// parseInst converts the provided LLVM IR instruction into an equivalent Go AST
// node (a statement).
func parseInst(inst llvm.Value) (ast.Stmt, error) {
// TODO: Remove debug output.
if flagVerbose {
fmt.Println("parseInst:")
fmt.Println(" nops:", inst.OperandsCount())
inst.Dump()
fmt.Println()
}
// Assignment operation.
// %foo = ...
opcode := inst.InstructionOpcode()
if _, err := getResult(inst); err == nil {
// Binary Operations
switch opcode {
case llvm.Add, llvm.FAdd:
return parseBinOp(inst, token.ADD)
case llvm.Sub, llvm.FSub:
return parseBinOp(inst, token.SUB)
case llvm.Mul, llvm.FMul:
return parseBinOp(inst, token.MUL)
case llvm.UDiv, llvm.SDiv, llvm.FDiv:
// TODO: Handle signed and unsigned div separately.
return parseBinOp(inst, token.QUO)
case llvm.URem, llvm.SRem, llvm.FRem:
// TODO: Handle signed and unsigned mod separately.
return parseBinOp(inst, token.REM)
// Bitwise Binary Operations
case llvm.Shl:
return parseBinOp(inst, token.SHL)
case llvm.LShr, llvm.AShr:
// TODO: Handle logical and arithmetic shift right separately.
return parseBinOp(inst, token.SHR)
case llvm.And:
return parseBinOp(inst, token.AND)
case llvm.Or:
return parseBinOp(inst, token.OR)
case llvm.Xor:
return parseBinOp(inst, token.XOR)
// Other Operators
case llvm.ICmp, llvm.FCmp:
pred, err := getCmpPred(inst)
if err != nil {
return nil, errutil.Err(err)
}
return parseBinOp(inst, pred)
}
}
return nil, errutil.Newf("support for LLVM IR instruction %q not yet implemented", prettyOpcode(opcode))
}
// parseOperand converts the provided LLVM IR operand into an equivalent Go AST
// expression node (a basic literal, a composite literal or an identifier).
//
// Syntax:
// i32 1
// %foo = ...
func parseOperand(op llvm.Value) (ast.Expr, error) {
// TODO: Support *BasicLit, *CompositeLit.
// Parse and validate tokens.
tokens, err := getTokens(op)
if err != nil {
return nil, err
}
if len(tokens) < 2 {
// TODO: Remove debug output.
op.Dump()
return nil, errutil.Newf("unable to parse operand; expected 2 >= tokens, got %d", len(tokens))
}
// TODO: Add support for operand of other types than int.
// TODO: Parse type.
// Create and return a constant operand.
// i32 42
if tokens[0].Kind == lltoken.Type {
switch tok := tokens[1]; tok.Kind {
case lltoken.Int:
return &ast.BasicLit{Kind: token.INT, Value: tok.Val}, nil
case lltoken.LocalVar:
return getIdent(tok)
default:
return nil, errutil.Newf("support for LLVM IR token kind %v not yet implemented", tok.Kind)
}
}
// Create and return a variable operand.
// %foo = ...
if tokens[1].Kind == lltoken.Equal {
switch tok := tokens[0]; tok.Kind {
case lltoken.LocalVar, lltoken.LocalID:
// %foo
// %42
return getIdent(tok)
default:
return nil, errutil.Newf("support for LLVM IR token kind %v not yet implemented", tok.Kind)
}
}
return nil, errutil.New("support for LLVM IR operand not yet implemented")
}
// hackDump returns the value dump as a string.
func hackDump(v llvm.Value) (string, error) {
// Open temp file.
// TODO: Use an in-memory file instead of /tmp/x.
fd, err := unix.Open("/tmp/x", unix.O_WRONLY|unix.O_TRUNC|unix.O_CREAT, 0644)
if err != nil {
return "", errutil.Err(err)
}
// Store original stderr.
stderr, err := unix.Dup(2)
if err != nil {
return "", errutil.Err(err)
}
// Capture stderr and redirect its output to the temp file.
err = unix.Dup2(fd, 2)
if err != nil {
return "", errutil.Err(err)
}
err = unix.Close(fd)
if err != nil {
return "", errutil.Err(err)
}
// Dump value.
v.Dump()
C.fflush_stderr()
// Restore stderr.
err = unix.Dup2(stderr, 2)
if err != nil {
return "", errutil.Err(err)
}
err = unix.Close(stderr)
if err != nil {
return "", errutil.Err(err)
}
// Return content of temp file.
buf, err := ioutil.ReadFile("/tmp/x")
if err != nil {
return "", errutil.Err(err)
}
return string(buf), nil
}
// getBrCond parses the provided branch instruction and returns its condition.
//
// Syntax:
// br i1 <cond>, label <target_true>, label <target_false>
func getBrCond(term llvm.Value) (cond ast.Expr, targetTrue, targetFalse string, err error) {
// Parse and validate tokens.
tokens, err := getTokens(term)
if err != nil {
return nil, "", "", err
}
if len(tokens) != 10 {
// TODO: Remove debug output.
term.Dump()
return nil, "", "", errutil.Newf("unable to parse conditional branch instruction; expected 10 tokens, got %d", len(tokens))
}
// Create and return the condition.
switch tok := tokens[2]; tok.Kind {
case lltoken.KwTrue, lltoken.KwFalse, lltoken.LocalVar, lltoken.LocalID:
// true
// false
// %foo
// %42
ident, err := getIdent(tok)
if err != nil {
return nil, "", "", errutil.Err(err)
}
return ident, tokens[5].Val, tokens[8].Val, nil
case lltoken.Int:
// 1
// 0
switch tok.Val {
case "0":
return newIdent("false"), tokens[5].Val, tokens[8].Val, nil
case "1":
return newIdent("true"), tokens[5].Val, tokens[8].Val, nil
default:
return nil, "", "", errutil.Newf("invalid integer value; expected boolean, got %q", tok.Val)
}
default:
return nil, "", "", errutil.Newf("support for LLVM IR token kind %v not yet implemented", tok.Kind)
}
}
// parseRetInst converts the provided LLVM IR ret instruction into an equivalent
// Go return statement.
//
// Syntax:
// ret void
// ret <type> <val>
func parseRetInst(inst llvm.Value) (*ast.ReturnStmt, error) {
// TODO: Make more robust by using proper parsing instead of relying on
// tokens. The current approach is used for a proof of concept and would fail
// for composite literals. This TODO applies to the use of tokens in all
// functions.
// Parse and validate tokens.
tokens, err := getTokens(inst)
if err != nil {
return nil, err
}
if len(tokens) < 4 {
// TODO: Remove debug output.
inst.Dump()
return nil, errutil.Newf("unable to parse return instruction; expected >= 4 tokens, got %d", len(tokens))
}
typ := tokens[1]
if typ.Kind != lltoken.Type {
return nil, errutil.Newf(`invalid return instruction; expected type token, got %q`, typ)
}
// Create and return a void return statement.
if typ.Val == "void" {
return &ast.ReturnStmt{}, nil
}
// Create and return a return statement.
val, err := parseOperand(inst.Operand(0))
if err != nil {
return nil, errutil.Err(err)
}
ret := &ast.ReturnStmt{
Results: []ast.Expr{val},
}
return ret, nil
}