// Copyright 2016 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. // Package dwarf generates DWARF debugging information. // DWARF generation is split between the compiler and the linker, // this package contains the shared code. package dwarf import ( "bytes" "errors" "fmt" "internal/buildcfg" "os/exec" "sort" "strconv" "strings" "cmd/internal/objabi" ) // InfoPrefix is the prefix for all the symbols containing DWARF info entries. const InfoPrefix = "go:info." // ConstInfoPrefix is the prefix for all symbols containing DWARF info // entries that contain constants. const ConstInfoPrefix = "go:constinfo." // CUInfoPrefix is the prefix for symbols containing information to // populate the DWARF compilation unit info entries. const CUInfoPrefix = "go:cuinfo." // Used to form the symbol name assigned to the DWARF 'abstract subprogram" // info entry for a function const AbstractFuncSuffix = "$abstract" // Controls logging/debugging for selected aspects of DWARF subprogram // generation (functions, scopes). var logDwarf bool // Sym represents a symbol. type Sym interface { Length(dwarfContext interface{}) int64 } // A Var represents a local variable or a function parameter. type Var struct { Name string Abbrev int // Either DW_ABRV_AUTO[_LOCLIST] or DW_ABRV_PARAM[_LOCLIST] IsReturnValue bool IsInlFormal bool DictIndex uint16 // index of the dictionary entry describing the type of this variable StackOffset int32 // This package can't use the ssa package, so it can't mention ssa.FuncDebug, // so indirect through a closure. PutLocationList func(listSym, startPC Sym) Scope int32 Type Sym DeclFile string DeclLine uint DeclCol uint InlIndex int32 // subtract 1 to form real index into InlTree ChildIndex int32 // child DIE index in abstract function IsInAbstract bool // variable exists in abstract function } // A Scope represents a lexical scope. All variables declared within a // scope will only be visible to instructions covered by the scope. // Lexical scopes are contiguous in source files but can end up being // compiled to discontiguous blocks of instructions in the executable. // The Ranges field lists all the blocks of instructions that belong // in this scope. type Scope struct { Parent int32 Ranges []Range Vars []*Var } // A Range represents a half-open interval [Start, End). type Range struct { Start, End int64 } // This container is used by the PutFunc* variants below when // creating the DWARF subprogram DIE(s) for a function. type FnState struct { Name string Importpath string Info Sym Filesym Sym Loc Sym Ranges Sym Absfn Sym StartPC Sym Size int64 External bool Scopes []Scope InlCalls InlCalls UseBASEntries bool dictIndexToOffset []int64 } func EnableLogging(doit bool) { logDwarf = doit } // MergeRanges creates a new range list by merging the ranges from // its two arguments, then returns the new list. func MergeRanges(in1, in2 []Range) []Range { out := make([]Range, 0, len(in1)+len(in2)) i, j := 0, 0 for { var cur Range if i < len(in2) && j < len(in1) { if in2[i].Start < in1[j].Start { cur = in2[i] i++ } else { cur = in1[j] j++ } } else if i < len(in2) { cur = in2[i] i++ } else if j < len(in1) { cur = in1[j] j++ } else { break } if n := len(out); n > 0 && cur.Start <= out[n-1].End { out[n-1].End = cur.End } else { out = append(out, cur) } } return out } // UnifyRanges merges the ranges from 'c' into the list of ranges for 's'. func (s *Scope) UnifyRanges(c *Scope) { s.Ranges = MergeRanges(s.Ranges, c.Ranges) } // AppendRange adds r to s, if r is non-empty. // If possible, it extends the last Range in s.Ranges; if not, it creates a new one. func (s *Scope) AppendRange(r Range) { if r.End <= r.Start { return } i := len(s.Ranges) if i > 0 && s.Ranges[i-1].End == r.Start { s.Ranges[i-1].End = r.End return } s.Ranges = append(s.Ranges, r) } type InlCalls struct { Calls []InlCall } type InlCall struct { // index into ctx.InlTree describing the call inlined here InlIndex int // Symbol of file containing inlined call site (really *obj.LSym). CallFile Sym // Line number of inlined call site. CallLine uint32 // Dwarf abstract subroutine symbol (really *obj.LSym). AbsFunSym Sym // Indices of child inlines within Calls array above. Children []int // entries in this list are PAUTO's created by the inliner to // capture the promoted formals and locals of the inlined callee. InlVars []*Var // PC ranges for this inlined call. Ranges []Range // Root call (not a child of some other call). Root bool } // A Context specifies how to add data to a Sym. type Context interface { PtrSize() int AddInt(s Sym, size int, i int64) AddBytes(s Sym, b []byte) AddAddress(s Sym, t interface{}, ofs int64) AddCURelativeAddress(s Sym, t interface{}, ofs int64) AddSectionOffset(s Sym, size int, t interface{}, ofs int64) AddDWARFAddrSectionOffset(s Sym, t interface{}, ofs int64) CurrentOffset(s Sym) int64 RecordDclReference(from Sym, to Sym, dclIdx int, inlIndex int) RecordChildDieOffsets(s Sym, vars []*Var, offsets []int32) AddString(s Sym, v string) AddFileRef(s Sym, f interface{}) Logf(format string, args ...interface{}) } // AppendUleb128 appends v to b using DWARF's unsigned LEB128 encoding. func AppendUleb128(b []byte, v uint64) []byte { for { c := uint8(v & 0x7f) v >>= 7 if v != 0 { c |= 0x80 } b = append(b, c) if c&0x80 == 0 { break } } return b } // AppendSleb128 appends v to b using DWARF's signed LEB128 encoding. func AppendSleb128(b []byte, v int64) []byte { for { c := uint8(v & 0x7f) s := uint8(v & 0x40) v >>= 7 if (v != -1 || s == 0) && (v != 0 || s != 0) { c |= 0x80 } b = append(b, c) if c&0x80 == 0 { break } } return b } // sevenbits contains all unsigned seven bit numbers, indexed by their value. var sevenbits = [...]byte{ 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f, 0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f, 0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f, 0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f, } // sevenBitU returns the unsigned LEB128 encoding of v if v is seven bits and nil otherwise. // The contents of the returned slice must not be modified. func sevenBitU(v int64) []byte { if uint64(v) < uint64(len(sevenbits)) { return sevenbits[v : v+1] } return nil } // sevenBitS returns the signed LEB128 encoding of v if v is seven bits and nil otherwise. // The contents of the returned slice must not be modified. func sevenBitS(v int64) []byte { if uint64(v) <= 63 { return sevenbits[v : v+1] } if uint64(-v) <= 64 { return sevenbits[128+v : 128+v+1] } return nil } // Uleb128put appends v to s using DWARF's unsigned LEB128 encoding. func Uleb128put(ctxt Context, s Sym, v int64) { b := sevenBitU(v) if b == nil { var encbuf [20]byte b = AppendUleb128(encbuf[:0], uint64(v)) } ctxt.AddBytes(s, b) } // Sleb128put appends v to s using DWARF's signed LEB128 encoding. func Sleb128put(ctxt Context, s Sym, v int64) { b := sevenBitS(v) if b == nil { var encbuf [20]byte b = AppendSleb128(encbuf[:0], v) } ctxt.AddBytes(s, b) } /* * Defining Abbrevs. This is hardcoded on a per-platform basis (that is, * each platform will see a fixed abbrev table for all objects); the number * of abbrev entries is fairly small (compared to C++ objects). The DWARF * spec places no restriction on the ordering of attributes in the * Abbrevs and DIEs, and we will always write them out in the order * of declaration in the abbrev. */ type dwAttrForm struct { attr uint16 form uint8 } // Go-specific type attributes. const ( DW_AT_go_kind = 0x2900 DW_AT_go_key = 0x2901 DW_AT_go_elem = 0x2902 // Attribute for DW_TAG_member of a struct type. // Nonzero value indicates the struct field is an embedded field. DW_AT_go_embedded_field = 0x2903 DW_AT_go_runtime_type = 0x2904 DW_AT_go_package_name = 0x2905 // Attribute for DW_TAG_compile_unit DW_AT_go_dict_index = 0x2906 // Attribute for DW_TAG_typedef_type, index of the dictionary entry describing the real type of this type shape DW_AT_internal_location = 253 // params and locals; not emitted ) // Index into the abbrevs table below. const ( DW_ABRV_NULL = iota DW_ABRV_COMPUNIT DW_ABRV_COMPUNIT_TEXTLESS DW_ABRV_FUNCTION DW_ABRV_WRAPPER DW_ABRV_FUNCTION_ABSTRACT DW_ABRV_FUNCTION_CONCRETE DW_ABRV_WRAPPER_CONCRETE DW_ABRV_INLINED_SUBROUTINE DW_ABRV_INLINED_SUBROUTINE_RANGES DW_ABRV_VARIABLE DW_ABRV_INT_CONSTANT DW_ABRV_AUTO DW_ABRV_AUTO_LOCLIST DW_ABRV_AUTO_ABSTRACT DW_ABRV_AUTO_CONCRETE DW_ABRV_AUTO_CONCRETE_LOCLIST DW_ABRV_PARAM DW_ABRV_PARAM_LOCLIST DW_ABRV_PARAM_ABSTRACT DW_ABRV_PARAM_CONCRETE DW_ABRV_PARAM_CONCRETE_LOCLIST DW_ABRV_LEXICAL_BLOCK_RANGES DW_ABRV_LEXICAL_BLOCK_SIMPLE DW_ABRV_STRUCTFIELD DW_ABRV_FUNCTYPEPARAM DW_ABRV_DOTDOTDOT DW_ABRV_ARRAYRANGE DW_ABRV_NULLTYPE DW_ABRV_BASETYPE DW_ABRV_ARRAYTYPE DW_ABRV_CHANTYPE DW_ABRV_FUNCTYPE DW_ABRV_IFACETYPE DW_ABRV_MAPTYPE DW_ABRV_PTRTYPE DW_ABRV_BARE_PTRTYPE // only for void*, no DW_AT_type attr to please gdb 6. DW_ABRV_SLICETYPE DW_ABRV_STRINGTYPE DW_ABRV_STRUCTTYPE DW_ABRV_TYPEDECL DW_ABRV_DICT_INDEX DW_NABRV ) type dwAbbrev struct { tag uint8 children uint8 attr []dwAttrForm } var abbrevsFinalized bool // expandPseudoForm takes an input DW_FORM_xxx value and translates it // into a platform-appropriate concrete form. Existing concrete/real // DW_FORM values are left untouched. For the moment the only // pseudo-form is DW_FORM_udata_pseudo, which gets expanded to // DW_FORM_data4 on Darwin and DW_FORM_udata everywhere else. See // issue #31459 for more context. func expandPseudoForm(form uint8) uint8 { // Is this a pseudo-form? if form != DW_FORM_udata_pseudo { return form } expandedForm := DW_FORM_udata if buildcfg.GOOS == "darwin" || buildcfg.GOOS == "ios" { expandedForm = DW_FORM_data4 } return uint8(expandedForm) } // Abbrevs returns the finalized abbrev array for the platform, // expanding any DW_FORM pseudo-ops to real values. func Abbrevs() []dwAbbrev { if abbrevsFinalized { return abbrevs[:] } for i := 1; i < DW_NABRV; i++ { for j := 0; j < len(abbrevs[i].attr); j++ { abbrevs[i].attr[j].form = expandPseudoForm(abbrevs[i].attr[j].form) } } abbrevsFinalized = true return abbrevs[:] } // abbrevs is a raw table of abbrev entries; it needs to be post-processed // by the Abbrevs() function above prior to being consumed, to expand // the 'pseudo-form' entries below to real DWARF form values. var abbrevs = [DW_NABRV]dwAbbrev{ /* The mandatory DW_ABRV_NULL entry. */ {0, 0, []dwAttrForm{}}, /* COMPUNIT */ { DW_TAG_compile_unit, DW_CHILDREN_yes, []dwAttrForm{ {DW_AT_name, DW_FORM_string}, {DW_AT_language, DW_FORM_data1}, {DW_AT_stmt_list, DW_FORM_sec_offset}, {DW_AT_low_pc, DW_FORM_addr}, {DW_AT_ranges, DW_FORM_sec_offset}, {DW_AT_comp_dir, DW_FORM_string}, {DW_AT_producer, DW_FORM_string}, {DW_AT_go_package_name, DW_FORM_string}, }, }, /* COMPUNIT_TEXTLESS */ { DW_TAG_compile_unit, DW_CHILDREN_yes, []dwAttrForm{ {DW_AT_name, DW_FORM_string}, {DW_AT_language, DW_FORM_data1}, {DW_AT_comp_dir, DW_FORM_string}, {DW_AT_producer, DW_FORM_string}, {DW_AT_go_package_name, DW_FORM_string}, }, }, /* FUNCTION */ { DW_TAG_subprogram, DW_CHILDREN_yes, []dwAttrForm{ {DW_AT_name, DW_FORM_string}, {DW_AT_low_pc, DW_FORM_addr}, {DW_AT_high_pc, DW_FORM_addr}, {DW_AT_frame_base, DW_FORM_block1}, {DW_AT_decl_file, DW_FORM_data4}, {DW_AT_external, DW_FORM_flag}, }, }, /* WRAPPER */ { DW_TAG_subprogram, DW_CHILDREN_yes, []dwAttrForm{ {DW_AT_name, DW_FORM_string}, {DW_AT_low_pc, DW_FORM_addr}, {DW_AT_high_pc, DW_FORM_addr}, {DW_AT_frame_base, DW_FORM_block1}, {DW_AT_trampoline, DW_FORM_flag}, }, }, /* FUNCTION_ABSTRACT */ { DW_TAG_subprogram, DW_CHILDREN_yes, []dwAttrForm{ {DW_AT_name, DW_FORM_string}, {DW_AT_inline, DW_FORM_data1}, {DW_AT_external, DW_FORM_flag}, }, }, /* FUNCTION_CONCRETE */ { DW_TAG_subprogram, DW_CHILDREN_yes, []dwAttrForm{ {DW_AT_abstract_origin, DW_FORM_ref_addr}, {DW_AT_low_pc, DW_FORM_addr}, {DW_AT_high_pc, DW_FORM_addr}, {DW_AT_frame_base, DW_FORM_block1}, }, }, /* WRAPPER_CONCRETE */ { DW_TAG_subprogram, DW_CHILDREN_yes, []dwAttrForm{ {DW_AT_abstract_origin, DW_FORM_ref_addr}, {DW_AT_low_pc, DW_FORM_addr}, {DW_AT_high_pc, DW_FORM_addr}, {DW_AT_frame_base, DW_FORM_block1}, {DW_AT_trampoline, DW_FORM_flag}, }, }, /* INLINED_SUBROUTINE */ { DW_TAG_inlined_subroutine, DW_CHILDREN_yes, []dwAttrForm{ {DW_AT_abstract_origin, DW_FORM_ref_addr}, {DW_AT_low_pc, DW_FORM_addr}, {DW_AT_high_pc, DW_FORM_addr}, {DW_AT_call_file, DW_FORM_data4}, {DW_AT_call_line, DW_FORM_udata_pseudo}, // pseudo-form }, }, /* INLINED_SUBROUTINE_RANGES */ { DW_TAG_inlined_subroutine, DW_CHILDREN_yes, []dwAttrForm{ {DW_AT_abstract_origin, DW_FORM_ref_addr}, {DW_AT_ranges, DW_FORM_sec_offset}, {DW_AT_call_file, DW_FORM_data4}, {DW_AT_call_line, DW_FORM_udata_pseudo}, // pseudo-form }, }, /* VARIABLE */ { DW_TAG_variable, DW_CHILDREN_no, []dwAttrForm{ {DW_AT_name, DW_FORM_string}, {DW_AT_location, DW_FORM_block1}, {DW_AT_type, DW_FORM_ref_addr}, {DW_AT_external, DW_FORM_flag}, }, }, /* INT CONSTANT */ { DW_TAG_constant, DW_CHILDREN_no, []dwAttrForm{ {DW_AT_name, DW_FORM_string}, {DW_AT_type, DW_FORM_ref_addr}, {DW_AT_const_value, DW_FORM_sdata}, }, }, /* AUTO */ { DW_TAG_variable, DW_CHILDREN_no, []dwAttrForm{ {DW_AT_name, DW_FORM_string}, {DW_AT_decl_line, DW_FORM_udata}, {DW_AT_type, DW_FORM_ref_addr}, {DW_AT_location, DW_FORM_block1}, }, }, /* AUTO_LOCLIST */ { DW_TAG_variable, DW_CHILDREN_no, []dwAttrForm{ {DW_AT_name, DW_FORM_string}, {DW_AT_decl_line, DW_FORM_udata}, {DW_AT_type, DW_FORM_ref_addr}, {DW_AT_location, DW_FORM_sec_offset}, }, }, /* AUTO_ABSTRACT */ { DW_TAG_variable, DW_CHILDREN_no, []dwAttrForm{ {DW_AT_name, DW_FORM_string}, {DW_AT_decl_line, DW_FORM_udata}, {DW_AT_type, DW_FORM_ref_addr}, }, }, /* AUTO_CONCRETE */ { DW_TAG_variable, DW_CHILDREN_no, []dwAttrForm{ {DW_AT_abstract_origin, DW_FORM_ref_addr}, {DW_AT_location, DW_FORM_block1}, }, }, /* AUTO_CONCRETE_LOCLIST */ { DW_TAG_variable, DW_CHILDREN_no, []dwAttrForm{ {DW_AT_abstract_origin, DW_FORM_ref_addr}, {DW_AT_location, DW_FORM_sec_offset}, }, }, /* PARAM */ { DW_TAG_formal_parameter, DW_CHILDREN_no, []dwAttrForm{ {DW_AT_name, DW_FORM_string}, {DW_AT_variable_parameter, DW_FORM_flag}, {DW_AT_decl_line, DW_FORM_udata}, {DW_AT_type, DW_FORM_ref_addr}, {DW_AT_location, DW_FORM_block1}, }, }, /* PARAM_LOCLIST */ { DW_TAG_formal_parameter, DW_CHILDREN_no, []dwAttrForm{ {DW_AT_name, DW_FORM_string}, {DW_AT_variable_parameter, DW_FORM_flag}, {DW_AT_decl_line, DW_FORM_udata}, {DW_AT_type, DW_FORM_ref_addr}, {DW_AT_location, DW_FORM_sec_offset}, }, }, /* PARAM_ABSTRACT */ { DW_TAG_formal_parameter, DW_CHILDREN_no, []dwAttrForm{ {DW_AT_name, DW_FORM_string}, {DW_AT_variable_parameter, DW_FORM_flag}, {DW_AT_type, DW_FORM_ref_addr}, }, }, /* PARAM_CONCRETE */ { DW_TAG_formal_parameter, DW_CHILDREN_no, []dwAttrForm{ {DW_AT_abstract_origin, DW_FORM_ref_addr}, {DW_AT_location, DW_FORM_block1}, }, }, /* PARAM_CONCRETE_LOCLIST */ { DW_TAG_formal_parameter, DW_CHILDREN_no, []dwAttrForm{ {DW_AT_abstract_origin, DW_FORM_ref_addr}, {DW_AT_location, DW_FORM_sec_offset}, }, }, /* LEXICAL_BLOCK_RANGES */ { DW_TAG_lexical_block, DW_CHILDREN_yes, []dwAttrForm{ {DW_AT_ranges, DW_FORM_sec_offset}, }, }, /* LEXICAL_BLOCK_SIMPLE */ { DW_TAG_lexical_block, DW_CHILDREN_yes, []dwAttrForm{ {DW_AT_low_pc, DW_FORM_addr}, {DW_AT_high_pc, DW_FORM_addr}, }, }, /* STRUCTFIELD */ { DW_TAG_member, DW_CHILDREN_no, []dwAttrForm{ {DW_AT_name, DW_FORM_string}, {DW_AT_data_member_location, DW_FORM_udata}, {DW_AT_type, DW_FORM_ref_addr}, {DW_AT_go_embedded_field, DW_FORM_flag}, }, }, /* FUNCTYPEPARAM */ { DW_TAG_formal_parameter, DW_CHILDREN_no, // No name! []dwAttrForm{ {DW_AT_type, DW_FORM_ref_addr}, }, }, /* DOTDOTDOT */ { DW_TAG_unspecified_parameters, DW_CHILDREN_no, []dwAttrForm{}, }, /* ARRAYRANGE */ { DW_TAG_subrange_type, DW_CHILDREN_no, // No name! []dwAttrForm{ {DW_AT_type, DW_FORM_ref_addr}, {DW_AT_count, DW_FORM_udata}, }, }, // Below here are the types considered public by ispubtype /* NULLTYPE */ { DW_TAG_unspecified_type, DW_CHILDREN_no, []dwAttrForm{ {DW_AT_name, DW_FORM_string}, }, }, /* BASETYPE */ { DW_TAG_base_type, DW_CHILDREN_no, []dwAttrForm{ {DW_AT_name, DW_FORM_string}, {DW_AT_encoding, DW_FORM_data1}, {DW_AT_byte_size, DW_FORM_data1}, {DW_AT_go_kind, DW_FORM_data1}, {DW_AT_go_runtime_type, DW_FORM_addr}, }, }, /* ARRAYTYPE */ // child is subrange with upper bound { DW_TAG_array_type, DW_CHILDREN_yes, []dwAttrForm{ {DW_AT_name, DW_FORM_string}, {DW_AT_type, DW_FORM_ref_addr}, {DW_AT_byte_size, DW_FORM_udata}, {DW_AT_go_kind, DW_FORM_data1}, {DW_AT_go_runtime_type, DW_FORM_addr}, }, }, /* CHANTYPE */ { DW_TAG_typedef, DW_CHILDREN_no, []dwAttrForm{ {DW_AT_name, DW_FORM_string}, {DW_AT_type, DW_FORM_ref_addr}, {DW_AT_go_kind, DW_FORM_data1}, {DW_AT_go_runtime_type, DW_FORM_addr}, {DW_AT_go_elem, DW_FORM_ref_addr}, }, }, /* FUNCTYPE */ { DW_TAG_subroutine_type, DW_CHILDREN_yes, []dwAttrForm{ {DW_AT_name, DW_FORM_string}, {DW_AT_byte_size, DW_FORM_udata}, {DW_AT_go_kind, DW_FORM_data1}, {DW_AT_go_runtime_type, DW_FORM_addr}, }, }, /* IFACETYPE */ { DW_TAG_typedef, DW_CHILDREN_yes, []dwAttrForm{ {DW_AT_name, DW_FORM_string}, {DW_AT_type, DW_FORM_ref_addr}, {DW_AT_go_kind, DW_FORM_data1}, {DW_AT_go_runtime_type, DW_FORM_addr}, }, }, /* MAPTYPE */ { DW_TAG_typedef, DW_CHILDREN_no, []dwAttrForm{ {DW_AT_name, DW_FORM_string}, {DW_AT_type, DW_FORM_ref_addr}, {DW_AT_go_kind, DW_FORM_data1}, {DW_AT_go_runtime_type, DW_FORM_addr}, {DW_AT_go_key, DW_FORM_ref_addr}, {DW_AT_go_elem, DW_FORM_ref_addr}, }, }, /* PTRTYPE */ { DW_TAG_pointer_type, DW_CHILDREN_no, []dwAttrForm{ {DW_AT_name, DW_FORM_string}, {DW_AT_type, DW_FORM_ref_addr}, {DW_AT_go_kind, DW_FORM_data1}, {DW_AT_go_runtime_type, DW_FORM_addr}, }, }, /* BARE_PTRTYPE */ { DW_TAG_pointer_type, DW_CHILDREN_no, []dwAttrForm{ {DW_AT_name, DW_FORM_string}, }, }, /* SLICETYPE */ { DW_TAG_structure_type, DW_CHILDREN_yes, []dwAttrForm{ {DW_AT_name, DW_FORM_string}, {DW_AT_byte_size, DW_FORM_udata}, {DW_AT_go_kind, DW_FORM_data1}, {DW_AT_go_runtime_type, DW_FORM_addr}, {DW_AT_go_elem, DW_FORM_ref_addr}, }, }, /* STRINGTYPE */ { DW_TAG_structure_type, DW_CHILDREN_yes, []dwAttrForm{ {DW_AT_name, DW_FORM_string}, {DW_AT_byte_size, DW_FORM_udata}, {DW_AT_go_kind, DW_FORM_data1}, {DW_AT_go_runtime_type, DW_FORM_addr}, }, }, /* STRUCTTYPE */ { DW_TAG_structure_type, DW_CHILDREN_yes, []dwAttrForm{ {DW_AT_name, DW_FORM_string}, {DW_AT_byte_size, DW_FORM_udata}, {DW_AT_go_kind, DW_FORM_data1}, {DW_AT_go_runtime_type, DW_FORM_addr}, }, }, /* TYPEDECL */ { DW_TAG_typedef, DW_CHILDREN_no, []dwAttrForm{ {DW_AT_name, DW_FORM_string}, {DW_AT_type, DW_FORM_ref_addr}, }, }, /* DICT_INDEX */ { DW_TAG_typedef, DW_CHILDREN_no, []dwAttrForm{ {DW_AT_name, DW_FORM_string}, {DW_AT_type, DW_FORM_ref_addr}, {DW_AT_go_dict_index, DW_FORM_udata}, }, }, } // GetAbbrev returns the contents of the .debug_abbrev section. func GetAbbrev() []byte { abbrevs := Abbrevs() var buf []byte for i := 1; i < DW_NABRV; i++ { // See section 7.5.3 buf = AppendUleb128(buf, uint64(i)) buf = AppendUleb128(buf, uint64(abbrevs[i].tag)) buf = append(buf, abbrevs[i].children) for _, f := range abbrevs[i].attr { buf = AppendUleb128(buf, uint64(f.attr)) buf = AppendUleb128(buf, uint64(f.form)) } buf = append(buf, 0, 0) } return append(buf, 0) } /* * Debugging Information Entries and their attributes. */ // DWAttr represents an attribute of a DWDie. // // For DW_CLS_string and _block, value should contain the length, and // data the data, for _reference, value is 0 and data is a DWDie* to // the referenced instance, for all others, value is the whole thing // and data is null. type DWAttr struct { Link *DWAttr Atr uint16 // DW_AT_ Cls uint8 // DW_CLS_ Value int64 Data interface{} } // DWDie represents a DWARF debug info entry. type DWDie struct { Abbrev int Link *DWDie Child *DWDie Attr *DWAttr Sym Sym } func putattr(ctxt Context, s Sym, abbrev int, form int, cls int, value int64, data interface{}) error { switch form { case DW_FORM_addr: // address // Allow nil addresses for DW_AT_go_runtime_type. if data == nil && value == 0 { ctxt.AddInt(s, ctxt.PtrSize(), 0) break } if cls == DW_CLS_GO_TYPEREF { ctxt.AddSectionOffset(s, ctxt.PtrSize(), data, value) break } ctxt.AddAddress(s, data, value) case DW_FORM_block1: // block if cls == DW_CLS_ADDRESS { ctxt.AddInt(s, 1, int64(1+ctxt.PtrSize())) ctxt.AddInt(s, 1, DW_OP_addr) ctxt.AddAddress(s, data, 0) break } value &= 0xff ctxt.AddInt(s, 1, value) p := data.([]byte)[:value] ctxt.AddBytes(s, p) case DW_FORM_block2: // block value &= 0xffff ctxt.AddInt(s, 2, value) p := data.([]byte)[:value] ctxt.AddBytes(s, p) case DW_FORM_block4: // block value &= 0xffffffff ctxt.AddInt(s, 4, value) p := data.([]byte)[:value] ctxt.AddBytes(s, p) case DW_FORM_block: // block Uleb128put(ctxt, s, value) p := data.([]byte)[:value] ctxt.AddBytes(s, p) case DW_FORM_data1: // constant ctxt.AddInt(s, 1, value) case DW_FORM_data2: // constant ctxt.AddInt(s, 2, value) case DW_FORM_data4: // constant, {line,loclist,mac,rangelist}ptr if cls == DW_CLS_PTR { // DW_AT_stmt_list and DW_AT_ranges ctxt.AddDWARFAddrSectionOffset(s, data, value) break } ctxt.AddInt(s, 4, value) case DW_FORM_data8: // constant, {line,loclist,mac,rangelist}ptr ctxt.AddInt(s, 8, value) case DW_FORM_sdata: // constant Sleb128put(ctxt, s, value) case DW_FORM_udata: // constant Uleb128put(ctxt, s, value) case DW_FORM_string: // string str := data.