[bindings/go] Add ParseIR

This commit adds a single method to the Context object to parse a
textual IR file. This is useful for reading input IR in unit tests.

Differential Revision: https://reviews.llvm.org/D66379

llvm-svn: 369210

llvm/bindings/go/llvm/irreader.go

+//===- irreader.go - Bindings for irreader --------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines bindings for the irreader component.
+//
+//===----------------------------------------------------------------------===//
+
+package llvm
+
+/*
+#include "llvm-c/IRReader.h"
+#include <stdlib.h>
+*/
+import "C"
+
+import (
+	"errors"
+	"unsafe"
+)
+
+// ParseIR parses the textual IR given in the memory buffer and returns a new
+// LLVM module in this context.
+func (c *Context) ParseIR(buf MemoryBuffer) (Module, error) {
+	var m Module
+	var errmsg *C.char
+	if C.LLVMParseIRInContext(c.C, buf.C, &m.C, &errmsg) != 0 {
+		err := errors.New(C.GoString(errmsg))
+		C.free(unsafe.Pointer(errmsg))
+		return Module{}, err
+	}
+	return m, nil
+}