Find limit of recursion: Difference between revisions

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=={{header|Zig}}==

===Leave TRE to the compiler===

'''Works with:''' 0.11.x, 0.12.0-dev.1381+61861ef39

In this version, Zig compiler is free to (not) optimize recursive function, so behaviour may change from one optimization mode to another, like it was with 2-nd example from C section.

<syntaxhighlight lang="zig">const std = @import("std");

fn recurse(i: c_uint) void {

std.debug.print("{d}\n", .{i});

// We use wrapping addition operator here to mirror C behaviour.

recurse(i +% 1);

// Line above is equivalent to:

// @call(.auto, recurse, .{i +% 1});

}

pub fn main() void {

recurse(0);

return;

}</syntaxhighlight>

===Force-disable TRE===

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Segmentation fault occurs at different values of "i", depending on running platform, but on my platform (with stack size reported by ulimit as 16384) both C and Zig versions (compiled without optimizations output last value in approximately [523500, 524000] range.

gcc compiler with -O2 flag eliminated tail recursion, as mentioned in ~~second~~ example from C section, but in this Zig example recurse function is never turned into loop, even when enabling different optimization modes — we explicitly prohibited compiler from doing it in any optimize/build mode!

gcc compiler with -O2 flag eliminated tail recursion, as mentioned in 2-nd example from C section, but in this Zig example recurse function is never turned into loop, even when enabling different optimization modes — we explicitly prohibited compiler from doing it in any optimize/build mode!

===Force-enable TRE===