(string) ctxt.AddString(s, str) // TODO(ribrdb): verify padded strings are never used and remove this for i := int64(len(str)); i < value; i++ { ctxt.AddInt(s, 1, 0) } case DW_FORM_flag: // flag if value != 0 { ctxt.AddInt(s, 1, 1) } else { ctxt.AddInt(s, 1, 0) } // As of DWARF 3 the ref_addr is always 32 bits, unless emitting a large // (> 4 GB of debug info aka "64-bit") unit, which we don't implement. case DW_FORM_ref_addr: // reference to a DIE in the .info section fallthrough case DW_FORM_sec_offset: // offset into a DWARF section other than .info if data == nil { return fmt.Errorf("dwarf: null reference in %d", abbrev) } ctxt.AddDWARFAddrSectionOffset(s, data, value) case DW_FORM_ref1, // reference within the compilation unit DW_FORM_ref2, // reference DW_FORM_ref4, // reference DW_FORM_ref8, // reference DW_FORM_ref_udata, // reference DW_FORM_strp, // string DW_FORM_indirect: // (see Section 7.5.3) fallthrough default: return fmt.Errorf("dwarf: unsupported attribute form %d / class %d", form, cls) } return nil } // PutAttrs writes the attributes for a DIE to symbol 's'. // // Note that we can (and do) add arbitrary attributes to a DIE, but // only the ones actually listed in the Abbrev will be written out. func PutAttrs(ctxt Context, s Sym, abbrev int, attr *DWAttr) { abbrevs := Abbrevs() Outer: for _, f := range abbrevs[abbrev].attr { for ap := attr; ap != nil; ap = ap.Link { if ap.Atr == f.attr { putattr(ctxt, s, abbrev, int(f.form), int(ap.Cls), ap.Value, ap.Data) continue Outer } } putattr(ctxt, s, abbrev, int(f.form), 0, 0, nil) } } // HasChildren reports whether 'die' uses an abbrev that supports children. func HasChildren(die *DWDie) bool { abbrevs := Abbrevs() return abbrevs[die.Abbrev].children != 0 } // PutIntConst writes a DIE for an integer constant func PutIntConst(ctxt Context, info, typ Sym, name string, val int64) { Uleb128put(ctxt, info, DW_ABRV_INT_CONSTANT) putattr(ctxt, info, DW_ABRV_INT_CONSTANT, DW_FORM_string, DW_CLS_STRING, int64(len(name)), name) putattr(ctxt, info, DW_ABRV_INT_CONSTANT, DW_FORM_ref_addr, DW_CLS_REFERENCE, 0, typ) putattr(ctxt, info, DW_ABRV_INT_CONSTANT, DW_FORM_sdata, DW_CLS_CONSTANT, val, nil) } // PutGlobal writes a DIE for a global variable. func PutGlobal(ctxt Context, info, typ, gvar Sym, name string) { Uleb128put(ctxt, info, DW_ABRV_VARIABLE) putattr(ctxt, info, DW_ABRV_VARIABLE, DW_FORM_string, DW_CLS_STRING, int64(len(name)), name) putattr(ctxt, info, DW_ABRV_VARIABLE, DW_FORM_block1, DW_CLS_ADDRESS, 0, gvar) putattr(ctxt, info, DW_ABRV_VARIABLE, DW_FORM_ref_addr, DW_CLS_REFERENCE, 0, typ) putattr(ctxt, info, DW_ABRV_VARIABLE, DW_FORM_flag, DW_CLS_FLAG, 1, nil) } // PutBasedRanges writes a range table to sym. All addresses in ranges are // relative to some base address, which must be arranged by the caller // (e.g., with a DW_AT_low_pc attribute, or in a BASE-prefixed range). func PutBasedRanges(ctxt Context, sym Sym, ranges []Range) { ps := ctxt.PtrSize() // Write ranges. for _, r := range ranges { ctxt.AddInt(sym, ps, r.Start) ctxt.AddInt(sym, ps, r.End) } // Write trailer. ctxt.AddInt(sym, ps, 0) ctxt.AddInt(sym, ps, 0) } // PutRanges writes a range table to s.Ranges. // All addresses in ranges are relative to s.base. func (s *FnState) PutRanges(ctxt Context, ranges []Range) { ps := ctxt.PtrSize() sym, base := s.Ranges, s.StartPC if s.UseBASEntries { // Using a Base Address Selection Entry reduces the number of relocations, but // this is not done on macOS because it is not supported by dsymutil/dwarfdump/lldb ctxt.AddInt(sym, ps, -1) ctxt.AddAddress(sym, base, 0) PutBasedRanges(ctxt, sym, ranges) return } // Write ranges full of relocations for _, r := range ranges { ctxt.AddCURelativeAddress(sym, base, r.Start) ctxt.AddCURelativeAddress(sym, base, r.End) } // Write trailer. ctxt.AddInt(sym, ps, 0) ctxt.AddInt(sym, ps, 0) } // Return TRUE if the inlined call in the specified slot is empty, // meaning it has a zero-length range (no instructions), and all // of its children are empty. func isEmptyInlinedCall(slot int, calls *InlCalls) bool { ic := &calls.Calls[slot] if ic.InlIndex == -2 { return true } live := false for _, k := range ic.Children { if !isEmptyInlinedCall(k, calls) { live = true } } if len(ic.Ranges) > 0 { live = true } if !live { ic.InlIndex = -2 } return !live } // Slot -1: return top-level inlines. // Slot >= 0: return children of that slot. func inlChildren(slot int, calls *InlCalls) []int { var kids []int if slot != -1 { for _, k := range calls.Calls[slot].Children { if !isEmptyInlinedCall(k, calls) { kids = append(kids, k) } } } else { for k := 0; k < len(calls.Calls); k += 1 { if calls.Calls[k].Root && !isEmptyInlinedCall(k, calls) { kids = append(kids, k) } } } return kids } func inlinedVarTable(inlcalls *InlCalls) map[*Var]bool { vars := make(map[*Var]bool) for _, ic := range inlcalls.Calls { for _, v := range ic.InlVars { vars[v] = true } } return vars } // The s.Scopes slice contains variables were originally part of the // function being emitted, as well as variables that were imported // from various callee functions during the inlining process. This // function prunes out any variables from the latter category (since // they will be emitted as part of DWARF inlined_subroutine DIEs) and // then generates scopes for vars in the former category. func putPrunedScopes(ctxt Context, s *FnState, fnabbrev int) error { if len(s.Scopes) == 0 { return nil } scopes := make([]Scope, len(s.Scopes), len(s.Scopes)) pvars := inlinedVarTable(&s.InlCalls) for k, s := range s.Scopes { var pruned Scope = Scope{Parent: s.Parent, Ranges: s.Ranges} for i := 0; i < len(s.Vars); i++ { _, found := pvars[s.Vars[i]] if !found { pruned.Vars = append(pruned.Vars, s.Vars[i]) } } sort.Sort(byChildIndex(pruned.Vars)) scopes[k] = pruned } s.dictIndexToOffset = putparamtypes(ctxt, s, scopes, fnabbrev) var encbuf [20]byte if putscope(ctxt, s, scopes, 