Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

debug/elf: improve File.Symbols() by not using reflection #61534

Closed
korniltsev opened this issue Jul 23, 2023 · 2 comments
Closed

debug/elf: improve File.Symbols() by not using reflection #61534

korniltsev opened this issue Jul 23, 2023 · 2 comments
Assignees
@prattmic
Labels
compiler/runtime Issues related to the Go compiler and/or runtime. NeedsFix The path to resolution is known, but the work has not been done. Performance
Milestone
Backlog

Comments

@korniltsev
Copy link
Contributor

What version of Go are you using (go version)?

$ go version devel go1.22-2eca0b1e16 Fri Jul 21 21:37:46 2023 +0000 linux/amd64

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

go env Output
$ go env
GO111MODULE=''
GOARCH='amd64'
GOBIN=''
GOCACHE='/home/korniltsev/.cache/go-build'
GOENV='/home/korniltsev/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMODCACHE='/home/korniltsev/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/home/korniltsev/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/home/korniltsev/github/go'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/home/korniltsev/github/go/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='devel go1.22-2eca0b1e16 Fri Jul 21 21:37:46 2023 +0000'
GCCGO='gccgo'
GOAMD64='v1'
AR='ar'
CC='gcc'
CXX='g++'
CGO_ENABLED='1'
GOMOD='/home/korniltsev/github/go/src/go.mod'
GOWORK=''
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
PKG_CONFIG='pkg-config'
GOGCCFLAGS='-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build2276453812=/tmp/go-build -gno-record-gcc-switches'

What did you do?

Invoke debug/elf.File.Symbols()

What did you expect to see?

Less allocations.

What did you see instead?

Some allocations which could be avoided.

Proposed fix

Currently elf.File.Symbols() reads symbols with reflection via binary.Read. We can read Symbol fields manually with ByteOrder.UintXX, this will avoid unnecessary allocations and reflection.

debug/elf.diff 
diff --git a/src/debug/elf/file.go b/src/debug/elf/file.go
index 7485337905..9416ddaefb 100644
--- a/src/debug/elf/file.go
+++ b/src/debug/elf/file.go
@@ -639,8 +639,7 @@ func (f *File) getSymbols32(typ SectionType) ([]Symbol, []byte, error) {
        if err != nil {
                return nil, nil, fmt.Errorf("cannot load symbol section: %w", err)
        }
-       symtab := bytes.NewReader(data)
-       if symtab.Len()%Sym32Size != 0 {
+       if len(data)%Sym32Size != 0 {
                return nil, nil, errors.New("length of symbol section is not a multiple of SymSize")
        }
 
@@ -650,15 +649,19 @@ func (f *File) getSymbols32(typ SectionType) ([]Symbol, []byte, error) {
        }
 
        // The first entry is all zeros.
-       var skip [Sym32Size]byte
-       symtab.Read(skip[:])
+       data = data[Sym32Size:]
 
-       symbols := make([]Symbol, symtab.Len()/Sym32Size)
+       symbols := make([]Symbol, len(data)/Sym32Size)
 
        i := 0
        var sym Sym32
-       for symtab.Len() > 0 {
-               binary.Read(symtab, f.ByteOrder, &sym)
+       for len(data) > 0 {
+               sym.Name = f.ByteOrder.Uint32(data[0:4])
+               sym.Value = f.ByteOrder.Uint32(data[4:8])
+               sym.Size = f.ByteOrder.Uint32(data[8:12])
+               sym.Info = data[12]
+               sym.Other = data[13]
+               sym.Shndx = f.ByteOrder.Uint16(data[14:16])
                str, _ := getString(strdata, int(sym.Name))
                symbols[i].Name = str
                symbols[i].Info = sym.Info
@@ -667,6 +670,7 @@ func (f *File) getSymbols32(typ SectionType) ([]Symbol, []byte, error) {
                symbols[i].Value = uint64(sym.Value)
                symbols[i].Size = uint64(sym.Size)
                i++
+               data = data[Sym32Size:]
        }
 
