tinygo/interp/frame.go
Ayke van Laethem e74db01f82 interp: improve error reporting
This commit improves error reporting in several ways:

  * Location information is read from the intruction that causes the
    error, as far as that's available.
  * The package that is being interpreted is included in the error
    message. This may be the most useful part of the improvements.
  * The hashmap update intrinsics now doesn't panic, instead it logs a
    clear error (with location information, as in the above two bullet
    points).

This is possible thanks to improvements in LLVM 9. This means that after
this change, TinyGo will depend on LLVM 9.
2019-11-26 07:18:42 +01:00

586 строки
25 КиБ
Go

package interp
// This file implements the core interpretation routines, interpreting single
// functions.
import (
"strings"
"tinygo.org/x/go-llvm"
)
type frame struct {
*evalPackage
fn llvm.Value
locals map[llvm.Value]Value
}
// evalBasicBlock evaluates a single basic block, returning the return value (if
// ending with a ret instruction), a list of outgoing basic blocks (if not
// ending with a ret instruction), or an error on failure.
// 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) {
for inst := bb.FirstInstruction(); !inst.IsNil(); inst = llvm.NextInstruction(inst) {
if fr.Debug {
print(indent)
inst.Dump()
println()
}
switch {
case !inst.IsABinaryOperator().IsNil():
lhs := fr.getLocal(inst.Operand(0)).(*LocalValue).Underlying
rhs := fr.getLocal(inst.Operand(1)).(*LocalValue).Underlying
switch inst.InstructionOpcode() {
// Standard binary operators
case llvm.Add:
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateAdd(lhs, rhs, "")}
case llvm.FAdd:
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateFAdd(lhs, rhs, "")}
case llvm.Sub:
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateSub(lhs, rhs, "")}
case llvm.FSub:
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateFSub(lhs, rhs, "")}
case llvm.Mul:
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateMul(lhs, rhs, "")}
case llvm.FMul:
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateFMul(lhs, rhs, "")}
case llvm.UDiv:
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateUDiv(lhs, rhs, "")}
case llvm.SDiv:
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateSDiv(lhs, rhs, "")}
case llvm.FDiv:
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateFDiv(lhs, rhs, "")}
case llvm.URem:
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateURem(lhs, rhs, "")}
case llvm.SRem:
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateSRem(lhs, rhs, "")}
case llvm.FRem:
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateFRem(lhs, rhs, "")}
// Logical operators
case llvm.Shl:
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateShl(lhs, rhs, "")}
case llvm.LShr:
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateLShr(lhs, rhs, "")}
case llvm.AShr:
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateAShr(lhs, rhs, "")}
case llvm.And:
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateAnd(lhs, rhs, "")}
case llvm.Or:
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateOr(lhs, rhs, "")}
case llvm.Xor:
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateXor(lhs, rhs, "")}
default:
return nil, nil, fr.unsupportedInstructionError(inst)
}
// Memory operators
case !inst.IsAAllocaInst().IsNil():
allocType := inst.Type().ElementType()
alloca := llvm.AddGlobal(fr.Mod, allocType, fr.packagePath+"$alloca")
alloca.SetInitializer(llvm.ConstNull(allocType))
alloca.SetLinkage(llvm.InternalLinkage)
fr.locals[inst] = &LocalValue{
Underlying: alloca,
Eval: fr.Eval,
}
case !inst.IsALoadInst().IsNil():
operand := fr.getLocal(inst.Operand(0)).(*LocalValue)
var value llvm.Value
if !operand.IsConstant() || inst.IsVolatile() || (!operand.Underlying.IsAConstantExpr().IsNil() && operand.Underlying.Opcode() == llvm.BitCast) {
value = fr.builder.CreateLoad(operand.Value(), inst.Name())
} else {
value = operand.Load()
}
if value.Type() != inst.Type() {
panic("interp: load: type does not match")
}
fr.locals[inst] = fr.getValue(value)
case !inst.IsAStoreInst().IsNil():
value := fr.getLocal(inst.Operand(0))
ptr := fr.getLocal(inst.Operand(1))
if inst.IsVolatile() {
fr.builder.CreateStore(value.Value(), ptr.Value())
} else {
ptr.Store(value.Value())
}
case !inst.IsAGetElementPtrInst().IsNil():
value := fr.getLocal(inst.Operand(0))
llvmIndices := make([]llvm.Value, inst.OperandsCount()-1)
for i := range llvmIndices {
llvmIndices[i] = inst.Operand(i + 1)
}
indices := make([]uint32, len(llvmIndices))
for i, llvmIndex := range llvmIndices {
operand := fr.getLocal(llvmIndex)
if !operand.IsConstant() {
// Not a constant operation.
