MIPS: [turbofan] Optimize Float32 to Int32 rep. changes with Float32 round ops.

src/compiler/mips64/instruction-selector-mips64.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 "src/base/adapters.h"
 #include "src/base/bits.h"
 #include "src/compiler/instruction-selector-impl.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/node-properties.h"
 
@@ skipping 819 matching lines @@
         return;
       case IrOpcode::kFloat64RoundTiesEven:
         Emit(kMips64RoundWD, g.DefineAsRegister(node),
              g.UseRegister(value->InputAt(0)));
         return;
       case IrOpcode::kFloat64RoundTruncate:
         Emit(kMips64TruncWD, g.DefineAsRegister(node),
              g.UseRegister(value->InputAt(0)));
         return;
       default:
-        VisitRR(this, kMips64TruncWD, node);
+        break;
+    }
+    if (value->opcode() == IrOpcode::kChangeFloat32ToFloat64) {
+      Node* next = value->InputAt(0);
+      if (CanCover(value, next)) {
+        // Match ChangeFloat64ToInt32(ChangeFloat32ToFloat64(Float64Round##OP))
+        switch (next->opcode()) {
+          case IrOpcode::kFloat32RoundDown:
+            Emit(kMips64FloorWS, g.DefineAsRegister(node),
+                 g.UseRegister(next->InputAt(0)));
+            return;
+          case IrOpcode::kFloat32RoundUp:
+            Emit(kMips64CeilWS, g.DefineAsRegister(node),
+                 g.UseRegister(next->InputAt(0)));
+            return;
+          case IrOpcode::kFloat32RoundTiesEven:
+            Emit(kMips64RoundWS, g.DefineAsRegister(node),
+                 g.UseRegister(next->InputAt(0)));
+            return;
+          case IrOpcode::kFloat32RoundTruncate:
+            Emit(kMips64TruncWS, g.DefineAsRegister(node),
+                 g.UseRegister(next->InputAt(0)));
+            return;
+          default:
+            Emit(kMips64TruncWS, g.DefineAsRegister(node),
+                 g.UseRegister(value->InputAt(0)));
+            return;
+        }
+      } else {
+        // Match float32 -> float64 -> int32 representation change path.
+        Emit(kMips64TruncWS, g.DefineAsRegister(node),
+             g.UseRegister(value->InputAt(0)));
         return;
+      }
     }
   }
   VisitRR(this, kMips64TruncWD, node);
 }
 
 
 void InstructionSelector::VisitChangeFloat64ToUint32(Node* node) {
   VisitRR(this, kMips64TruncUwD, node);
 }
 
@@ skipping 74 matching lines @@
       default:
         break;
     }
   }
   Emit(kMips64Ext, g.DefineAsRegister(node), g.UseRegister(node->InputAt(0)),
        g.TempImmediate(0), g.TempImmediate(32));
 }
 
 
 void InstructionSelector::VisitTruncateFloat64ToFloat32(Node* node) {
+  Mips64OperandGenerator g(this);
+  Node* value = node->InputAt(0);
+  // Match TruncateFloat64ToFloat32(ChangeInt32ToFloat64) to corresponding
+  // instruction.
+  if (CanCover(node, value) &&
+      value->opcode() == IrOpcode::kChangeInt32ToFloat64) {
+    Emit(kMips64CvtSW, g.DefineAsRegister(node),
+         g.UseRegister(value->InputAt(0)));
+    return;
+  }
   VisitRR(this, kMips64CvtSD, node);
 }
 
 
 void InstructionSelector::VisitTruncateFloat64ToInt32(Node* node) {
   switch (TruncationModeOf(node->op())) {
     case TruncationMode::kJavaScript:
       return VisitRR(this, kArchTruncateDoubleToI, node);
     case TruncationMode::kRoundToZero:
       return VisitRR(this, kMips64TruncWD, node);
@@ skipping 820 matching lines @@
          MachineOperatorBuilder::kFloat32RoundUp |
          MachineOperatorBuilder::kFloat64RoundTruncate |
          MachineOperatorBuilder::kFloat32RoundTruncate |
          MachineOperatorBuilder::kFloat64RoundTiesEven |
          MachineOperatorBuilder::kFloat32RoundTiesEven;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8