        return symbols, strdata, nil
@@ -682,8 +686,7 @@ func (f *File) getSymbols64(typ SectionType) ([]Symbol, []byte, error) {
        if err != nil {
                return nil, nil, fmt.Errorf("cannot load symbol section: %w", err)
        }
-       symtab := bytes.NewReader(data)
-       if symtab.Len()%Sym64Size != 0 {
+       if len(data)%Sym64Size != 0 {
                return nil, nil, errors.New("length of symbol section is not a multiple of Sym64Size")
        }
 
@@ -693,15 +696,19 @@ func (f *File) getSymbols64(typ SectionType) ([]Symbol, []byte, error) {
        }
 
        // The first entry is all zeros.
-       var skip [Sym64Size]byte
-       symtab.Read(skip[:])
+       data = data[Sym64Size:]
 
-       symbols := make([]Symbol, symtab.Len()/Sym64Size)
+       symbols := make([]Symbol, len(data)/Sym64Size)
 
        i := 0
        var sym Sym64
-       for symtab.Len() > 0 {
-               binary.Read(symtab, f.ByteOrder, &sym)
+       for len(data) > 0 {
+               sym.Name = f.ByteOrder.Uint32(data[0:4])
+               sym.Info = data[4]
+               sym.Other = data[5]
+               sym.Shndx = f.ByteOrder.Uint16(data[6:8])
+               sym.Value = f.ByteOrder.Uint64(data[8:16])
+               sym.Size = f.ByteOrder.Uint64(data[16:24])
                str, _ := getString(strdata, int(sym.Name))
                symbols[i].Name = str
                symbols[i].Info = sym.Info
@@ -710,6 +717,7 @@ func (f *File) getSymbols64(typ SectionType) ([]Symbol, []byte, error) {
                symbols[i].Value = sym.Value
                symbols[i].Size = sym.Size
                i++
+               data = data[Sym64Size:]
        }
 
        return symbols, strdata, nil
diff --git a/src/debug/elf/file_test.go b/src/debug/elf/file_test.go
index 51a3634db9..58b17334c1 100644
--- a/src/debug/elf/file_test.go
+++ b/src/debug/elf/file_test.go
@@ -28,6 +28,7 @@ type fileTest struct {
        sections []SectionHeader
        progs    []ProgHeader
        needed   []string
+       symbols  []Symbol
 }
 
