[wasm] add atomic opcodes

R=titzer@chromium.org,binji@chromium.org
BUG=v8:4614

Review-Url: https://codereview.chromium.org/2423883003
Cr-Commit-Position: refs/heads/master@{#40606}

src/flag-definitions.h

@@ -528,6 +528,8 @@ DEFINE_BOOL(wasm_eh_prototype, false,
             "enable prototype exception handling opcodes for wasm")
 DEFINE_BOOL(wasm_mv_prototype, false,
             "enable prototype multi-value support for wasm")
+DEFINE_BOOL(wasm_atomics_prototype, false,
+            "enable prototype atomic opcodes for wasm")
 
 DEFINE_BOOL(wasm_trap_handler, false,
             "use signal handlers to catch out of bounds memory access in wasm"

src/wasm/ast-decoder.cc

@@ -1158,6 +1158,24 @@ class WasmFullDecoder : public WasmDecoder {
             len += DecodeSimdOpcode(opcode);
             break;
           }
+          case kAtomicPrefix: {
+            if (!module_ || module_->origin != kAsmJsOrigin) {
+              error("Atomics are allowed only in AsmJs modules");
+              break;
+            }
+            if (!FLAG_wasm_atomics_prototype) {
+              error("Invalid opcode (enable with --wasm_atomics_prototype)");
+              break;
+            }
+            len = 2;
+            byte atomic_opcode = checked_read_u8(pc_, 1, "atomic index");
+            opcode = static_cast<WasmOpcode>(opcode << 8 | atomic_opcode);
+            sig = WasmOpcodes::AtomicSignature(opcode);
+            if (sig) {
+              BuildAtomicOperator(opcode);
+            }
+            break;
+          }
           default: {
             // Deal with special asmjs opcodes.
             if (module_ && module_->origin == kAsmJsOrigin) {
@@ -1340,6 +1358,8 @@ class WasmFullDecoder : public WasmDecoder {
     return len;
   }
 
+  void BuildAtomicOperator(WasmOpcode opcode) { UNIMPLEMENTED(); }
+
   void DoReturn() {
     int count = static_cast<int>(sig_->return_count());
     TFNode** buffer = nullptr;

src/wasm/wasm-opcodes.cc

@@ -88,6 +88,7 @@ static const FunctionSig* kSimdExprSigs[] = {
 static byte kSimpleExprSigTable[256];
 static byte kSimpleAsmjsExprSigTable[256];
 static byte kSimdExprSigTable[256];
+static byte kAtomicExprSigTable[256];
 
 // Initialize the signature table.
 static void InitSigTables() {
@@ -105,6 +106,12 @@ static void InitSigTables() {
   kSimdExprSigTable[simd_index] = static_cast<int>(kSigEnum_##sig) + 1;
   FOREACH_SIMD_0_OPERAND_OPCODE(SET_SIG_TABLE)
 #undef SET_SIG_TABLE
+  byte atomic_index;
+#define SET_ATOMIC_SIG_TABLE(name, opcode, sig) \
+  atomic_index = opcode & 0xff;                 \
+  kAtomicExprSigTable[atomic_index] = static_cast<int>(kSigEnum_##sig) + 1;
+  FOREACH_ATOMIC_OPCODE(SET_ATOMIC_SIG_TABLE)
+#undef SET_ATOMIC_SIG_TABLE
 }
 
 class SigTable {
@@ -125,6 +132,10 @@ class SigTable {
     return const_cast<FunctionSig*>(
         kSimdExprSigs[kSimdExprSigTable[static_cast<byte>(opcode & 0xff)]]);
   }
+  FunctionSig* AtomicSignature(WasmOpcode opcode) const {
+    return const_cast<FunctionSig*>(
+        kSimpleExprSigs[kAtomicExprSigTable[static_cast<byte>(opcode & 0xff)]]);
+  }
 };
 
 static base::LazyInstance<SigTable>::type sig_table = LAZY_INSTANCE_INITIALIZER;
@@ -141,6 +152,10 @@ FunctionSig* WasmOpcodes::AsmjsSignature(WasmOpcode opcode) {
   return sig_table.Get().AsmjsSignature(opcode);
 }
 
+FunctionSig* WasmOpcodes::AtomicSignature(WasmOpcode opcode) {
+  return sig_table.Get().AtomicSignature(opcode);
+}
+
 // TODO(titzer): pull WASM_64 up to a common header.
 #if !V8_TARGET_ARCH_32_BIT || V8_TARGET_ARCH_X64
 #define WASM_64 1

src/wasm/wasm-opcodes.h

@@ -400,6 +400,43 @@ const WasmCodePosition kNoCodePosition = -1;
   V(I16x8ExtractLane, 0xe539, _)         \
   V(I8x16ExtractLane, 0xe558, _)
 
