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

runtime/vm/intermediate_language_mips.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_MIPS.
 #if defined(TARGET_ARCH_MIPS)
 
 #include "vm/intermediate_language.h"
 
 #include "vm/dart_entry.h"
@@ skipping 2461 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) {
         __ addu(result, left, right);
       } else {
         Register temp = locs()->temp(0).reg();
         __ AdduDetectOverflow(result, left, right, CMPRES1, temp);
         __ bltz(CMPRES1, deopt);
       }
       break;
@@ skipping 29 matching lines @@
       // No overflow check.
       __ or_(result, left, right);
       break;
     }
     case Token::kBIT_XOR: {
       // No overflow check.
       __ xor_(result, left, right);
       break;
     }
     case Token::kTRUNCDIV: {
-      // Handle divide by zero in runtime.
-      __ beq(right, ZR, deopt);
+      if ((right_range == NULL) || right_range->IsWithin(0, 0)) {
+        // Handle divide by zero in runtime.
+        __ beq(right, ZR, deopt);
+      }
       Register temp = locs()->temp(0).reg();
       __ sra(temp, left, kSmiTagSize);  // SmiUntag left into temp.
       __ sra(TMP, right, kSmiTagSize);  // SmiUntag right into TMP.
       __ div(temp, TMP);
       __ mflo(result);
       // Check the corner case of dividing the 'MIN_SMI' with -1, in which
       // case we cannot tag the result.
       __ BranchEqual(result, 0x40000000, deopt);
       __ SmiTag(result);
       break;
     }
     case Token::kMOD: {
-      // Handle divide by zero in runtime.
-      __ beq(right, ZR, deopt);
+      if ((right_range == NULL) || right_range->IsWithin(0, 0)) {
+        // Handle divide by zero in runtime.
+        __ beq(right, ZR, deopt);
+      }
       Register temp = locs()->temp(0).reg();
       __ sra(temp, left, kSmiTagSize);  // SmiUntag left into temp.
       __ sra(TMP, right, kSmiTagSize);  // SmiUntag right into TMP.
       __ div(temp, TMP);
       __ mfhi(result);
       //  res = left % right;
       //  if (res < 0) {
       //    if (right < 0) {
       //      res = res - right;
       //    } else {
       //      res = res + right;
       //    }
       //  }
-      Label done, subtract;
-      __ bgez(result, &done);
-      __ bltz(right, &subtract);
-      __ addu(result, result, TMP);
-      __ b(&done);
-      __ Bind(&subtract);
-      __ subu(result, result, TMP);
+      Label done;
+      if ((right_range == NULL) || right_range->IsWithin(-1, 1)) {
+        Label subtract;
+        __ bgez(result, &done);
+        __ bltz(right, &subtract);
+        __ addu(result, result, TMP);
+        __ b(&done);
+        __ Bind(&subtract);
+        __ subu(result, result, TMP);
+      } else if (right_range->IsWithin(0, RangeBoundary::kPlusInfinity)) {
+        // Right is positive.
+        __ addu(result, result, TMP);
+      } else {
+        // Right is negative.
+        __ subu(result, result, TMP);
+      }
       __ Bind(&done);
       __ SmiTag(result);
       break;
     }
     case Token::kSHR: {
       Register temp = locs()->temp(0).reg();
       if (CanDeoptimize()) {
         __ bltz(right, deopt);
       }
       __ sra(temp, right, kSmiTagSize);  // SmiUntag right into temp.
       // sra 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)) {
         Label ok;
         __ BranchSignedLessEqual(temp, kCountLimit, &ok);
         __ LoadImmediate(temp, kCountLimit);
         __ Bind(&ok);
       }
 
       __ sra(CMPRES1, left, kSmiTagSize);  // SmiUntag left into CMPRES1.
       __ srav(result, CMPRES1, temp);
@@ skipping 831 matching lines @@
   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();
     Register temp = locs()->temp(0).reg();
     Register result_div = locs()->temp(1).reg();
     Register result_mod = locs()->temp(2).reg();
-    // Handle divide by zero in runtime.
-    __ beq(right, ZR, deopt);
+    Range* right_range = InputAt(1)->definition()->range();
+    if ((right_range == NULL) || right_range->IsWithin(0, 0)) {
+      // Handle divide by zero in runtime.
+      __ beq(right, ZR, deopt);
+    }
     __ sra(temp, left, kSmiTagSize);  // SmiUntag left into temp.
     __ sra(TMP, right, kSmiTagSize);  // SmiUntag right into TMP.
     __ div(temp, TMP);
     __ mflo(result_div);
     __ mfhi(result_mod);
     // Check the corner case of dividing the 'MIN_SMI' with -1, in which
     // case we cannot tag the result.
     __ BranchEqual(result_div, 0x40000000, deopt);
     //  res = left % right;
     //  if (res < 0) {
     //    if (right < 0) {
     //      res = res - right;
     //    } else {
     //      res = res + right;
     //    }
     //  }
-    Label done, subtract;
+    Label done;
     __ bgez(result_mod, &done);
-    __ bltz(right, &subtract);
-    __ addu(result_mod, result_mod, TMP);
-    __ b(&done);
-    __ Bind(&subtract);
-    __ subu(result_mod, result_mod, TMP);
+    if ((right_range == NULL) || right_range->IsWithin(-1, 1)) {
+      Label subtract;
+      __ bltz(right, &subtract);
+      __ addu(result_mod, result_mod, TMP);
+      __ b(&done);
+      __ Bind(&subtract);
+      __ subu(result_mod, result_mod, TMP);
+    } else if (right_range->IsWithin(0, RangeBoundary::kPlusInfinity)) {
+      // Right is positive.
+      __ addu(result_mod, result_mod, TMP);
+    } else {
+      // Right is negative.
+      __ subu(result_mod, result_mod, TMP);
+    }
     __ Bind(&done);
 
     __ SmiTag(result_div);
     __ SmiTag(result_mod);
     __ LoadObject(result, Array::ZoneHandle(Array::New(2, Heap::kOld)));
     // Note that index is expected smi-tagged, (i.e, times 2) for all arrays.
     // [0]: divide resut, [1]: mod result.
     __ LoadImmediate(temp,
         FlowGraphCompiler::DataOffsetFor(kArrayCid) - kHeapObjectTag);
     __ addu(temp, result, temp);
@@ skipping 505 matching lines @@
   compiler->GenerateCall(token_pos(),
                          &label,
                          PcDescriptors::kOther,
                          locs());
   __ Drop(2);  // Discard type arguments and receiver.
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_MIPS