llvm-project/llgo/debug/debug.go

433 lines
13 KiB
Go

//===- debug.go - debug info builder --------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This package builds LLVM debug info from go/* data structures.
//
//===----------------------------------------------------------------------===//
package debug
import (
"debug/dwarf"
"fmt"
"go/token"
"os"
"strings"
"llvm.org/llgo/third_party/gotools/go/ssa"
"llvm.org/llgo/third_party/gotools/go/types"
"llvm.org/llgo/third_party/gotools/go/types/typeutil"
"llvm.org/llvm/bindings/go/llvm"
)
const (
// non-standard debug metadata tags
tagAutoVariable dwarf.Tag = 0x100
tagArgVariable dwarf.Tag = 0x101
)
type PrefixMap struct {
Source, Replacement string
}
// DIBuilder builds debug metadata for Go programs.
type DIBuilder struct {
// builder is the current builder; there is one per CU.
builder *llvm.DIBuilder
module llvm.Module
files map[*token.File]llvm.Metadata
cu, fn, lb llvm.Metadata
fnFile string
sizes types.Sizes
fset *token.FileSet
prefixMaps []PrefixMap
types typeutil.Map
voidType llvm.Metadata
}
// NewDIBuilder creates a new debug information builder.
func NewDIBuilder(sizes types.Sizes, module llvm.Module, fset *token.FileSet, prefixMaps []PrefixMap) *DIBuilder {
var d DIBuilder
d.module = module
d.files = make(map[*token.File]llvm.Metadata)
d.sizes = sizes
d.fset = fset
d.prefixMaps = prefixMaps
d.builder = llvm.NewDIBuilder(d.module)
d.cu = d.createCompileUnit()
return &d
}
// Destroy destroys the DIBuilder.
func (d *DIBuilder) Destroy() {
d.builder.Destroy()
}
func (d *DIBuilder) scope() llvm.Metadata {
if d.lb.C != nil {
return d.lb
}
if d.fn.C != nil {
return d.fn
}
return d.cu
}
func (d *DIBuilder) remapFilePath(path string) string {
for _, pm := range d.prefixMaps {
if strings.HasPrefix(path, pm.Source) {
return pm.Replacement + path[len(pm.Source):]
}
}
return path
}
func (d *DIBuilder) getFile(file *token.File) llvm.Metadata {
if diFile := d.files[file]; diFile.C != nil {
return diFile
}
diFile := d.builder.CreateFile(d.remapFilePath(file.Name()), "")
d.files[file] = diFile
return diFile
}
// createCompileUnit creates and returns debug metadata for the compile
// unit as a whole, using the first file in the file set as a representative
// (the choice of file is arbitrary).
func (d *DIBuilder) createCompileUnit() llvm.Metadata {
var file *token.File
d.fset.Iterate(func(f *token.File) bool {
file = f
return false
})
dir, err := os.Getwd()
if err != nil {
panic("could not get current directory: " + err.Error())
}
return d.builder.CreateCompileUnit(llvm.DICompileUnit{
Language: llvm.DW_LANG_Go,
File: d.remapFilePath(file.Name()),
Dir: dir,
Producer: "llgo",
})
}
// PushFunction creates debug metadata for the specified function,
// and pushes it onto the scope stack.
func (d *DIBuilder) PushFunction(fnptr llvm.Value, sig *types.Signature, pos token.Pos) {
var diFile llvm.Metadata
var line int
if file := d.fset.File(pos); file != nil {
d.fnFile = file.Name()
diFile = d.getFile(file)
line = file.Line(pos)
}
d.fn = d.builder.CreateFunction(d.scope(), llvm.DIFunction{
Name: fnptr.Name(), // TODO(axw) unmangled name?
LinkageName: fnptr.Name(),
File: diFile,
Line: line,
Type: d.DIType(sig),
IsDefinition: true,
})
fnptr.SetSubprogram(d.fn)
}
// PopFunction pops the previously pushed function off the scope stack.
func (d *DIBuilder) PopFunction() {
d.lb = llvm.Metadata{}
d.fn = llvm.Metadata{}
d.fnFile = ""
}
// Value creates an llvm.dbg.value call for the specified register value.
func (d *DIBuilder) Value(b llvm.Builder, v ssa.Value, llv llvm.Value, paramIndex int) {
// TODO(axw)
}
// SetLocation sets the current debug location.
func (d *DIBuilder) SetLocation(b llvm.Builder, pos token.Pos) {
position := d.fset.Position(pos)
d.lb = llvm.Metadata{}
if position.Filename != d.fnFile && position.Filename != "" {
// This can happen rarely, e.g. in init functions.
diFile := d.builder.CreateFile(d.remapFilePath(position.Filename), "")
d.lb = d.builder.CreateLexicalBlockFile(d.scope(), diFile, 0)
}
b.SetCurrentDebugLocation(uint(position.Line), uint(position.Column), d.scope(), llvm.Metadata{})
}
// Finalize must be called after all compilation units are translated,
// generating the final debug metadata for the module.
