Improve smi shift operations and avoid repeated deoptimizations.

runtime/vm/intermediate_language_ia32.cc

Index: runtime/vm/intermediate_language_ia32.cc
===================================================================
--- runtime/vm/intermediate_language_ia32.cc	(revision 14704)
+++ runtime/vm/intermediate_language_ia32.cc	(working copy)
@@ -1732,15 +1732,13 @@
     summary->set_out(Location::SameAsFirstInput());
     return summary;
   } else if (op_kind() == Token::kSHL) {
-    // Two Smi operands can easily overflow into Mint.
-    const intptr_t kNumTemps = 2;
+    const intptr_t kNumTemps = 1;
     LocationSummary* summary =
-        new LocationSummary(kNumInputs, kNumTemps, LocationSummary::kCall);
-    summary->set_in(0, Location::RegisterLocation(EAX));
-    summary->set_in(1, Location::RegisterLocation(EDX));
-    summary->set_temp(0, Location::RegisterLocation(EBX));
-    summary->set_temp(1, Location::RegisterLocation(ECX));
-    summary->set_out(Location::RegisterLocation(EAX));
+        new LocationSummary(kNumInputs, kNumTemps, LocationSummary::kNoCall);
+    summary->set_in(0, Location::RequiresRegister());
+    summary->set_in(1, Location::FixedRegisterOrConstant(right(), ECX));
+    summary->set_temp(0, Location::RequiresRegister());
+    summary->set_out(Location::SameAsFirstInput());
     return summary;
   } else {
     const intptr_t kNumTemps = 0;
@@ -1822,6 +1820,25 @@
         __ SmiTag(left);
         break;
       }
+      case Token::kSHL: {
+        // shll operation masks the count to 5 bits.
+        const intptr_t kCountLimit = 0x1F;
+        intptr_t value = Smi::Cast(constant).Value();
+        if (value == 0) break;
+        if (value < 0 || value >= kCountLimit) {

[srdjan, 2012/11/08 21:37:27]

Add parenthesis.

+          __ jmp(deopt);

[srdjan, 2012/11/08 21:37:27]

Make a note that this may not be known at instruction creation time (because of
constant propagation, inlining, ...)

[Florian Schneider, 2012/11/08 22:03:00]

Done.

+          break;
+        }
+        Register temp = locs()->temp(0).reg();
+        __ movl(temp, left);
+        __ shll(left, Immediate(value));
+        __ sarl(left, Immediate(value));
+        __ cmpl(left, temp);
+        __ j(NOT_EQUAL, deopt);  // Overflow.
+        // Shift for result now we know there is no overflow.
+        __ shll(left, Immediate(value));
+        break;
+      }
 
       default:
         UNREACHABLE();
@@ -1906,7 +1923,6 @@
     }
     case Token::kSHL: {
       Register temp = locs()->temp(0).reg();
-      Label call_method, done;
       // Check if count too large for handling it inlined.
       __ movl(temp, left);
       Range* right_range = this->right()->definition()->range();
@@ -1915,38 +1931,17 @@
       if (right_needs_check) {
         __ cmpl(right,
           Immediate(reinterpret_cast<int32_t>(Smi::New(Smi::kBits))));
-        __ j(ABOVE_EQUAL, &call_method, Assembler::kNearJump);
+        __ j(ABOVE_EQUAL, deopt);
       }
-      Register right_temp = locs()->temp(1).reg();
-      ASSERT(right_temp == ECX);  // Count must be in ECX
-      __ movl(right_temp, right);
-      __ SmiUntag(right_temp);
+      ASSERT(right == ECX);  // Count must be in ECX
+      __ SmiUntag(right);
       // Overflow test (preserve temp and right);
-      __ shll(left, right_temp);
-      __ sarl(left, right_temp);
+      __ shll(left, right);
+      __ sarl(left, right);
       __ cmpl(left, temp);
-      __ j(NOT_EQUAL, &call_method, Assembler::kNearJump);  // Overflow.
+      __ j(NOT_EQUAL, deopt);  // Overflow.
       // Shift for result now we know there is no overflow.
-      __ shll(left, right_temp);
-      __ jmp(&done);
-      {
-        __ Bind(&call_method);
-        Function& target = Function::ZoneHandle(
-            ic_data()->GetTargetForReceiverClassId(kSmiCid));
-        ASSERT(!target.IsNull());
-        const intptr_t kArgumentCount = 2;
-        __ pushl(temp);
-        __ pushl(right);
-        compiler->GenerateStaticCall(
-            deopt_id(),
-            instance_call()->token_pos(),
-            target,
-            kArgumentCount,
-            Array::Handle(),  // No argument names.
-            locs());
-        ASSERT(result == EAX);
-      }
-      __ Bind(&done);
+      __ shll(left, right);
       break;
     }
     case Token::kDIV: {