gdb go optimized out

[mount...@gmail.com]

Very strange, when I compile with go build -o main -gcflags "-N -l" main.go, it appears optimized out when debugging with gdb.

Who knows why?

[jake...@gmail.com]

First off. Please don't use a giant font in this group. It adds no valuable information, and makes it seem like you are yelling at the reader.

I use delve not gdb, so I can not speak directly to that. I use -gcflags="-N -l", and so far it has always produced a reasonably debuggable (with delve at least) executable.

Your question is probably too vague to answer though. What, specifically, are you experiencing as being "optimized out"? If you provided code for a small sample program, and told us what you actually see, and what you expect to see, you would have a better chance of a useful response.

[mount...@gmail.com]

First of all, thank you very much for your answer. I use the giant font because I copied it directly from Google Translate.
When I debug grow func of mheap.go file, I print the ask variable, it output No symbol "ask" in current context, print npage it output optimized out.

func (h *mheap) grow(npage uintptr) bool {

ask := npage << _PageShift

v, size := h.sysAlloc(ask)

if v == nil {

print("runtime: out of memory: cannot allocate ", ask, "-byte block (", memstats.heap_sys, " in use)\n")

return false

}

// Create a fake "in use" span and free it, so that the

// right coalescing happens.

s := (*mspan)(h.spanalloc.alloc())

s.init(uintptr(v), size/pageSize)

h.setSpans(s.base(), s.npages, s)

atomic.Store(&s.sweepgen, h.sweepgen)

s.state = _MSpanInUse

h.pagesInUse += uint64(s.npages)

h.freeSpanLocked(s, false, true, 0)

return true

}

在 2019年3月15日星期五 UTC+8上午12:49:51，Jake Montgomery写道：

[mount...@gmail.com]

在 2019年3月15日星期五 UTC+8下午12:56:38，mount...@gmail.com写道：

[mount...@gmail.com]

在 2019年3月15日星期五 UTC+8上午12:49:51，Jake Montgomery写道：

First off. Please don't use a giant font in this group. It adds no valuable information, and makes it seem like you are yelling at the reader.

[jake...@gmail.com]

First off, we are always happy to have new users in the group. But one more bit of etiquette - Please don't post screenshots of text. Instead copy paste the text into the message. I like to use fixed width font, or put it in a code block. See the recent discussion at https://groups.google.com/d/topic/golang-nuts/KR_JXhBWCk8/discussion for the many reasons why.

Looking at the screenshot, I see that you are trying to debug into a runtime library  function. That is why it is optimized. IIRC, the way you have built will only build main.go without optimization, but it will not effect the standard libraries. I think you want something like  go build -o main -gcflags "all=-N -l" main.go . The "all=" is the key here.

Good luck

[mount...@gmail.com]

I set the parameters in your way and execute dlv or not.Thanks.