[wasm] Add ProtectedStore 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 82 matching lines @@
   inputs[count++] = control;
 
   Node* node =
       jsgraph->graph()->NewNode(jsgraph->common()->Call(desc), count, inputs);
   *effect_ptr = node;
   return node;
 }
 
 }  // namespace
 
+// TODO(eholk): Support trap handlers on other platforms.
+#if V8_TARGET_ARCH_X64 && V8_OS_LINUX
+const bool kTrapHandlerSupported = true;
+#else
+const bool kTrapHandlerSupported = false;
+#endif
+
 // A helper that handles building graph fragments for trapping.
 // To avoid generating a ton of redundant code that just calls the runtime
 // to trap, we generate a per-trap-reason block of code that all trap sites
 // in this function will branch to.
 class WasmTrapHelper : public ZoneObject {
  public:
   explicit WasmTrapHelper(WasmGraphBuilder* builder)
       : builder_(builder),
         jsgraph_(builder->jsgraph()),
         graph_(builder->jsgraph() ? builder->jsgraph()->graph() : nullptr) {}
@@ skipping 2828 matching lines @@
 }
 
 
 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.
-  if (!FLAG_wasm_trap_handler) {
+  if (!FLAG_wasm_trap_handler || !kTrapHandlerSupported) {
     BoundsCheckMem(memtype, index, offset, position);
   }
   bool aligned = static_cast<int>(alignment) >=
                  ElementSizeLog2Of(memtype.representation());
 
   if (aligned ||
       jsgraph()->machine()->UnalignedLoadSupported(memtype, alignment)) {
-    if (FLAG_wasm_trap_handler) {
+    if (FLAG_wasm_trap_handler && kTrapHandlerSupported) {
       DCHECK(FLAG_wasm_guard_pages);
       Node* context = HeapConstant(module_->instance->context);
       Node* position_node = jsgraph()->Int32Constant(position);
       load = graph()->NewNode(jsgraph()->machine()->ProtectedLoad(memtype),
                               MemBuffer(offset), index, context, position_node,
                               *effect_, *control_);
     } else {
       load = graph()->NewNode(jsgraph()->machine()->Load(memtype),
                               MemBuffer(offset), index, *effect_, *control_);
     }
   } else {
-    DCHECK(!FLAG_wasm_trap_handler);
+    // TODO(eholk): Support unaligned loads with trap handlers.
+    DCHECK(!FLAG_wasm_trap_handler || !kTrapHandlerSupported);
     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 13 matching lines @@
   return load;
 }
 
 
 Node* WasmGraphBuilder::StoreMem(MachineType memtype, Node* index,
                                  uint32_t offset, uint32_t alignment, Node* val,
                                  wasm::WasmCodePosition position) {
   Node* store;
 
   // WASM semantics throw on OOB. Introduce explicit bounds check.
-  BoundsCheckMem(memtype, index, offset, position);
+  if (!FLAG_wasm_trap_handler || !kTrapHandlerSupported) {
+    BoundsCheckMem(memtype, index, offset, position);
+  }
   StoreRepresentation rep(memtype.representation(), kNoWriteBarrier);
 
   bool aligned = static_cast<int>(alignment) >=
                  ElementSizeLog2Of(memtype.representation());
 
 #if defined(V8_TARGET_BIG_ENDIAN)
   val = BuildChangeEndianness(val, memtype);
 #endif
 
   if (aligned ||
       jsgraph()->machine()->UnalignedStoreSupported(memtype, alignment)) {
-    StoreRepresentation rep(memtype.representation(), kNoWriteBarrier);
-    store =
-        graph()->NewNode(jsgraph()->machine()->Store(rep), MemBuffer(offset),
-                         index, val, *effect_, *control_);
+    if (FLAG_wasm_trap_handler && kTrapHandlerSupported) {
+      Node* context = HeapConstant(module_->instance->context);
+      Node* position_node = jsgraph()->Int32Constant(position);
+      store = graph()->NewNode(
+          jsgraph()->machine()->ProtectedStore(memtype.representation()),
+          MemBuffer(offset), index, val, context, position_node, *effect_,
+          *control_);
+    } else {
+      StoreRepresentation rep(memtype.representation(), kNoWriteBarrier);
+      store =
+          graph()->NewNode(jsgraph()->machine()->Store(rep), MemBuffer(offset),
+                           index, val, *effect_, *control_);
+    }
   } else {
+    // TODO(eholk): Support unaligned stores with trap handlers.
+    DCHECK(!FLAG_wasm_trap_handler || !kTrapHandlerSupported);
     UnalignedStoreRepresentation rep(memtype.representation());
     store =
         graph()->NewNode(jsgraph()->machine()->UnalignedStore(rep),
                          MemBuffer(offset), index, val, *effect_, *control_);
   }
 
   *effect_ = store;
 
   return store;
 }
@@ skipping 456 matching lines @@
                             function_->code_start_offset),
            compile_ms);
   }
 
   return code;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8