[turbofan] Remove minus zero check for rhs of CheckedInt32Sub.

test/cctest/compiler/test-representation-change.cc

 // Copyright 2014 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 <limits>
 
 #include "test/cctest/cctest.h"
 #include "test/cctest/compiler/codegen-tester.h"
 #include "test/cctest/compiler/graph-builder-tester.h"
 #include "test/cctest/compiler/value-helper.h"
@@ skipping 425 matching lines @@
       Node* use = r.Return(n);
       Node* c = r.changer()->GetRepresentationFor(
           n, MachineRepresentation::kTagged, Type::Unsigned32(), use,
           UseInfo(MachineRepresentation::kWord32, Truncation::None()));
       r.CheckUint32Constant(c, *i);
     }
   }
 }
 
 static void CheckChange(IrOpcode::Value expected, MachineRepresentation from,
+                        Type* from_type, UseInfo use_info) {
+  RepresentationChangerTester r;
+
+  Node* n = r.Parameter();
+  Node* use = r.Return(n);
+  Node* c =
+      r.changer()->GetRepresentationFor(n, from, from_type, use, use_info);
+
+  CHECK_NE(c, n);
+  CHECK_EQ(expected, c->opcode());
+  CHECK_EQ(n, c->InputAt(0));
+
+  if (expected == IrOpcode::kCheckedFloat64ToInt32) {
+    CheckForMinusZeroMode mode =
+        from_type->Maybe(Type::MinusZero())
+            ? use_info.minus_zero_check()
+            : CheckForMinusZeroMode::kDontCheckForMinusZero;
+    CHECK_EQ(mode, CheckMinusZeroModeOf(c->op()));
+  }
+}
+
+static void CheckChange(IrOpcode::Value expected, MachineRepresentation from,
                         Type* from_type, MachineRepresentation to) {
-  RepresentationChangerTester r;
-
-  Node* n = r.Parameter();
-  Node* use = r.Return(n);
-  Node* c = r.changer()->GetRepresentationFor(n, from, from_type, use,
-                                              UseInfo(to, Truncation::None()));
-
-  CHECK_NE(c, n);
-  CHECK_EQ(expected, c->opcode());
-  CHECK_EQ(n, c->InputAt(0));
+  CheckChange(expected, from, from_type, UseInfo(to, Truncation::None()));
 }
 
-
 static void CheckTwoChanges(IrOpcode::Value expected2,
                             IrOpcode::Value expected1,
                             MachineRepresentation from, Type* from_type,
                             MachineRepresentation to) {
   RepresentationChangerTester r;
 
   Node* n = r.Parameter();
   Node* use = r.Return(n);
   Node* c1 = r.changer()->GetRepresentationFor(n, from, from_type, use,
                                                UseInfo(to, Truncation::None()));
@@ skipping 127 matching lines @@
   CheckTwoChanges(IrOpcode::kChangeInt32ToFloat64,
                   IrOpcode::kTruncateFloat64ToFloat32,
                   MachineRepresentation::kWord32, Type::Signed32(),
                   MachineRepresentation::kFloat32);
   CheckTwoChanges(IrOpcode::kChangeFloat32ToFloat64,
                   IrOpcode::kTruncateFloat64ToWord32,
                   MachineRepresentation::kFloat32, Type::Number(),
                   MachineRepresentation::kWord32);
 }
 
+static void TestMinusZeroCheck(IrOpcode::Value expected, Type* from_type) {
+  RepresentationChangerTester r;
+
+  CheckChange(expected, MachineRepresentation::kFloat64, from_type,
+              UseInfo::CheckedSignedSmallAsWord32(
+                  CheckForMinusZeroMode::kCheckForMinusZero));
+
+  CheckChange(expected, MachineRepresentation::kFloat64, from_type,
+              UseInfo::CheckedSignedSmallAsWord32(
+                  CheckForMinusZeroMode::kDontCheckForMinusZero));
+
+  CheckChange(expected, MachineRepresentation::kFloat64, from_type,
+              UseInfo::CheckedSigned32AsWord32(
+                  CheckForMinusZeroMode::kCheckForMinusZero));
+
+  CheckChange(expected, MachineRepresentation::kFloat64, from_type,
+              UseInfo::CheckedSigned32AsWord32(
+                  CheckForMinusZeroMode::kDontCheckForMinusZero));
+}
+
+TEST(MinusZeroCheck) {
+  TestMinusZeroCheck(IrOpcode::kCheckedFloat64ToInt32, Type::NumberOrOddball());
+  // PlainNumber cannot be minus zero so the minus zero check should be
+  // eliminated.
+  TestMinusZeroCheck(IrOpcode::kCheckedFloat64ToInt32, Type::PlainNumber());
+}
 
 TEST(Nops) {
   RepresentationChangerTester r;
 
   // X -> X is always a nop for any single representation X.
   for (size_t i = 0; i < arraysize(kMachineTypes); i++) {
     r.CheckNop(kMachineTypes[i].representation(), Type::Number(),
                kMachineTypes[i].representation());
   }
 
@@ skipping 51 matching lines @@
                    MachineRepresentation::kWord64);
   r.CheckTypeError(MachineRepresentation::kWord32, Type::Signed32(),
                    MachineRepresentation::kWord64);
   r.CheckTypeError(MachineRepresentation::kWord32, Type::Unsigned32(),
                    MachineRepresentation::kWord64);
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8