// This should be detected by the scanner, but isn't at the
// moment.
panic("todo: non-const gep")
}
indices[i] = uint32(operand.Value().ZExtValue())
}
result := value.GetElementPtr(indices)
if result.Type() != inst.Type() {
println(" expected:", inst.Type().String())
println(" actual: ", result.Type().String())
panic("interp: gep: type does not match")
}
fr.locals[inst] = result
// Cast operators
case !inst.IsATruncInst().IsNil():
value := fr.getLocal(inst.Operand(0))
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateTrunc(value.(*LocalValue).Value(), inst.Type(), "")}
case !inst.IsAZExtInst().IsNil():
value := fr.getLocal(inst.Operand(0))
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateZExt(value.(*LocalValue).Value(), inst.Type(), "")}
case !inst.IsASExtInst().IsNil():
value := fr.getLocal(inst.Operand(0))
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateSExt(value.(*LocalValue).Value(), inst.Type(), "")}
case !inst.IsAFPToUIInst().IsNil():
value := fr.getLocal(inst.Operand(0))
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateFPToUI(value.(*LocalValue).Value(), inst.Type(), "")}
case !inst.IsAFPToSIInst().IsNil():
value := fr.getLocal(inst.Operand(0))
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateFPToSI(value.(*LocalValue).Value(), inst.Type(), "")}
case !inst.IsAUIToFPInst().IsNil():
value := fr.getLocal(inst.Operand(0))
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateUIToFP(value.(*LocalValue).Value(), inst.Type(), "")}
case !inst.IsASIToFPInst().IsNil():
value := fr.getLocal(inst.Operand(0))
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateSIToFP(value.(*LocalValue).Value(), inst.Type(), "")}
case !inst.IsAFPTruncInst().IsNil():
value := fr.getLocal(inst.Operand(0))
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateFPTrunc(value.(*LocalValue).Value(), inst.Type(), "")}
case !inst.IsAFPExtInst().IsNil():
value := fr.getLocal(inst.Operand(0))
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateFPExt(value.(*LocalValue).Value(), inst.Type(), "")}
case !inst.IsAPtrToIntInst().IsNil():
value := fr.getLocal(inst.Operand(0))
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreatePtrToInt(value.Value(), inst.Type(), "")}
case !inst.IsABitCastInst().IsNil() && inst.Type().TypeKind() == llvm.PointerTypeKind:
operand := inst.Operand(0)
if !operand.IsACallInst().IsNil() {
fn := operand.CalledValue()
if !fn.IsAFunction().IsNil() && fn.Name() == "runtime.alloc" {
continue // special case: bitcast of alloc
}
}
if _, ok := fr.getLocal(operand).(*MapValue); ok {
// Special case for runtime.trackPointer calls.
// Note: this might not be entirely sound in some rare cases
// where the map is stored in a dirty global.
uses := getUses(inst)
if len(uses) == 1 {
use := uses[0]
if !use.IsACallInst().IsNil() && !use.CalledValue().IsAFunction().IsNil() && use.CalledValue().Name() == "runtime.trackPointer" {
continue
}
}
// It is not possible in Go to bitcast a map value to a pointer.
panic("unimplemented: bitcast of map")
}
value := fr.getLocal(operand).(*LocalValue)
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateBitCast(value.Value(), inst.Type(), "")}
// Other operators
case !inst.IsAICmpInst().IsNil():
lhs := fr.getLocal(inst.Operand(0)).(*LocalValue).Underlying
rhs := fr.getLocal(inst.Operand(1)).(*LocalValue).Underlying
predicate := inst.IntPredicate()
if predicate == llvm.IntEQ && lhs.Type().TypeKind() == llvm.PointerTypeKind {
// Unfortunately, the const propagation in the IR builder
// doesn't handle pointer compares of inttoptr values. So we
// implement it manually here.
