[wasm] Fix location for error in asm.js ToNumber conversion

src/wasm/wasm-objects.cc

 // Copyright 2015 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/wasm/wasm-objects.h"
 #include "src/utils.h"
 
 #include "src/wasm/module-decoder.h"
 #include "src/wasm/wasm-module.h"
 #include "src/wasm/wasm-text.h"
@@ skipping 470 matching lines @@
     asm_offsets = wasm::DecodeAsmJsOffsets(bytes_start, bytes_end);
   }
   // Wasm bytes must be valid and must contain asm.js offset table.
   DCHECK(asm_offsets.ok());
   DCHECK_GE(kMaxInt, asm_offsets.val.size());
   int num_functions = static_cast<int>(asm_offsets.val.size());
   int num_imported_functions =
       static_cast<int>(compiled_module->module()->num_imported_functions);
   DCHECK_EQ(compiled_module->module()->functions.size(),
             static_cast<size_t>(num_functions) + num_imported_functions);
+  int num_entries = 0;
+  for (int func = 0; func < num_functions; ++func) {
+    size_t new_size = asm_offsets.val[func].size();
+    DCHECK_LE(new_size, static_cast<size_t>(kMaxInt) - num_entries);
+    num_entries += static_cast<int>(new_size);
+  }
   // One byte to encode that this is a decoded table.
-  int total_size = 1;
-  for (int func = 0; func < num_functions; ++func) {
-    size_t new_size = asm_offsets.val[func].size() * 2 * kIntSize;
-    DCHECK_LE(new_size, static_cast<size_t>(kMaxInt) - total_size);
-    total_size += static_cast<int>(new_size);
-  }
+  DCHECK_GE(kMaxInt, 1 + static_cast<uint64_t>(num_entries) * 3 * kIntSize);
+  int total_size = 1 + num_entries * 3 * kIntSize;
   Handle<ByteArray> decoded_table =
       isolate->factory()->NewByteArray(total_size, TENURED);
   decoded_table->set(total_size - 1, AsmJsTableType::Decoded);
   compiled_module->set_asm_js_offset_table(decoded_table);
 
   int idx = 0;
   std::vector<WasmFunction>& wasm_funs = compiled_module->module()->functions;
   for (int func = 0; func < num_functions; ++func) {
-    std::vector<std::pair<int, int>>& func_asm_offsets = asm_offsets.val[func];
+    std::vector<AsmJsOffsetEntry>& func_asm_offsets = asm_offsets.val[func];
     if (func_asm_offsets.empty()) continue;
     int func_offset =
         wasm_funs[num_imported_functions + func].code_start_offset;
-    for (std::pair<int, int> p : func_asm_offsets) {
+    for (AsmJsOffsetEntry& e : func_asm_offsets) {
       // Byte offsets must be strictly monotonously increasing:
       DCHECK(idx == 0 ||
-             func_offset + p.first > decoded_table->get_int(idx - 2));
-      decoded_table->set_int(idx++, func_offset + p.first);
-      decoded_table->set_int(idx++, p.second);
+             func_offset + e.byte_offset > decoded_table->get_int(idx - 3));
+      decoded_table->set_int(idx++, func_offset + e.byte_offset);
+      decoded_table->set_int(idx++, e.source_position_call);
+      decoded_table->set_int(idx++, e.source_position_number_conversion);
     }
   }
   DCHECK_EQ(total_size, idx * kIntSize + 1);
   return decoded_table;
 }
 }  // namespace
 
 int WasmCompiledModule::GetAsmJsSourcePosition(
     Handle<WasmCompiledModule> compiled_module, uint32_t func_index,
-    uint32_t byte_offset) {
+    uint32_t byte_offset, bool is_at_number_conversion) {
   Isolate* isolate = compiled_module->GetIsolate();
   Handle<ByteArray> offset_table =
       GetDecodedAsmJsOffsetTable(compiled_module, isolate);
 
   DCHECK_LT(func_index, compiled_module->module()->functions.size());
   uint32_t func_code_offset =
       compiled_module->module()->functions[func_index].code_start_offset;
   uint32_t total_offset = func_code_offset + byte_offset;
 
   // Binary search for the total byte offset.
   int left = 0;                                       // inclusive
-  int right = offset_table->length() / kIntSize / 2;  // exclusive
+  int right = offset_table->length() / kIntSize / 3;  // exclusive

[bradnelson, 2016/12/07 19:19:06]

At the point you've got 3 fields, maybe have an enum and given them a name
(including size as the last one)?

[Clemens Hammacher, 2016/12/08 10:50:23]

Cool idea, done!

   DCHECK_LT(left, right);
   while (right - left > 1) {
     int mid = left + (right - left) / 2;
-    int mid_entry = offset_table->get_int(2 * mid);
+    int mid_entry = offset_table->get_int(3 * mid);
     DCHECK_GE(kMaxInt, mid_entry);
     if (static_cast<uint32_t>(mid_entry) <= total_offset) {
       left = mid;
     } else {
       right = mid;
     }
   }
   // There should be an entry for each position that could show up on the stack
   // trace:
   DCHECK_EQ(total_offset,
-            static_cast<uint32_t>(offset_table->get_int(2 * left)));
-  return offset_table->get_int(2 * left + 1);
+            static_cast<uint32_t>(offset_table->get_int(3 * left)));
+  return offset_table->get_int(3 * left + (is_at_number_conversion ? 2 : 1));
 }
 
 v8::debug::WasmDisassembly WasmCompiledModule::DisassembleFunction(
     int func_index) {
   DisallowHeapAllocation no_gc;
 
   if (func_index < 0 ||
       static_cast<uint32_t>(func_index) >= module()->functions.size())
     return {};
 
@@ skipping 33 matching lines @@
       !array->get(kPreviousInstanceWrapper)->IsFixedArray())
     return false;
   return true;
 }
 
 void WasmInstanceWrapper::set_instance_object(Handle<JSObject> instance,
                                               Isolate* isolate) {
   Handle<WeakCell> cell = isolate->factory()->NewWeakCell(instance);
   set(kWrapperInstanceObject, *cell);
 }