[cleanup][wasm] Set the return type of wasm stores to void

The return type of stores is void according to the WebAssembly spec.
In wasm-opcodes.h, however, the return type of stores was set to the
value type. This CL changes the signature of stores, and fixes some
issues which were caused because now there exist opcodes with a return
count different to 1.

R=titzer@chromium.org, clemensh@chromium.org

Bug: v8:7109
Change-Id: I94d1b049e6d0032868b2ce83f52e16b474de3dea
Reviewed-on: https://chromium-review.googlesource.com/803495Reviewed-by: Ben Titzer <titzer@chromium.org>
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49836}

src/wasm/function-body-decoder.cc

@@ -223,8 +223,8 @@ class WasmGraphBuildingInterface {
 
   void BinOp(Decoder* decoder, WasmOpcode opcode, FunctionSig* sig,
              const Value& lhs, const Value& rhs, Value* result) {
-    result->node =
-        BUILD(Binop, opcode, lhs.node, rhs.node, decoder->position());
+    auto node = BUILD(Binop, opcode, lhs.node, rhs.node, decoder->position());
+    if (result) result->node = node;
   }
 
   void I32Const(Decoder* decoder, Value* result, int32_t value) {

src/wasm/wasm-opcodes.cc

@@ -340,11 +340,12 @@ enum WasmOpcodeSig : byte {
   FOREACH_SIGNATURE(DECLARE_SIG_ENUM)
 };
 #undef DECLARE_SIG_ENUM
-
 #define DECLARE_SIG(name, ...)                                                \
   constexpr ValueType kTypes_##name[] = {__VA_ARGS__};                        \
+  constexpr int kReturnsCount_##name = kTypes_##name[0] == kWasmStmt ? 0 : 1; \
   constexpr FunctionSig kSig_##name(                                          \
-      1, static_cast<int>(arraysize(kTypes_##name)) - 1, kTypes_##name);
+      kReturnsCount_##name, static_cast<int>(arraysize(kTypes_##name)) - 1,   \
+      kTypes_##name + (1 - kReturnsCount_##name));
 FOREACH_SIGNATURE(DECLARE_SIG)
 #undef DECLARE_SIG
 

src/wasm/wasm-opcodes.h

@@ -102,15 +102,15 @@ constexpr WasmCodePosition kNoCodePosition = -1;
 
 // Store memory expressions.
 #define FOREACH_STORE_MEM_OPCODE(V) \
-  V(I32StoreMem, 0x36, i_ii)        \
-  V(I64StoreMem, 0x37, l_il)        \
-  V(F32StoreMem, 0x38, f_if)        \
-  V(F64StoreMem, 0x39, d_id)        \
-  V(I32StoreMem8, 0x3a, i_ii)       \
-  V(I32StoreMem16, 0x3b, i_ii)      \
-  V(I64StoreMem8, 0x3c, l_il)       \
-  V(I64StoreMem16, 0x3d, l_il)      \
-  V(I64StoreMem32, 0x3e, l_il)
+  V(I32StoreMem, 0x36, v_ii)        \
+  V(I64StoreMem, 0x37, v_il)        \
+  V(F32StoreMem, 0x38, v_if)        \
+  V(F64StoreMem, 0x39, v_id)        \
+  V(I32StoreMem8, 0x3a, v_ii)       \
+  V(I32StoreMem16, 0x3b, v_ii)      \
+  V(I64StoreMem8, 0x3c, v_il)       \
+  V(I64StoreMem16, 0x3d, v_il)      \
+  V(I64StoreMem32, 0x3e, v_il)
 
 // Miscellaneous memory expressions
 #define FOREACH_MISC_MEM_OPCODE(V) \
@@ -413,15 +413,15 @@ constexpr WasmCodePosition kNoCodePosition = -1;
 
 #define FOREACH_SIMD_MEM_OPCODE(V) \
   V(S128LoadMem, 0xfd80, s_i)      \
-  V(S128StoreMem, 0xfd81, s_is)
+  V(S128StoreMem, 0xfd81, v_is)
 
 #define FOREACH_ATOMIC_OPCODE(V)               \
   V(I32AtomicLoad, 0xfe10, i_i)                \
   V(I32AtomicLoad8U, 0xfe12, i_i)              \
   V(I32AtomicLoad16U, 0xfe13, i_i)             \
-  V(I32AtomicStore, 0xfe17, i_ii)              \
-  V(I32AtomicStore8U, 0xfe19, i_ii)            \
-  V(I32AtomicStore16U, 0xfe1a, i_ii)           \
+  V(I32AtomicStore, 0xfe17, v_ii)              \
+  V(I32AtomicStore8U, 0xfe19, v_ii)            \
+  V(I32AtomicStore16U, 0xfe1a, v_ii)           \
   V(I32AtomicAdd, 0xfe1e, i_ii)                \
   V(I32AtomicAdd8U, 0xfe20, i_ii)              \
   V(I32AtomicAdd16U, 0xfe21, i_ii)             \
@@ -486,9 +486,12 @@ constexpr WasmCodePosition kNoCodePosition = -1;
   V(d_f, kWasmF64, kWasmF32)             \
   V(d_i, kWasmF64, kWasmI32)             \
   V(d_l, kWasmF64, kWasmI64)             \
+  V(v_ii, kWasmStmt, kWasmI32, kWasmI32) \
+  V(v_id, kWasmStmt, kWasmI32, kWasmF64) \
   V(d_id, kWasmF64, kWasmI32, kWasmF64)  \
+  V(v_if, kWasmStmt, kWasmI32, kWasmF32) \
   V(f_if, kWasmF32, kWasmI32, kWasmF32)  \
-  V(l_il, kWasmI64, kWasmI32, kWasmI64) \
+  V(v_il, kWasmI64, kWasmI32, kWasmI64)  \
   V(i_iii, kWasmI32, kWasmI32, kWasmI32, kWasmI32)
 
 #define FOREACH_SIMD_SIGNATURE(V)          \