Initial support for emitting unwinding information in perf jitdump.

test/cctest/test-eh-frame-hdr.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 "src/objects.h"
+#include "test/cctest/cctest.h"
+
+using namespace v8::internal;
+
+TEST(EhFrameHdr) {
+  CcTest::InitializeVM();
+  HandleScope handle_scope(CcTest::i_isolate());
+
+  // The content is not relevant in this test
+  byte buffer[10] = {0};
+  byte unwinding_info[30 + EhFrameHdr::kRecordSize] = {0};
+
+  CodeDesc code_desc;
+  code_desc.buffer = &buffer[0];
+  code_desc.buffer_size = sizeof(buffer);
+  code_desc.constant_pool_size = 0;
+  code_desc.instr_size = sizeof(buffer);
+  code_desc.reloc_size = 0;
+  code_desc.origin = nullptr;
+  code_desc.unwinding_info = &unwinding_info[0];
+  code_desc.unwinding_info_size = sizeof(unwinding_info);
+
+  Handle<Code> code = CcTest::i_isolate()->factory()->NewCode(
+      code_desc, 0, Handle<Object>::null());
+
+  EhFrameHdr eh_frame_hdr(*code);
+  CHECK_EQ(eh_frame_hdr.lut_entries_number(), 1);
+
+  //
+  // 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.
+  //
+  int N = EhFrameHdr::kCIESize;

[rmcilroy, 2016/06/24 09:45:26]

No need for this local, just use directly below

[Stefano Sanfilippo, 2016/06/24 10:36:37]

Done.

+  CHECK_EQ(eh_frame_hdr.offset_to_eh_frame(), -(4 + 30));        // A -> D
+  CHECK_EQ(eh_frame_hdr.offset_to_procedure(), -(30 + 6 + 10));  // B -> E
+  CHECK_EQ(eh_frame_hdr.offset_to_fde(), -(30 - N));             // B -> C
+}
+
+TEST(DummyEhFrameHdr) {
+  CcTest::InitializeVM();
+  HandleScope handle_scope(CcTest::i_isolate());
+
+  byte buffer[10] = {0};  // The content is not relevant in this test
+
+  CodeDesc code_desc;
+  code_desc.buffer = &buffer[0];
+  code_desc.buffer_size = sizeof(buffer);
+  code_desc.constant_pool_size = 0;
+  code_desc.instr_size = sizeof(buffer);
+  code_desc.reloc_size = 0;
+  code_desc.origin = nullptr;
+  code_desc.unwinding_info = nullptr;
+  code_desc.unwinding_info_size = 0;
+
+  Handle<Code> code = CcTest::i_isolate()->factory()->NewCode(
+      code_desc, 0, Handle<Object>::null());
+
+  EhFrameHdr eh_frame_hdr(*code);
+  // A dummy header has an empty LUT
+  CHECK_EQ(eh_frame_hdr.lut_entries_number(), 0);
+  // These values should be irrelevant, but check that they have been zeroed.
+  CHECK_EQ(eh_frame_hdr.offset_to_eh_frame(), 0);
+  CHECK_EQ(eh_frame_hdr.offset_to_procedure(), 0);
+  CHECK_EQ(eh_frame_hdr.offset_to_fde(), 0);
+}