Go compilation tools
Posted on :: Updated on :: go

Source: https://www.youtube.com/watch?v=qPIB3STWXVk

Flow

flowchart TD;
A[*.go]--> |Compiler| B[*.a];
B--> C[Linker];
C--> D[Binary];

If go files are unmodified, there's no need to compile them again. This makes rebuild faster.

Compilation

flowchart TD;
A[Code]--> |Lexing & Parsing| B[AST];
B--> |Transformations on AST| C[SSA];
C--> |Optimizations| D[Machine code];

SSA is platform agnostic

go build flags

  • -a = force rebuild after clearing cache
  • -v = shows list of packages used in the build
  • -x = shows internal tooling invocation
  • -n = same as -x but dry run options, just shows the plan what will be done
  • -work = print and keep the work dir (where all intermediate artifacts are stored)

Explore compilation internal steps

GOSSAFUNC=main go build -a # generates ssa html for going into depth

This is fun interactive way to check the intermediate compilation steps.

Compiler flags

  • -gcflags="-S" = shows intermediate assembly

    • This is different from platform specifc assembly, if you want to see platform specific code:
    go tool objdump -S main.main <bin_name>

  • -gcflags="-N" = disable compiler optimization

  • -gcflags="-m" = shows escape analysis (explains what goes in heap vs stack) -m=2 for verbose, useful to see how much garbage is generated

  • -gcflags="-live" = shows liveness analysis. calculate live variables at each point in program.

  • -gcflags="-bench=bench.out" = shows benchmark

  • -gcflags="-race" = race detection

  • -gcflags="-memprofile=profile.out" = shows memory profile in lifetime of build

    • Use go tool pprof -http :7070 profile.out to open in webui

  • -gcflags="-traceprofile=trace.out"= shows execution trace

go list

Shows meta information about gocode. See docs for all fields available in templating.

List all go files that go in the build

go list -f {{.GoFiles}} 

GOOS=windows go list -f {{.GoFiles}} # includes main_windows.go (windows specific files)

nm tool

Shows all symbols used by the binary. Useful for figuring out dynamic libararies used etc.

go tool nm <binname>

Questions

  • While this does go in depth on practical tools, need more indepth understanding of compilation process #question
    • https://www.youtube.com/watch?v=uTMvKVma5ms&t=10s
  • Need to explore go runtime as well #question
  • How does this integrate with gdb and other debuggers ? #question