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1. Bernie (codewiz@mstdn.io)'s status on Sunday, 05-Feb-2023 23:42:40 UTC Bernie

   C++ compiler puzzle: can you guess why GCC 10.3 generates slightly worse code when switching from -std=c++17 to -std=c++20?

   https://godbolt.org/z/99z7jxM1c
   #cpp #programming #cpp20 #assembly #gcc #compilers

   • Bernie (codewiz@mstdn.io)'s status on Sunday, 05-Feb-2023 23:53:07 UTC Bernie

     in reply to

     This is a reduced testcase from a large codebase for 32-bit ARM microcontrollers.

     Yesterday I noticed that GCC 12 generates the exact same code in C++17 and C++20 mode.

     This morning, a GCC developer guessed the issue and pointed me at the fix that was merged two years ago.

     I can't update my toolchain right now, but knowing what triggers the bug made it easy to come up with a workaround for GCC 10.

     #programming #cpp #embedded #gcc