cmd/vendor/.../pprof: update to 0f7d9ba1

In particular, to pull a few fixes that were causing some tests to be
flaky on our build dashboard.

Fixes #24405.
Fixes #24508.
Fixes #24611.

Change-Id: I713156ad11c924e4a4b603144d10395523d526ed
Reviewed-on: https://go-review.googlesource.com/105275
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

1 files changed, 16 insertions, 9 deletions

diff --git a/src/cmd/vendor/github.com/google/pprof/internal/binutils/addr2liner.go b/src/cmd/vendor/github.com/google/pprof/internal/binutils/addr2liner.go
index 71e471b5d6..c0661bf4aa 100644
--- a/src/cmd/vendor/github.com/google/pprof/internal/binutils/addr2liner.go
+++ b/src/cmd/vendor/github.com/google/pprof/internal/binutils/addr2liner.go
@@ -41,9 +41,11 @@ type addr2Liner struct {
 	rw   lineReaderWriter
 	base uint64
 
-	// nm holds an NM based addr2Liner which can provide
-	// better full names compared to addr2line, which often drops
-	// namespaces etc. from the names it returns.
+	// nm holds an addr2Liner using nm tool. Certain versions of addr2line
+	// produce incomplete names due to
+	// https://sourceware.org/bugzilla/show_bug.cgi?id=17541. As a workaround,
+	// the names from nm are used when they look more complete. See addrInfo()
+	// code below for the exact heuristic.
 	nm *addr2LinerNM
 }
 
@@ -215,17 +217,22 @@ func (d *addr2Liner) addrInfo(addr uint64) ([]plugin.Frame, error) {
 		return nil, err
 	}
 
-	// Get better name from nm if possible.
+	// Certain versions of addr2line produce incomplete names due to
+	// https://sourceware.org/bugzilla/show_bug.cgi?id=17541. Attempt to replace
+	// the name with a better one from nm.
 	if len(stack) > 0 && d.nm != nil {
 		nm, err := d.nm.addrInfo(addr)
 		if err == nil && len(nm) > 0 {
-			// Last entry in frame list should match since
-			// it is non-inlined. As a simple heuristic,
-			// we only switch to the nm-based name if it
-			// is longer.
+			// Last entry in frame list should match since it is non-inlined. As a
+			// simple heuristic, we only switch to the nm-based name if it is longer
+			// by 2 or more characters. We consider nm names that are longer by 1
+			// character insignificant to avoid replacing foo with _foo on MacOS (for
+			// unknown reasons read2line produces the former and nm produces the
+			// latter on MacOS even though both tools are asked to produce mangled
+			// names).
 			nmName := nm[len(nm)-1].Func
 			a2lName := stack[len(stack)-1].Func
-			if len(nmName) > len(a2lName) {
+			if len(nmName) > len(a2lName)+1 {
 				stack[len(stack)-1].Func = nmName
 			}
 		}