interp: show backtrace with error

This should make it much easier to figure out why and where an error
happens at package initialization time.
Этот коммит содержится в:
Ayke van Laethem 2020-03-28 20:46:09 +01:00 коммит произвёл Ron Evans
родитель 2501602b4f
коммит cc4a4c755f
6 изменённых файлов: 70 добавлений и 73 удалений

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@ -887,7 +887,8 @@ func (b *builder) createFunctionDefinition() {
if b.fn.Synthetic == "package initializer" {
// Package initializers have no debug info. Create some fake debug
// info to at least have *something*.
b.difunc = b.attachDebugInfoRaw(b.fn, b.fn.LLVMFn, "", "", 0)
filename := b.fn.Package().Pkg.Path() + "/<init>"
b.difunc = b.attachDebugInfoRaw(b.fn, b.fn.LLVMFn, "", filename, 0)
} else if b.fn.Syntax() != nil {
// Create debug info file if needed.
b.difunc = b.attachDebugInfo(b.fn)

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@ -13,55 +13,44 @@ import (
// errUnreachable is returned when an unreachable instruction is executed. This
// error should not be visible outside of the interp package.
var errUnreachable = errors.New("interp: unreachable executed")
// Unsupported is the specific error that is returned when an unsupported
// instruction is hit while trying to interpret all initializers.
type Unsupported struct {
ImportPath string
Inst llvm.Value
Pos token.Position
}
func (e Unsupported) Error() string {
// TODO: how to return the actual instruction string?
// It looks like LLVM provides no function for that...
return scanner.Error{
Pos: e.Pos,
Msg: "interp: unsupported instruction",
}.Error()
}
var errUnreachable = &Error{Err: errors.New("interp: unreachable executed")}
// unsupportedInstructionError returns a new "unsupported instruction" error for
// the given instruction. It includes source location information, when
// available.
func (e *evalPackage) unsupportedInstructionError(inst llvm.Value) *Unsupported {
return &Unsupported{
ImportPath: e.packagePath,
Inst: inst,
Pos: getPosition(inst),
}
func (e *evalPackage) unsupportedInstructionError(inst llvm.Value) *Error {
return e.errorAt(inst, errors.New("interp: unsupported instruction"))
}
// ErrorLine is one line in a traceback. The position may be missing.
type ErrorLine struct {
Pos token.Position
Inst llvm.Value
}
// Error encapsulates compile-time interpretation errors with an associated
// import path. The errors may not have a precise location attached.
type Error struct {
ImportPath string
Errs []scanner.Error
Inst llvm.Value
Pos token.Position
Err error
Traceback []ErrorLine
}
// Error returns the string of the first error in the list of errors.
func (e Error) Error() string {
return e.Errs[0].Error()
func (e *Error) Error() string {
return e.Pos.String() + ": " + e.Err.Error()
}
// errorAt returns an error value for the currently interpreted package at the
// location of the instruction. The location information may not be complete as
// it depends on debug information in the IR.
func (e *evalPackage) errorAt(inst llvm.Value, msg string) Error {
return Error{
func (e *evalPackage) errorAt(inst llvm.Value, err error) *Error {
return &Error{
ImportPath: e.packagePath,
Errs: []scanner.Error{errorAt(inst, msg)},
Pos: getPosition(inst),
Err: err,
}
}

