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Diffstat (limited to 'vendor/github.com/google/gops/internal/dwarf/dwarf.go')
-rw-r--r--vendor/github.com/google/gops/internal/dwarf/dwarf.go600
1 files changed, 600 insertions, 0 deletions
diff --git a/vendor/github.com/google/gops/internal/dwarf/dwarf.go b/vendor/github.com/google/gops/internal/dwarf/dwarf.go
new file mode 100644
index 00000000..c72ef5b0
--- /dev/null
+++ b/vendor/github.com/google/gops/internal/dwarf/dwarf.go
@@ -0,0 +1,600 @@
+// 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 (
+ "fmt"
+)
+
+// InfoPrefix is the prefix for all the symbols containing DWARF info entries.
+const InfoPrefix = "go.info."
+
+// Sym represents a symbol.
+type Sym interface {
+}
+
+// A Var represents a local variable or a function parameter.
+type Var struct {
+ Name string
+ Abbrev int // Either DW_ABRV_AUTO or DW_ABRV_PARAM
+ Offset int32
+ Type Sym
+ Link *Var
+}
+
+// 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)
+ AddSectionOffset(s Sym, size int, t interface{}, ofs int64)
+ AddString(s Sym, v string)
+ SymValue(s Sym) int64
+}
+
+// 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
+}
+
+var encbuf [20]byte
+
+// AppendUleb128 appends v to s using DWARF's unsigned LEB128 encoding.
+func Uleb128put(ctxt Context, s Sym, v int64) {
+ b := AppendUleb128(encbuf[:0], uint64(v))
+ ctxt.AddBytes(s, b)
+}
+
+// AppendUleb128 appends v to s using DWARF's signed LEB128 encoding.
+func Sleb128put(ctxt Context, s Sym, v int64) {
+ b := AppendSleb128(encbuf[:0], v)
+ ctxt.AddBytes(s, b)
+}
+
+/*
+ * Defining Abbrevs. This is hardcoded, and there will be
+ * only a handful of them. 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
+
+ DW_AT_internal_location = 253 // params and locals; not emitted
+)
+
+// Index into the abbrevs table below.
+// Keep in sync with ispubname() and ispubtype() below.
+// ispubtype considers >= NULLTYPE public
+const (
+ DW_ABRV_NULL = iota
+ DW_ABRV_COMPUNIT
+ DW_ABRV_FUNCTION
+ DW_ABRV_VARIABLE
+ DW_ABRV_AUTO
+ DW_ABRV_PARAM
+ 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 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_low_pc, DW_FORM_addr},
+ {DW_AT_high_pc, DW_FORM_addr},
+ {DW_AT_stmt_list, DW_FORM_data4},
+ {DW_AT_comp_dir, 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_external, DW_FORM_flag},
+ },
+ },
+
+ /* 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},
+ },
+ },
+
+ /* AUTO */
+ {
+ 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},
+ },
+ },
+
+ /* PARAM */
+ {
+ DW_TAG_formal_parameter,
+ DW_CHILDREN_no,
+ []dwAttrForm{
+ {DW_AT_name, DW_FORM_string},
+ {DW_AT_location, DW_FORM_block1},
+ {DW_AT_type, DW_FORM_ref_addr},
+ },
+ },
+
+ /* STRUCTFIELD */
+ {
+ DW_TAG_member,
+ DW_CHILDREN_no,
+ []dwAttrForm{
+ {DW_AT_name, DW_FORM_string},
+ {DW_AT_data_member_location, DW_FORM_block1},
+ {DW_AT_type, DW_FORM_ref_addr},
+ },
+ },
+
+ /* 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},
+ },
+ },
+
+ /* 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},
+ },
+ },
+
+ /* 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_elem, DW_FORM_ref_addr},
+ },
+ },
+
+ /* FUNCTYPE */
+ {
+ DW_TAG_subroutine_type,
+ DW_CHILDREN_yes,
+ []dwAttrForm{
+ {DW_AT_name, DW_FORM_string},
+ // {DW_AT_type, DW_FORM_ref_addr},
+ {DW_AT_go_kind, DW_FORM_data1},
+ },
+ },
+
+ /* 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},
+ },
+ },
+
+ /* 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_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},
+ },
+ },
+
+ /* 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_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},
+ },
+ },
+
+ /* 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},
+ },
+ },
+
+ /* 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 {
+ 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, byte(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
+ 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
+ ctxt.AddSectionOffset(s, 4, data, 0)
+ 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)
+ }
+
+ // In DWARF 2 (which is what we claim to generate),
+ // the ref_addr is the same size as a normal address.
+ // In DWARF 3 it 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
+ if data == nil {
+ return fmt.Errorf("dwarf: null reference in %d", abbrev)
+ } else {
+ ctxt.AddSectionOffset(s, ctxt.PtrSize(), data, 0)
+ }
+
+ 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) {
+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 returns true if 'die' uses an abbrev that supports children.
+func HasChildren(die *DWDie) bool {
+ return abbrevs[die.Abbrev].children != 0
+}
+
+// PutFunc writes a DIE for a function to s.
+// It also writes child DIEs for each variable in vars.
+func PutFunc(ctxt Context, s Sym, name string, external bool, startPC Sym, size int64, vars *Var) {
+ Uleb128put(ctxt, s, DW_ABRV_FUNCTION)
+ putattr(ctxt, s, DW_ABRV_FUNCTION, DW_FORM_string, DW_CLS_STRING, int64(len(name)), name)
+ putattr(ctxt, s, DW_ABRV_FUNCTION, DW_FORM_addr, DW_CLS_ADDRESS, 0, startPC)
+ putattr(ctxt, s, DW_ABRV_FUNCTION, DW_FORM_addr, DW_CLS_ADDRESS, size+ctxt.SymValue(startPC), startPC)
+ var ev int64
+ if external {
+ ev = 1
+ }
+ putattr(ctxt, s, DW_ABRV_FUNCTION, DW_FORM_flag, DW_CLS_FLAG, ev, 0)
+ names := make(map[string]bool)
+ for v := vars; v != nil; v = v.Link {
+ var n string
+ if names[v.Name] {
+ n = fmt.Sprintf("%s#%d", v.Name, len(names))
+ } else {
+ n = v.Name
+ }
+ names[n] = true
+
+ Uleb128put(ctxt, s, int64(v.Abbrev))
+ putattr(ctxt, s, v.Abbrev, DW_FORM_string, DW_CLS_STRING, int64(len(n)), n)
+ loc := append(encbuf[:0], DW_OP_call_frame_cfa)
+ if v.Offset != 0 {
+ loc = append(loc, DW_OP_consts)
+ loc = AppendSleb128(loc, int64(v.Offset))
+ loc = append(loc, DW_OP_plus)
+ }
+ putattr(ctxt, s, v.Abbrev, DW_FORM_block1, DW_CLS_BLOCK, int64(len(loc)), loc)
+ putattr(ctxt, s, v.Abbrev, DW_FORM_ref_addr, DW_CLS_REFERENCE, 0, v.Type)
+
+ }
+ Uleb128put(ctxt, s, 0)
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-01 16:27:34 +0000