X87: [TurboFan] Change the implementation of Float32's NaN comparision's return value in kX87Float3…

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 726 matching lines @@
     }
     case kX87Float32Max: {
       Label check_nan_left, check_zero, return_left, return_right;
       Condition condition = below;
       __ fstp(0);
       __ fld_s(MemOperand(esp, kFloatSize));
       __ fld_s(MemOperand(esp, 0));
       __ fld(1);
       __ fld(1);
       __ FCmp();
-      __ j(parity_even, &check_nan_left, Label::kNear);  // At least one NaN.
+
+      // At least one NaN.
+      // Return the second operands if one of the two operands is NaN
+      __ j(parity_even, &return_right, Label::kNear);
       __ j(equal, &check_zero, Label::kNear);            // left == right.
       __ j(condition, &return_left, Label::kNear);
       __ jmp(&return_right, Label::kNear);
 
       __ bind(&check_zero);
       __ fld(0);
       __ fldz();
       __ FCmp();
       __ j(not_equal, &return_left, Label::kNear);  // left == right != 0.
 
       __ fadd(1);
       __ jmp(&return_left, Label::kNear);
 
-      __ bind(&check_nan_left);
-      __ fld(0);
-      __ fld(0);
-      __ FCmp();                                      // NaN check.
-      __ j(parity_even, &return_left, Label::kNear);  // left == NaN.
-
       __ bind(&return_right);
       __ fxch();
 
       __ bind(&return_left);
       __ fstp(0);
       __ lea(esp, Operand(esp, 2 * kFloatSize));
       break;
     }
     case kX87Float32Min: {
       Label check_nan_left, check_zero, return_left, return_right;
       Condition condition = above;
       __ fstp(0);
       __ fld_s(MemOperand(esp, kFloatSize));
       __ fld_s(MemOperand(esp, 0));
       __ fld(1);
       __ fld(1);
       __ FCmp();
-      __ j(parity_even, &check_nan_left, Label::kNear);  // At least one NaN.
+      // At least one NaN.
+      // Return the second operands if one of the two operands is NaN
+      __ j(parity_even, &return_right, Label::kNear);
       __ j(equal, &check_zero, Label::kNear);            // left == right.
       __ j(condition, &return_left, Label::kNear);
       __ jmp(&return_right, Label::kNear);
 
       __ bind(&check_zero);
       __ fld(0);
       __ fldz();
       __ FCmp();
       __ j(not_equal, &return_left, Label::kNear);  // left == right != 0.
       // At this point, both left and right are either 0 or -0.
       // Push st0 and st1 to stack, then pop them to temp registers and OR them,
       // load it to left.
       __ push(eax);
       __ fld(1);
       __ fld(1);
       __ sub(esp, Immediate(2 * kPointerSize));
       __ fstp_s(MemOperand(esp, 0));
       __ fstp_s(MemOperand(esp, kPointerSize));
       __ pop(eax);
       __ xor_(MemOperand(esp, 0), eax);
       __ fstp(0);
       __ fld_s(MemOperand(esp, 0));
       __ pop(eax);  // restore esp
       __ pop(eax);  // restore esp
       __ jmp(&return_left, Label::kNear);
 
-      __ bind(&check_nan_left);
-      __ fld(0);
-      __ fld(0);
-      __ FCmp();                                      // NaN check.
-      __ j(parity_even, &return_left, Label::kNear);  // left == NaN.
 
       __ bind(&return_right);
       __ fxch();
 
       __ bind(&return_left);
       __ fstp(0);
       __ lea(esp, Operand(esp, 2 * kFloatSize));
       break;
     }
     case kX87Float32Sqrt: {
@@ skipping 1181 matching lines @@
     int padding_size = last_lazy_deopt_pc_ + space_needed - current_pc;
     __ Nop(padding_size);
   }
 }
 
 #undef __
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8