[compiler] Add relocatable pointer constants for wasm memory references.

test/cctest/compiler/test-run-wasm-machops.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 <cmath>
+#include <functional>
+#include <limits>
+
+#include "src/base/bits.h"
+#include "src/base/utils/random-number-generator.h"
+#include "src/codegen.h"
+#include "test/cctest/cctest.h"
+#include "test/cctest/compiler/codegen-tester.h"
+#include "test/cctest/compiler/graph-builder-tester.h"
+#include "test/cctest/compiler/value-helper.h"
+
+using namespace v8::internal;
+using namespace v8::internal::compiler;
+
+template <typename CType>
+static void RunLoadStoreRelocation(MachineType rep) {

[titzer, 2016/03/23 20:35:36]

Can you split out some simple cases (e.g. offset 0) into their own separate
tests?

[gdeepti1, 2016/03/31 22:29:54]

Added a simple load/store test with 0 offset. 

+  RawMachineAssemblerTester<int32_t> r(MachineType::Int32());
+  const int kNumElems = 4;
+  CType buffer[kNumElems];
+  CType new_buffer[kNumElems + 1];
+  Isolate* isolate = CcTest::i_isolate();
+
+  for (int32_t x = 0; x < kNumElems; x++) {
+    int32_t y = kNumElems - x - 1;
+    // initialize the buffer with raw data.
+    byte* raw = reinterpret_cast<byte*>(buffer);
+    for (size_t i = 0; i < sizeof(buffer); i++) {
+      raw[i] = static_cast<byte>((i + sizeof(buffer)) ^ 0xAA);
+    }
+
+    RawMachineAssemblerTester<int32_t> m;
+    int32_t OK = 0x29000 + x;
+    Node* base = m.RelocatableIntPtrConstant(reinterpret_cast<intptr_t>(buffer),
+                                             RelocInfo::WASM_MEMORY_REFERENCE);
+    Node* index0 = m.IntPtrConstant(x * sizeof(buffer[0]));
+    Node* load = m.Load(rep, base, index0);
+    Node* index1 = m.IntPtrConstant(y * sizeof(buffer[0]));
+    m.Store(rep.representation(), base, index1, load, kNoWriteBarrier);
+    m.Return(m.Int32Constant(OK));
+
+    CHECK(buffer[x] != buffer[y]);
+    CHECK_EQ(OK, m.Call());
+    CHECK(buffer[x] == buffer[y]);
+    m.GenerateCode();
+
+    // Initialize new buffer and set old_buffer to 0
+    byte* new_raw = reinterpret_cast<byte*>(new_buffer);
+    for (size_t i = 0; i < sizeof(buffer); i++) {
+      raw[i] = 0;
+      new_raw[i] = static_cast<byte>((i + sizeof(buffer)) ^ 0xAA);
+    }
+
+    // Perform relocation on generated code
+    Handle<Code> code = m.GetCode();

[titzer, 2016/03/23 20:35:36]

This is OK for now, but this operation probably needs to be pulled out to an
operation in the production code that you can simply call.

[gdeepti1, 2016/03/31 22:29:54]

Pulled out a method to update memory references. 

+
+    bool modified = false;
+    int mode_mask = (1 << RelocInfo::WASM_MEMORY_REFERENCE);
+    for (RelocIterator it(*code, mode_mask); !it.done(); it.next()) {
+      RelocInfo::Mode mode = it.rinfo()->rmode();
+      if (RelocInfo::IsWasmMemoryReference(mode)) {
+        // Patch addresses with change in memory start address
+        it.rinfo()->update_wasm_memory_reference(raw, new_raw, sizeof(buffer),
+                                                 sizeof(new_buffer),
+                                                 SKIP_ICACHE_FLUSH);
+        modified = true;
+      }
+    }
+    if (modified) {
+      Assembler::FlushICache(isolate, code->instruction_start(),
+                             code->instruction_size());
+    }
+
+    CHECK(new_buffer[x] != new_buffer[y]);
+    CHECK_EQ(OK, m.Call());
+    CHECK(new_buffer[x] == new_buffer[y]);
+  }
+}
+
+TEST(RunLoadStoreRelocation) {
+  RunLoadStoreRelocation<int8_t>(MachineType::Int8());
+  RunLoadStoreRelocation<uint8_t>(MachineType::Uint8());
+  RunLoadStoreRelocation<int16_t>(MachineType::Int16());
+  RunLoadStoreRelocation<uint16_t>(MachineType::Uint16());
+  RunLoadStoreRelocation<int32_t>(MachineType::Int32());
+  RunLoadStoreRelocation<uint32_t>(MachineType::Uint32());
+  RunLoadStoreRelocation<void*>(MachineType::AnyTagged());
+  RunLoadStoreRelocation<float>(MachineType::Float32());
+  RunLoadStoreRelocation<double>(MachineType::Float64());
+}