[wasm] Int64Lowering of Int64Mul on ia32 and arm.

src/compiler/ia32/instruction-selector-ia32.cc

Index: src/compiler/ia32/instruction-selector-ia32.cc
diff --git a/src/compiler/ia32/instruction-selector-ia32.cc b/src/compiler/ia32/instruction-selector-ia32.cc
index d1e789dff947f12681ba611ebaf04cbb5eafb724..6cb30b8cb70a3f5e7a24d9bb529cd65d9027df14 100644
--- a/src/compiler/ia32/instruction-selector-ia32.cc
+++ b/src/compiler/ia32/instruction-selector-ia32.cc
@@ -620,6 +620,24 @@ void InstructionSelector::VisitInt32PairSub(Node* node) {
   Emit(kIA32SubPair, 2, outputs, 4, inputs, 1, temps);
 }
 
+void InstructionSelector::VisitInt32PairMul(Node* node) {
+  IA32OperandGenerator g(this);
+
+  // InputAt(3) explicitly shares ecx with OutputRegister(1) to save one
+  // register and one mov instruction.
+  InstructionOperand inputs[] = {
+      g.UseUnique(node->InputAt(0)), g.UseUnique(node->InputAt(1)),
+      g.UseUniqueRegister(node->InputAt(2)), g.UseFixed(node->InputAt(3), ecx)};
+
+  InstructionOperand outputs[] = {
+      g.DefineAsFixed(node, eax),
+      g.DefineAsFixed(NodeProperties::FindProjection(node, 1), ecx)};
+
+  InstructionOperand temps[] = {g.TempRegister(edx)};
+
+  Emit(kIA32MulPair, 2, outputs, 4, inputs, 1, temps);
+}
+
 void InstructionSelector::VisitWord32PairShl(Node* node) {
   IA32OperandGenerator g(this);