[wasm] Trap handling: ProtectedLoad instruction

src/compiler/wasm-compiler.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/compiler/wasm-compiler.h"
 
 #include <memory>
 
 #include "src/isolate-inl.h"
 
@@ skipping 27 matching lines @@
 
 // TODO(titzer): pull WASM_64 up to a common header.
 #if !V8_TARGET_ARCH_32_BIT || V8_TARGET_ARCH_X64
 #define WASM_64 1
 #else
 #define WASM_64 0
 #endif
 
 namespace v8 {
 namespace internal {
+
 namespace compiler {
 
 namespace {
 const Operator* UnsupportedOpcode(wasm::WasmOpcode opcode) {
   V8_Fatal(__FILE__, __LINE__, "Unsupported opcode #%d:%s", opcode,
            wasm::WasmOpcodes::OpcodeName(opcode));
   return nullptr;
 }
 
 void MergeControlToEnd(JSGraph* jsgraph, Node* node) {
@@ skipping 2686 matching lines @@
     }
   }
 
   Node* cond = graph()->NewNode(jsgraph()->machine()->Uint32LessThan(), index,
                                 jsgraph()->RelocatableInt32Constant(
                                     static_cast<uint32_t>(effective_size),
                                     RelocInfo::WASM_MEMORY_SIZE_REFERENCE));
   trap_->AddTrapIfFalse(wasm::kTrapMemOutOfBounds, cond, position);
 }
 
-

[Mircea Trofin, 2016/09/02 04:05:45]

We want to keep this space here. Did "git cl upload" not complain?

[Eric Holk, 2016/09/02 20:05:32]

Done.

 Node* WasmGraphBuilder::LoadMem(wasm::LocalType type, MachineType memtype,
                                 Node* index, uint32_t offset,
                                 uint32_t alignment,
                                 wasm::WasmCodePosition position) {
   Node* load;
 
   // WASM semantics throw on OOB. Introduce explicit bounds check.
-  BoundsCheckMem(memtype, index, offset, position);
+  if (!FLAG_wasm_trap_handler) {
+    BoundsCheckMem(memtype, index, offset, position);
+  }
   bool aligned = static_cast<int>(alignment) >=
                  ElementSizeLog2Of(memtype.representation());
 
   if (aligned ||
       jsgraph()->machine()->UnalignedLoadSupported(memtype, alignment)) {
-    load = graph()->NewNode(jsgraph()->machine()->Load(memtype),
-                            MemBuffer(offset), index, *effect_, *control_);
+    if (!FLAG_wasm_trap_handler) {
+      load = graph()->NewNode(jsgraph()->machine()->Load(memtype),
+                              MemBuffer(offset), index, *effect_, *control_);
+    } else {
+      auto* context = HeapConstant(module_->instance->context);

[Mircea Trofin, 2016/09/02 04:05:45]

HeapConstant* instead of auto. AFAIK, auto would have been fine if this were an
instantiation. It's a function call.

[Eric Holk, 2016/09/02 20:05:32]

Done. It was actually Node* instead of HeapConstant*.

+      auto position_node = jsgraph()->Int32Constant(position);
+      load = graph()->NewNode(jsgraph()->machine()->ProtectedLoad(memtype),

[Mircea Trofin, 2016/09/02 04:05:45]

What's position_node's type? (i.e. please no auto)

[Eric Holk, 2016/09/02 20:05:32]

Done. This was also Node*.

+                              MemBuffer(offset), index, context, position_node,
+                              *effect_, *control_);
+    }
   } else {
+    DCHECK(!FLAG_wasm_trap_handler);
     load = graph()->NewNode(jsgraph()->machine()->UnalignedLoad(memtype),
                             MemBuffer(offset), index, *effect_, *control_);
   }
 
   *effect_ = load;
 
 #if defined(V8_TARGET_BIG_ENDIAN)
   load = BuildChangeEndianness(load, memtype, type);
 #endif
 
@@ skipping 468 matching lines @@
                             function_->code_start_offset),
            compile_ms);
   }
 
   return code;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8