+#define FOREACH_ATOMIC_OPCODE(V)               \
+  V(I32AtomicAdd8S, 0xe601, i_ii)              \
+  V(I32AtomicAdd8U, 0xe602, i_ii)              \
+  V(I32AtomicAdd16S, 0xe603, i_ii)             \
+  V(I32AtomicAdd16U, 0xe604, i_ii)             \
+  V(I32AtomicAdd32, 0xe605, i_ii)              \
+  V(I32AtomicAnd8S, 0xe606, i_ii)              \
+  V(I32AtomicAnd8U, 0xe607, i_ii)              \
+  V(I32AtomicAnd16S, 0xe608, i_ii)             \
+  V(I32AtomicAnd16U, 0xe609, i_ii)             \
+  V(I32AtomicAnd32, 0xe60a, i_ii)              \
+  V(I32AtomicCompareExchange8S, 0xe60b, i_ii)  \
+  V(I32AtomicCompareExchange8U, 0xe60c, i_ii)  \
+  V(I32AtomicCompareExchange16S, 0xe60d, i_ii) \
+  V(I32AtomicCompareExchange16U, 0xe60e, i_ii) \
+  V(I32AtomicCompareExchange32, 0xe60f, i_ii)  \
+  V(I32AtomicExchange8S, 0xe610, i_ii)         \
+  V(I32AtomicExchange8U, 0xe611, i_ii)         \
+  V(I32AtomicExchange16S, 0xe612, i_ii)        \
+  V(I32AtomicExchange16U, 0xe613, i_ii)        \
+  V(I32AtomicExchange32, 0xe614, i_ii)         \
+  V(I32AtomicOr8S, 0xe615, i_ii)               \
+  V(I32AtomicOr8U, 0xe616, i_ii)               \
+  V(I32AtomicOr16S, 0xe617, i_ii)              \
+  V(I32AtomicOr16U, 0xe618, i_ii)              \
+  V(I32AtomicOr32, 0xe619, i_ii)               \
+  V(I32AtomicSub8S, 0xe61a, i_ii)              \
+  V(I32AtomicSub8U, 0xe61b, i_ii)              \
+  V(I32AtomicSub16S, 0xe61c, i_ii)             \
+  V(I32AtomicSub16U, 0xe61d, i_ii)             \
+  V(I32AtomicSub32, 0xe61e, i_ii)              \
+  V(I32AtomicXor8S, 0xe61f, i_ii)              \
+  V(I32AtomicXor8U, 0xe620, i_ii)              \
+  V(I32AtomicXor16S, 0xe621, i_ii)             \
+  V(I32AtomicXor16U, 0xe622, i_ii)             \
+  V(I32AtomicXor32, 0xe623, i_ii)
+
 // All opcodes.
 #define FOREACH_OPCODE(V)          \
   FOREACH_CONTROL_OPCODE(V)        \
@@ -410,7 +447,8 @@ const WasmCodePosition kNoCodePosition = -1;
   FOREACH_MISC_MEM_OPCODE(V)       \
   FOREACH_ASMJS_COMPAT_OPCODE(V)   \
   FOREACH_SIMD_0_OPERAND_OPCODE(V) \
-  FOREACH_SIMD_1_OPERAND_OPCODE(V)
+  FOREACH_SIMD_1_OPERAND_OPCODE(V) \
+  FOREACH_ATOMIC_OPCODE(V)
 
 // All signatures.
 #define FOREACH_SIGNATURE(V)         \
@@ -453,7 +491,9 @@ const WasmCodePosition kNoCodePosition = -1;
   V(s_sii, kAstS128, kAstS128, kAstI32, kAstI32)   \
   V(s_si, kAstS128, kAstS128, kAstI32)
 
-#define FOREACH_PREFIX(V) V(Simd, 0xe5)
+#define FOREACH_PREFIX(V) \
+  V(Simd, 0xe5)           \
+  V(Atomic, 0xe6)
 
 enum WasmOpcode {
 // Declare expression opcodes.
@@ -491,6 +531,7 @@ class V8_EXPORT_PRIVATE WasmOpcodes {
   static const char* ShortOpcodeName(WasmOpcode opcode);
   static FunctionSig* Signature(WasmOpcode opcode);
   static FunctionSig* AsmjsSignature(WasmOpcode opcode);
+  static FunctionSig* AtomicSignature(WasmOpcode opcode);
   static bool IsPrefixOpcode(WasmOpcode opcode);
 
   static int TrapReasonToMessageId(TrapReason reason);