lhsNil, ok1 := isPointerNil(lhs)
rhsNil, ok2 := isPointerNil(rhs)
if ok1 && ok2 {
if lhsNil && rhsNil {
// Both are nil, so this icmp is always evaluated to true.
fr.locals[inst] = &LocalValue{fr.Eval, llvm.ConstInt(fr.Mod.Context().Int1Type(), 1, false)}
continue
}
if lhsNil != rhsNil {
// Only one of them is nil, so this comparison must return false.
fr.locals[inst] = &LocalValue{fr.Eval, llvm.ConstInt(fr.Mod.Context().Int1Type(), 0, false)}
continue
}
}
}
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateICmp(predicate, lhs, rhs, "")}
case !inst.IsAFCmpInst().IsNil():
lhs := fr.getLocal(inst.Operand(0)).(*LocalValue).Underlying
rhs := fr.getLocal(inst.Operand(1)).(*LocalValue).Underlying
predicate := inst.FloatPredicate()
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateFCmp(predicate, lhs, rhs, "")}
case !inst.IsAPHINode().IsNil():
for i := 0; i < inst.IncomingCount(); i++ {
if inst.IncomingBlock(i) == incoming {
fr.locals[inst] = fr.getLocal(inst.IncomingValue(i))
}
}
case !inst.IsACallInst().IsNil():
callee := inst.CalledValue()
switch {
case callee.Name() == "runtime.alloc":
// heap allocation
users := getUses(inst)
var resultInst = inst
if len(users) == 1 && !users[0].IsABitCastInst().IsNil() {
// happens when allocating something other than i8*
resultInst = users[0]
}
size := fr.getLocal(inst.Operand(0)).(*LocalValue).Underlying.ZExtValue()
allocType := resultInst.Type().ElementType()
typeSize := fr.TargetData.TypeAllocSize(allocType)
elementCount := 1
if size != typeSize {
// allocate an array
if size%typeSize != 0 {
return nil, nil, fr.unsupportedInstructionError(inst)
}
elementCount = int(size / typeSize)
allocType = llvm.ArrayType(allocType, elementCount)
}
alloc := llvm.AddGlobal(fr.Mod, allocType, fr.packagePath+"$alloc")
alloc.SetInitializer(llvm.ConstNull(allocType))
alloc.SetLinkage(llvm.InternalLinkage)
result := &LocalValue{
Underlying: alloc,
Eval: fr.Eval,
}
if elementCount == 1 {
fr.locals[resultInst] = result
} else {
fr.locals[resultInst] = result.GetElementPtr([]uint32{0, 0})
}
case callee.Name() == "runtime.hashmapMake":
// create a map
keySize := inst.Operand(0).ZExtValue()
valueSize := inst.Operand(1).ZExtValue()
fr.locals[inst] = &MapValue{
Eval: fr.Eval,
PkgName: fr.packagePath,
KeySize: int(keySize),
ValueSize: int(valueSize),
}
case callee.Name() == "runtime.hashmapStringSet":
// set a string key in the map
m, ok := fr.getLocal(inst.Operand(0)).(*MapValue)
if !ok {
return nil, nil, fr.errorAt(inst, "could not update map with string key")
}
// "key" is a Go string value, which in the TinyGo calling convention is split up
// into separate pointer and length parameters.