 var fileTests = []fileTest{
@@ -74,6 +75,82 @@ var fileTests = []fileTest{
                        {PT_DYNAMIC, PF_R + PF_W, 0x60c, 0x804960c, 0x804960c, 0x98, 0x98, 0x4},
                },
                []string{"libc.so.6"},
+               []Symbol{
+                       {"", 3, 0, 1, 134512852, 0, "", ""},
+                       {"", 3, 0, 2, 134512876, 0, "", ""},
+                       {"", 3, 0, 3, 134513020, 0, "", ""},
+                       {"", 3, 0, 4, 134513292, 0, "", ""},
+                       {"", 3, 0, 5, 134513480, 0, "", ""},
+                       {"", 3, 0, 6, 134513512, 0, "", ""},
+                       {"", 3, 0, 7, 134513532, 0, "", ""},
+                       {"", 3, 0, 8, 134513612, 0, "", ""},
+                       {"", 3, 0, 9, 134513996, 0, "", ""},
+                       {"", 3, 0, 10, 134514008, 0, "", ""},
+                       {"", 3, 0, 11, 134518268, 0, "", ""},
+                       {"", 3, 0, 12, 134518280, 0, "", ""},
+                       {"", 3, 0, 13, 134518284, 0, "", ""},
+                       {"", 3, 0, 14, 134518436, 0, "", ""},
+                       {"", 3, 0, 15, 134518444, 0, "", ""},
+                       {"", 3, 0, 16, 134518452, 0, "", ""},
+                       {"", 3, 0, 17, 134518456, 0, "", ""},
+                       {"", 3, 0, 18, 134518484, 0, "", ""},
+                       {"", 3, 0, 19, 0, 0, "", ""},
+                       {"", 3, 0, 20, 0, 0, "", ""},
+                       {"", 3, 0, 21, 0, 0, "", ""},
+                       {"", 3, 0, 22, 0, 0, "", ""},
+                       {"", 3, 0, 23, 0, 0, "", ""},
+                       {"", 3, 0, 24, 0, 0, "", ""},
+                       {"", 3, 0, 25, 0, 0, "", ""},
+                       {"", 3, 0, 26, 0, 0, "", ""},
+                       {"", 3, 0, 27, 0, 0, "", ""},
+                       {"", 3, 0, 28, 0, 0, "", ""},
+                       {"", 3, 0, 29, 0, 0, "", ""},
+                       {"crt1.c", 4, 0, 65521, 0, 0, "", ""},
+                       {"/usr/src/lib/csu/i386-elf/crti.S", 4, 0, 65521, 0, 0, "", ""},
+                       {"<command line>", 4, 0, 65521, 0, 0, "", ""},
+                       {"<built-in>", 4, 0, 65521, 0, 0, "", ""},
+                       {"/usr/src/lib/csu/i386-elf/crti.S", 4, 0, 65521, 0, 0, "", ""},
+                       {"crtstuff.c", 4, 0, 65521, 0, 0, "", ""},
+                       {"__CTOR_LIST__", 1, 0, 14, 134518436, 0, "", ""},
+                       {"__DTOR_LIST__", 1, 0, 15, 134518444, 0, "", ""},
+                       {"__EH_FRAME_BEGIN__", 1, 0, 12, 134518280, 0, "", ""},
+                       {"__JCR_LIST__", 1, 0, 16, 134518452, 0, "", ""},
+                       {"p.0", 1, 0, 11, 134518276, 0, "", ""},
+                       {"completed.1", 1, 0, 18, 134518484, 1, "", ""},
+                       {"__do_global_dtors_aux", 2, 0, 8, 134513760, 0, "", ""},
+                       {"object.2", 1, 0, 18, 134518488, 24, "", ""},
+                       {"frame_dummy", 2, 0, 8, 134513836, 0, "", ""},
+                       {"crtstuff.c", 4, 0, 65521, 0, 0, "", ""},
+                       {"__CTOR_END__", 1, 0, 14, 134518440, 0, "", ""},
+                       {"__DTOR_END__", 1, 0, 15, 134518448, 0, "", ""},
+                       {"__FRAME_END__", 1, 0, 12, 134518280, 0, "", ""},
+                       {"__JCR_END__", 1, 0, 16, 134518452, 0, "", ""},
+                       {"__do_global_ctors_aux", 2, 0, 8, 134513960, 0, "", ""},
+                       {"/usr/src/lib/csu/i386-elf/crtn.S", 4, 0, 65521, 0, 0, "", ""},
+                       {"<command line>", 4, 0, 65521, 0, 0, "", ""},
+                       {"<built-in>", 4, 0, 65521, 0, 0, "", ""},
+                       {"/usr/src/lib/csu/i386-elf/crtn.S", 4, 0, 65521, 0, 0, "", ""},
+                       {"hello.c", 4, 0, 65521, 0, 0, "", ""},
+                       {"printf", 18, 0, 0, 0, 44, "", ""},
+                       {"_DYNAMIC", 17, 0, 65521, 134518284, 0, "", ""},
+                       {"__dso_handle", 17, 2, 11, 134518272, 0, "", ""},