0, fnabbrev, encbuf[:0]) < int32(len(scopes)) { return errors.New("multiple toplevel scopes") } return nil } // Emit DWARF attributes and child DIEs for an 'abstract' subprogram. // The abstract subprogram DIE for a function contains its // location-independent attributes (name, type, etc). Other instances // of the function (any inlined copy of it, or the single out-of-line // 'concrete' instance) will contain a pointer back to this abstract // DIE (as a space-saving measure, so that name/type etc doesn't have // to be repeated for each inlined copy). func PutAbstractFunc(ctxt Context, s *FnState) error { if logDwarf { ctxt.Logf("PutAbstractFunc(%v)\n", s.Absfn) } abbrev := DW_ABRV_FUNCTION_ABSTRACT Uleb128put(ctxt, s.Absfn, int64(abbrev)) fullname := s.Name if strings.HasPrefix(s.Name, "\"\".") { // Generate a fully qualified name for the function in the // abstract case. This is so as to avoid the need for the // linker to process the DIE with patchDWARFName(); we can't // allow the name attribute of an abstract subprogram DIE to // be rewritten, since it would change the offsets of the // child DIEs (which we're relying on in order for abstract // origin references to work). fullname = objabi.PathToPrefix(s.Importpath) + "." + s.Name[3:] } putattr(ctxt, s.Absfn, abbrev, DW_FORM_string, DW_CLS_STRING, int64(len(fullname)), fullname) // DW_AT_inlined value putattr(ctxt, s.Absfn, abbrev, DW_FORM_data1, DW_CLS_CONSTANT, int64(DW_INL_inlined), nil) var ev int64 if s.External { ev = 1 } putattr(ctxt, s.Absfn, abbrev, DW_FORM_flag, DW_CLS_FLAG, ev, 0) // Child variables (may be empty) var flattened []*Var // This slice will hold the offset in bytes for each child var DIE // with respect to the start of the parent subprogram DIE. var offsets []int32 // Scopes/vars if len(s.Scopes) > 0 { // For abstract subprogram DIEs we want to flatten out scope info: // lexical scope DIEs contain range and/or hi/lo PC attributes, // which we explicitly don't want for the abstract subprogram DIE. pvars := inlinedVarTable(&s.InlCalls) for _, scope := range s.Scopes { for i := 0; i < len(scope.Vars); i++ { _, found := pvars[scope.Vars[i]] if found || !scope.Vars[i].IsInAbstract { continue } flattened = append(flattened, scope.Vars[i]) } } if len(flattened) > 0 { sort.Sort(byChildIndex(flattened)) if logDwarf { ctxt.Logf("putAbstractScope(%v): vars:", s.Info) for i, v := range flattened { ctxt.Logf(" %d:%s", i, v.Name) } ctxt.Logf("\n") } // This slice will hold the offset in bytes for each child // variable DIE with respect to the start of the parent // subprogram DIE. for _, v := range flattened { offsets = append(offsets, int32(ctxt.CurrentOffset(s.Absfn))) putAbstractVar(ctxt, s.Absfn, v) } } } ctxt.RecordChildDieOffsets(s.Absfn, flattened, offsets) Uleb128put(ctxt, s.Absfn, 0) return nil } // Emit DWARF attributes and child DIEs for an inlined subroutine. The // first attribute of an inlined subroutine DIE is a reference back to // its corresponding 'abstract' DIE (containing location-independent // attributes such as name, type, etc). Inlined subroutine DIEs can // have other inlined subroutine DIEs as children. func putInlinedFunc(ctxt Context, s *FnState, callIdx int) error { ic := s.InlCalls.Calls[callIdx] callee := ic.AbsFunSym abbrev := DW_ABRV_INLINED_SUBROUTINE_RANGES if len(ic.Ranges) == 1 { abbrev = DW_ABRV_INLINED_SUBROUTINE } Uleb128put(ctxt, s.Info, int64(abbrev)) if logDwarf { ctxt.Logf("putInlinedFunc(callee=%v,abbrev=%d)\n", callee, abbrev) } // Abstract origin. putattr(ctxt, s.Info, abbrev, DW_FORM_ref_addr, DW_CLS_REFERENCE, 0, callee) if abbrev == DW_ABRV_INLINED_SUBROUTINE_RANGES { putattr(ctxt, s.Info, abbrev, DW_FORM_sec_offset, DW_CLS_PTR, s.Ranges.Length(ctxt), s.Ranges) s.PutRanges(ctxt, ic.Ranges) } else { st := ic.Ranges[0].Start en := ic.Ranges[0].End putattr(ctxt, s.Info, abbrev, DW_FORM_addr, DW_CLS_ADDRESS, st, s.StartPC) putattr(ctxt, s.Info, abbrev, DW_FORM_addr, DW_CLS_ADDRESS, en, s.StartPC) } // Emit call file, line attrs. ctxt.AddFileRef(s.Info, ic.CallFile) form := int(expandPseudoForm(DW_FORM_udata_pseudo)) putattr(ctxt, s.Info, abbrev, form, DW_CLS_CONSTANT, int64(ic.CallLine), nil) // Variables associated with this inlined routine instance. vars := ic.InlVars sort.Sort(byChildIndex(vars)) inlIndex := ic.InlIndex var encbuf [20]byte for _, v := range vars { if !v.IsInAbstract { continue } putvar(ctxt, s, v, callee, abbrev, inlIndex, encbuf[:0]) } // Children of this inline. for _, sib := range inlChildren(callIdx, &s.InlCalls) { err := putInlinedFunc(ctxt, s, sib) if err != nil { return err } } Uleb128put(ctxt, s.Info, 0) return nil } // Emit DWARF attributes and child DIEs for a 'concrete' subprogram, // meaning the out-of-line copy of a function that was inlined at some // point during the compilation of its containing package. The first // attribute for a concrete DIE is a reference to the 'abstract' DIE // for the function (which holds location-independent attributes such // as name, type), then the remainder of the attributes are specific // to this instance (location, frame base, etc). func PutConcreteFunc(ctxt Context, s *FnState, isWrapper bool) error { if logDwarf { ctxt.Logf("PutConcreteFunc(%v)\n", s.Info) } abbrev := DW_ABRV_FUNCTION_CONCRETE if isWrapper { abbrev = DW_ABRV_WRAPPER_CONCRETE } Uleb128put(ctxt, s.Info, int64(abbrev)) // Abstract origin. putattr(ctxt, s.Info, abbrev, DW_FORM_ref_addr, DW_CLS_REFERENCE, 0, s.Absfn) // Start/end