在macOS上使用GDB调试Go程序

Question

A simple Go program, say main.go:

package main

func main() {
    println("hello, world!")
}

Then build with

go build -gcflags "-N -l" -o main main.go

Using GDB:

$ gdb main
GNU gdb (GDB) 8.2
(...)
Reading symbols from main...(no debugging symbols found)...done.
Loading Go Runtime support.
(gdb) source /usr/local/Cellar/go/1.11/libexec/src/runtime/runtime-gdb.py
Loading Go Runtime support.
(gdb) info files
Symbols from "/Users/changkun/Desktop/demo/main".
Local exec file:
        `/Users/changkun/Desktop/demo/main', file type mach-o-x86-64.
        Entry point: 0x1049e20
        0x0000000001001000 - 0x000000000104dfcf is .text
        0x000000000104dfe0 - 0x0000000001077344 is __TEXT.__rodata
        (...)
(gdb) b *0x1049e20
Breakpoint 1 at 0x1049e20
(gdb)

There is no at in the GDB outputs, the version of Go is go version go1.11 darwin/amd64 and:

$ ls -al /usr/local/bin | grep go
lrwxr-xr-x    1 changkun  admin        24 Aug 25 16:37 go -> ../Cellar/go/1.11/bin/go

======

Same process in linux environment:

docker run -itd --name golang golang:1.11
docker exec -it golang bash

then entering container install gdb

root@1326d3f1a957:/# gdb main
GNU gdb (Debian 7.12-6) 7.12.0.20161007-git
(...)
(gdb) info files
Symbols from "/main".
Local exec file:
        `/main', file type elf64-x86-64.
        Entry point: 0x44a2e0
        0x0000000000401000 - 0x000000000044ea8f is .text
        (...)
(gdb) b *0x44a2e0
Breakpoint 1 at 0x44a2e0: file /usr/local/go/src/runtime/rt0_linux_amd64.s, line 8.
(gdb)

Linux is able to show (gdb) b *0x44a2e0 Breakpoint 1 at 0x44a2e0: file /usr/local/go/src/runtime/rt0_linux_amd64.s, line 8.

What did I miss in macOS? How can I debug and trace the program on macOS?

Answer 1

In Go 1.11, the debug information is compressed for purpose of reduce binary size, and gdb on the Mac does not understand compressed DWARF.

The workaround is to also specify -ldflags=-compressdwarf=false which does exactly what it claims.

To do this generally:

export GOFLAGS="-ldflags=-compressdwarf=false"

See discussion: https://groups.google.com/forum/#!topic/golang-nuts/LlgN1qpbRE8