[wasm] Fix printing of reloc info on the native heap

Tag RelocInfo which belongs to native wasm code, and fix printing to
not try to access the Code object for CODE_TARGET, but rather just
print "(wasm trampoline)".

Bug: chromium:801785

R=mstarzinger@chromium.org

Change-Id: I84a37f0c48ed7397cccf677b4d0f0352e5aceb9d
Reviewed-on: https://chromium-review.googlesource.com/875271
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50758}

src/assembler.cc

@@ -560,7 +560,8 @@ void RelocIterator::next() {
   done_ = true;
 }
 
-RelocIterator::RelocIterator(Code* code, int mode_mask) {
+RelocIterator::RelocIterator(Code* code, int mode_mask)
+    : mode_mask_(mode_mask) {
   rinfo_.host_ = code;
   rinfo_.pc_ = code->instruction_start();
   rinfo_.data_ = 0;
@@ -568,35 +569,30 @@ RelocIterator::RelocIterator(Code* code, int mode_mask) {
   // Relocation info is read backwards.
   pos_ = code->relocation_start() + code->relocation_size();
   end_ = code->relocation_start();
-  done_ = false;
-  mode_mask_ = mode_mask;
   if (mode_mask_ == 0) pos_ = end_;
   next();
 }
 
-RelocIterator::RelocIterator(const CodeDesc& desc, int mode_mask) {
+RelocIterator::RelocIterator(const CodeDesc& desc, int mode_mask)
+    : mode_mask_(mode_mask) {
   rinfo_.pc_ = desc.buffer;
-  rinfo_.data_ = 0;
   // Relocation info is read backwards.
   pos_ = desc.buffer + desc.buffer_size;
   end_ = pos_ - desc.reloc_size;
-  done_ = false;
-  mode_mask_ = mode_mask;
   if (mode_mask_ == 0) pos_ = end_;
   next();
 }
 
 RelocIterator::RelocIterator(Vector<byte> instructions,
                              Vector<const byte> reloc_info, Address const_pool,
-                             int mode_mask) {
+                             int mode_mask)
+    : mode_mask_(mode_mask) {
   rinfo_.pc_ = instructions.start();
-  rinfo_.data_ = 0;
   rinfo_.constant_pool_ = const_pool;
+  rinfo_.flags_ = RelocInfo::kInNativeWasmCode;
   // Relocation info is read backwards.
   pos_ = reloc_info.start() + reloc_info.size();
   end_ = reloc_info.start();
-  done_ = false;
-  mode_mask_ = mode_mask;
   if (mode_mask_ == 0) pos_ = end_;
   next();
 }
@@ -685,9 +681,15 @@ void RelocInfo::Print(Isolate* isolate, std::ostream& os) {  // NOLINT
        << ")  (" << static_cast<const void*>(target_external_reference())
        << ")";
   } else if (IsCodeTarget(rmode_)) {
-    Code* code = Code::GetCodeFromTargetAddress(target_address());
-    os << " (" << Code::Kind2String(code->kind()) << ")  ("
-       << static_cast<const void*>(target_address()) << ")";
+    const Address code_target = target_address();
+    if (flags_ & kInNativeWasmCode) {
+      os << " (wasm trampoline) ";
+    } else {
+      Code* code = Code::GetCodeFromTargetAddress(code_target);
+      DCHECK(code->IsCode());
+      os << " (" << Code::Kind2String(code->kind()) << ") ";
+    }
+    os << " (" << static_cast<const void*>(target_address()) << ")";
   } else if (IsRuntimeEntry(rmode_) && isolate->deoptimizer_data() != nullptr) {
     // Depotimization bailouts are stored as runtime entries.
     int id = Deoptimizer::GetDeoptimizationId(

src/assembler.h

@@ -341,6 +341,12 @@ enum ICacheFlushMode { FLUSH_ICACHE_IF_NEEDED, SKIP_ICACHE_FLUSH };
 
 class RelocInfo {
  public:
+  enum Flag : uint8_t {
+    kNoFlags = 0,
+    kInNativeWasmCode = 1u << 0,  // Reloc info belongs to native wasm code.
+  };
+  typedef base::Flags<Flag> Flags;
+
   // This string is used to add padding comments to the reloc info in cases
   // where we are not sure to have enough space for patching in during
   // lazy deoptimization. This is the case if we have indirect calls for which
@@ -623,9 +629,10 @@ class RelocInfo {
   // comment).
   byte* pc_;
   Mode rmode_;
-  intptr_t data_;
+  intptr_t data_ = 0;
   Code* host_;
   Address constant_pool_ = nullptr;
+  Flags flags_;
   friend class RelocIterator;
 };
 
@@ -728,8 +735,9 @@ class RelocIterator: public Malloced {
   const byte* pos_;
   const byte* end_;
   RelocInfo rinfo_;
-  bool done_;
-  int mode_mask_;
+  bool done_ = false;
+  const int mode_mask_;
+
   DISALLOW_COPY_AND_ASSIGN(RelocIterator);
 };
 

test/mjsunit/regress/wasm/regress-801785.js

@@ -0,0 +1,22 @@
+// Copyright 2018 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.
+
+load('test/mjsunit/wasm/wasm-constants.js');
+load('test/mjsunit/wasm/wasm-module-builder.js');
+
+// Flags: --print-wasm-code
+
+const builder = new WasmModuleBuilder();
+builder.addMemory(8, 16);
+builder.addFunction(undefined, kSig_i_i).addBody([
+  // wasm to wasm call.
+  kExprGetLocal, 0, kExprCallFunction, 0x1
+]);
+builder.addFunction(undefined, kSig_i_i).addBody([
+  // load from <get_local 0> to create trap code.
+  kExprGetLocal, 0, kExprI32LoadMem, 0,
+  // unreachable to create a runtime call.
+  kExprUnreachable
+]);
+builder.instantiate();