Add getting strings from string constants

ir.go

@@ -19,8 +19,10 @@ package llvm
 #include <stdlib.h>
 */
 import "C"
-import "unsafe"
-import "errors"
+import (
+	"errors"
+	"unsafe"
+)
 
 type (
 	// We use these weird structs here because *Ref types are pointers and
@@ -910,6 +912,18 @@ func ConstVector(scalarConstVals []Value, packed bool) (v Value) {
 	return
 }
 
+// IsConstantString checks if the constant is an array of i8.
+func (v Value) IsConstantString() bool {
+	return C.LLVMIsConstantString(v.C) != 0
+}
+
+// ConstGetAsString will return the string contained in a constant.
+func (v Value) ConstGetAsString() string {
+	length := C.ulong(0)
+	cstr := C.LLVMGetAsString(v.C, &length)
+	return C.GoStringN(cstr, C.int(length))
+}
+
 // Constant expressions
 func (v Value) Opcode() Opcode             { return Opcode(C.LLVMGetConstOpcode(v.C)) }
 func (v Value) InstructionOpcode() Opcode  { return Opcode(C.LLVMGetInstructionOpcode(v.C)) }