cmd/compile,cmd/link: set DW_AT_decl_line for function declarations

DW_AT_decl_line provides the line number of function declarations (the
line containing the func keyword). This is the equivalent to CL 429638,
but provided via DWARF.

Note that the file of declarations (DW_AT_decl_file) is already provided
for non-inlined functions. It is omitted for inlined functions because
those DWARF subprograms may be generated outside of their source
compilation unit, where referencing the file table is difficult.

Fixes #57308.

Change-Id: I3ad12e1f366c4465c2a588297988a5825ef7efec
Reviewed-on: https://go-review.googlesource.com/c/go/+/458195
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Auto-Submit: Michael Pratt <mpratt@google.com>
Run-TryBot: Michael Pratt <mpratt@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>

diff --git a/src/cmd/compile/internal/dwarfgen/dwarf.go b/src/cmd/compile/internal/dwarfgen/dwarf.go
index 90c331f0b6ed087709a69de54366c6d74f02a616..886250a62f1a7335c7e407f2ad2bd188bba44a1d 100644 (file)
--- a/src/cmd/compile/internal/dwarfgen/dwarf.go
+++ b/src/cmd/compile/internal/dwarfgen/dwarf.go
@@ -23,7 +23,7 @@ import (
        "cmd/internal/src"
 )
 
-func Info(fnsym *obj.LSym, infosym *obj.LSym, curfn interface{}) ([]dwarf.Scope, dwarf.InlCalls) {
+func Info(fnsym *obj.LSym, infosym *obj.LSym, curfn interface{}) (scopes []dwarf.Scope, inlcalls dwarf.InlCalls, startPos src.XPos) {
        fn := curfn.(*ir.Func)
 
        if fn.Nname != nil {
@@ -124,12 +124,11 @@ func Info(fnsym *obj.LSym, infosym *obj.LSym, curfn interface{}) ([]dwarf.Scope,
                varScopes = append(varScopes, findScope(fn.Marks, pos))
        }
 
-       scopes := assembleScopes(fnsym, fn, dwarfVars, varScopes)
-       var inlcalls dwarf.InlCalls
+       scopes = assembleScopes(fnsym, fn, dwarfVars, varScopes)
        if base.Flag.GenDwarfInl > 0 {
                inlcalls = assembleInlines(fnsym, dwarfVars)
        }
-       return scopes, inlcalls
+       return scopes, inlcalls, fn.Pos()
 }
 
 func declPos(decl *ir.Name) src.XPos {

diff --git a/src/cmd/internal/dwarf/dwarf.go b/src/cmd/internal/dwarf/dwarf.go
index a6d19c61d1d04f3bd41edf157e795ec7506f3e27..d4a4e33652d01a11dbef2f2bba40692a5276f772 100644 (file)
--- a/src/cmd/internal/dwarf/dwarf.go
+++ b/src/cmd/internal/dwarf/dwarf.go
@@ -94,6 +94,7 @@ type FnState struct {
        Absfn         Sym
        StartPC       Sym
        Size          int64
+       StartLine     int32
        External      bool
        Scopes        []Scope
        InlCalls      InlCalls
@@ -458,6 +459,7 @@ var abbrevs = [DW_NABRV]dwAbbrev{
                        {DW_AT_high_pc, DW_FORM_addr},
                        {DW_AT_frame_base, DW_FORM_block1},
                        {DW_AT_decl_file, DW_FORM_data4},
+                       {DW_AT_decl_line, DW_FORM_udata},
                        {DW_AT_external, DW_FORM_flag},
                },
        },
@@ -482,6 +484,7 @@ var abbrevs = [DW_NABRV]dwAbbrev{
                []dwAttrForm{
                        {DW_AT_name, DW_FORM_string},
                        {DW_AT_inline, DW_FORM_data1},
+                       {DW_AT_decl_line, DW_FORM_udata},
                        {DW_AT_external, DW_FORM_flag},
                },
        },
@@ -1254,6 +1257,8 @@ func PutAbstractFunc(ctxt Context, s *FnState) error {
        // DW_AT_inlined value
        putattr(ctxt, s.Absfn, abbrev, DW_FORM_data1, DW_CLS_CONSTANT, int64(DW_INL_inlined), nil)
 