+                       {"_init", 18, 0, 6, 134513512, 0, "", ""},
+                       {"environ", 17, 0, 18, 134518512, 4, "", ""},
+                       {"__deregister_frame_info", 32, 0, 0, 0, 0, "", ""},
+                       {"__progname", 17, 0, 11, 134518268, 4, "", ""},
+                       {"_start", 18, 0, 8, 134513612, 145, "", ""},
+                       {"__bss_start", 16, 0, 65521, 134518484, 0, "", ""},
+                       {"main", 18, 0, 8, 134513912, 46, "", ""},
+                       {"_init_tls", 18, 0, 0, 0, 5, "", ""},
+                       {"_fini", 18, 0, 9, 134513996, 0, "", ""},
+                       {"atexit", 18, 0, 0, 0, 43, "", ""},
+                       {"_edata", 16, 0, 65521, 134518484, 0, "", ""},
+                       {"_GLOBAL_OFFSET_TABLE_", 17, 0, 65521, 134518456, 0, "", ""},
+                       {"_end", 16, 0, 65521, 134518516, 0, "", ""},
+                       {"exit", 18, 0, 0, 0, 68, "", ""},
+                       {"_Jv_RegisterClasses", 32, 0, 0, 0, 0, "", ""},
+                       {"__register_frame_info", 32, 0, 0, 0, 0, "", ""},
+               },
        },
        {
                "testdata/gcc-amd64-linux-exec",
@@ -128,6 +205,81 @@ var fileTests = []fileTest{
                        {PT_LOOS + 0x474E551, PF_R + PF_W, 0x0, 0x0, 0x0, 0x0, 0x0, 0x8},
                },
                []string{"libc.so.6"},
+               []Symbol{
+                       {"", 3, 0, 1, 4194816, 0, "", ""},
+                       {"", 3, 0, 2, 4194844, 0, "", ""},
+                       {"", 3, 0, 3, 4194880, 0, "", ""},
+                       {"", 3, 0, 4, 4194920, 0, "", ""},
+                       {"", 3, 0, 5, 4194952, 0, "", ""},
+                       {"", 3, 0, 6, 4195048, 0, "", ""},
+                       {"", 3, 0, 7, 4195110, 0, "", ""},
+                       {"", 3, 0, 8, 4195120, 0, "", ""},
+                       {"", 3, 0, 9, 4195152, 0, "", ""},
+                       {"", 3, 0, 10, 4195176, 0, "", ""},
+                       {"", 3, 0, 11, 4195224, 0, "", ""},
+                       {"", 3, 0, 12, 4195248, 0, "", ""},
+                       {"", 3, 0, 13, 4195296, 0, "", ""},
+                       {"", 3, 0, 14, 4195732, 0, "", ""},
+                       {"", 3, 0, 15, 4195748, 0, "", ""},
+                       {"", 3, 0, 16, 4195768, 0, "", ""},
+                       {"", 3, 0, 17, 4195808, 0, "", ""},
+                       {"", 3, 0, 18, 6293128, 0, "", ""},
+                       {"", 3, 0, 19, 6293144, 0, "", ""},
+                       {"", 3, 0, 20, 6293160, 0, "", ""},
+                       {"", 3, 0, 21, 6293168, 0, "", ""},
+                       {"", 3, 0, 22, 6293584, 0, "", ""},
+                       {"", 3, 0, 23, 6293592, 0, "", ""},
+                       {"", 3, 0, 24, 6293632, 0, "", ""},
+                       {"", 3, 0, 25, 6293656, 0, "", ""},
+                       {"", 3, 0, 26, 0, 0, "", ""},
+                       {"", 3, 0, 27, 0, 0, "", ""},
+                       {"", 3, 0, 28, 0, 0, "", ""},
+                       {"", 3, 0, 29, 0, 0, "", ""},
+                       {"", 3, 0, 30, 0, 0, "", ""},
+                       {"", 3, 0, 31, 0, 0, "", ""},
+                       {"", 3, 0, 32, 0, 0, "", ""},
+                       {"", 3, 0, 33, 0, 0, "", ""},
+                       {"init.c", 4, 0, 65521, 0, 0, "", ""},
+                       {"initfini.c", 4, 0, 65521, 0, 0, "", ""},
+                       {"call_gmon_start", 2, 0, 13, 4195340, 0, "", ""},
+                       {"crtstuff.c", 4, 0, 65521, 0, 0, "", ""},
+                       {"__CTOR_LIST__", 1, 0, 18, 6293128, 0, "", ""},
+                       {"__DTOR_LIST__", 1, 0, 19, 6293144, 0, "", ""},
+                       {"__JCR_LIST__", 1, 0, 20, 6293160, 0, "", ""},
+                       {"__do_global_dtors_aux", 2, 0, 13, 4195376, 0, "", ""},
+                       {"completed.6183", 1, 0, 25, 6293656, 1, "", ""},
+                       {"p.6181", 1, 0, 24, 6293648, 0, "", ""},
