Small ReleaseSafe binaries with backtraces #18520
Description
Problem: for TigerBetele, we want our release binary to be relatively small and self-contained, but we also want to see at least a minimal backtrace on assert faliures, overflow errors, indexing out of bounds and such.
As far as I am aware:
- No combination of Zig build flags gets us the desired result: either a binary is huge, or the stacktrace is absent
- This should be theoretically possible, as Rust does that
Specifically (non-expert, might be talking nonsense here), I think including frame pointers, and debug symbols (but not the entire of debug info) should give both a small executable, and a reasonable stack trace.
Here's a reproducible log of my experiments:
This is what I tried:
- Baseline, just
ReleaseSafe: huge binary because of debuginfo, good backtrace module.omit_frame_pointer = false; module.strip = false;: small file, but no backtrace at alladdObjCopystep with.strip = .debug: small file, but bad backtrace:
thread 33065 panic: integer overflow
Unwind information for `exe:0x10318a0` was not available, trace may be incomplete
???:?:?: 0x100c274 in ??? (exe)
???:?:?: 0x100bbc8 in ??? (exe)
???:?:?: 0x100bbb8 in ??? (exe)
???:?:?: 0x100bb93 in ??? (exe)
???:?:?: 0x100ba41 in ??? (exe)
In comparison, here's what Rust gives with strip=debuginfo:
thread 'main' panicked at ./main.rs:3:5:
attempt to multiply with overflow
stack backtrace:
0: rust_begin_unwind
1: core::panicking::panic_fmt
2: core::panicking::panic
3: main::foo
4: main::bar
5: main::main
I think 3) is what I want big-picture wise, but a few details prevent it from being actually useful:
- having names, and not just addresses, would be great.
- it would be great to have line number information for the root failure. I think we can get that for
asserts, by providing our own assert using@src(), but that's also important for things like arithmertic overflows - The build.zig incantaiton with separate ObjCopy invocation to get the desired behavior is gnarly. I'd love to just
module.strip = .strip_debuginfo_keep_symbols. See the repo linked above for build.zig.