func (d *DIBuilder) Finalize() {
d.module.AddNamedMetadataOperand(
"llvm.module.flags",
llvm.GlobalContext().MDNode([]llvm.Metadata{
llvm.ConstInt(llvm.Int32Type(), 2, false).ConstantAsMetadata(), // Warn on mismatch
llvm.GlobalContext().MDString("Dwarf Version"),
llvm.ConstInt(llvm.Int32Type(), 4, false).ConstantAsMetadata(),
}),
)
d.module.AddNamedMetadataOperand(
"llvm.module.flags",
llvm.GlobalContext().MDNode([]llvm.Metadata{
llvm.ConstInt(llvm.Int32Type(), 1, false).ConstantAsMetadata(), // Error on mismatch
llvm.GlobalContext().MDString("Debug Info Version"),
llvm.ConstInt(llvm.Int32Type(), 3, false).ConstantAsMetadata(),
}),
)
d.builder.Finalize()
}
// DIType maps a Go type to DIType debug metadata value.
func (d *DIBuilder) DIType(t types.Type) llvm.Metadata {
return d.typeDebugDescriptor(t, types.TypeString(nil, t))
}
func (d *DIBuilder) typeDebugDescriptor(t types.Type, name string) llvm.Metadata {
// Signature needs to be handled specially, to preprocess
// methods, moving the receiver to the parameter list.
if t, ok := t.(*types.Signature); ok {
return d.descriptorSignature(t, name)
}
if t == nil {
if d.voidType.C == nil {
d.voidType = d.builder.CreateBasicType(llvm.DIBasicType{Name: "void"})
}
return d.voidType
}
if dt, ok := d.types.At(t).(llvm.Metadata); ok {
return dt
}
dt := d.descriptor(t, name)
d.types.Set(t, dt)
return dt
}
func (d *DIBuilder) descriptor(t types.Type, name string) llvm.Metadata {
switch t := t.(type) {
case *types.Basic:
return d.descriptorBasic(t, name)
case *types.Pointer:
return d.descriptorPointer(t)
case *types.Struct:
return d.descriptorStruct(t, name)
case *types.Named:
return d.descriptorNamed(t)
case *types.Array:
return d.descriptorArray(t, name)
case *types.Slice:
return d.descriptorSlice(t, name)
case *types.Map:
return d.descriptorMap(t, name)
case *types.Chan:
return d.descriptorChan(t, name)
case *types.Interface:
return d.descriptorInterface(t, name)
default:
panic(fmt.Sprintf("unhandled type: %T", t))
}
}
func (d *DIBuilder) descriptorBasic(t *types.Basic, name string) llvm.Metadata {
switch t.Kind() {
case types.String:
return d.typeDebugDescriptor(types.NewStruct([]*types.Var{
types.NewVar(0, nil, "ptr", types.NewPointer(types.Typ[types.Uint8])),
types.NewVar(0, nil, "len", types.Typ[types.Int]),
}, nil), name)
case types.UnsafePointer:
return d.builder.CreateBasicType(llvm.DIBasicType{
Name: name,
SizeInBits: uint64(d.sizes.Sizeof(t) * 8),
Encoding: llvm.DW_ATE_unsigned,
})
default:
bt := llvm.DIBasicType{
Name: t.String(),
SizeInBits: uint64(d.sizes.Sizeof(t) * 8),
}
switch bi := t.Info(); {
case bi&types.IsBoolean != 0:
bt.Encoding = llvm.DW_ATE_boolean
case bi&types.IsUnsigned != 0:
bt.Encoding = llvm.DW_ATE_unsigned
case bi&types.IsInteger != 0:
bt.Encoding = llvm.DW_ATE_signed
case bi&types.IsFloat != 0:
bt.Encoding = llvm.DW_ATE_float
case bi&types.IsComplex != 0:
bt.Encoding = llvm.DW_ATE_imaginary_float
case bi&types.IsUnsigned != 0:
bt.Encoding = llvm.DW_ATE_unsigned
default:
panic(fmt.Sprintf("unhandled: %#v", t))
}
return d.builder.CreateBasicType(bt)
}
}
func (d *DIBuilder) descriptorPointer(t *types.Pointer) llvm.Metadata {
return d.builder.CreatePointerType(llvm.DIPointerType{
Pointee: d.DIType(t.Elem()),
SizeInBits: uint64(d.sizes.Sizeof(t) * 8),
AlignInBits: uint32(d.sizes.Alignof(t) * 8),
})
}
func (d *DIBuilder) descriptorStruct(t *types.Struct, name string) llvm.Metadata {
fields := make([]*types.Var, t.NumFields())
for i := range fields {
fields[i] = t.Field(i)
}
offsets := d.sizes.Offsetsof(fields)
members := make([]llvm.Metadata, len(fields))
for i, f := range fields {
// TODO(axw) file/line where member is defined.
