runtime/pprof: delete unused locForPC

Change-Id: Ie4754fefba6057b1cf558d0096fe0e83355f8eff
Reviewed-on: https://go-review.googlesource.com/c/go/+/205098
TryBot-Result: Gobot Gobot <gobot@golang.org>
Run-TryBot: Hyang-Ah Hana Kim <hyangah@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>

src/runtime/pprof/proto.go

@@ -239,91 +239,6 @@ func allFrames(addr uintptr) ([]runtime.Frame, symbolizeFlag) {
 	return ret, symbolizeResult
 }
 
-// locForPC returns the location ID for addr.
-// addr must a return PC or 1 + the PC of an inline marker. This returns the location of the corresponding call.
-// It may emit to b.pb, so there must be no message encoding in progress.
-func (b *profileBuilder) locForPC(addr uintptr) uint64 {
-	if loc, ok := b.locs[addr]; ok {
-		return loc.id
-	}
-
-	// Expand this one address using CallersFrames so we can cache
-	// each expansion. In general, CallersFrames takes a whole
-	// stack, but in this case we know there will be no skips in
-	// the stack and we have return PCs anyway.
-	frames := runtime.CallersFrames([]uintptr{addr})
-	frame, more := frames.Next()
-	if frame.Function == "runtime.goexit" {
-		// Short-circuit if we see runtime.goexit so the loop
-		// below doesn't allocate a useless empty location.
-		return 0
-	}
-
-	symbolizeResult := lookupTried
-	if frame.PC == 0 || frame.Function == "" || frame.File == "" || frame.Line == 0 {
-		symbolizeResult |= lookupFailed
-	}
-
-	if frame.PC == 0 {
-		// If we failed to resolve the frame, at least make up
-		// a reasonable call PC. This mostly happens in tests.
-		frame.PC = addr - 1
-	}
-
-	// We can't write out functions while in the middle of the
-	// Location message, so record new functions we encounter and
-	// write them out after the Location.
-	type newFunc struct {
-		id         uint64
-		name, file string
-	}
-	newFuncs := make([]newFunc, 0, 8)
-
-	id := uint64(len(b.locs)) + 1
-	b.locs[addr] = locInfo{id: id, pcs: []uintptr{addr}}
-	start := b.pb.startMessage()
-	b.pb.uint64Opt(tagLocation_ID, id)
-	b.pb.uint64Opt(tagLocation_Address, uint64(frame.PC))
-	for frame.Function != "runtime.goexit" {
-		// Write out each line in frame expansion.
-		funcID := uint64(b.funcs[frame.Function])
-		if funcID == 0 {
-			funcID = uint64(len(b.funcs)) + 1
-			b.funcs[frame.Function] = int(funcID)
-			newFuncs = append(newFuncs, newFunc{funcID, frame.Function, frame.File})
-		}
-		b.pbLine(tagLocation_Line, funcID, int64(frame.Line))
-		if !more {
-			break
-		}
-		frame, more = frames.Next()
-	}
-	for i := range b.mem {
-		if b.mem[i].start <= addr && addr < b.mem[i].end || b.mem[i].fake {
-			b.pb.uint64Opt(tagLocation_MappingID, uint64(i+1))
-
-			m := b.mem[i]
-			m.funcs |= symbolizeResult
-			b.mem[i] = m
-			break
-		}
-	}
-	b.pb.endMessage(tagProfile_Location, start)
-
-	// Write out functions we found during frame expansion.
-	for _, fn := range newFuncs {
-		start := b.pb.startMessage()
-		b.pb.uint64Opt(tagFunction_ID, fn.id)
-		b.pb.int64Opt(tagFunction_Name, b.stringIndex(fn.name))
-		b.pb.int64Opt(tagFunction_SystemName, b.stringIndex(fn.name))
-		b.pb.int64Opt(tagFunction_Filename, b.stringIndex(fn.file))
-		b.pb.endMessage(tagProfile_Function, start)
-	}
-
-	b.flush()
-	return id
-}
-
 type locInfo struct {
 	// location id assigned by the profileBuilder
 	id uint64