Convert SIMD wasm ops to runtime function calls

src/wasm/ast-decoder.cc

Index: src/wasm/ast-decoder.cc
diff --git a/src/wasm/ast-decoder.cc b/src/wasm/ast-decoder.cc
index 70f7bfdd1d7306dd8908feef1a054dbcd1ac9337..102bca96bdbc1c29aecc99ffc360d0b403112b4e 100644
--- a/src/wasm/ast-decoder.cc
+++ b/src/wasm/ast-decoder.cc
@@ -996,6 +996,13 @@ class WasmFullDecoder : public WasmDecoder {
             len = 1 + operand.length;
             break;
           }
+          case kSimdPrefix: {
+            len++;
+            byte simd_index = *(pc_ + 1);
+            opcode = static_cast<WasmOpcode>(opcode << 8 | simd_index);
+            DecodeSimdOpcode(opcode);

[bradnelson, 2016/07/13 18:10:42]

Add an --enable-wasm-simd flag, and error if this shows up without it on.

[gdeepti, 2016/07/13 18:58:35]

Added --enable-wasm-simd flag, falls through to invalid opcode case without the
flag. 

+            break;
+          }
           default:
             error("Invalid opcode");
             return;
@@ -1101,6 +1108,17 @@ class WasmFullDecoder : public WasmDecoder {
     return 1 + operand.length;
   }
 
+  void DecodeSimdOpcode(WasmOpcode opcode) {
+    FunctionSig* sig = WasmOpcodes::Signature(opcode);
+    compiler::NodeVector inputs(sig->parameter_count(), zone_);
+    for (int i = static_cast<int>(sig->parameter_count()); i > 0; i--) {

[bradnelson, 2016/07/13 18:10:42]

size_t drop cast?

[gdeepti, 2016/07/13 18:58:35]

Done.

+      Value val = Pop(i - 1, sig->GetParam(i - 1));
+      inputs[i - 1] = val.node;
+    }
+    TFNode* node = BUILD(SimdOp, opcode, inputs);
+    Push(GetReturnType(sig), node);
+  }
+
   void DoReturn() {
     int count = static_cast<int>(sig_->return_count());
     TFNode** buffer = nullptr;