Correction, 'go build' took many minutes but did finish eventually.

.zip files are a real pain to use for diagnostics. Can you reproduce the problem in the Go Playground (https://play.golang.org)? If so, please provide a Playground link; otherwise, a link to a public repo would be acceptable.

You say that the build consumes “all the CPU” — exactly which process is it that is stuck? (Is it the compiler, the linker, or something else?)

Finally, why is this particular generated file important, and how much control do you have over the generator?

It's almost always possible to build an adversarial input to a compiler, so sometimes it's easier to fix the generator to avoid pathological cases than to fix the compiler to handle them efficiently.

Building the SSA seems to be the culprit.

Flamegraph from 1 minute of perf recording go tool compile:

Edit: go version devel +3fc276ccf8 Mon Feb 4 06:53:49 2019 +0000 linux/amd64

This is the process consuming CPU:

  PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND
32420 esmarqu+  20   0 1769892 1,593g  10620 S 100,0  5,1   0:56.51 compile

Finally, why is this particular generated file important, and how much control do you have over the generator?

Well, I control the code generator. If I find what is the pathological case for the Go compiler, I can avoid it.

Not sure if it should be simple to paste 44k line Go file to Playground, but I am failing at it.

Are you generating very large functions by any chance? I've seen situations where that makes SSA terribly slow, since you essentially create massive scopes for it to take care of. If that's the case, you could try splitting large functions into pieces, and calling all of those.

Are you generating very large functions by any chance? I've seen situations where that makes SSA terribly slow, since you essentially create massive scopes for it to take care of. If that's the case, you could try splitting large functions into pieces, and calling all of those.

Yes, main() is one single huge function.

CC @randall77

See previously #14775, #14774, #17926.

The offending code has been located, I guess.

Generated code had multiple large 'switch' statements like this:

switch index {
case 0: goto gosub_return_0
// (snip)
case 111: goto gosub_return_111
}

I reworked code generation to issue a single large 'switch' statment, and jump into it as needed.

Compilation is much faster now.