keyBuf := fr.getLocal(inst.Operand(1)).(*LocalValue)
keyLen := fr.getLocal(inst.Operand(2)).(*LocalValue)
valPtr := fr.getLocal(inst.Operand(3)).(*LocalValue)
m.PutString(keyBuf, keyLen, valPtr)
case callee.Name() == "runtime.hashmapBinarySet":
// set a binary (int etc.) key in the map
m, ok := fr.getLocal(inst.Operand(0)).(*MapValue)
if !ok {
return nil, nil, fr.errorAt(inst, "could not update map")
}
keyBuf := fr.getLocal(inst.Operand(1)).(*LocalValue)
valPtr := fr.getLocal(inst.Operand(2)).(*LocalValue)
m.PutBinary(keyBuf, valPtr)
case callee.Name() == "runtime.stringConcat":
// adding two strings together
buf1Ptr := fr.getLocal(inst.Operand(0))
buf1Len := fr.getLocal(inst.Operand(1))
buf2Ptr := fr.getLocal(inst.Operand(2))
buf2Len := fr.getLocal(inst.Operand(3))
buf1 := getStringBytes(buf1Ptr, buf1Len.Value())
buf2 := getStringBytes(buf2Ptr, buf2Len.Value())
result := []byte(string(buf1) + string(buf2))
vals := make([]llvm.Value, len(result))
for i := range vals {
vals[i] = llvm.ConstInt(fr.Mod.Context().Int8Type(), uint64(result[i]), false)
}
globalType := llvm.ArrayType(fr.Mod.Context().Int8Type(), len(result))
globalValue := llvm.ConstArray(fr.Mod.Context().Int8Type(), vals)
global := llvm.AddGlobal(fr.Mod, globalType, fr.packagePath+"$stringconcat")
global.SetInitializer(globalValue)
global.SetLinkage(llvm.InternalLinkage)
global.SetGlobalConstant(true)
global.SetUnnamedAddr(true)
stringType := fr.Mod.GetTypeByName("runtime._string")
retPtr := llvm.ConstGEP(global, getLLVMIndices(fr.Mod.Context().Int32Type(), []uint32{0, 0}))
retLen := llvm.ConstInt(stringType.StructElementTypes()[1], uint64(len(result)), false)
ret := llvm.ConstNull(stringType)
ret = llvm.ConstInsertValue(ret, retPtr, []uint32{0})
ret = llvm.ConstInsertValue(ret, retLen, []uint32{1})
fr.locals[inst] = &LocalValue{fr.Eval, ret}
case callee.Name() == "runtime.sliceCopy":
elementSize := fr.getLocal(inst.Operand(4)).(*LocalValue).Value().ZExtValue()
dstArray := fr.getLocal(inst.Operand(0)).(*LocalValue).stripPointerCasts()
srcArray := fr.getLocal(inst.Operand(1)).(*LocalValue).stripPointerCasts()
dstLen := fr.getLocal(inst.Operand(2)).(*LocalValue)
srcLen := fr.getLocal(inst.Operand(3)).(*LocalValue)
if elementSize != 1 && dstArray.Type().ElementType().TypeKind() == llvm.ArrayTypeKind && srcArray.Type().ElementType().TypeKind() == llvm.ArrayTypeKind {
// Slice data pointers are created by adding a global array
// and getting the address of the first element using a GEP.
// However, before the compiler can pass it to
// runtime.sliceCopy, it has to perform a bitcast to a *i8,
// to make it a unsafe.Pointer. Now, when the IR builder
// sees a bitcast of a GEP with zero indices, it will make
// a bitcast of the original array instead of the GEP,
// which breaks our assumptions.
// Re-add this GEP, in the hope that it it is then of the correct type...
dstArray = dstArray.GetElementPtr([]uint32{0, 0}).(*LocalValue)
srcArray = srcArray.GetElementPtr([]uint32{0, 0}).(*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")
}
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")
}
if dstArray.Type() != srcArray.Type() {
return nil, nil, fr.errorAt(inst, "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?")