+       putattr(ctxt, s.Absfn, abbrev, DW_FORM_udata, DW_CLS_CONSTANT, int64(s.StartLine), nil)
+
        var ev int64
        if s.External {
                ev = 1
@@ -1446,6 +1451,8 @@ func PutDefaultFunc(ctxt Context, s *FnState, isWrapper bool) error {
                putattr(ctxt, s.Info, abbrev, DW_FORM_flag, DW_CLS_FLAG, int64(1), 0)
        } else {
                ctxt.AddFileRef(s.Info, s.Filesym)
+               putattr(ctxt, s.Info, abbrev, DW_FORM_udata, DW_CLS_CONSTANT, int64(s.StartLine), nil)
+
                var ev int64
                if s.External {
                        ev = 1

diff --git a/src/cmd/internal/obj/dwarf.go b/src/cmd/internal/obj/dwarf.go
index a9c13fdc8c5544d117464c01fcfad8947d9d04e0..121a9f6ee96e2afb95f59cf27e3c16aa8d58d3f9 100644 (file)
--- a/src/cmd/internal/obj/dwarf.go
+++ b/src/cmd/internal/obj/dwarf.go
@@ -353,7 +353,9 @@ func (ctxt *Link) populateDWARF(curfn interface{}, s *LSym, myimportpath string)
        var scopes []dwarf.Scope
        var inlcalls dwarf.InlCalls
        if ctxt.DebugInfo != nil {
-               scopes, inlcalls = ctxt.DebugInfo(s, info, curfn)
+               // Don't need startPos because s.Func().StartLine is populated,
+               // as s is in this package.
+               scopes, inlcalls, _ = ctxt.DebugInfo(s, info, curfn)
        }
        var err error
        dwctxt := dwCtxt{ctxt}
@@ -368,6 +370,7 @@ func (ctxt *Link) populateDWARF(curfn interface{}, s *LSym, myimportpath string)
                Absfn:         absfunc,
                StartPC:       s,
                Size:          s.Size,
+               StartLine:     s.Func().StartLine,
                External:      !s.Static(),
                Scopes:        scopes,
                InlCalls:      inlcalls,
@@ -427,8 +430,12 @@ func (ctxt *Link) DwarfAbstractFunc(curfn interface{}, s *LSym, myimportpath str
        if s.Func() == nil {
                s.NewFuncInfo()
        }
-       scopes, _ := ctxt.DebugInfo(s, absfn, curfn)
+       scopes, _, startPos := ctxt.DebugInfo(s, absfn, curfn)
+       _, startLine := ctxt.getFileSymbolAndLine(startPos)
        dwctxt := dwCtxt{ctxt}
+       // TODO(prattmic): this returns nil for symbols outside of the current
+       // package because s.Func() is empty. This doesn't matter because
+       // PutAbstractFunc doesn't use Filesym. Use startPos or remove.
        filesym := ctxt.fileSymbol(s)
        fnstate := dwarf.FnState{
                Name:          s.Name,
@@ -436,6 +443,7 @@ func (ctxt *Link) DwarfAbstractFunc(curfn interface{}, s *LSym, myimportpath str
                Info:          absfn,
                Filesym:       filesym,
                Absfn:         absfn,
+               StartLine:     startLine,
                External:      !s.Static(),
                Scopes:        scopes,
                UseBASEntries: ctxt.UseBASEntries,

diff --git a/src/cmd/internal/obj/link.go b/src/cmd/internal/obj/link.go
index 80370173af4ef10d89e883b6013c4831d47c708f..6d40b334afda37ac6e018e9b0526c8bfb194a604 100644 (file)
--- a/src/cmd/internal/obj/link.go
+++ b/src/cmd/internal/obj/link.go
@@ -916,7 +916,7 @@ type Link struct {
        Imports            []goobj.ImportedPkg
        DiagFunc           func(string, ...interface{})
        DiagFlush          func()
-       DebugInfo          func(fn *LSym, info *LSym, curfn interface{}) ([]dwarf.Scope, dwarf.InlCalls) // if non-nil, curfn is a *gc.Node
+       DebugInfo          func(fn *LSym, info *LSym, curfn interface{}) ([]dwarf.Scope, dwarf.InlCalls, src.XPos) // if non-nil, curfn is a *ir.Func
        GenAbstractFunc    func(fn *LSym)
        Errors             int
 

