[turbofan] Implemented the optional Float32RoundDown operator.

src/arm/assembler-arm.cc

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // 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.
 //
@@ skipping 3386 matching lines @@
   DCHECK(CpuFeatures::IsSupported(ARMv8));
   int vd, d;
   dst.split_code(&vd, &d);
   int vm, m;
   src.split_code(&vm, &m);
   emit(kSpecialCondition | 0x1D * B23 | d * B22 | 0x3 * B20 | B19 | 0x2 * B16 |
        vd * B12 | 0x5 * B9 | B8 | B6 | m * B5 | vm);
 }
 
 
+void Assembler::vrintm(const SwVfpRegister dst, const SwVfpRegister src) {
+  // cond=kSpecialCondition(31-28) | 11101(27-23)| D(22) | 11(21-20) |
+  // 10(19-18) | RM=11(17-16) |  Vd(15-12) | 101(11-9) | sz=0(8) | 01(7-6) |
+  // M(5) | 0(4) | Vm(3-0)
+  DCHECK(CpuFeatures::IsSupported(ARMv8));
+  int vd, d;
+  dst.split_code(&vd, &d);
+  int vm, m;
+  src.split_code(&vm, &m);
+  emit(kSpecialCondition | 0x1D * B23 | d * B22 | 0x3 * B20 | B19 | 0x3 * B16 |
+       vd * B12 | 0x5 * B9 | B6 | m * B5 | vm);
+}
+
+
 void Assembler::vrintm(const DwVfpRegister dst, const DwVfpRegister src) {
   // cond=kSpecialCondition(31-28) | 11101(27-23)| D(22) | 11(21-20) |
   // 10(19-18) | RM=11(17-16) |  Vd(15-12) | 101(11-9) | sz=1(8) | 01(7-6) |
   // M(5) | 0(4) | Vm(3-0)
   DCHECK(CpuFeatures::IsSupported(ARMv8));
   int vd, d;
   dst.split_code(&vd, &d);
   int vm, m;
   src.split_code(&vm, &m);
   emit(kSpecialCondition | 0x1D * B23 | d * B22 | 0x3 * B20 | B19 | 0x3 * B16 |
@@ skipping 622 matching lines @@
     DCHECK(is_uint12(offset));
     instr_at_put(pc, SetLdrRegisterImmediateOffset(instr, offset));
   }
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_ARM