compiler: add location information to the IR checker

compiler/errors.go

@@ -1,8 +1,12 @@
 package compiler
 
 import (
+	"go/scanner"
 	"go/token"
 	"go/types"
+	"path/filepath"
+
+	"tinygo.org/x/go-llvm"
 )
 
 func (c *Compiler) makeError(pos token.Pos, msg string) types.Error {
@@ -16,3 +20,31 @@ func (c *Compiler) makeError(pos token.Pos, msg string) types.Error {
 func (c *Compiler) addError(pos token.Pos, msg string) {
 	c.diagnostics = append(c.diagnostics, c.makeError(pos, msg))
 }
+
+// errorAt returns an error value at the location of the instruction.
+// The location information may not be complete as it depends on debug
+// information in the IR.
+func errorAt(inst llvm.Value, msg string) scanner.Error {
+	return scanner.Error{
+		Pos: getPosition(inst),
+		Msg: msg,
+	}
+}
+
+// getPosition returns the position information for the given instruction, as
+// far as it is available.
+func getPosition(inst llvm.Value) token.Position {
+	if inst.IsAInstruction().IsNil() {
+		return token.Position{}
+	}
+	loc := inst.InstructionDebugLoc()
+	if loc.IsNil() {
+		return token.Position{}
+	}
+	file := loc.LocationScope().ScopeFile()
+	return token.Position{
+		Filename: filepath.Join(file.FileDirectory(), file.FileFilename()),
+		Line:     int(loc.LocationLine()),
+		Column:   int(loc.LocationColumn()),
+	}
+}