PC. putattr(ctxt, s.Info, abbrev, DW_FORM_addr, DW_CLS_ADDRESS, 0, s.StartPC) putattr(ctxt, s.Info, abbrev, DW_FORM_addr, DW_CLS_ADDRESS, s.Size, s.StartPC) // cfa / frame base putattr(ctxt, s.Info, abbrev, DW_FORM_block1, DW_CLS_BLOCK, 1, []byte{DW_OP_call_frame_cfa}) if isWrapper { putattr(ctxt, s.Info, abbrev, DW_FORM_flag, DW_CLS_FLAG, int64(1), 0) } // Scopes if err := putPrunedScopes(ctxt, s, abbrev); err != nil { return err } // Inlined subroutines. for _, sib := range inlChildren(-1, &s.InlCalls) { err := putInlinedFunc(ctxt, s, sib) if err != nil { return err } } Uleb128put(ctxt, s.Info, 0) return nil } // Emit DWARF attributes and child DIEs for a subprogram. Here // 'default' implies that the function in question was not inlined // when its containing package was compiled (hence there is no need to // emit an abstract version for it to use as a base for inlined // routine records). func PutDefaultFunc(ctxt Context, s *FnState, isWrapper bool) error { if logDwarf { ctxt.Logf("PutDefaultFunc(%v)\n", s.Info) } abbrev := DW_ABRV_FUNCTION if isWrapper { abbrev = DW_ABRV_WRAPPER } Uleb128put(ctxt, s.Info, int64(abbrev)) // Expand '"".' to import path. name := s.Name if s.Importpath != "" { name = strings.Replace(name, "\"\".", objabi.PathToPrefix(s.Importpath)+".", -1) } putattr(ctxt, s.Info, DW_ABRV_FUNCTION, DW_FORM_string, DW_CLS_STRING, int64(len(name)), name) putattr(ctxt, s.Info, abbrev, DW_FORM_addr, DW_CLS_ADDRESS, 0, s.StartPC) putattr(ctxt, s.Info, abbrev, DW_FORM_addr, DW_CLS_ADDRESS, s.Size, s.StartPC) putattr(ctxt, s.Info, abbrev, DW_FORM_block1, DW_CLS_BLOCK, 1, []byte{DW_OP_call_frame_cfa}) if isWrapper { putattr(ctxt, s.Info, abbrev, DW_FORM_flag, DW_CLS_FLAG, int64(1), 0) } else { ctxt.AddFileRef(s.Info, s.Filesym) var ev int64 if s.External { ev = 1 } putattr(ctxt, s.Info, abbrev, DW_FORM_flag, DW_CLS_FLAG, ev, 0) } // Scopes if err := putPrunedScopes(ctxt, s, abbrev); err != nil { return err } // Inlined subroutines. for _, sib := range inlChildren(-1, &s.InlCalls) { err := putInlinedFunc(ctxt, s, sib) if err != nil { return err } } Uleb128put(ctxt, s.Info, 0) return nil } // putparamtypes writes typedef DIEs for any parametric types that are used by this function. func putparamtypes(ctxt Context, s *FnState, scopes []Scope, fnabbrev int) []int64 { if fnabbrev == DW_ABRV_FUNCTION_CONCRETE { return nil } maxDictIndex := uint16(0) for i := range scopes { for _, v := range scopes[i].Vars { if v.DictIndex > maxDictIndex { maxDictIndex = v.DictIndex } } } if maxDictIndex == 0 { return nil } dictIndexToOffset := make([]int64, maxDictIndex) for i := range scopes { for _, v := range scopes[i].Vars { if v.DictIndex == 0 || dictIndexToOffset[v.DictIndex-1] != 0 { continue } dictIndexToOffset[v.DictIndex-1] = ctxt.CurrentOffset(s.Info) Uleb128put(ctxt, s.Info, int64(DW_ABRV_DICT_INDEX)) n := fmt.Sprintf(".param%d", v.DictIndex-1) putattr(ctxt, s.Info, DW_ABRV_DICT_INDEX, DW_FORM_string, DW_CLS_STRING, int64(len(n)), n) putattr(ctxt, s.Info, DW_ABRV_DICT_INDEX, DW_FORM_ref_addr, DW_CLS_REFERENCE, 0, v.Type) putattr(ctxt, s.Info, DW_ABRV_DICT_INDEX, DW_FORM_udata, DW_CLS_CONSTANT, int64(v.DictIndex-1), nil) } } return dictIndexToOffset } func putscope(ctxt Context, s *FnState, scopes []Scope, curscope int32, fnabbrev int, encbuf []byte) int32 { if logDwarf { ctxt.Logf("putscope(%v,%d): vars:", s.Info, curscope) for i, v := range scopes[curscope].Vars { ctxt.Logf(" %d:%d:%s", i, v.ChildIndex, v.Name) } ctxt.Logf("\n") } for _, v := range scopes[curscope].Vars { putvar(ctxt, s, v, s.Absfn, fnabbrev, -1, encbuf) } this := curscope curscope++ for curscope < int32(len(scopes)) { scope := scopes[curscope] if scope.Parent != this { return curscope } if len(scopes[curscope].Vars) == 0 { curscope = putscope(ctxt, s, scopes, curscope, fnabbrev, encbuf) continue } if len(scope.Ranges) == 1 { Uleb128put(ctxt, s.Info, DW_ABRV_LEXICAL_BLOCK_SIMPLE) putattr(ctxt, s.Info, DW_ABRV_LEXICAL_BLOCK_SIMPLE, DW_FORM_addr, DW_CLS_ADDRESS, scope.Ranges[0].Start, s.StartPC) putattr(ctxt, s.Info, DW_ABRV_LEXICAL_BLOCK_SIMPLE, DW_FORM_addr, DW_CLS_ADDRESS, scope.Ranges[0].End, s.StartPC) } else { Uleb128put(ctxt, s.Info, DW_ABRV_LEXICAL_BLOCK_RANGES) putattr(ctxt, s.Info, DW_ABRV_LEXICAL_BLOCK_RANGES, DW_FORM_sec_offset, DW_CLS_PTR, s.Ranges.Length(ctxt), s.Ranges) s.PutRanges(ctxt, scope.Ranges) } curscope = putscope(ctxt, s, scopes, curscope, fnabbrev, encbuf) Uleb128put(ctxt, s.Info, 0) } return curscope } // Given a default var abbrev code, select corresponding concrete code. func concreteVarAbbrev(varAbbrev int) int { switch varAbbrev { case DW_ABRV_AUTO: return DW_ABRV_AUTO_CONCRETE case DW_ABRV_PARAM: return DW_ABRV_PARAM_CONCRETE case DW_ABRV_AUTO_LOCLIST: return DW_ABRV_AUTO_CONCRETE_LOCLIST case DW_ABRV_PARAM_LOCLIST: return DW_ABRV_PARAM_CONCRETE_LOCLIST default: panic("should never happen") } } // Pick the correct abbrev code for variable or parameter DIE. func determineVarAbbrev(v *Var, fnabbrev int) (int, bool, bool) { abbrev := v.Abbrev // If the variable was entirely optimized out, don't emit a location list; // convert to an inline abbreviation and emit an empty location. missing := false switch { case abbrev == DW_ABRV_AUTO_LOCLIST && v.PutLocationList == nil: missing = true abbrev = DW_ABRV_AUTO case abbrev == DW_ABRV_PARAM_LOCLIST && v.PutLocationList == nil: missing = true abbrev = DW_ABRV_PARAM } // Determine whether to use a concrete variable or regular