}
for i := int64(0); i < length; i++ {
// *dst = *src
dstArray.Store(srcArray.Load())
// dst++
dstArray = dstArray.GetElementPtr([]uint32{1}).(*LocalValue)
// src++
srcArray = srcArray.GetElementPtr([]uint32{1}).(*LocalValue)
}
case callee.Name() == "runtime.stringToBytes":
// convert a string to a []byte
bufPtr := fr.getLocal(inst.Operand(0))
bufLen := fr.getLocal(inst.Operand(1))
result := getStringBytes(bufPtr, bufLen.Value())
vals := make([]llvm.Value, len(result))
for i := range vals {
vals[i] = llvm.ConstInt(fr.Mod.Context().Int8Type(), uint64(result[i]), false)
}
globalType := llvm.ArrayType(fr.Mod.Context().Int8Type(), len(result))
globalValue := llvm.ConstArray(fr.Mod.Context().Int8Type(), vals)
global := llvm.AddGlobal(fr.Mod, globalType, fr.packagePath+"$bytes")
global.SetInitializer(globalValue)
global.SetLinkage(llvm.InternalLinkage)
global.SetGlobalConstant(true)
global.SetUnnamedAddr(true)
sliceType := inst.Type()
retPtr := llvm.ConstGEP(global, getLLVMIndices(fr.Mod.Context().Int32Type(), []uint32{0, 0}))
retLen := llvm.ConstInt(sliceType.StructElementTypes()[1], uint64(len(result)), false)
ret := llvm.ConstNull(sliceType)
ret = llvm.ConstInsertValue(ret, retPtr, []uint32{0}) // ptr
ret = llvm.ConstInsertValue(ret, retLen, []uint32{1}) // len
ret = llvm.ConstInsertValue(ret, retLen, []uint32{2}) // cap
fr.locals[inst] = &LocalValue{fr.Eval, ret}
case callee.Name() == "runtime.interfaceImplements":
typecode := fr.getLocal(inst.Operand(0)).(*LocalValue).Underlying
interfaceMethodSet := fr.getLocal(inst.Operand(1)).(*LocalValue).Underlying
if typecode.IsAConstantExpr().IsNil() || typecode.Opcode() != llvm.PtrToInt {
panic("interp: expected typecode to be a ptrtoint")
}
typecode = typecode.Operand(0)
if interfaceMethodSet.IsAConstantExpr().IsNil() || interfaceMethodSet.Opcode() != llvm.GetElementPtr {
panic("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 {
panic("interp: expected method set to be a constant gep")
}
methodSet = methodSet.Operand(0).Initializer()
// Make a set of all the methods on the concrete type, for
// easier checking in the next step.
definedMethods := map[string]struct{}{}
for i := 0; i < methodSet.Type().ArrayLength(); i++ {
methodInfo := llvm.ConstExtractValue(methodSet, []uint32{uint32(i)})
name := llvm.ConstExtractValue(methodInfo, []uint32{0}).Name()
definedMethods[name] = struct{}{}
}
// Check whether all interface methods are also in the list
// of defined methods calculated above.
implements := uint64(1) // i1 true
for i := 0; i < interfaceMethodSet.Type().ArrayLength(); i++ {
name := llvm.ConstExtractValue(interfaceMethodSet, []uint32{uint32(i)}).Name()
if _, ok := definedMethods[name]; !ok {
// There is a method on the interface that is not
// implemented by the type.
implements = 0 // i1 false
break
}
}
fr.locals[inst] = &LocalValue{fr.Eval, llvm.ConstInt(fr.Mod.Context().Int1Type(), implements, false)}
case callee.Name() == "runtime.nanotime":
fr.locals[inst] = &LocalValue{fr.Eval, llvm.ConstInt(fr.Mod.Context().Int64Type(), 0, false)}
case callee.Name() == "llvm.dbg.value":
// do nothing
case callee.Name() == "runtime.trackPointer":
// do nothing
case strings.HasPrefix(callee.Name(), "runtime.print") || callee.Name() == "runtime._panic":
// This are all print instructions, which necessarily have side
// effects but no results.
// TODO: print an error when executing runtime._panic (with the
// exact error message it would print at runtime).
var params []llvm.Value
for i := 0; i < inst.OperandsCount()-1; i++ {
operand := fr.getLocal(inst.Operand(i)).Value()
fr.markDirty(operand)
params = append(params, operand)
}
// TODO: accurate debug info, including call chain
fr.builder.CreateCall(callee, params, inst.Name())
case !callee.IsAFunction().IsNil() && callee.IsDeclaration():
// external functions
var params []llvm.Value
for i := 0; i < inst.OperandsCount()-1; i++ {
operand := fr.getLocal(inst.Operand(i)).Value()
fr.markDirty(operand)
params = append(params, operand)
}
// TODO: accurate debug info, including call chain
result := fr.builder.CreateCall(callee, params, inst.Name())
if inst.Type().TypeKind() != llvm.VoidTypeKind {
fr.markDirty(result)
fr.locals[inst] = &LocalValue{fr.Eval, result}
}
case !callee.IsAFunction().IsNil():
// regular function
var params []Value
dirtyParams := false
for i := 0; i < inst.OperandsCount()-1; i++ {
local := fr.getLocal(inst.Operand(i))
if !local.IsConstant() {
dirtyParams = true
}
params = append(params, local)
}
var ret Value
scanResult := fr.Eval.hasSideEffects(callee)
if scanResult.severity == sideEffectLimited || dirtyParams && scanResult.severity != sideEffectAll {
// Side effect is bounded. This means the operation invokes
// side effects (like calling an external function) but it
// is known at compile time which side effects it invokes.