+                       {"frame_dummy", 2, 0, 13, 4195440, 0, "", ""},
+                       {"crtstuff.c", 4, 0, 65521, 0, 0, "", ""},
+                       {"__CTOR_END__", 1, 0, 18, 6293136, 0, "", ""},
+                       {"__DTOR_END__", 1, 0, 19, 6293152, 0, "", ""},
+                       {"__FRAME_END__", 1, 0, 17, 4195968, 0, "", ""},
+                       {"__JCR_END__", 1, 0, 20, 6293160, 0, "", ""},
+                       {"__do_global_ctors_aux", 2, 0, 13, 4195680, 0, "", ""},
+                       {"initfini.c", 4, 0, 65521, 0, 0, "", ""},
+                       {"hello.c", 4, 0, 65521, 0, 0, "", ""},
+                       {"_GLOBAL_OFFSET_TABLE_", 1, 2, 23, 6293592, 0, "", ""},
+                       {"__init_array_end", 0, 2, 18, 6293124, 0, "", ""},
+                       {"__init_array_start", 0, 2, 18, 6293124, 0, "", ""},
+                       {"_DYNAMIC", 1, 2, 21, 6293168, 0, "", ""},
+                       {"data_start", 32, 0, 24, 6293632, 0, "", ""},
+                       {"__libc_csu_fini", 18, 0, 13, 4195520, 2, "", ""},
+                       {"_start", 18, 0, 13, 4195296, 0, "", ""},
+                       {"__gmon_start__", 32, 0, 0, 0, 0, "", ""},
+                       {"_Jv_RegisterClasses", 32, 0, 0, 0, 0, "", ""},
+                       {"puts@@GLIBC_2.2.5", 18, 0, 0, 0, 396, "", ""},
+                       {"_fini", 18, 0, 14, 4195732, 0, "", ""},
+                       {"__libc_start_main@@GLIBC_2.2.5", 18, 0, 0, 0, 450, "", ""},
+                       {"_IO_stdin_used", 17, 0, 15, 4195748, 4, "", ""},
+                       {"__data_start", 16, 0, 24, 6293632, 0, "", ""},
+                       {"__dso_handle", 17, 2, 24, 6293640, 0, "", ""},
+                       {"__libc_csu_init", 18, 0, 13, 4195536, 137, "", ""},
+                       {"__bss_start", 16, 0, 65521, 6293656, 0, "", ""},
+                       {"_end", 16, 0, 65521, 6293664, 0, "", ""},
+                       {"_edata", 16, 0, 65521, 6293656, 0, "", ""},
+                       {"main", 18, 0, 13, 4195480, 27, "", ""},
+                       {"_init", 18, 0, 11, 4195224, 0, "", ""},
+               },
        },
        {
                "testdata/hello-world-core.gz",
@@ -153,6 +305,7 @@ var fileTests = []fileTest{
                        {Type: PT_LOAD, Flags: PF_X + PF_R, Off: 0x3b000, Vaddr: 0xffffffffff600000, Paddr: 0x0, Filesz: 0x1000, Memsz: 0x1000, Align: 0x1000},
                },
                nil,
+               nil,
        },
        {
                "testdata/compressed-32.obj",
@@ -182,6 +335,23 @@ var fileTests = []fileTest{
                },
                []ProgHeader{},
                nil,
+               []Symbol{
+                       {"hello.c", 4, 0, 65521, 0, 0, "", ""},
+                       {"", 3, 0, 1, 0, 0, "", ""},
+                       {"", 3, 0, 3, 0, 0, "", ""},
+                       {"", 3, 0, 4, 0, 0, "", ""},
+                       {"", 3, 0, 5, 0, 0, "", ""},
+                       {"", 3, 0, 6, 0, 0, "", ""},
+                       {"", 3, 0, 8, 0, 0, "", ""},
+                       {"", 3, 0, 9, 0, 0, "", ""},
+                       {"", 3, 0, 11, 0, 0, "", ""},
+                       {"", 3, 0, 13, 0, 0, "", ""},
+                       {"", 3, 0, 15, 0, 0, "", ""},
+                       {"", 3, 0, 16, 0, 0, "", ""},
+                       {"", 3, 0, 14, 0, 0, "", ""},
+                       {"main", 18, 0, 1, 0, 23, "", ""},
+                       {"puts", 16, 0, 0, 0, 0, "", ""},
+               },
        },
        {
                "testdata/compressed-64.obj",
@@ -211,6 +381,69 @@ var fileTests = []fileTest{
                },
                []ProgHeader{},
                nil,
+               []Symbol{
+                       {"hello.c", 4, 0, 65521, 0, 0, "", ""},
+                       {"", 3, 0, 1, 0, 0, "", ""},
+                       {"", 3, 0, 3, 0, 0, "", ""},
+                       {"", 3, 0, 4, 0, 0, "", ""},
+                       {"", 3, 0, 5, 0, 0, "", ""},
+                       {"", 3, 0, 6, 0, 0, "", ""},
