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Diffstat (limited to '')
-rw-r--r-- | src/cmd/internal/dwarf/dwarf.go | 1655 |
1 files changed, 1655 insertions, 0 deletions
diff --git a/src/cmd/internal/dwarf/dwarf.go b/src/cmd/internal/dwarf/dwarf.go new file mode 100644 index 0000000..8de4096 --- /dev/null +++ b/src/cmd/internal/dwarf/dwarf.go @@ -0,0 +1,1655 @@ +// 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" + "cmd/internal/objabi" + "errors" + "fmt" + exec "internal/execabs" + "sort" + "strconv" + "strings" +) + +// 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 + 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 +} + +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_internal_location = 253 // params and locals; not emitted +) + +// Index into the abbrevs table below. +// Keep in sync with ispubname() and ispubtype() in ld/dwarf.go. +// ispubtype considers >= NULLTYPE public +const ( + DW_ABRV_NULL = iota + DW_ABRV_COMPUNIT + DW_ABRV_COMPUNIT_TEXTLESS + DW_ABRV_FUNCTION + DW_ABRV_FUNCTION_ABSTRACT + DW_ABRV_FUNCTION_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_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 objabi.GOOS == "darwin" || objabi.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}, + }, + }, + + /* 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}, + }, + }, + + /* 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}, + }, + }, +} + +// 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) +} + +// 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 + } + 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, callersym Sym, 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(caller=%v,callee=%v,abbrev=%d)\n", callersym, 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) { + absfn := s.InlCalls.Calls[sib].AbsFunSym + err := PutInlinedFunc(ctxt, s, absfn, 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) error { + if logDwarf { + ctxt.Logf("PutConcreteFunc(%v)\n", s.Info) + } + abbrev := DW_ABRV_FUNCTION_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}) + + // Scopes + if err := putPrunedScopes(ctxt, s, abbrev); err != nil { + return err + } + + // Inlined subroutines. + for _, sib := range inlChildren(-1, &s.InlCalls) { + absfn := s.InlCalls.Calls[sib].AbsFunSym + err := PutInlinedFunc(ctxt, s, absfn, 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) error { + if logDwarf { + ctxt.Logf("PutDefaultFunc(%v)\n", s.Info) + } + abbrev := DW_ABRV_FUNCTION + 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}) + 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) { + absfn := s.InlCalls.Calls[sib].AbsFunSym + err := PutInlinedFunc(ctxt, s, absfn, sib) + if err != nil { + return err + } + } + + Uleb128put(ctxt, s.Info, 0) + return nil +} + +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: + concrete = false + break + case DW_ABRV_FUNCTION_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) + 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 +} + +// VarsByOffset attaches the methods of sort.Interface to []*Var, +// sorting in increasing StackOffset. +type VarsByOffset []*Var + +func (s VarsByOffset) Len() int { return len(s) } +func (s VarsByOffset) Less(i, j int) bool { return s[i].StackOffset < s[j].StackOffset } +func (s VarsByOffset) Swap(i, j int) { s[i], s[j] = s[j], s[i] } + +// 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] } + +// IsDWARFEnabledOnAIX 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) { + out, err := exec.Command(extld, "-Wl,-V").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 +} |