variable DIE. concrete := true switch fnabbrev { case DW_ABRV_FUNCTION, DW_ABRV_WRAPPER: concrete = false case DW_ABRV_FUNCTION_CONCRETE, DW_ABRV_WRAPPER_CONCRETE: // If we're emitting a concrete subprogram DIE and the variable // in question is not part of the corresponding abstract function DIE, // then use the default (non-concrete) abbrev for this param. if !v.IsInAbstract { concrete = false } case DW_ABRV_INLINED_SUBROUTINE, DW_ABRV_INLINED_SUBROUTINE_RANGES: default: panic("should never happen") } // Select proper abbrev based on concrete/non-concrete if concrete { abbrev = concreteVarAbbrev(abbrev) } return abbrev, missing, concrete } func abbrevUsesLoclist(abbrev int) bool { switch abbrev { case DW_ABRV_AUTO_LOCLIST, DW_ABRV_AUTO_CONCRETE_LOCLIST, DW_ABRV_PARAM_LOCLIST, DW_ABRV_PARAM_CONCRETE_LOCLIST: return true default: return false } } // Emit DWARF attributes for a variable belonging to an 'abstract' subprogram. func putAbstractVar(ctxt Context, info Sym, v *Var) { // Remap abbrev abbrev := v.Abbrev switch abbrev { case DW_ABRV_AUTO, DW_ABRV_AUTO_LOCLIST: abbrev = DW_ABRV_AUTO_ABSTRACT case DW_ABRV_PARAM, DW_ABRV_PARAM_LOCLIST: abbrev = DW_ABRV_PARAM_ABSTRACT } Uleb128put(ctxt, info, int64(abbrev)) putattr(ctxt, info, abbrev, DW_FORM_string, DW_CLS_STRING, int64(len(v.Name)), v.Name) // Isreturn attribute if this is a param if abbrev == DW_ABRV_PARAM_ABSTRACT { var isReturn int64 if v.IsReturnValue { isReturn = 1 } putattr(ctxt, info, abbrev, DW_FORM_flag, DW_CLS_FLAG, isReturn, nil) } // Line if abbrev != DW_ABRV_PARAM_ABSTRACT { // See issue 23374 for more on why decl line is skipped for abs params. putattr(ctxt, info, abbrev, DW_FORM_udata, DW_CLS_CONSTANT, int64(v.DeclLine), nil) } // Type putattr(ctxt, info, abbrev, DW_FORM_ref_addr, DW_CLS_REFERENCE, 0, v.Type) // Var has no children => no terminator } func putvar(ctxt Context, s *FnState, v *Var, absfn Sym, fnabbrev, inlIndex int, encbuf []byte) { // Remap abbrev according to parent DIE abbrev abbrev, missing, concrete := determineVarAbbrev(v, fnabbrev) Uleb128put(ctxt, s.Info, int64(abbrev)) // Abstract origin for concrete / inlined case if concrete { // Here we are making a reference to a child DIE of an abstract // function subprogram DIE. The child DIE has no LSym, so instead // after the call to 'putattr' below we make a call to register // the child DIE reference. putattr(ctxt, s.Info, abbrev, DW_FORM_ref_addr, DW_CLS_REFERENCE, 0, absfn) ctxt.RecordDclReference(s.Info, absfn, int(v.ChildIndex), inlIndex) } else { // Var name, line for abstract and default cases n := v.Name putattr(ctxt, s.Info, abbrev, DW_FORM_string, DW_CLS_STRING, int64(len(n)), n) if abbrev == DW_ABRV_PARAM || abbrev == DW_ABRV_PARAM_LOCLIST || abbrev == DW_ABRV_PARAM_ABSTRACT { var isReturn int64 if v.IsReturnValue { isReturn = 1 } putattr(ctxt, s.Info, abbrev, DW_FORM_flag, DW_CLS_FLAG, isReturn, nil) } putattr(ctxt, s.Info, abbrev, DW_FORM_udata, DW_CLS_CONSTANT, int64(v.DeclLine), nil) if v.DictIndex > 0 && s.dictIndexToOffset != nil && s.dictIndexToOffset[v.DictIndex-1] != 0 { // If the type of this variable is parametric use the entry emitted by putparamtypes putattr(ctxt, s.Info, abbrev, DW_FORM_ref_addr, DW_CLS_REFERENCE, s.dictIndexToOffset[v.DictIndex-1], s.Info) } else { putattr(ctxt, s.Info, abbrev, DW_FORM_ref_addr, DW_CLS_REFERENCE, 0, v.Type) } } if abbrevUsesLoclist(abbrev) { putattr(ctxt, s.Info, abbrev, DW_FORM_sec_offset, DW_CLS_PTR, s.Loc.Length(ctxt), s.Loc) v.PutLocationList(s.Loc, s.StartPC) } else { loc := encbuf[:0] switch { case missing: break // no location case v.StackOffset == 0: loc = append(loc, DW_OP_call_frame_cfa) default: loc = append(loc, DW_OP_fbreg) loc = AppendSleb128(loc, int64(v.StackOffset)) } putattr(ctxt, s.Info, abbrev, DW_FORM_block1, DW_CLS_BLOCK, int64(len(loc)), loc) } // Var has no children => no terminator } // byChildIndex implements sort.Interface for []*dwarf.Var by child index. type byChildIndex []*Var func (s byChildIndex) Len() int { return len(s) } func (s byChildIndex) Less(i, j int) bool { return s[i].ChildIndex < s[j].ChildIndex } func (s byChildIndex) Swap(i, j int) { s[i], s[j] = s[j], s[i] } // IsDWARFEnabledOnAIXLd returns true if DWARF is possible on the // current extld. // AIX ld doesn't support DWARF with -bnoobjreorder with version // prior to 7.2.2. func IsDWARFEnabledOnAIXLd(extld []string) (bool, error) { name, args := extld[0], extld[1:] args = append(args, "-Wl,-V") out, err := exec.Command(name, args...).CombinedOutput() if err != nil { // The normal output should display ld version and // then fails because ".main" is not defined: // ld: 0711-317 ERROR: Undefined symbol: .main if !bytes.Contains(out, []byte("0711-317")) { return false, fmt.Errorf("%s -Wl,-V failed: %v\n%s", extld, err, out) } } // gcc -Wl,-V output should be: // /usr/bin/ld: LD X.X.X(date) // ... out = bytes.TrimPrefix(out, []byte("/usr/bin/ld: LD ")) vers := string(bytes.Split(out, []byte("("))[0]) subvers := strings.Split(vers, ".") if len(subvers) != 3 { return false, fmt.Errorf("cannot parse %s -Wl,-V (%s): %v\n", extld, out, err) } if v, err := strconv.Atoi(subvers[0]); err != nil || v < 7 { return false, nil } else if v > 7 { return true, nil } if v, err := strconv.Atoi(subvers[1]); err != nil || v < 2 { return false, nil } else if v > 2 { return true, nil } if v, err := strconv.Atoi(subvers[2]); err != nil || v < 2 { return false, nil } return true, nil }