Emit VMLS for multiply-subtract on ARM.

src/arm/simulator-arm.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2765 matching lines @@
     } else if ((instr->Opc1Value() == 0x2) && !(instr->Opc3Value() & 0x1)) {
       // vmul
       if (instr->SzValue() != 0x1) {
         UNREACHABLE();  // Not used by V8.
       }
 
       double dn_value = get_double_from_d_register(vn);
       double dm_value = get_double_from_d_register(vm);
       double dd_value = dn_value * dm_value;
       set_d_register_from_double(vd, dd_value);
-    } else if ((instr->Opc1Value() == 0x0) && !(instr->Opc3Value() & 0x1)) {
-      // vmla
+    } else if ((instr->Opc1Value() == 0x0)) {
+      // vmla, vmls
+      const bool is_vmls = (instr->Opc3Value() & 0x1);
+
       if (instr->SzValue() != 0x1) {
         UNREACHABLE();  // Not used by V8.
       }
 
-      double dd_value = get_double_from_d_register(vd);
-      double dn_value = get_double_from_d_register(vn);
-      double dm_value = get_double_from_d_register(vm);
+      const double dd_val = get_double_from_d_register(vd);
+      const double dn_val = get_double_from_d_register(vn);
+      const double dm_val = get_double_from_d_register(vm);
 
-      // Note: we do the mul and add in separate steps to avoid getting a result
-      // with too high precision.
-      set_d_register_from_double(vd, dn_value * dm_value);
-      set_d_register_from_double(vd, get_double_from_d_register(vd) + dd_value);
+      // Note: we do the mul and add/sub in separate steps to avoid getting a
+      // result with too high precision.
+      set_d_register_from_double(vd, dn_val * dm_val);
+      if (is_vmls) {
+        set_d_register_from_double(vd, dd_val - get_double_from_d_register(vd));
+      } else {
+        set_d_register_from_double(vd, dd_val + get_double_from_d_register(vd));
+      }
     } else if ((instr->Opc1Value() == 0x4) && !(instr->Opc3Value() & 0x1)) {
       // vdiv
       if (instr->SzValue() != 0x1) {
         UNREACHABLE();  // Not used by V8.
       }
 
       double dn_value = get_double_from_d_register(vn);
       double dm_value = get_double_from_d_register(vm);
       double dd_value = dn_value / dm_value;
       div_zero_vfp_flag_ = (dm_value == 0);
@@ skipping 650 matching lines @@
   uintptr_t address = *stack_slot;
   set_register(sp, current_sp + sizeof(uintptr_t));
   return address;
 }
 
 } }  // namespace v8::internal
 
 #endif  // USE_SIMULATOR
 
 #endif  // V8_TARGET_ARCH_ARM