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@ -4,6 +4,7 @@ package interp
// functions.
import (
"errors"
"strings"
"tinygo.org/x/go-llvm"
@ -21,7 +22,7 @@ type frame struct {
// Most of it works at compile time. Some calls get translated into calls to be
// executed at runtime: calls to functions with side effects, external calls,
// and operations on the result of such instructions.
func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (retval Value, outgoing []llvm.Value, err error) {
func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (retval Value, outgoing []llvm.Value, err *Error) {
for inst := bb.FirstInstruction(); !inst.IsNil(); inst = llvm.NextInstruction(inst) {
if fr.Debug {
print(indent)
@ -97,7 +98,7 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
value = operand.Load()
}
if value.Type() != inst.Type() {
return nil, nil, fr.errorAt(inst, "interp: load: type does not match")
return nil, nil, fr.errorAt(inst, errors.New("interp: load: type does not match"))
}
fr.locals[inst] = fr.getValue(value)
case !inst.IsAStoreInst().IsNil():
@ -121,16 +122,16 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
// Not a constant operation.
// This should be detected by the scanner, but isn't at the
// moment.
return nil, nil, fr.errorAt(inst, "todo: non-const gep")
return nil, nil, fr.errorAt(inst, errors.New("todo: non-const gep"))
}
indices[i] = uint32(operand.Value().ZExtValue())
}
result, err := value.GetElementPtr(indices)
if err != nil {
return nil, nil, fr.errorAt(inst, err.Error())
return nil, nil, fr.errorAt(inst, err)
}
if result.Type() != inst.Type() {
return nil, nil, fr.errorAt(inst, "interp: gep: type does not match")
return nil, nil, fr.errorAt(inst, errors.New("interp: gep: type does not match"))
}
fr.locals[inst] = result
@ -185,7 +186,7 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
}
}
// It is not possible in Go to bitcast a map value to a pointer.
return nil, nil, fr.errorAt(inst, "unimplemented: bitcast of map")
return nil, nil, fr.errorAt(inst, errors.New("unimplemented: bitcast of map"))
}
value := fr.getLocal(operand).(*LocalValue)
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateBitCast(value.Value(), inst.Type(), "")}
@ -269,7 +270,7 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
} else {
result, err := result.GetElementPtr([]uint32{0, 0})
if err != nil {
return nil, nil, errorAt(inst, err.Error())
return nil, nil, fr.errorAt(inst, err)
}
fr.locals[resultInst] = result
}
@ -374,30 +375,30 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
// Re-add this GEP, in the hope that it it is then of the correct type...
dstArrayValue, err := dstArray.GetElementPtr([]uint32{0, 0})
if err != nil {
return nil, nil, errorAt(inst, err.Error())
return nil, nil, fr.errorAt(inst, err)
}
dstArray = dstArrayValue.(*LocalValue)
srcArrayValue, err := srcArray.GetElementPtr([]uint32{0, 0})
if err != nil {
return nil, nil, errorAt(inst, err.Error())
return nil, nil, fr.errorAt(inst, err)
}
srcArray = srcArrayValue.(*LocalValue)
}
if fr.Eval.TargetData.TypeAllocSize(dstArray.Type().ElementType()) != elementSize {
return nil, nil, fr.errorAt(inst, "interp: slice dst element size does not match pointer type")
return nil, nil, fr.errorAt(inst, errors.New("interp: slice dst element size does not match pointer type"))
}
if fr.Eval.TargetData.TypeAllocSize(srcArray.Type().ElementType()) != elementSize {
return nil, nil, fr.errorAt(inst, "interp: slice src element size does not match pointer type")
return nil, nil, fr.errorAt(inst, errors.New("interp: slice src element size does not match pointer type"))
}
if dstArray.Type() != srcArray.Type() {
return nil, nil, fr.errorAt(inst, "interp: slice element types don't match")
return nil, nil, fr.errorAt(inst, errors.New("interp: slice element types don't match"))
}
length := dstLen.Value().SExtValue()
if srcLength := srcLen.Value().SExtValue(); srcLength < length {
length = srcLength
}
if length < 0 {
return nil, nil, fr.errorAt(inst, "interp: trying to copy a slice with negative length?")
return nil, nil, fr.errorAt(inst, errors.New("interp: trying to copy a slice with negative length?"))
}
for i := int64(0); i < length; i++ {
var err error
@ -406,13 +407,13 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
// dst++
dstArrayValue, err := dstArray.GetElementPtr([]uint32{1})
if err != nil {
return nil, nil, errorAt(inst, err.Error())
return nil, nil, fr.errorAt(inst, err)
}
dstArray = dstArrayValue.(*LocalValue)
// src++
srcArrayValue, err := srcArray.GetElementPtr([]uint32{1})
if err != nil {
return nil, nil, errorAt(inst, err.Error())
return nil, nil, fr.errorAt(inst, err)
}
srcArray = srcArrayValue.(*LocalValue)
}
@ -444,11 +445,11 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
actualTypeInt := fr.getLocal(inst.Operand(0)).(*LocalValue).Underlying
assertedType := fr.getLocal(inst.Operand(1)).(*LocalValue).Underlying