+                       {"", 3, 0, 8, 0, 0, "", ""},
+                       {"", 3, 0, 9, 0, 0, "", ""},
+                       {"", 3, 0, 11, 0, 0, "", ""},
+                       {"", 3, 0, 13, 0, 0, "", ""},
+                       {"", 3, 0, 15, 0, 0, "", ""},
+                       {"", 3, 0, 16, 0, 0, "", ""},
+                       {"", 3, 0, 14, 0, 0, "", ""},
+                       {"main", 18, 0, 1, 0, 27, "", ""},
+                       {"puts", 16, 0, 0, 0, 0, "", ""},
+               },
+       },
+       {
+               "testdata/go-relocation-test-gcc620-sparc64.obj",
+               FileHeader{Class: ELFCLASS64, Data: ELFDATA2MSB, Version: EV_CURRENT, OSABI: ELFOSABI_NONE, ABIVersion: 0x0, ByteOrder: binary.BigEndian, Type: ET_REL, Machine: EM_SPARCV9, Entry: 0x0},
+               []SectionHeader{
+                       {"", SHT_NULL, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0},
+                       {".text", SHT_PROGBITS, SHF_ALLOC + SHF_EXECINSTR, 0x0, 0x40, 0x2c, 0x0, 0x0, 0x4, 0x0, 0x2c},
+                       {".rela.text", SHT_RELA, SHF_INFO_LINK, 0x0, 0xa58, 0x48, 0x13, 0x1, 0x8, 0x18, 0x48},
+                       {".data", SHT_PROGBITS, SHF_WRITE + SHF_ALLOC, 0x0, 0x6c, 0x0, 0x0, 0x0, 0x1, 0x0, 0x0},
+                       {".bss", SHT_NOBITS, SHF_WRITE + SHF_ALLOC, 0x0, 0x6c, 0x0, 0x0, 0x0, 0x1, 0x0, 0x0},
+                       {".rodata", SHT_PROGBITS, SHF_ALLOC, 0x0, 0x70, 0xd, 0x0, 0x0, 0x8, 0x0, 0xd},
+                       {".debug_info", SHT_PROGBITS, 0x0, 0x0, 0x7d, 0x346, 0x0, 0x0, 0x1, 0x0, 0x346},
+                       {".rela.debug_info", SHT_RELA, SHF_INFO_LINK, 0x0, 0xaa0, 0x630, 0x13, 0x6, 0x8, 0x18, 0x630},
+                       {".debug_abbrev", SHT_PROGBITS, 0x0, 0x0, 0x3c3, 0xf1, 0x0, 0x0, 0x1, 0x0, 0xf1},
+                       {".debug_aranges", SHT_PROGBITS, 0x0, 0x0, 0x4b4, 0x30, 0x0, 0x0, 0x1, 0x0, 0x30},
+                       {".rela.debug_aranges", SHT_RELA, SHF_INFO_LINK, 0x0, 0x10d0, 0x30, 0x13, 0x9, 0x8, 0x18, 0x30},
+                       {".debug_line", SHT_PROGBITS, 0x0, 0x0, 0x4e4, 0xd3, 0x0, 0x0, 0x1, 0x0, 0xd3},
+                       {".rela.debug_line", SHT_RELA, SHF_INFO_LINK, 0x0, 0x1100, 0x18, 0x13, 0xb, 0x8, 0x18, 0x18},
+                       {".debug_str", SHT_PROGBITS, SHF_MERGE + SHF_STRINGS, 0x0, 0x5b7, 0x2a3, 0x0, 0x0, 0x1, 0x1, 0x2a3},
+                       {".comment", SHT_PROGBITS, SHF_MERGE + SHF_STRINGS, 0x0, 0x85a, 0x2e, 0x0, 0x0, 0x1, 0x1, 0x2e},
+                       {".note.GNU-stack", SHT_PROGBITS, 0x0, 0x0, 0x888, 0x0, 0x0, 0x0, 0x1, 0x0, 0x0},
+                       {".debug_frame", SHT_PROGBITS, 0x0, 0x0, 0x888, 0x38, 0x0, 0x0, 0x8, 0x0, 0x38},
+                       {".rela.debug_frame", SHT_RELA, SHF_INFO_LINK, 0x0, 0x1118, 0x30, 0x13, 0x10, 0x8, 0x18, 0x30},
+                       {".shstrtab", SHT_STRTAB, 0x0, 0x0, 0x1148, 0xb3, 0x0, 0x0, 0x1, 0x0, 0xb3},
+                       {".symtab", SHT_SYMTAB, 0x0, 0x0, 0x8c0, 0x180, 0x14, 0xe, 0x8, 0x18, 0x180},
+                       {".strtab", SHT_STRTAB, 0x0, 0x0, 0xa40, 0x13, 0x0, 0x0, 0x1, 0x0, 0x13},
+               },
+               []ProgHeader{},
+               nil,
+               []Symbol{
+                       {"hello.c", 4, 0, 65521, 0, 0, "", ""},
+                       {"", 3, 0, 1, 0, 0, "", ""},
+                       {"", 3, 0, 3, 0, 0, "", ""},
+                       {"", 3, 0, 4, 0, 0, "", ""},
+                       {"", 3, 0, 5, 0, 0, "", ""},
+                       {"", 3, 0, 6, 0, 0, "", ""},
+                       {"", 3, 0, 8, 0, 0, "", ""},
+                       {"", 3, 0, 9, 0, 0, "", ""},
+                       {"", 3, 0, 11, 0, 0, "", ""},
+                       {"", 3, 0, 13, 0, 0, "", ""},
+                       {"", 3, 0, 15, 0, 0, "", ""},
+                       {"", 3, 0, 16, 0, 0, "", ""},
+                       {"", 3, 0, 14, 0, 0, "", ""},
+                       {"main", 18, 0, 1, 0, 44, "", ""},
+                       {"puts", 16, 0, 0, 0, 0, "", ""},
+               },
        },
 }
 
