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nlrxtensa.c
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Damien George authoredRecent versions of gcc perform optimisations which can lead to the following code from the MP_NLR_JUMP_HEAD macro being omitted: top->ret_val = val; \ MP_NLR_RESTORE_PYSTACK(top); \ *_top_ptr = top->prev; \ This is noticeable (at least) in the unix coverage on x86-64 built with gcc 9.1.0. This is because the nlr_jump function is marked as no-return, so gcc deduces that the above code has no effect. Adding MP_UNREACHABLE tells the compiler that the asm code may branch elsewhere, and so it cannot optimise away the code.Damien George authoredRecent versions of gcc perform optimisations which can lead to the following code from the MP_NLR_JUMP_HEAD macro being omitted: top->ret_val = val; \ MP_NLR_RESTORE_PYSTACK(top); \ *_top_ptr = top->prev; \ This is noticeable (at least) in the unix coverage on x86-64 built with gcc 9.1.0. This is because the nlr_jump function is marked as no-return, so gcc deduces that the above code has no effect. Adding MP_UNREACHABLE tells the compiler that the asm code may branch elsewhere, and so it cannot optimise away the code.