if actualTypeInt.IsAConstantExpr().IsNil() || actualTypeInt.Opcode() != llvm.PtrToInt {
return nil, nil, fr.errorAt(inst, "interp: expected typecode in runtime.typeAssert to be a ptrtoint")
return nil, nil, fr.errorAt(inst, errors.New("interp: expected typecode in runtime.typeAssert to be a ptrtoint"))
}
actualType := actualTypeInt.Operand(0)
if actualType.IsAConstant().IsNil() || assertedType.IsAConstant().IsNil() {
return nil, nil, fr.errorAt(inst, "interp: unimplemented: type assert with non-constant interface value")
return nil, nil, fr.errorAt(inst, errors.New("interp: unimplemented: type assert with non-constant interface value"))
}
assertOk := uint64(0)
if llvm.ConstExtractValue(actualType.Initializer(), []uint32{0}) == assertedType {
@ -459,16 +460,16 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
typecode := fr.getLocal(inst.Operand(0)).(*LocalValue).Underlying
interfaceMethodSet := fr.getLocal(inst.Operand(1)).(*LocalValue).Underlying
if typecode.IsAConstantExpr().IsNil() || typecode.Opcode() != llvm.PtrToInt {
return nil, nil, fr.errorAt(inst, "interp: expected typecode to be a ptrtoint")
return nil, nil, fr.errorAt(inst, errors.New("interp: expected typecode to be a ptrtoint"))
}
typecode = typecode.Operand(0)
if interfaceMethodSet.IsAConstantExpr().IsNil() || interfaceMethodSet.Opcode() != llvm.GetElementPtr {
return nil, nil, fr.errorAt(inst, "interp: expected method set in runtime.interfaceImplements to be a constant gep")
return nil, nil, fr.errorAt(inst, errors.New("interp: expected method set in runtime.interfaceImplements to be a constant gep"))
}
interfaceMethodSet = interfaceMethodSet.Operand(0).Initializer()
methodSet := llvm.ConstExtractValue(typecode.Initializer(), []uint32{1})
if methodSet.IsAConstantExpr().IsNil() || methodSet.Opcode() != llvm.GetElementPtr {
return nil, nil, fr.errorAt(inst, "interp: expected method set to be a constant gep")
return nil, nil, fr.errorAt(inst, errors.New("interp: expected method set to be a constant gep"))
}
methodSet = methodSet.Operand(0).Initializer()
@ -568,6 +569,11 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
// interpret anyway and hope for the best.
ret, err = fr.function(callee, params, indent+" ")
if err != nil {
// Record this function call in the backtrace.
err.Traceback = append(err.Traceback, ErrorLine{
Pos: getPosition(inst),
Inst: inst,
})
return nil, nil, err
}
}
@ -586,7 +592,7 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
fr.locals[inst] = fr.getValue(newValue)
} else {
if len(indices) != 1 {
return nil, nil, fr.errorAt(inst, "interp: cannot handle extractvalue with not exactly 1 index")
return nil, nil, fr.errorAt(inst, errors.New("interp: cannot handle extractvalue with not exactly 1 index"))
}
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateExtractValue(agg.Underlying, int(indices[0]), inst.Name())}
}
@ -599,7 +605,7 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
fr.locals[inst] = &LocalValue{fr.Eval, newValue}
} else {
if len(indices) != 1 {
return nil, nil, fr.errorAt(inst, "interp: cannot handle insertvalue with not exactly 1 index")
return nil, nil, fr.errorAt(inst, errors.New("interp: cannot handle insertvalue with not exactly 1 index"))
}
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateInsertValue(agg.Underlying, val.Value(), int(indices[0]), inst.Name())}
}
@ -624,17 +630,17 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
// conditional branch (if/then/else)
cond := fr.getLocal(inst.Operand(0)).Value()
if cond.Type() != fr.Mod.Context().Int1Type() {
return nil, nil, fr.errorAt(inst, "expected an i1 in a branch instruction")
return nil, nil, fr.errorAt(inst, errors.New("expected an i1 in a branch instruction"))
}
thenBB := inst.Operand(1)
elseBB := inst.Operand(2)
if !cond.IsAInstruction().IsNil() {
return nil, nil, fr.errorAt(inst, "interp: branch on a non-constant")
return nil, nil, fr.errorAt(inst, errors.New("interp: branch on a non-constant"))
}
if !cond.IsAConstantExpr().IsNil() {
// This may happen when the instruction builder could not
// const-fold some instructions.
return nil, nil, fr.errorAt(inst, "interp: branch on a non-const-propagated constant expression")
return nil, nil, fr.errorAt(inst, errors.New("interp: branch on a non-const-propagated constant expression"))
}
switch cond {
case llvm.ConstInt(fr.Mod.Context().Int1Type(), 0, false): // false
@ -642,7 +648,7 @@ func (fr *frame) evalBasicBlock(bb, incoming llvm.BasicBlock, indent string) (re
case llvm.ConstInt(fr.Mod.Context().Int1Type(), 1, false): // true
return nil, []llvm.Value{elseBB}, nil // else
default:
return nil, nil, fr.errorAt(inst, "branch was not true or false")
return nil, nil, fr.errorAt(inst, errors.New("branch was not true or false"))
}
case !inst.IsABranchInst().IsNil() && inst.OperandsCount() == 1:
// unconditional branch (goto)

