interp: avoid an extra TargetData argument

This can be easily calculated from the module datalayout string.

compiler/compiler.go

@@ -187,11 +187,6 @@ func (c *Compiler) Module() llvm.Module {
 	return c.mod
 }
 
-// Return the LLVM target data object. Only valid after a successful compile.
-func (c *Compiler) TargetData() llvm.TargetData {
-	return c.targetData
-}
-
 // selectGC picks an appropriate GC strategy if none was provided.
 func (c *Compiler) selectGC() string {
 	if c.GC != "" {

interp/interp.go

@@ -24,7 +24,7 @@ type Eval struct {
 
 // Run evaluates the function with the given name and then eliminates all
 // callers.
-func Run(mod llvm.Module, targetData llvm.TargetData, debug bool) error {
+func Run(mod llvm.Module, debug bool) error {
 	if debug {
 		println("\ncompile-time evaluation:")
 	}
@@ -32,7 +32,7 @@ func Run(mod llvm.Module, targetData llvm.TargetData, debug bool) error {
 	name := "runtime.initAll"
 	e := &Eval{
 		Mod:          mod,
-		TargetData:   targetData,
+		TargetData:   llvm.NewTargetData(mod.DataLayout()),
 		Debug:        debug,
 		dirtyGlobals: map[llvm.Value]struct{}{},
 	}

main.go

@@ -145,7 +145,7 @@ func Compile(pkgName, outpath string, spec *TargetSpec, config *BuildConfig, act
 		return errors.New("verification error after IR construction")
 	}
 
-	err = interp.Run(c.Module(), c.TargetData(), config.dumpSSA)
+	err = interp.Run(c.Module(), config.dumpSSA)
 	if err != nil {
 		return err
 	}