Reland Implement .eh_frame writer and disassembler.

test/unittests/eh-frame-hdr-unittest.cc

+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "src/eh-frame.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace {
+
+class EhFrameHdrLayoutTest : public testing::Test {};
+
+}  // namespace
+
+using v8::internal::EhFrameHdr;
+
+TEST_F(EhFrameHdrLayoutTest, Real) {
+  EhFrameHdr eh_frame_hdr(10, 30, 10);
+  //
+  // Plugging some numbers in the DSO layout shown in eh-frame.cc:
+  //
+  //  |      ...      |
+  //  +---------------+ <-- (E) --------
+  //  |               |                ^
+  //  |  Instructions |  10 bytes      | .text
+  //  |               |                v
+  //  +---------------+ <---------------
+  //  |///////////////|
+  //  |////Padding////|   6 bytes
+  //  |///////////////|
+  //  +---------------+ <---(D)---------
+  //  |               |                ^
+  //  |      CIE      |   N bytes*     |
+  //  |               |                |
+  //  +---------------+ <-- (C)        | .eh_frame
+  //  |               |                |
+  //  |      FDE      |  30 - N bytes  |
+  //  |               |                v
+  //  +---------------+ <-- (B) --------
+  //  |    version    |                ^
+  //  +---------------+   4 bytes      |
+  //  |   encoding    |                |
+  //  |  specifiers   |                |
+  //  +---------------+ <---(A)        | .eh_frame_hdr
+  //  |   offset to   |                |
+  //  |   .eh_frame   |                |
+  //  +---------------+                |
+  //  |      ...      |               ...
+  //
+  //  (*) the size of the CIE is platform dependent, 10 for this test.
+  //
+  EXPECT_EQ(1, eh_frame_hdr.lut_entries_number());
+  EXPECT_EQ(-(4 + 30), eh_frame_hdr.offset_to_eh_frame());        // A -> D
+  EXPECT_EQ(-(30 + 6 + 10), eh_frame_hdr.offset_to_procedure());  // B -> E
+  EXPECT_EQ(-(30 - 10), eh_frame_hdr.offset_to_fde());            // B -> C
+}
+
+TEST_F(EhFrameHdrLayoutTest, Empty) {
+  EhFrameHdr dummy_eh_frame_hdr = EhFrameHdr::CreateEmptyHeader();
+
+  // An emtpy header has an empty LUT
+  EXPECT_EQ(0, dummy_eh_frame_hdr.lut_entries_number());
+
+  // These values should be irrelevant, but check that they have been zeroed.
+  EXPECT_EQ(0, dummy_eh_frame_hdr.offset_to_eh_frame());
+  EXPECT_EQ(0, dummy_eh_frame_hdr.offset_to_procedure());
+  EXPECT_EQ(0, dummy_eh_frame_hdr.offset_to_fde());
+}