X87: [turbofan] Implemented the optional Float32RoundDown operator.

src/compiler/x87/code-generator-x87.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 816 matching lines @@
       __ lea(esp, Operand(esp, kFloatSize));
       break;
     }
     case kX87Float32Abs: {
       __ fstp(0);
       __ fld_s(MemOperand(esp, 0));
       __ fabs();
       __ lea(esp, Operand(esp, kFloatSize));
       break;
     }
+    case kX87Float32Round: {
+      RoundingMode mode =
+          static_cast<RoundingMode>(MiscField::decode(instr->opcode()));
+      // Set the correct round mode in x87 control register
+      __ X87SetRC((mode << 10));
+
+      if (!instr->InputAt(0)->IsDoubleRegister()) {
+        InstructionOperand* input = instr->InputAt(0);
+        USE(input);
+        DCHECK(input->IsDoubleStackSlot());
+        __ fstp(0);
+        __ fld_s(i.InputOperand(0));
+      }
+      __ frndint();
+      __ X87SetRC(0x0000);
+      break;
+    }
     case kX87Float64Add: {
       __ X87SetFPUCW(0x027F);
       __ fstp(0);
       __ fld_d(MemOperand(esp, 0));
       __ fld_d(MemOperand(esp, kDoubleSize));
       __ faddp();
       // Clear stack.
       __ lea(esp, Operand(esp, 2 * kDoubleSize));
       // Restore the default value of control word.
       __ X87SetFPUCW(0x037F);
@@ skipping 1141 matching lines @@
     int padding_size = last_lazy_deopt_pc_ + space_needed - current_pc;
     __ Nop(padding_size);
   }
 }
 
 #undef __
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8