On Sat, Mar 6, 2021 at 7:59 AM Henrik Grubbström (Lysator) @ Pike (-) developers forum 10353@lyskom.lysator.liu.se wrote:

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Playing around with generators, and have come across a strange oddity. This code works fine:

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But remove any of the 'if' guards, and the function terminates prematurely.

continue int gen(int x) { if (x == 1) continue return 1; continue return 2; if (x == 1) continue return 3; return 4; }

This will print out 1, 2, 0, and then halt. It appears that perhaps an unconditional 'continue return' causes subsequent code to be eliminated as if following a hard 'return' statement?

Indeed. Looks like it is probably a bug in treeopt, where there's likely some rule that doesn't know about continue return.

Thanks for the pointer! Found it, I think. I've pushed it to the branch rosuav/deoptimize-continue-return - would appreciate a second opinion on this!

-F_COMMA_EXPR(0 = F_COMMA_EXPR(*, F_RETURN), +[!($$->tree_info & OPT_CASE)]): +// Code after a return statement can be eliminated, as long as +// it's not a 'continue return' statement. +F_COMMA_EXPR(0 = F_COMMA_EXPR(*, F_RETURN(*, F_CONSTANT[!($$->u.sval.u.integer)])), + +[!($$->tree_info & OPT_CASE)]): $0;

ChrisA