diff --git a/src/cmd/link/internal/ld/dwarf_test.go b/src/cmd/link/internal/ld/dwarf_test.go
index a3db4a99ffbb10facce0d42a9367355a67c579f5..a11541f3208ab5f672ddaf19bd1e94f028dfb36b 100644 (file)
--- a/src/cmd/link/internal/ld/dwarf_test.go
+++ b/src/cmd/link/internal/ld/dwarf_test.go
@@ -334,10 +334,12 @@ func main() {
        }
 }
 
-func varDeclCoordsAndSubrogramDeclFile(t *testing.T, testpoint string, expectFile string, expectLine int, directive string) {
+// expectLine is the expected line for main.
+func varDeclCoordsAndSubprogramDeclFile(t *testing.T, testpoint string, expectFile string, expectLine int, directive string) {
        t.Parallel()
 
        prog := fmt.Sprintf("package main\n%s\nfunc main() {\n\nvar i int\ni = i\n}\n", directive)
+       const iLineOffset = 2
 
        dir := t.TempDir()
 
@@ -385,9 +387,12 @@ func varDeclCoordsAndSubrogramDeclFile(t *testing.T, testpoint string, expectFil
        }
 
        // Verify line/file attributes.
-       line := iEntry.Val(dwarf.AttrDeclLine)
-       if line == nil || line.(int64) != int64(expectLine) {
-               t.Errorf("DW_AT_decl_line for i is %v, want %d", line, expectLine)
+       line, lineOK := iEntry.Val(dwarf.AttrDeclLine).(int64)
+       if !lineOK {
+               t.Errorf("missing or invalid DW_AT_decl_line for i")
+       }
+       if line != int64(expectLine+iLineOffset) {
+               t.Errorf("DW_AT_decl_line for i is %v, want %d", line, expectLine+iLineOffset)
        }
 
        fileIdx, fileIdxOK := maindie.Val(dwarf.AttrDeclFile).(int64)
@@ -402,6 +407,14 @@ func varDeclCoordsAndSubrogramDeclFile(t *testing.T, testpoint string, expectFil
        if base != expectFile {
                t.Errorf("DW_AT_decl_file for main is %v, want %v", base, expectFile)
        }
+
+       line, lineOK = maindie.Val(dwarf.AttrDeclLine).(int64)
+       if !lineOK {
+               t.Errorf("missing or invalid DW_AT_decl_line for main")
+       }
+       if line != int64(expectLine) {
+               t.Errorf("DW_AT_decl_line for main is %v, want %d", line, expectLine)
+       }
 }
 
 func TestVarDeclCoordsAndSubrogramDeclFile(t *testing.T) {
@@ -411,7 +424,7 @@ func TestVarDeclCoordsAndSubrogramDeclFile(t *testing.T) {
                t.Skip("skipping on plan9; no DWARF symbol table in executables")
        }
 
-       varDeclCoordsAndSubrogramDeclFile(t, "TestVarDeclCoords", "test.go", 5, "")
+       varDeclCoordsAndSubprogramDeclFile(t, "TestVarDeclCoords", "test.go", 3, "")
 }
 
 func TestVarDeclCoordsWithLineDirective(t *testing.T) {
@@ -421,8 +434,8 @@ func TestVarDeclCoordsWithLineDirective(t *testing.T) {
                t.Skip("skipping on plan9; no DWARF symbol table in executables")
        }
 
-       varDeclCoordsAndSubrogramDeclFile(t, "TestVarDeclCoordsWithLineDirective",
-               "foobar.go", 202, "//line /foobar.go:200")
+       varDeclCoordsAndSubprogramDeclFile(t, "TestVarDeclCoordsWithLineDirective",
+               "foobar.go", 200, "//line /foobar.go:200")
 }
 
 func TestInlinedRoutineRecords(t *testing.T) {