From 13baf4b2cd34dfb41c570e35b48ec287713f4d7f Mon Sep 17 00:00:00 2001 From: Keith Randall Date: Sun, 4 Nov 2018 19:23:08 -0800 Subject: cmd/compile: encourage inlining of functions with single-call bodies This is a simple tweak to allow a bit more mid-stack inlining. In cases like this: func f() { g() } We'd really like to inline f into its callers. It can't hurt. We implement this optimization by making calls a bit cheaper, enough to afford a single call in the function body, but not 2. The remaining budget allows for some argument modification, or perhaps a wrapping conditional: func f(x int) { g(x, 0) } func f(x int) { if x > 0 { g() } } Update #19348 Change-Id: Ifb1ea0dd1db216c3fd5c453c31c3355561fe406f Reviewed-on: https://go-review.googlesource.com/c/147361 Reviewed-by: Austin Clements Reviewed-by: David Chase --- src/runtime/extern.go | 1 + src/runtime/runtime-gdb_test.go | 8 +++----- src/runtime/stack_test.go | 3 +++ 3 files changed, 7 insertions(+), 5 deletions(-) (limited to 'src/runtime') diff --git a/src/runtime/extern.go b/src/runtime/extern.go index 640688e004..997e1cb278 100644 --- a/src/runtime/extern.go +++ b/src/runtime/extern.go @@ -202,6 +202,7 @@ func Caller(skip int) (pc uintptr, file string, line int, ok bool) { // directly is discouraged, as is using FuncForPC on any of the // returned PCs, since these cannot account for inlining or return // program counter adjustment. +//go:noinline func Callers(skip int, pc []uintptr) int { // runtime.callers uses pc.array==nil as a signal // to print a stack trace. Pick off 0-length pc here diff --git a/src/runtime/runtime-gdb_test.go b/src/runtime/runtime-gdb_test.go index 5d35813708..2c1653172e 100644 --- a/src/runtime/runtime-gdb_test.go +++ b/src/runtime/runtime-gdb_test.go @@ -181,12 +181,11 @@ func testGdbPython(t *testing.T, cgo bool) { } args = append(args, "-ex", "set python print-stack full", - "-ex", "br fmt.Println", + "-ex", "br main.go:15", "-ex", "run", "-ex", "echo BEGIN info goroutines\n", "-ex", "info goroutines", "-ex", "echo END\n", - "-ex", "up", // up from fmt.Println to main "-ex", "echo BEGIN print mapvar\n", "-ex", "print mapvar", "-ex", "echo END\n", @@ -196,14 +195,13 @@ func testGdbPython(t *testing.T, cgo bool) { "-ex", "echo BEGIN info locals\n", "-ex", "info locals", "-ex", "echo END\n", - "-ex", "down", // back to fmt.Println (goroutine 2 below only works at bottom of stack. TODO: fix that) "-ex", "echo BEGIN goroutine 1 bt\n", "-ex", "goroutine 1 bt", "-ex", "echo END\n", "-ex", "echo BEGIN goroutine 2 bt\n", "-ex", "goroutine 2 bt", "-ex", "echo END\n", - "-ex", "clear fmt.Println", // clear the previous break point + "-ex", "clear main.go:15", // clear the previous break point "-ex", fmt.Sprintf("br main.go:%d", nLines), // new break point at the end of main "-ex", "c", "-ex", "echo BEGIN goroutine 1 bt at the end\n", @@ -274,7 +272,7 @@ func testGdbPython(t *testing.T, cgo bool) { t.Fatalf("info locals failed: %s", bl) } - btGoroutine1Re := regexp.MustCompile(`(?m)^#0\s+(0x[0-9a-f]+\s+in\s+)?fmt\.Println.+at`) + btGoroutine1Re := regexp.MustCompile(`(?m)^#0\s+(0x[0-9a-f]+\s+in\s+)?main\.main.+at`) if bl := blocks["goroutine 1 bt"]; !btGoroutine1Re.MatchString(bl) { t.Fatalf("goroutine 1 bt failed: %s", bl) } diff --git a/src/runtime/stack_test.go b/src/runtime/stack_test.go index dc65395141..f52381710d 100644 --- a/src/runtime/stack_test.go +++ b/src/runtime/stack_test.go @@ -595,6 +595,9 @@ func (s structWithMethod) callers() []uintptr { return pc[:Callers(0, pc)] } +// The noinline prevents this function from being inlined +// into a wrapper. TODO: remove this when issue 28640 is fixed. +//go:noinline func (s structWithMethod) stack() string { buf := make([]byte, 4<<10) return string(buf[:Stack(buf, false)]) -- cgit v1.3