@@ -273,6 +506,10 @@ func TestOpen(t *testing.T) {
                if !reflect.DeepEqual(tl, fl) {
                        t.Errorf("open %s: DT_NEEDED = %v, want %v", tt.file, tl, fl)
                }
+               symbols, _ := f.Symbols()
+               if !reflect.DeepEqual(symbols, tt.symbols) {
+                       t.Errorf("open %s: Symbols() = %v, want %v", tt.file, symbols, tt.symbols)
+               }
        }
 }
 
@@ -1288,3 +1525,41 @@ func TestIssue59208(t *testing.T) {
                t.Errorf("DWARF = %v; want %q", err, want)
        }
 }
+
+func BenchmarkSymbols64(b *testing.B) {
+       const testdata = "testdata/gcc-amd64-linux-exec"
+       f, err := Open(testdata)
+       if err != nil {
+               b.Fatalf("could not read %s: %v", testdata, err)
+       }
+       defer f.Close()
+       b.ResetTimer()
+       for i := 0; i < b.N; i++ {
+               symbols, err := f.Symbols()
+               if err != nil {
+                       b.Fatalf("Symbols(): got unexpected error %v", err)
+               }
+               if len(symbols) != 73 {
+                       b.Errorf("\nhave %d symbols\nwant %d symbols\n", len(symbols), 73)
+               }
+       }
+}
+
+func BenchmarkSymbols32(b *testing.B) {
+       const testdata = "testdata/gcc-386-freebsd-exec"
+       f, err := Open(testdata)
+       if err != nil {
+               b.Fatalf("could not read %s: %v", testdata, err)
+       }
+       defer f.Close()
+       b.ResetTimer()
+       for i := 0; i < b.N; i++ {
+               symbols, err := f.Symbols()
+               if err != nil {
+                       b.Fatalf("Symbols(): got unexpected error %v", err)
+               }
+               if len(symbols) != 74 {
+                       b.Errorf("\nhave %d symbols\nwant %d symbols\n", len(symbols), 74)
+               }
+       }
+}

