@@ -8,6 +8,7 @@ package obj
88
99import (
1010 "cmd/internal/dwarf"
11+ "cmd/internal/src"
1112 "fmt"
1213)
1314
@@ -31,95 +32,51 @@ const (
3132func (ctxt * Link ) generateDebugLinesSymbol (s , lines * LSym ) {
3233 dctxt := dwCtxt {ctxt }
3334
34- // The Pcfile table is used to generate the debug_lines section, and the file
35- // indices for that data could differ from the files we write out for the
36- // debug_lines section. Here we generate a LUT between those two indices.
37- fileNums := make (map [int32 ]int64 )
38- for i , filename := range s .Func .Pcln .File {
39- if symbolIndex := ctxt .PosTable .FileIndex (filename ); symbolIndex >= 0 {
40- fileNums [int32 (i )] = int64 (symbolIndex ) + 1
41- } else {
42- panic (fmt .Sprintf ("First time we've seen filename: %q" , filename ))
43- }
44- }
45-
4635 // Set up the debug_lines state machine.
4736 // NB: This state machine is reset to this state when we've finished
4837 // generating the line table. See below.
4938 // TODO: Once delve can support multiple DW_LNS_end_statements, we don't have
5039 // to do this.
51- is_stmt := uint8 (1 )
40+ stmt := true
41+ line := int64 (1 )
5242 pc := s .Func .Text .Pc
53- line := 1
54- file := 1
55-
56- // The linker will insert the DW_LNE_set_address once determined; therefore,
57- // it's omitted here.
58-
59- // Generate the actual line information.
60- // We use the pcline and pcfile to generate this section, and it's suboptimal.
61- // Likely better would be to generate this dirrectly from the progs and not
62- // parse those tables.
63- // TODO: Generate from the progs if it's faster.
64- pcfile := NewPCIter (uint32 (ctxt .Arch .Arch .MinLC ))
65- pcline := NewPCIter (uint32 (ctxt .Arch .Arch .MinLC ))
66- pcstmt := NewPCIter (uint32 (ctxt .Arch .Arch .MinLC ))
67- pcfile .Init (s .Func .Pcln .Pcfile .P )
68- pcline .Init (s .Func .Pcln .Pcline .P )
69- var pctostmtData Pcdata
70- funcpctab (ctxt , & pctostmtData , s , "pctostmt" , pctostmt , nil )
71- pcstmt .Init (pctostmtData .P )
72- var thispc uint32
73-
74- for ! pcfile .Done && ! pcline .Done {
75- // Only changed if it advanced
76- if int32 (file ) != pcfile .Value {
77- dctxt .AddUint8 (lines , dwarf .DW_LNS_set_file )
78- dwarf .Uleb128put (dctxt , lines , fileNums [pcfile .Value ])
79- file = int (pcfile .Value )
43+ name := ""
44+ prologue , wrotePrologue := false , false
45+
46+ // Walk the progs, generating the DWARF table.
47+ for p := s .Func .Text ; p != nil ; p = p .Link {
48+ prologue = prologue || (p .Pos .Xlogue () == src .PosPrologueEnd )
49+ // If we're not at a real instruction, keep looping!
50+ if p .Pos .Line () == 0 || (p .Link != nil && p .Link .Pc == pc ) {
51+ continue
8052 }
53+ newStmt := p .Pos .IsStmt () != src .PosNotStmt
54+ newName , newLine := linkgetlineFromPos (ctxt , p .Pos )
8155
82- // Only changed if it advanced
83- if is_stmt != uint8 (pcstmt .Value ) {
84- new_stmt := uint8 (pcstmt .Value )
85- switch new_stmt &^ 1 {
86- case PrologueEnd :
87- dctxt .AddUint8 (lines , uint8 (dwarf .DW_LNS_set_prologue_end ))
88- case EpilogueBegin :
89- // TODO if there is a use for this, add it.
90- // Don't forget to increase OPCODE_BASE by 1 and add entry for standard_opcode_lengths[11]
91- panic ("unsupported EpilogueBegin" )
92- }
93- new_stmt &= 1
94- if is_stmt != new_stmt {
95- is_stmt = new_stmt
96- dctxt .AddUint8 (lines , uint8 (dwarf .DW_LNS_negate_stmt ))
97- }
56+ // Output debug info.
57+ wrote := false
58+ if name != newName {
59+ newFile := ctxt .PosTable .FileIndex (newName ) + 1 // 1 indexing for the table.
60+ dctxt .AddUint8 (lines , dwarf .DW_LNS_set_file )
61+ dwarf .Uleb128put (dctxt , lines , int64 (newFile ))
62+ name = newName
63+ wrote = true
9864 }
99-
100- // putpcldelta makes a row in the DWARF matrix, always, even if line is unchanged.
101- putpclcdelta (ctxt , dctxt , lines , uint64 (s .Func .Text .Pc + int64 (thispc )- pc ), int64 (pcline .Value )- int64 (line ))
102-
103- pc = s .Func .Text .Pc + int64 (thispc )
104- line = int (pcline .Value )
105-
106- // Take the minimum step forward for the three iterators
107- thispc = pcfile .NextPC
108- if pcline .NextPC < thispc {
109- thispc = pcline .NextPC
65+ if prologue && ! wrotePrologue {
66+ dctxt .AddUint8 (lines , uint8 (dwarf .DW_LNS_set_prologue_end ))
67+ wrotePrologue = true
68+ wrote = true
11069 }
111- if ! pcstmt .Done && pcstmt .NextPC < thispc {
112- thispc = pcstmt .NextPC
70+ if stmt != newStmt {
71+ dctxt .AddUint8 (lines , uint8 (dwarf .DW_LNS_negate_stmt ))
72+ stmt = newStmt
73+ wrote = true
11374 }
11475
115- if pcfile .NextPC == thispc {
116- pcfile .Next ()
117- }
118- if ! pcstmt .Done && pcstmt .NextPC == thispc {
119- pcstmt .Next ()
120- }
121- if pcline .NextPC == thispc {
122- pcline .Next ()
76+ if line != int64 (newLine ) || wrote {
77+ pcdelta := (p .Pc - pc ) / int64 (ctxt .Arch .MinLC )
78+ putpclcdelta (ctxt , dctxt , lines , uint64 (pcdelta ), int64 (newLine )- line )
79+ line , pc = int64 (newLine ), p .Pc
12380 }
12481 }
12582
@@ -129,16 +86,16 @@ func (ctxt *Link) generateDebugLinesSymbol(s, lines *LSym) {
12986 // file = 1
13087 // line = 1
13188 // column = 0
132- // is_stmt = set in header, we assume true
89+ // stmt = set in header, we assume true
13390 // basic_block = false
13491 // Careful readers of the DWARF specification will note that we don't reset
13592 // the address of the state machine -- but this will happen at the beginning
136- // of the NEXT block of opcodes. (See the SetAddress call above.)
93+ // of the NEXT block of opcodes.
13794 dctxt .AddUint8 (lines , dwarf .DW_LNS_set_file )
13895 dwarf .Uleb128put (dctxt , lines , 1 )
13996 dctxt .AddUint8 (lines , dwarf .DW_LNS_advance_line )
14097 dwarf .Sleb128put (dctxt , lines , int64 (1 - line ))
141- if is_stmt != 1 {
98+ if ! stmt {
14299 dctxt .AddUint8 (lines , dwarf .DW_LNS_negate_stmt )
143100 }
144101 dctxt .AddUint8 (lines , dwarf .DW_LNS_copy )
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