexvar_epi8/epi16/epi32/epi64/ps/pd (and mask/maskz variants)
_mm256_permutexvar_epi8/epi16/epi32/epi64/ps/pd (and mask/maskz variants)

🟣 Permutex2var Intrinsics (November 2025)
PR #165085 | AVX-512 Permutation Constexpr
Two-source permutation with extended shuffle generic support.

_mm512_permutex2var_epi8/epi16/epi32/epi64/ps/pd (and mask/maskz variants)
_mm256_permutex2var_epi8/epi16/epi32/epi64/ps/pd (and mask/maskz variants)
_mm_permutex2var_epi8/epi16/epi32/epi64/ps/pd (and mask/maskz variants)

🟢 SSE/AVX Fundamental Operations

🟢 Shuffle Operations (October 2025)
PR #164078 | Resolves #161208 | SSE AVX AVX-512 Constexpr
Fundamental shuffle operations used in nearly all vectorized code.

SSE: _mm_shuffle_ps
SSE2: _mm_shuffle_pd
AVX: _mm256_shuffle_ps, _mm256_shuffle_pd
AVX-512: All corresponding mask/maskz variants for 512-bit vectors

🟢 GFNI Intrinsics (December 2025)
PR #169619 | Resolves #169295 | GFNI Cryptographic Constexpr
Galois Field New Instructions for cryptographic applications.

_mm512_gf2p8affineinv_epi64_epi8, _mm512_gf2p8affine_epi64_epi8, _mm512_gf2p8mul_epi8 (and mask/maskz variants)
_mm256_gf2p8affineinv_epi64_epi8, _mm256_gf2p8affine_epi64_epi8, _mm256_gf2p8mul_epi8 (and mask/maskz variants)
_mm_gf2p8affineinv_epi64_epi8, _mm_gf2p8affine_epi64_epi8, _mm_gf2p8mul_epi8 (and mask/maskz variants)

🟢 Variable Shift Operations (November 2025)
PR #169276 | Resolves #169176 | SSE AVX AVX-512 Constexpr
Variable shift intrinsics (shift amount per element).

Logical left: _mm512_sllv_epi16/epi32/epi64, _mm256_sllv_epi16/epi32/epi64, _mm_sllv_epi16/epi32/epi64 (and mask/maskz variants)
Arithmetic right: _mm512_srav_epi16/epi32/epi64, _mm256_srav_epi16/epi32/epi64, _mm_srav_epi16/epi32/epi64 (and mask/maskz variants)
Logical right: _mm512_srlv_epi16/epi32/epi64, _mm256_srlv_epi16/epi32/epi64, _mm_srlv_epi16/epi32/epi64 (and mask/maskz variants)

🟢 Floating-Point Min/Max (January 2026)
PR #171966 | SSE AVX AVX-512 FP16 Constexpr
Vector FP maximum/minimum operations across SSE/AVX families.

SSE: _mm_min_ps, _mm_max_ps, _mm_min_pd, _mm_max_pd
AVX: _mm256_min_ps, _mm256_max_ps, _mm256_min_pd, _mm256_max_pd
AVX-512: _mm512_min_ps, _mm512_max_ps, _mm512_min_pd, _mm512_max_pd (and mask/maskz variants)
AVX-512 FP16: _mm512_min_ph, _mm512_max_ph, _mm256_min_ph, _mm256_max_ph, _mm_min_ph, _mm_max_ph (and mask/maskz variants)

🟢 Scalar Min/Max with AVX-512 FP16 (February 2026)
PR #178029 | SSE SSE2 AVX-512 FP16 Constexpr
Extended scalar operations including new FP16 intrinsics:

SSE scalar single-precision: _mm_min_ss, _mm_max_ss
SSE2 scalar double-precision: _mm_min_sd, _mm_max_sd
AVX-512 FP16 scalar: _mm_min_sh, _mm_max_sh (and mask/maskz variants)

🔧 Implementation Approach:

✅ Extended VectorExprEvaluator::VisitCallExpr and InterpretBuiltin evaluation paths
✅ Added comprehensive test coverage for NaN, denormal, infinity, and rounding mode edge cases
✅ Handled special cases: saturation boundaries, broadcast patterns, cross-lane operations

3️⃣ SelectionDAG Optimizations

🟢 computeKnownFPClass SELECT/VSELECT Handling (April 2026) PR #194009 | Fixes #193500 | Merged April 30, 2026 | SelectionDAG Optimization Extended SelectionDAG::computeKnownFPClass to handle ISD::SELECT and ISD::VSELECT nodes, propagating floating-point class information (e.g. nofpclass(nan), nofpclass(inf), nofpclass(zero)) through select operations.

