[wasm] Implement I32x4ReplaceLane, I32x4Add, I32x4Sub.

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 02d1db5bdad3b38998b0fd5b11e75c6202c58eab..0088e111220617023991fce38e61c0014b90b774 100644
--- a/src/wasm/ast-decoder.cc
+++ b/src/wasm/ast-decoder.cc
@@ -1245,16 +1245,33 @@ class WasmFullDecoder : public WasmDecoder {
     return 1 + operand.length;
   }
 
+  uint8_t LaneValue(uint8_t max_lanes) {

[titzer, 2016/10/07 12:20:14]

Maybe you should introduce a LaneOperand, since if we eventually do implement
this in the interpreter, we can use it there, too?

[gdeepti, 2016/11/22 01:15:20]

LaneOperand introduced by ScalarLowering, merged to use here as well. 

+    uint8_t lane = this->checked_read_u8(pc_, 2, "lane number");
+    if (lane < 0 || lane > (max_lanes - 1)) {
+      error(pc_, pc_ + 2, "invalid Simd128 lane value");
+    }
+    return lane;
+  }
+
   unsigned DecodeSimdOpcode(WasmOpcode opcode) {
     unsigned len = 0;
+    static const int kInt32x4MaxLanes = 4;
     switch (opcode) {
+      case kExprI32x4ReplaceLane: {
+        compiler::NodeVector inputs(3, zone_);
+        inputs[2] = Pop(1, LocalType::kWord32).node;
+        inputs[1] = builder_->Int32Constant(LaneValue(kInt32x4MaxLanes));
+        inputs[0] = Pop(0, LocalType::kSimd128).node;
+        TFNode* node = BUILD(SimdOp, opcode, inputs);
+        Push(LocalType::kSimd128, node);
+        len++;
+        break;
+      }
       case kExprI32x4ExtractLane: {
-        uint8_t lane = this->checked_read_u8(pc_, 2, "lane number");
-        if (lane < 0 || lane > 3) {
-          error(pc_, pc_ + 2, "invalid extract lane value");
-        }
-        TFNode* input = Pop(0, LocalType::kSimd128).node;
-        TFNode* node = BUILD(SimdExtractLane, opcode, lane, input);
+        compiler::NodeVector inputs(2, zone_);
+        inputs[1] = builder_->Int32Constant(LaneValue(kInt32x4MaxLanes));
+        inputs[0] = Pop(0, LocalType::kSimd128).node;
+        TFNode* node = BUILD(SimdOp, opcode, inputs);
         Push(LocalType::kWord32, node);
         len++;
         break;