[WIP] Edit code for SIMD instruction availability checks

[Copilot]

SIMD Instruction Feature Checks Enhancement

• Analyze current SIMD instruction usage across the codebase
• Update warmup_space.hpp to ensure _mm512_popcnt_epi64 has correct feature check (requires AVX512VPOPCNTDQ)
• Review and update highacc_fastscan.hpp for proper AVX512BW checks
• Verify fastscan.hpp has correct SIMD feature checks
• Check space.hpp and rotator.hpp for any missing SIMD feature checks
• Build and test the changes to ensure no regressions
• Document any findings about SIMD instruction dependencies

Original prompt

Can you help me edit code in the cloud mode of this copilot?

[Chronological Review: The conversation began with the user asking about the differences between various SIMD instructions, specifically `_mm256_loadu_epi16` vs. `_mm256_loadu_si256`, and later `_mm_storeu_epi8` vs. `_mm_storeu_si128`. The user then encountered an error related to the inlining of the `_mm512_popcnt_epi64` function, leading to questions about CPU support for AVX512F and related instructions. The user requested modifications to preprocessor directives to check for specific AVX512 features, such as AVX512DQ and AVX512BW. The conversation progressed to issues with the `accumulate_hacc` function, where discrepancies were noted between results when compiling with different AVX settings. The user sought assistance in ensuring that the code correctly checks for SIMD instruction availability across various scopes, particularly for AVX2 and AVX512F. The user also expressed a desire for help editing code in a cloud mode of a copilot.]

[Intent Mapping: The user explicitly requested information on SIMD instruction differences, error troubleshooting, and code modifications to ensure proper feature checks. They aimed to understand compatibility between AVX512F and other AVX512 extensions, and to ensure that their code correctly handles SIMD instruction availability.]

[Technical Inventory: The conversation involved SIMD instructions from Intel's AVX512 instruction set, including _mm512_popcnt_epi64, _mm512_mask_xor_ps, and _mm512_add_epi16. The user referenced preprocessor directives like #if defined(__AVX512F__) and #if defined(__AVX2__) to manage conditional compilation based on CPU capabilities.]

[Code Archaeology: The user is working within the file /home/yutong/RaBitQ-Library/include/rabitqlib/fastscan/highacc_fastscan.hpp. Specific lines of code were referenced for modification, particularly those involving SIMD checks and operations.]

[Progress Assessment: The user has made inquiries about various SIMD instructions and their requirements, identified errors in their code, and requested modifications to ensure proper checks for SIMD availability. They are actively seeking to resolve discrepancies in function outputs based on different compilation flags.]

[Context Validation: All critical information regarding SIMD instruction checks, error handling, and code modifications is captured, allowing for seamless continuation of the user's work.]

[Recent Commands Analysis: The user requested modifications to the preprocessor directives to check for specific AVX512 features and to ensure that the code correctly checks for SIMD instruction availability. The immediate pre-summarization state involved the user asking for help with editing code in a cloud mode of a copilot, indicating a desire for collaborative coding assistance.]

1. Conversation Overview: - Primary Objectives: The user requested information on SIMD instruction differences, error troubleshooting, and code modifications to ensure proper feature checks. Key quotes include "difference between `_mm256_loadu_epi16` and `_mm256_loadu_si256`" and "I want to change this line to update to check if the `_mm512_popcnt_epi64` will be available." - Session Context: The conversation flowed from inquiries about SIMD instructions to troubleshooting errors and requesting code modifications for proper checks on SIMD availability. - User Intent Evolution: The user's needs evolved from understanding instruction differences to ensuring their code correctly handles SIMD instruction availability and resolving discrepancies in function outputs.

2. Technical Foundation:

• AVX512F: Intel's Advanced Vector Extensions 512 Foundation, which provides a set of SIMD instructions.
• AVX512DQ: An extension of AVX512F that includes additional instructions for double-precision floating-point operations.
• AVX512BW: An extension that adds support for 8-bit and 16-bit integer operations.
• AVX512VPOPCNTDQ: An extension that provides population count instructions for 64-bit integers.

3. Codebase Status:

• File Name: highacc_fastscan.hpp
• Purpose: Contains SIMD-related operations and checks for the user's library.
• Current State: The user is actively modifying preprocessor directives to ensure compatibility with various AVX512 features.
• Key Code Segments: The user is focusing on modifying lines that check for SIMD instruction availability, particularly those involving _mm512_popcnt_epi64.
• Dependencies: The code relies on specific CPU features to enable certain SIMD operations.

4. Problem Resolution:

• Issues Encountered: The user faced an error related to the inlining of _mm512_popcnt_epi64 and discrepancies in results when compiling with different AVX settings.
• Solutions Implemented: The user is working on modifying preprocessor directives to ensure proper checks for SIMD instruction availability.
• Debugging Context: Ongoing troubleshooting of discrepan...

Created from VS Code.

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