// This means the function can be called at runtime and the
// affected globals can be marked dirty at compile time.
llvmParams := make([]llvm.Value, len(params))
for i, param := range params {
llvmParams[i] = param.Value()
}
result := fr.builder.CreateCall(callee, llvmParams, inst.Name())
ret = &LocalValue{fr.Eval, result}
// mark all mentioned globals as dirty
for global := range scanResult.mentionsGlobals {
fr.markDirty(global)
}
} else {
// Side effect is one of:
// * None: no side effects, can be fully interpreted at
// compile time.
// * Unbounded: cannot call at runtime so we'll try to
// interpret anyway and hope for the best.
ret, err = fr.function(callee, params, indent+" ")
if err != nil {
return nil, nil, err
}
}
if inst.Type().TypeKind() != llvm.VoidTypeKind {
fr.locals[inst] = ret
}
default:
// function pointers, etc.
return nil, nil, fr.unsupportedInstructionError(inst)
}
case !inst.IsAExtractValueInst().IsNil():
agg := fr.getLocal(inst.Operand(0)).(*LocalValue) // must be constant
indices := inst.Indices()
if agg.Underlying.IsConstant() {
newValue := llvm.ConstExtractValue(agg.Underlying, indices)
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")
}
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateExtractValue(agg.Underlying, int(indices[0]), inst.Name())}
}
case !inst.IsAInsertValueInst().IsNil():
agg := fr.getLocal(inst.Operand(0)).(*LocalValue) // must be constant
val := fr.getLocal(inst.Operand(1))
indices := inst.Indices()
if agg.IsConstant() && val.IsConstant() {
newValue := llvm.ConstInsertValue(agg.Underlying, val.Value(), indices)
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")
}
fr.locals[inst] = &LocalValue{fr.Eval, fr.builder.CreateInsertValue(agg.Underlying, val.Value(), int(indices[0]), inst.Name())}
}
case !inst.IsAReturnInst().IsNil() && inst.OperandsCount() == 0:
return nil, nil, nil // ret void
case !inst.IsAReturnInst().IsNil() && inst.OperandsCount() == 1:
return fr.getLocal(inst.Operand(0)), nil, nil
case !inst.IsABranchInst().IsNil() && inst.OperandsCount() == 3:
// conditional branch (if/then/else)
cond := fr.getLocal(inst.Operand(0)).Value()
if cond.Type() != fr.Mod.Context().Int1Type() {
panic("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")
}
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")
}
switch cond {
case llvm.ConstInt(fr.Mod.Context().Int1Type(), 0, false): // false
return nil, []llvm.Value{thenBB}, nil // then
case llvm.ConstInt(fr.Mod.Context().Int1Type(), 1, false): // true
return nil, []llvm.Value{elseBB}, nil // else
default:
panic("branch was not true or false")
}
case !inst.IsABranchInst().IsNil() && inst.OperandsCount() == 1:
// unconditional branch (goto)
return nil, []llvm.Value{inst.Operand(0)}, nil
case !inst.IsAUnreachableInst().IsNil():
// Unreachable was reached (e.g. after a call to panic()).
// Report this as an error, as it is not supposed to happen.
// This is a sentinel error value.
return nil, nil, errUnreachable
default:
return nil, nil, fr.unsupportedInstructionError(inst)
}
}
panic("interp: reached end of basic block without terminator")
}
// Get the Value for an operand, which is a constant value of some sort.
func (fr *frame) getLocal(v llvm.Value) Value {
if ret, ok := fr.locals[v]; ok {
return ret
} else if value := fr.getValue(v); value != nil {
return value
} else {
panic("cannot find value")
}
}