proc/tests: testing apparatus for complex location expressions

pkg/dwarf/dwarfbuilder/builder.go

@@ -0,0 +1,50 @@
+// Package dwarfbuilder provides a way to build DWARF sections with
+// arbitrary contents.
+package dwarfbuilder
+
+import (
+	"bytes"
+	"debug/dwarf"
+	"encoding/binary"
+	"fmt"
+)
+
+type Builder struct {
+	info     bytes.Buffer
+	loc      bytes.Buffer
+	abbrevs  []tagDescr
+	tagStack []*tagState
+}
+
+// New creates a new DWARF builder.
+func New() *Builder {
+	b := &Builder{}
+
+	b.info.Write([]byte{
+		0x0, 0x0, 0x0, 0x0, // length
+		0x4, 0x0, // version
+		0x0, 0x0, 0x0, 0x0, // debug_abbrev_offset
+		0x8, // address_size
+	})
+
+	b.TagOpen(dwarf.TagCompileUnit, "go")
+	b.Attr(dwarf.AttrLanguage, uint8(22))
+
+	return b
+}
+
+// Build closes b and returns all the dwarf sections.
+func (b *Builder) Build() (abbrev, aranges, frame, info, line, pubnames, ranges, str []byte, err error) {
+	b.TagClose()
+
+	if len(b.tagStack) > 0 {
+		err = fmt.Errorf("unbalanced TagOpen/TagClose %d", len(b.tagStack))
+		return
+	}
+
+	abbrev = b.makeAbbrevTable()
+	info = b.info.Bytes()
+	binary.LittleEndian.PutUint32(info, uint32(len(info)-4))
+
+	return
+}