[wasm] Int64Lowering of Int64Sub on ia32 and arm.

src/compiler/ia32/code-generator-ia32.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/code-generator.h"
 
 #include "src/ast/scopes.h"
 #include "src/compiler/code-generator-impl.h"
 #include "src/compiler/gap-resolver.h"
 #include "src/compiler/node-matchers.h"
@@ skipping 687 matching lines @@
       }
       __ adc(i.InputRegister(1), Operand(i.InputRegister(3)));
       if (i.OutputRegister(1).code() != i.InputRegister(1).code()) {
         __ Move(i.OutputRegister(1), i.InputRegister(1));
       }
       if (use_temp) {
         __ Move(i.OutputRegister(0), i.TempRegister(0));
       }
       break;
     }
+    case kIA32SubPair: {
+      // i.OutputRegister(0) == i.InputRegister(0) ... left low word.
+      // i.InputRegister(1) ... left high word.
+      // i.InputRegister(2) ... right low word.
+      // i.InputRegister(3) ... right high word.
+      bool use_temp = false;
+      if (i.OutputRegister(0).code() == i.InputRegister(1).code() ||
+          i.OutputRegister(0).code() == i.InputRegister(3).code()) {
+        // We cannot write to the output register directly, because it would
+        // overwrite an input for adc. We have to use the temp register.
+        use_temp = true;
+        __ Move(i.TempRegister(0), i.InputRegister(0));
+        __ sub(i.TempRegister(0), i.InputRegister(2));
+      } else {
+        __ sub(i.OutputRegister(0), i.InputRegister(2));
+      }
+      __ sbb(i.InputRegister(1), Operand(i.InputRegister(3)));
+      if (i.OutputRegister(1).code() != i.InputRegister(1).code()) {
+        __ Move(i.OutputRegister(1), i.InputRegister(1));
+      }
+      if (use_temp) {
+        __ Move(i.OutputRegister(0), i.TempRegister(0));
+      }
+      break;
+    }
     case kIA32ShlPair:
       if (HasImmediateInput(instr, 2)) {
         __ ShlPair(i.InputRegister(1), i.InputRegister(0), i.InputInt6(2));
       } else {
         // Shift has been loaded into CL by the register allocator.
         __ ShlPair_cl(i.InputRegister(1), i.InputRegister(0));
       }
       break;
     case kIA32ShrPair:
       if (HasImmediateInput(instr, 2)) {
@@ skipping 1134 matching lines @@
     int padding_size = last_lazy_deopt_pc_ + space_needed - current_pc;
     __ Nop(padding_size);
   }
 }
 
 #undef __
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8