| // Copyright 2023 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| // Preprofile creates an intermediate representation of a pprof profile for use |
| // during PGO in the compiler. This transformation depends only on the profile |
| // itself and is thus wasteful to perform in every invocation of the compiler. |
| // |
| // Usage: |
| // |
| // go tool preprofile [-v] [-o output] -i input |
| // |
| // |
| |
| package main |
| |
| import ( |
| "bufio" |
| "cmd/internal/pgo" |
| "flag" |
| "fmt" |
| "log" |
| "os" |
| ) |
| |
| func usage() { |
| fmt.Fprintf(os.Stderr, "usage: go tool preprofile [-v] [-o output] -i input\n\n") |
| flag.PrintDefaults() |
| os.Exit(2) |
| } |
| |
| var ( |
| output = flag.String("o", "", "output file path") |
| input = flag.String("i", "", "input pprof file path") |
| ) |
| |
| func preprocess(profileFile string, outputFile string) error { |
| f, err := os.Open(profileFile) |
| if err != nil { |
| return fmt.Errorf("error opening profile: %w", err) |
| } |
| defer f.Close() |
| |
| r := bufio.NewReader(f) |
| d, err := pgo.FromPProf(r) |
| if err != nil { |
| return fmt.Errorf("error parsing profile: %w", err) |
| } |
| |
| var out *os.File |
| if outputFile == "" { |
| out = os.Stdout |
| } else { |
| out, err = os.Create(outputFile) |
| if err != nil { |
| return fmt.Errorf("error creating output file: %w", err) |
| } |
| defer out.Close() |
| } |
| |
| w := bufio.NewWriter(out) |
| if _, err := d.WriteTo(w); err != nil { |
| return fmt.Errorf("error writing output file: %w", err) |
| } |
| |
| return nil |
| } |
| |
| func main() { |
| log.SetFlags(0) |
| log.SetPrefix("preprofile: ") |
| |
| flag.Usage = usage |
| flag.Parse() |
| if *input == "" { |
| log.Print("Input pprof path required (-i)") |
| usage() |
| } |
| |
| if err := preprocess(*input, *output); err != nil { |
| log.Fatal(err) |
| } |
| } |