💡 Technical Approach:

✅ Computes KnownFPClass for both true and false arms of a select, then intersects the results
✅ Bails out early if the false arm is fully unknown, avoiding unnecessary work
✅ Covers scalar SELECT, fixed-vector VSELECT, and scalable-vector VSELECT
✅ Comprehensive RISC-V test coverage for symmetric, asymmetric, and unknown-arm cases

🎯 Impact: Enables the backend to eliminate redundant is.fpclass checks on select results when both arms share a known FP class constraint, reducing generated code size and improving optimization quality.

4️⃣ Early Work: Tooling & API Improvements (2023)

Clang ExtractAPI Enhancements

A series of fixes to Clang’s API documentation extraction:

Objective-C Lightweight Generics (March-May 2023)
PRs: Declaration fragments, pointer indirection, instancetype handling
Fixed ExtractAPI’s handling of Objective-C generics for accurate API documentation generation.

Declaration Fragment Completeness (March 2023)
Added missing semicolons to function, enum, typedef, and struct declaration fragments for syntactically complete generated documentation.

Clang-Tidy Improvements (May 2023)

Extended error code checking to all functions with error-like return types:

std::error_code, std::expected
boost::system::error_code
absl::Status

Helps catch ignored error conditions across multiple libraries.

libc++ Enhancements (October 2025)

PR #162030
Added compile-time assertion to std::string::resize_and_overwrite() verifying the operation returns an integer-like type, improving template error messages and preventing misuse.

🔗 Resources

All Commits: GitHub Search

📬 Connect

I’m actively contributing to LLVM and exploring compiler engineering opportunities. If you’re working on interesting compiler problems—especially in optimization, code generation, or language implementation—I’d love to connect.

Open Source

LLVM

1️⃣ C23 Standard Library Builtins

🟢 `__builtin_stdc_*` Bit Manipulation Builtins (April 2026)

🟢 Typed Variants for C23 stdbit.h Builtins (April 2026)

🟢 Rotate Builtins (January 2026)

2️⃣ Constexpr SIMD Intrinsics:

🔵 AVX-512 Advanced Intrinsics

🟣 AVX-512 Permutation & Shuffle Operations

🟢 SSE/AVX Fundamental Operations

3️⃣ SelectionDAG Optimizations

4️⃣ Early Work: Tooling & API Improvements (2023)

Clang ExtractAPI Enhancements

Clang-Tidy Improvements (May 2023)

libc++ Enhancements (October 2025)

🔗 Resources

📬 Connect

Rust

FreeBSD

Scala tools, compiler (2.13.x)

FFmpeg

RubyGems

RubyOnRails Contribution

LLVM

1️⃣ C23 Standard Library Builtins

🟢 __builtin_stdc_* Bit Manipulation Builtins (April 2026)

🟢 Typed Variants for C23 stdbit.h Builtins (April 2026)

🟢 Rotate Builtins (January 2026)

2️⃣ Constexpr SIMD Intrinsics:

🔵 AVX-512 Advanced Intrinsics

🟣 AVX-512 Permutation & Shuffle Operations

🟢 SSE/AVX Fundamental Operations

3️⃣ SelectionDAG Optimizations

4️⃣ Early Work: Tooling & API Improvements (2023)

Clang ExtractAPI Enhancements

Clang-Tidy Improvements (May 2023)

libc++ Enhancements (October 2025)

🔗 Resources

📬 Connect

Rust

FreeBSD

Scala tools, compiler (2.13.x)

FFmpeg

RubyGems

RubyOnRails Contribution

🟢 `__builtin_stdc_*` Bit Manipulation Builtins (April 2026)