PPC: [turbofan] Optimize loading 64-bit SMIs.

src/compiler/ppc/instruction-selector-ppc.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/compiler/instruction-selector-impl.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/node-properties.h"
 #include "src/ppc/frames-ppc.h"
 
@@ skipping 845 matching lines @@
   VisitPairShift(this, kPPC_ShiftRightPair, node);
 }
 
 void InstructionSelector::VisitWord32PairSar(Node* node) {
   VisitPairShift(this, kPPC_ShiftRightAlgPair, node);
 }
 #endif
 
 #if V8_TARGET_ARCH_PPC64
 void InstructionSelector::VisitWord64Sar(Node* node) {
+  PPCOperandGenerator g(this);
+  Int64BinopMatcher m(node);
+  if (CanCover(m.node(), m.left().node()) && m.left().IsLoad() &&
+      m.right().Is(32)) {
+    // Just load and sign-extend the interesting 4 bytes instead. This happens,
+    // for example, when we're loading and untagging SMIs.
+    BaseWithIndexAndDisplacement64Matcher mleft(m.left().node(), true);
+    if (mleft.matches() && mleft.index() == nullptr) {
+      int64_t offset = 0;
+      Node* displacement = mleft.displacement();
+      if (displacement != nullptr) {
+        Int64Matcher mdisplacement(displacement);
+        DCHECK(mdisplacement.HasValue());
+        offset = mdisplacement.Value();
+      }
+      offset = SmiWordOffset(offset);
+      if (g.CanBeImmediate(offset, kInt16Imm_4ByteAligned)) {
+        Emit(kPPC_LoadWordS32 | AddressingModeField::encode(kMode_MRI),
+             g.DefineAsRegister(node), g.UseRegister(mleft.base()),
+             g.TempImmediate(offset));
+        return;
+      }
+    }
+  }
   VisitRRO(this, kPPC_ShiftRightAlg64, node, kShift64Imm);
 }
 #endif
 
 
 // TODO(mbrandy): Absorb logical-and into rlwinm?
 void InstructionSelector::VisitWord32Ror(Node* node) {
   VisitRRO(this, kPPC_RotRight32, node, kShift32Imm);
 }
 
@@ skipping 1033 matching lines @@
          MachineOperatorBuilder::kFloat64RoundTruncate |
          MachineOperatorBuilder::kFloat64RoundTiesAway |
          MachineOperatorBuilder::kWord32Popcnt |
          MachineOperatorBuilder::kWord64Popcnt;
   // We omit kWord32ShiftIsSafe as s[rl]w use 0x3f as a mask rather than 0x1f.
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8