Faster 64-bit right-shift for the ia32 compiler.

runtime/vm/flow_graph_optimizer.cc

Index: runtime/vm/flow_graph_optimizer.cc
===================================================================
--- runtime/vm/flow_graph_optimizer.cc	(revision 13286)
+++ runtime/vm/flow_graph_optimizer.cc	(working copy)
@@ -148,7 +148,8 @@
     if (join_entry->phis() != NULL) {
       for (intptr_t i = 0; i < join_entry->phis()->length(); ++i) {
         PhiInstr* phi = (*join_entry->phis())[i];
-        if ((phi != NULL) && (phi->GetPropagatedCid() == kDoubleCid)) {
+        if (phi == NULL) continue;
+        if (phi->GetPropagatedCid() == kDoubleCid) {
           phi->set_representation(kUnboxedDouble);
         }
       }
@@ -520,8 +521,17 @@
         return false;
       }
       break;
+    case Token::kSHR:
+      if (HasOnlyTwoSmi(ic_data)) {

[Kevin Millikin (Google), 2012/10/05 12:52:58]

Should really be ...TwoSmis.

[Florian Schneider, 2012/10/05 14:40:31]

Done.

+        operands_type = kSmiCid;
+      } else if (HasTwoMintOrSmi(ic_data) &&
+                 FlowGraphCompiler::SupportsUnboxedMints()) {
+        operands_type = kMintCid;
+      } else {
+        return false;
+      }
+      break;
     case Token::kTRUNCDIV:
-    case Token::kSHR:
     case Token::kSHL:
       if (HasOnlyTwoSmi(ic_data)) {
         operands_type = kSmiCid;
@@ -554,9 +564,15 @@
   } else if (operands_type == kMintCid) {
     Value* left = call->ArgumentAt(0)->value();
     Value* right = call->ArgumentAt(1)->value();
-    BinaryMintOpInstr* bin_op =
-        new BinaryMintOpInstr(op_kind, left, right, call);
-    call->ReplaceWith(bin_op, current_iterator());
+    if (op_kind == Token::kSHR) {
+      ShiftMintOpInstr* shift_op =
+          new ShiftMintOpInstr(op_kind, left, right, call);
+      call->ReplaceWith(shift_op, current_iterator());
+    } else {
+      BinaryMintOpInstr* bin_op =
+          new BinaryMintOpInstr(op_kind, left, right, call);
+      call->ReplaceWith(bin_op, current_iterator());
+    }
     RemovePushArguments(call);
   } else if (op_kind == Token::kMOD) {
     // TODO(vegorov): implement fast path code for modulo.
@@ -2983,6 +2999,13 @@
 }
 
 
+void ConstantPropagator::VisitShiftMintOp(
+    ShiftMintOpInstr* instr) {
+  // TODO(kmillikin): Handle shift operations.
+  SetValue(instr, non_constant_);
+}
+
+
 void ConstantPropagator::VisitUnaryMintOp(
     UnaryMintOpInstr* instr) {
   // TODO(kmillikin): Handle unary operations.