add -fstrip=debug_info command line option

[leroycep]

This pull request adds a third option for -fstrip, -fstrip=debug_info. It also gives aliases to -fno-strip and -fstrip, -fstrip=none and -fstrip=all respectively.

-fstrip=debug_info is similar to objcopy --strip-debug, removing DWARF debug sections, but retaining the ELF symbol table.

Note that this pull request does not currently update the zig build system to expose this functionality.

See also #18520 and #22077

Trying out all 3 strip options on a test case.

Test case:

const std = @import("std");

noinline fn foo(x: u32) u32 {
    return x * x;
}

noinline fn bar() u32 {
    return foo(std.math.maxInt(u32));
}

pub fn main() !void {
    std.debug.print("{}", .{bar()});
}

Not stripping anything, equivalent to -fno-strip:

~/code/zig/build/example-elfsymtab-backtrace> ../stage4/bin/zig build-exe main.zig -fstrip=none -femit-bin=main-strip-none
~/code/zig/build/example-elfsymtab-backtrace> try { ./main-strip-none }

thread 396791 panic: integer overflow
/home/geemili/code/zig/build/example-elfsymtab-backtrace/main.zig:4:14: 0x103a6d2 in foo (main)
    return x * x;
             ^
/home/geemili/code/zig/build/example-elfsymtab-backtrace/main.zig:8:15: 0x1038acd in bar (main)
    return foo(std.math.maxInt(u32));
              ^
/home/geemili/code/zig/build/example-elfsymtab-backtrace/main.zig:12:32: 0x1038aa0 in main (main)
    std.debug.print("{}", .{bar()});
                               ^
/home/geemili/code/zig/lib/std/start.zig:656:37: 0x1038a62 in posixCallMainAndExit (main)
            const result = root.main() catch |err| {
                                    ^
/home/geemili/code/zig/lib/std/start.zig:271:5: 0x103863d in _start (main)
    asm volatile (switch (native_arch) {
    ^
???:?:?: 0x0 in ??? (???)

Stripping debug info but leaving symbols in:

~/code/zig/build/example-elfsymtab-backtrace> ../stage4/bin/zig build-exe main.zig -fstrip=debug_info -femit-bin=main-strip-debuginfo
~/code/zig/build/example-elfsymtab-backtrace> try { ./main-strip-debuginfo }

thread 396316 panic: integer overflow
Unwind information for `exe:0x1051fd4` was not available, trace may be incomplete

???:?:?: 0x103876f in ??? (exe)
???:?:?: 0x103708d in ??? (exe)
???:?:?: 0x1037060 in ??? (exe)
???:?:?: 0x1037029 in ??? (exe)
???:?:?: 0x1036d1d in ??? (exe)

Stripping debug info and symbol table, equivalent to -fstrip:

~/code/zig/build/example-elfsymtab-backtrace> ../stage4/bin/zig build-exe main.zig -fstrip=all -femit-bin=main-strip-all
~/code/zig/build/example-elfsymtab-backtrace> try { ./main-strip-all }

thread 397178 panic: integer overflow
Unable to dump stack trace: debug info stripped

Combining with #22077 (teaching std.debug to read the Elf symbol table)

~/code/zig/build/example-elfsymtab-backtrace> ../stage4/bin/zig build-exe main.zig -fstrip=debug_info -femit-bin=main-strip-debuginfo
~/code/zig/build/example-elfsymtab-backtrace> try { ./main-strip-debuginfo }

thread 397866 panic: integer overflow
???:?:?: 0x1039a1f in main.foo (???)
???:?:?: 0x103833d in main.bar (???)
???:?:?: 0x1038310 in main.main (???)
???:?:?: 0x10382d9 in start.posixCallMainAndExit (???)
???:?:?: 0x1037fcd in _start (???)
???:?:?: 0x0 in ??? (???)

This work is licensed on the same terms as the Zig project.

Copyright © 2025 TigerBeetle, Inc.

This code was written under contract for TigerBeetle. As a work made for hire, authorship and copyright goes to TigerBeetle.

Author certificate

LeRoyce Pearson <[email protected]> [TigerBeetle, Inc.]

This work is licensed on the same terms as this project (Zig).