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@ -97,7 +97,7 @@ func Run(mod llvm.Module, debug bool) error {
// function interprets the given function. The params are the function params
// and the indent is the string indentation to use when dumping all interpreted
// instructions.
func (e *evalPackage) function(fn llvm.Value, params []Value, indent string) (Value, error) {
func (e *evalPackage) function(fn llvm.Value, params []Value, indent string) (Value, *Error) {
fr := frame{
evalPackage: e,
fn: fn,

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@ -1,6 +1,7 @@
package interp
import (
"errors"
"strings"
"tinygo.org/x/go-llvm"
@ -40,7 +41,7 @@ type sideEffectResult struct {
// hasSideEffects scans this function and all descendants, recursively. It
// returns whether this function has side effects and if it does, which globals
// it mentions anywhere in this function or any called functions.
func (e *evalPackage) hasSideEffects(fn llvm.Value) (*sideEffectResult, error) {
func (e *evalPackage) hasSideEffects(fn llvm.Value) (*sideEffectResult, *Error) {
name := fn.Name()
switch {
case name == "runtime.alloc":
@ -99,7 +100,7 @@ func (e *evalPackage) hasSideEffects(fn llvm.Value) (*sideEffectResult, error) {
switch inst.InstructionOpcode() {
case llvm.IndirectBr, llvm.Invoke:
// Not emitted by the compiler.
return nil, e.errorAt(inst, "unknown instructions")
return nil, e.errorAt(inst, errors.New("unknown instructions"))
case llvm.Call:
child := inst.CalledValue()
if !child.IsAInlineAsm().IsNil() {

26
main.go
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@ -658,22 +658,22 @@ func usage() {
// to limitations in the LLVM bindings.
func printCompilerError(logln func(...interface{}), err error) {
switch err := err.(type) {
case *interp.Unsupported:
// hit an unknown/unsupported instruction
logln("#", err.ImportPath)
msg := "unsupported instruction during init evaluation:"
if err.Pos.String() != "" {
msg = err.Pos.String() + " " + msg
}
logln(msg)
err.Inst.Dump()
logln()
case types.Error, scanner.Error:
logln(err)
case interp.Error:
case *interp.Error:
logln("#", err.ImportPath)
for _, err := range err.Errs {
logln(err)
logln(err.Error())
if !err.Inst.IsNil() {
err.Inst.Dump()
logln()
}
if len(err.Traceback) > 0 {
logln("\ntraceback:")
for _, line := range err.Traceback {
logln(line.Pos.String() + ":")
line.Inst.Dump()
logln()
}
}
case loader.Errors:
logln("#", err.Pkg.ImportPath)