Use range information to omit checks in TRUNCDIV/MOD operations.

runtime/vm/intermediate_language_arm.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_ARM.
 #if defined(TARGET_ARCH_ARM)
 
 #include "vm/intermediate_language.h"
 
 #include "vm/dart_entry.h"
@@ skipping 2362 matching lines @@
       }
 
       default:
         UNREACHABLE();
         break;
     }
     return;
   }
 
   Register right = locs()->in(1).reg();
+  Range* right_range = this->right()->definition()->range();
   switch (op_kind()) {
     case Token::kADD: {
       if (deopt == NULL) {
         __ add(result, left, ShifterOperand(right));
       } else {
         __ adds(result, left, ShifterOperand(right));
         __ b(deopt, VS);
       }
       break;
     }
@@ skipping 27 matching lines @@
       // No overflow check.
       __ orr(result, left, ShifterOperand(right));
       break;
     }
     case Token::kBIT_XOR: {
       // No overflow check.
       __ eor(result, left, ShifterOperand(right));
       break;
     }
     case Token::kTRUNCDIV: {
-      // Handle divide by zero in runtime.
-      __ cmp(right, ShifterOperand(0));
-      __ b(deopt, EQ);
+      if ((right_range == NULL) || right_range->IsWithin(0, 0)) {
+        // Handle divide by zero in runtime.
+        __ cmp(right, ShifterOperand(0));
+        __ b(deopt, EQ);
+      }
       Register temp = locs()->temp(0).reg();
       DRegister dtemp = EvenDRegisterOf(locs()->temp(1).fpu_reg());
       __ Asr(temp, left, kSmiTagSize);  // SmiUntag left into temp.
       __ Asr(IP, right, kSmiTagSize);  // SmiUntag right into IP.
 
       __ IntegerDivide(result, temp, IP, dtemp, DTMP);
 
       // Check the corner case of dividing the 'MIN_SMI' with -1, in which
       // case we cannot tag the result.
       __ CompareImmediate(result, 0x40000000);
       __ b(deopt, EQ);
       __ SmiTag(result);
       break;
     }
     case Token::kMOD: {
-      // Handle divide by zero in runtime.
-      __ cmp(right, ShifterOperand(0));
-      __ b(deopt, EQ);
+      if ((right_range == NULL) || right_range->IsWithin(0, 0)) {
+        // Handle divide by zero in runtime.
+        __ cmp(right, ShifterOperand(0));
+        __ b(deopt, EQ);
+      }
       Register temp = locs()->temp(0).reg();
       DRegister dtemp = EvenDRegisterOf(locs()->temp(1).fpu_reg());
       __ Asr(temp, left, kSmiTagSize);  // SmiUntag left into temp.
       __ Asr(IP, right, kSmiTagSize);  // SmiUntag right into IP.
 
       __ IntegerDivide(result, temp, IP, dtemp, DTMP);
 
       __ Asr(IP, right, kSmiTagSize);  // SmiUntag right into IP.
       __ mls(result, IP, result, temp);  // result <- left - right * result
       __ SmiTag(result);
@@ skipping 16 matching lines @@
       break;
     }
     case Token::kSHR: {
       if (CanDeoptimize()) {
         __ CompareImmediate(right, 0);
         __ b(deopt, LT);
       }
       __ Asr(IP, right, kSmiTagSize);  // SmiUntag right into IP.
       // sarl operation masks the count to 5 bits.
       const intptr_t kCountLimit = 0x1F;
-      Range* right_range = this->right()->definition()->range();
       if ((right_range == NULL) ||
           !right_range->IsWithin(RangeBoundary::kMinusInfinity, kCountLimit)) {
         __ CompareImmediate(IP, kCountLimit);
         __ LoadImmediate(IP, kCountLimit, GT);
       }
       Register temp = locs()->temp(0).reg();
       __ Asr(temp, left, kSmiTagSize);  // SmiUntag left into temp.
       __ Asr(result, temp, IP);
       __ SmiTag(result);
       break;
@@ skipping 1589 matching lines @@
 
 void MergedMathInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   Label* deopt = NULL;
   if (CanDeoptimize()) {
     deopt = compiler->AddDeoptStub(deopt_id(), kDeoptBinarySmiOp);
   }
   if (kind() == MergedMathInstr::kTruncDivMod) {
     Register left = locs()->in(0).reg();
     Register right = locs()->in(1).reg();
     Register result = locs()->out().reg();
-    // Handle divide by zero in runtime.
-    __ cmp(right, ShifterOperand(0));
-    __ b(deopt, EQ);
+    Range* right_range = InputAt(1)->definition()->range();
+    if ((right_range == NULL) || right_range->IsWithin(0, 0)) {
+      // Handle divide by zero in runtime.
+      __ cmp(right, ShifterOperand(0));
+      __ b(deopt, EQ);
+    }
     Register temp = locs()->temp(0).reg();
     DRegister dtemp = EvenDRegisterOf(locs()->temp(1).fpu_reg());
     Register result_div = locs()->temp(2).reg();
     Register result_mod = locs()->temp(3).reg();
     __ Asr(temp, left, kSmiTagSize);  // SmiUntag left into temp.
     __ Asr(IP, right, kSmiTagSize);  // SmiUntag right into IP.
 
     __ IntegerDivide(result_div, temp, IP, dtemp, DTMP);
 
     // Check the corner case of dividing the 'MIN_SMI' with -1, in which
@@ skipping 519 matching lines @@
   compiler->GenerateCall(token_pos(),
                          &label,
                          PcDescriptors::kOther,
                          locs());
   __ Drop(2);  // Discard type arguments and receiver.
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM