[wasm] Int64Lowering of Int64Mul on ia32 and arm.

src/compiler/int64-lowering.cc

Index: src/compiler/int64-lowering.cc
diff --git a/src/compiler/int64-lowering.cc b/src/compiler/int64-lowering.cc
index 9f749224da5f86b48370f324665bf9251909dd5a..fe4a70aed2d5a264d497ef651c7bd9a61ab450de 100644
--- a/src/compiler/int64-lowering.cc
+++ b/src/compiler/int64-lowering.cc
@@ -197,6 +197,12 @@ void Int64Lowering::PrepareReplacements(Node* node) {
       PrepareProjectionReplacements(node);
       break;
     }
+    case IrOpcode::kInt64Mul: {
+      // An Int64Sub node is changed into a Int32PairSub node. The two
+      // outputs of the Int32PairSub will be accessed through projections.
+      PrepareProjectionReplacements(node);
+      break;
+    }
     case IrOpcode::kWord64Or: {
       Node* low_node =
           graph()->NewNode(machine()->Word32Or(), placeholder_, placeholder_);
@@ -491,6 +497,20 @@ void Int64Lowering::LowerNode(Node* node) {
       NodeProperties::ChangeOp(node, machine()->Int32PairSub());
       break;
     }
+    case IrOpcode::kInt64Mul: {
+      DCHECK(node->InputCount() == 2);
+
+      Node* right = node->InputAt(1);
+      node->ReplaceInput(1, GetReplacementLow(right));
+      node->AppendInput(zone(), GetReplacementHigh(right));
+
+      Node* left = node->InputAt(0);
+      node->ReplaceInput(0, GetReplacementLow(left));
+      node->InsertInput(zone(), 1, GetReplacementHigh(left));
+
+      NodeProperties::ChangeOp(node, machine()->Int32PairMul());
+      break;
+    }
     case IrOpcode::kWord64Or: {
       DCHECK(node->InputCount() == 2);
       Node* left = node->InputAt(0);