runtime/pprof: fix inlined generics locations

When generic function[a,b] is inlined to the same generic function[b,a]
with different types (not recursion) it is expected to get a pprof with
a single Location with two functions. However due to incorrect check
for generics names using runtime.Frame.Function, the profileBuilder
assumes it is a recursion and emits separate Location.

This change fixes the recursion check for generics functions by using
runtime_expandFinalInlineFrame

Fixes #64641

Change-Id: I3f58818f08ee322b281daa377fa421555ad328c9
Reviewed-on: https://go-review.googlesource.com/c/go/+/549135
Run-TryBot: Michael Pratt <mpratt@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

2 files changed, 89 insertions, 12 deletions

diff --git a/src/runtime/pprof/proto.go b/src/runtime/pprof/proto.go
index db9384eb21..5214374bd9 100644
--- a/src/runtime/pprof/proto.go
+++ b/src/runtime/pprof/proto.go
@@ -561,7 +561,7 @@ func (d *pcDeck) tryAdd(pc uintptr, frames []runtime.Frame, symbolizeResult symb
 		if last.Entry != newFrame.Entry { // newFrame is for a different function.
 			return false
 		}
-		if last.Function == newFrame.Function { // maybe recursion.
+		if runtime_FrameSymbolName(&last) == runtime_FrameSymbolName(&newFrame) { // maybe recursion.
 			return false
 		}
 	}
diff --git a/src/runtime/pprof/protomem_test.go b/src/runtime/pprof/protomem_test.go
index 505c323d68..5fb67c53f6 100644
--- a/src/runtime/pprof/protomem_test.go
+++ b/src/runtime/pprof/protomem_test.go
@@ -8,6 +8,7 @@ import (
 	"bytes"
 	"fmt"
 	"internal/profile"
+	"internal/testenv"
 	"runtime"
 	"slices"
 	"strings"
@@ -90,22 +91,31 @@ func genericAllocFunc[T interface{ uint32 | uint64 }](n int) []T {
 	return make([]T, n)
 }
 
-func profileToString(p *profile.Profile) []string {
+func profileToStrings(p *profile.Profile) []string {
 	var res []string
 	for _, s := range p.Sample {
-		var funcs []string
-		for i := len(s.Location) - 1; i >= 0; i-- {
-			loc := s.Location[i]
-			for j := len(loc.Line) - 1; j >= 0; j-- {
-				line := loc.Line[j]
-				funcs = append(funcs, line.Function.Name)
-			}
-		}
-		res = append(res, fmt.Sprintf("%s %v", strings.Join(funcs, ";"), s.Value))
+		res = append(res, sampleToString(s))
 	}
 	return res
 }
 
+func sampleToString(s *profile.Sample) string {
+	var funcs []string
+	for i := len(s.Location) - 1; i >= 0; i-- {
+		loc := s.Location[i]
+		funcs = locationToStrings(loc, funcs)
+	}
+	return fmt.Sprintf("%s %v", strings.Join(funcs, ";"), s.Value)
+}
+
+func locationToStrings(loc *profile.Location, funcs []string) []string {
+	for j := range loc.Line {
+		line := loc.Line[len(loc.Line)-1-j]
+		funcs = append(funcs, line.Function.Name)
+	}
+	return funcs
+}
+
 // This is a regression test for https://go.dev/issue/64528 .
 func TestGenericsHashKeyInPprofBuilder(t *testing.T) {
 	previousRate := runtime.MemProfileRate
@@ -130,7 +140,7 @@ func TestGenericsHashKeyInPprofBuilder(t *testing.T) {
 		t.Fatalf("profile.Parse: %v", err)
 	}
 
-	actual := profileToString(p)
+	actual := profileToStrings(p)
 	expected := []string{
 		"testing.tRunner;runtime/pprof.TestGenericsHashKeyInPprofBuilder;runtime/pprof.genericAllocFunc[go.shape.uint32] [1 128 0 0]",
 		"testing.tRunner;runtime/pprof.TestGenericsHashKeyInPprofBuilder;runtime/pprof.genericAllocFunc[go.shape.uint32] [1 256 0 0]",
@@ -144,3 +154,70 @@ func TestGenericsHashKeyInPprofBuilder(t *testing.T) {
 		}
 	}
 }
+
+type opAlloc struct {
+	buf [128]byte
+}
+
+type opCall struct {
+}
+
+var sink []byte
+
+func storeAlloc() {
+	sink = make([]byte, 16)
+}
+
+func nonRecursiveGenericAllocFunction[CurrentOp any, OtherOp any](alloc bool) {
+	if alloc {
+		storeAlloc()
+	} else {
+		nonRecursiveGenericAllocFunction[OtherOp, CurrentOp](true)
+	}
+}
+
+func TestGenericsInlineLocations(t *testing.T) {
+	if testenv.OptimizationOff() {
+		t.Skip("skipping test with optimizations disabled")
+	}
+
+	previousRate := runtime.MemProfileRate
+	runtime.MemProfileRate = 1
+	defer func() {
+		runtime.MemProfileRate = previousRate
+		sink = nil
+	}()
+
+	nonRecursiveGenericAllocFunction[opAlloc, opCall](true)
+	nonRecursiveGenericAllocFunction[opCall, opAlloc](false)
+
+	runtime.GC()
+
+	buf := bytes.NewBuffer(nil)
+	if err := WriteHeapProfile(buf); err != nil {
+		t.Fatalf("writing profile: %v", err)
+	}
+	p, err := profile.Parse(buf)
+	if err != nil {
+		t.Fatalf("profile.Parse: %v", err)
+	}
+
+	const expectedSample = "testing.tRunner;runtime/pprof.TestGenericsInlineLocations;runtime/pprof.nonRecursiveGenericAllocFunction[go.shape.struct {},go.shape.struct { runtime/pprof.buf [128]uint8 }];runtime/pprof.nonRecursiveGenericAllocFunction[go.shape.struct { runtime/pprof.buf [128]uint8 },go.shape.struct {}];runtime/pprof.storeAlloc [1 16 1 16]"
+	const expectedLocation = "runtime/pprof.nonRecursiveGenericAllocFunction[go.shape.struct {},go.shape.struct { runtime/pprof.buf [128]uint8 }];runtime/pprof.nonRecursiveGenericAllocFunction[go.shape.struct { runtime/pprof.buf [128]uint8 },go.shape.struct {}];runtime/pprof.storeAlloc"
+	const expectedLocationNewInliner = "runtime/pprof.TestGenericsInlineLocations;" + expectedLocation
+	var s *profile.Sample
+	for _, sample := range p.Sample {
+		if sampleToString(sample) == expectedSample {
+			s = sample
+			break
+		}
+	}
+	if s == nil {
+		t.Fatalf("expected \n%s\ngot\n%s", expectedSample, strings.Join(profileToStrings(p), "\n"))
+	}
+	loc := s.Location[0]
+	actual := strings.Join(locationToStrings(loc, nil), ";")
+	if expectedLocation != actual && expectedLocationNewInliner != actual {
+		t.Errorf("expected a location with at least 3 functions\n%s\ngot\n%s\n", expectedLocation, actual)
+	}
+}