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tensorflow / tflite-micro

Infrastructure to enable deployment of ML models to low-power resource-constrained embedded targets (including microcontrollers and digital signal processors).
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build: begin using -std=c++17 and c17 in Makefile builds #2648

Closed rkuester closed 3 months ago

rkuester commented 3 months ago

Begin using -std=c++17 and -std=c17 in Makefile builds on all platforms. Bazel builds have been using C++17 since 52c9568.

Set -stdlib=libc++ on xt-clang on Xtensa to add C++17 library support in addition to compiler support. From the xt-clang docs:

Starting with the RI-2019.1 release, XT-CLANG has included support
for C++14 and C++17 language features. The compiler support for
C++14 and C++17 is accompanied by the C++ library from the LLVM
project. This library can be selected with the -stdlib=libc++
option, and this is strongly recommended when compiling with
-std=c++14 or - std=c++17. Starting with the RI-2021.6 release, two
additional versions of this C++ library are provided— one that
excludes support for exception handling, and one that excludes both
exception handling and run-time type identification. These libraries
can be selected with -stdlib=libc ++-e and -stdlib=libc++-re options
respectively.

Based on the docker run command in tflite-micro/.github/workflows/xtensa_presubmit.yml, our CI is currently using RI-2020.4.

Refactor the make/ext_libs/xtensa_download.sh script to make it eaiser to patch downloads for all Xtensa platforms. The old script made overly strict assumptions about the name of the patch.

Patch the Xtensa vision_p6 platform download xi_tflmlib_vision_p6 for compatibility with the C++ library standard. Use the header to access constants such as INT_MAX.

BUG=#2650

rkuester commented 3 months ago

Closing and punting, for now, to issue #2650.