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VectorCamp / vectorscan

A portable fork of the high-performance regular expression matching library
https://www.vectorcamp.gr/project/vectorscan/
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Why vectorscan require GCC9+ while hyperscan require only GCC4.8? #109

Closed leeyiw closed 2 years ago

leeyiw commented 2 years ago

I'm compiling vectorscan with GCC6.5 and got this error:

[0m-- The C compiler identification is GNU 6.5.1
-- The CXX compiler identification is GNU 6.5.1
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /apsara/alicpp/built/gcc-6.5.1/gcc-6.5.1/bin/gcc - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /apsara/alicpp/built/gcc-6.5.1/gcc-6.5.1/bin/g++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Performing Test ARCH_X86_64
-- Performing Test ARCH_X86_64 - Failed
-- Performing Test ARCH_IA32
-- Performing Test ARCH_IA32 - Failed
-- Performing Test ARCH_AARCH64
-- Performing Test ARCH_AARCH64 - Success
-- Performing Test ARCH_ARM32
-- Performing Test ARCH_ARM32 - Failed
-- Performing Test ARCH_PPC64EL
-- Performing Test ARCH_PPC64EL - Failed
-- Default build type 'Release with debug info'
-- using release build
-- Boost version: 1.64.0
-- Found PythonInterp: /usr/bin/python (found version "2.7.5")
-- Build date: 2022-06-01
-- Building static libraries
-- gcc version 6.5.1
CMake Warning at CMakeLists.txt:187 (message):
Something went wrong determining gcc tune: -mtune=ARCH not valid, falling
back to -mtune=native
-- ARCH_C_FLAGS   :
-- ARCH_CXX_FLAGS :
-- g++ version 6.5.1
CMake Error at CMakeLists.txt:273 (message):
A minimum of g++ 9 is required for C++17 support
-- Configuring incomplete, errors occurred!

it's weird while hyperscan is supporting GCC4.8 and vectorscan raise version requirements to GCC9+ with this commit.

Anyone would explain this?

markos commented 2 years ago

For one thing, we require proper Arm NEON and Power VSX intrinsics, which were not working properly in such an old gcc version and secondly we started using some C++ constructs that are C++17 only. The requirement is not going to go away. Perhaps, we might allow fallback to C++14 but at worst we will require gcc 8. gcc 4.8 is out of the question. Closing this as a non-issue.