re PR go/88202 (FAIL: runtime/pprof)

	PR go/88202
    runtime: in sigprof, skip to sigtrampgo if we don't find sigtramp
    
    Fixes https://gcc.gnu.org/PR88202
    
    Reviewed-on: https://go-review.googlesource.com/c/158218

From-SVN: r268057

gcc/go/gofrontend/MERGE

-d6576c83016d856217758c06d945bfc363ffb817
+d16e9181a760796802c067730bb030b92b63fb2c
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

libgo/go/runtime/proc.go

@@ -3600,10 +3600,17 @@ func sigprof(pc uintptr, gp *g, mp *m) {
 		// To ensure a sane profile, walk through the frames in
 		// "stklocs" until we find the "runtime.sigtramp" frame, then
 		// report only those frames below the frame one down from
-		// that. If for some reason "runtime.sigtramp" is not present,
-		// don't make any changes.
+		// that. On systems that don't split stack, "sigtramp" can
+		// do a sibling call to "sigtrampgo", so use "sigtrampgo"
+		// if we don't find "sigtramp". If for some reason
+		// neither "runtime.sigtramp" nor "runtime.sigtrampgo" is
+		// present, don't make any changes.
 		framesToDiscard := 0
 		for i := 0; i < n; i++ {
+			if stklocs[i].function == "runtime.sigtrampgo" && i+2 < n {
+				framesToDiscard = i + 2
+				n -= framesToDiscard
+			}
 			if stklocs[i].function == "runtime.sigtramp" && i+2 < n {
 				framesToDiscard = i + 2
 				n -= framesToDiscard