Before:

goos: linux
goarch: amd64
pkg: debug/elf
cpu: AMD Ryzen 9 5950X 16-Core Processor
BenchmarkSymbols64-32              80662             18282 ns/op           10936 B/op        119 allocs/op
BenchmarkSymbols32-32              65638             19048 ns/op           10008 B/op        125 allocs/op

After:

goos: linux
goarch: amd64
pkg: debug/elf
cpu: AMD Ryzen 9 5950X 16-Core Processor
BenchmarkSymbols64-32             339198              5225 ns/op            9136 B/op         45 allocs/op
BenchmarkSymbols32-32             191618              6037 ns/op            8776 B/op         50 allocs/op

I will be happy to submit a CL if it can be considered to be merged.
@gopherbot gopherbot added the compiler/runtime Issues related to the Go compiler and/or runtime. label Jul 23, 2023
@mauri870
Copy link
Member

Thanks for the report and investigation, I would advise to submit a CL so you can get feedback on the proposed changes, it is clearly a performance improvement over the current implementation.

@gopherbot
Copy link

Change https://go.dev/cl/512395 mentions this issue: debug/elf: improve File.Symbols()

@mknyszek mknyszek added this to the Backlog milestone Jul 26, 2023
@mknyszek mknyszek added the NeedsFix The path to resolution is known, but the work has not been done. label Jul 26, 2023
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Assignees

@prattmic prattmic

Labels
compiler/runtime Issues related to the Go compiler and/or runtime. NeedsFix The path to resolution is known, but the work has not been done. Performance
Projects
None yet
Milestone
Backlog
Development

No branches or pull requests
6 participants
@korniltsev @mknyszek @prattmic @bcmills @gopherbot @mauri870