t := f.Type()
members[i] = d.builder.CreateMemberType(d.cu, llvm.DIMemberType{
Name: f.Name(),
Type: d.DIType(t),
SizeInBits: uint64(d.sizes.Sizeof(t) * 8),
AlignInBits: uint32(d.sizes.Alignof(t) * 8),
OffsetInBits: uint64(offsets[i] * 8),
})
}
// TODO(axw) file/line where struct is defined.
return d.builder.CreateStructType(d.cu, llvm.DIStructType{
Name: name,
SizeInBits: uint64(d.sizes.Sizeof(t) * 8),
AlignInBits: uint32(d.sizes.Alignof(t) * 8),
Elements: members,
})
}
func (d *DIBuilder) descriptorNamed(t *types.Named) llvm.Metadata {
var diFile llvm.Metadata
var line int
if file := d.fset.File(t.Obj().Pos()); file != nil {
line = file.Line(t.Obj().Pos())
diFile = d.getFile(file)
}
// Create a placeholder for the named type, to terminate cycles.
name := t.Obj().Name()
placeholder := d.builder.CreateReplaceableCompositeType(d.scope(), llvm.DIReplaceableCompositeType{
Tag: dwarf.TagStructType,
Name: name,
File: diFile,
Line: line,
})
d.types.Set(t, placeholder)
typedef := d.builder.CreateTypedef(llvm.DITypedef{
Type: d.DIType(t.Underlying()),
Name: name,
File: diFile,
Line: line,
})
placeholder.ReplaceAllUsesWith(typedef)
return typedef
}
func (d *DIBuilder) descriptorArray(t *types.Array, name string) llvm.Metadata {
return d.builder.CreateArrayType(llvm.DIArrayType{
SizeInBits: uint64(d.sizes.Sizeof(t) * 8),
AlignInBits: uint32(d.sizes.Alignof(t) * 8),
ElementType: d.DIType(t.Elem()),
Subscripts: []llvm.DISubrange{{Count: t.Len()}},
})
}
func (d *DIBuilder) descriptorSlice(t *types.Slice, name string) llvm.Metadata {
sliceStruct := types.NewStruct([]*types.Var{
types.NewVar(0, nil, "ptr", types.NewPointer(t.Elem())),
types.NewVar(0, nil, "len", types.Typ[types.Int]),
types.NewVar(0, nil, "cap", types.Typ[types.Int]),
}, nil)
return d.typeDebugDescriptor(sliceStruct, name)
}
func (d *DIBuilder) descriptorMap(t *types.Map, name string) llvm.Metadata {
// FIXME: This should be DW_TAG_pointer_type to __go_map.
return d.descriptorBasic(types.Typ[types.Uintptr], name)
}
func (d *DIBuilder) descriptorChan(t *types.Chan, name string) llvm.Metadata {
// FIXME: This should be DW_TAG_pointer_type to __go_channel.
return d.descriptorBasic(types.Typ[types.Uintptr], name)
}
func (d *DIBuilder) descriptorInterface(t *types.Interface, name string) llvm.Metadata {
ifaceStruct := types.NewStruct([]*types.Var{
types.NewVar(0, nil, "type", types.NewPointer(types.Typ[types.Uint8])),
types.NewVar(0, nil, "data", types.NewPointer(types.Typ[types.Uint8])),
}, nil)
return d.typeDebugDescriptor(ifaceStruct, name)
}
func (d *DIBuilder) descriptorSignature(t *types.Signature, name string) llvm.Metadata {
// If there's a receiver change the receiver to an
// additional (first) parameter, and take the value of
// the resulting signature instead.
if recv := t.Recv(); recv != nil {
params := t.Params()
paramvars := make([]*types.Var, int(params.Len()+1))
paramvars[0] = recv
for i := 0; i < int(params.Len()); i++ {
paramvars[i+1] = params.At(i)
}
params = types.NewTuple(paramvars...)
t := types.NewSignature(nil, nil, params, t.Results(), t.Variadic())
return d.typeDebugDescriptor(t, name)
}
if dt, ok := d.types.At(t).(llvm.Metadata); ok {
return dt
}
var returnType llvm.Metadata
results := t.Results()
switch n := results.Len(); n {
case 0:
returnType = d.DIType(nil) // void
case 1:
returnType = d.DIType(results.At(0).Type())
default:
fields := make([]*types.Var, results.Len())
for i := range fields {
f := results.At(i)
// Structs may not have multiple fields
// with the same name, excepting "_".
if f.Name() == "" {
f = types.NewVar(f.Pos(), f.Pkg(), "_", f.Type())
}
fields[i] = f
}
returnType = d.typeDebugDescriptor(types.NewStruct(fields, nil), "")
}
var paramTypes []llvm.Metadata
params := t.Params()
if params != nil && params.Len() > 0 {
paramTypes = make([]llvm.Metadata, params.Len()+1)
paramTypes[0] = returnType
for i := range paramTypes[1:] {
paramTypes[i+1] = d.DIType(params.At(i).Type())
}
} else {
paramTypes = []llvm.Metadata{returnType}
}
// TODO(axw) get position of type definition for File field
return d.builder.CreateSubroutineType(llvm.DISubroutineType{
Parameters: paramTypes,
})
}