libgo: delay applying profile stack-frame skip until fixup

    
    When the runtime collects a stack trace to associate it with some
    profiling event (mem alloc, mutex, etc) there is a skip count passed
    to runtime.Callers (or equivalent) to skip some known count of frames
    in order to get to the "interesting" frame corresponding to the
    profile event. Now that the profiling mechanism uses lazy fixup (when
    removing compiler artifacts like thunks, morestack calls etc), we also
    need to move the frame skipping logic after the fixup, so as to insure
    that the skip count isn't thrown off by these artifacts.
    
    Fixes golang/go#32290.
    
    Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/179740

From-SVN: r271892

1 files changed, 1 insertions, 9 deletions

diff --git a/libgo/runtime/go-callers.c b/libgo/runtime/go-callers.c
index 4a9c1a7..e7d53a3 100644
--- a/libgo/runtime/go-callers.c
+++ b/libgo/runtime/go-callers.c
@@ -268,7 +268,6 @@ Callers (intgo skip, struct __go_open_array pc)
 struct callersRaw_data
 {
   uintptr* pcbuf;
-  int skip;
   int index;
   int max;
 };
@@ -280,12 +279,6 @@ static int callback_raw (void *data, uintptr_t pc)
 {
   struct callersRaw_data *arg = (struct callersRaw_data *) data;
 
-  if (arg->skip > 0)
-    {
-      --arg->skip;
-      return 0;
-    }
-
   /* On the call to backtrace_simple the pc value was most likely
      decremented if there was a normal call, since the pc referred to
      the instruction where the call returned and not the call itself.
@@ -306,13 +299,12 @@ static int callback_raw (void *data, uintptr_t pc)
 /* runtime_callersRaw is similar to runtime_callers() above, but
    it returns raw PC values as opposed to file/func/line locations. */
 int32
-runtime_callersRaw (int32 skip, uintptr *pcbuf, int32 m)
+runtime_callersRaw (uintptr *pcbuf, int32 m)
 {
   struct callersRaw_data data;
   struct backtrace_state* state;
 
   data.pcbuf = pcbuf;
-  data.skip = skip + 1;
   data.index = 0;
   data.max = m;
   runtime_xadd (&__go_runtime_in_callers, 1);