Skip some conditional deopts for Div/Mul when all uses are truncating

src/ia32/lithium-codegen-ia32.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1326 matching lines @@
     __ mov(result_reg, left_reg);
 
     __ bind(&done);
   }
 }
 
 
 void LCodeGen::DoDivI(LDivI* instr) {
   if (!instr->is_flooring() && instr->hydrogen()->HasPowerOf2Divisor()) {
     Register dividend = ToRegister(instr->left());
-    int32_t divisor =
-        HConstant::cast(instr->hydrogen()->right())->Integer32Value();
+    int32_t divisor = instr->hydrogen()->right()->GetInteger32Constant();
     int32_t test_value = 0;
     int32_t power = 0;
 
     if (divisor > 0) {
       test_value = divisor - 1;
       power = WhichPowerOf2(divisor);
     } else {
       // Check for (0 / -x) that will produce negative zero.
       if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
         __ test(dividend, Operand(dividend));
         DeoptimizeIf(zero, instr->environment());
       }
       // Check for (kMinInt / -1).
       if (divisor == -1 && instr->hydrogen()->CheckFlag(HValue::kCanOverflow)) {
         __ cmp(dividend, kMinInt);
         DeoptimizeIf(zero, instr->environment());
       }
       test_value = - divisor - 1;
       power = WhichPowerOf2(-divisor);
     }
 
     if (test_value != 0) {
-      // Deoptimize if remainder is not 0.
-      __ test(dividend, Immediate(test_value));
-      DeoptimizeIf(not_zero, instr->environment());
-      __ sar(dividend, power);
+      if (instr->hydrogen()->CheckFlag(
+          HInstruction::kAllUsesTruncatingToInt32)) {
+        Label done, negative;
+        __ cmp(dividend, 0);
+        __ j(less, &negative, Label::kNear);
+        __ sar(dividend, power);
+        __ jmp(&done, Label::kNear);
+
+        __ bind(&negative);
+        __ neg(dividend);
+        __ sar(dividend, power);
+        if (divisor > 0) __ neg(dividend);
+        __ bind(&done);
+        return;  // Don't fall through to "__ neg" below.
+      } else {
+        // Deoptimize if remainder is not 0.
+        __ test(dividend, Immediate(test_value));
+        DeoptimizeIf(not_zero, instr->environment());
+        __ sar(dividend, power);
+      }
     }
 
     if (divisor < 0) __ neg(dividend);
 
     return;
   }
 
   LOperand* right = instr->right();
   ASSERT(ToRegister(instr->result()).is(eax));
   ASSERT(ToRegister(instr->left()).is(eax));
@@ skipping 26 matching lines @@
     __ j(not_zero, &left_not_min_int, Label::kNear);
     __ cmp(right_reg, -1);
     DeoptimizeIf(zero, instr->environment());
     __ bind(&left_not_min_int);
   }
 
   // Sign extend to edx.
   __ cdq();
   __ idiv(right_reg);
 
-  if (!instr->is_flooring()) {
-    // Deoptimize if remainder is not 0.
-    __ test(edx, Operand(edx));
-    DeoptimizeIf(not_zero, instr->environment());
-  } else {
+  if (instr->is_flooring()) {
     Label done;
     __ test(edx, edx);
     __ j(zero, &done, Label::kNear);
     __ xor_(edx, right_reg);
     __ sar(edx, 31);
     __ add(eax, edx);
     __ bind(&done);
+  } else if (!instr->hydrogen()->CheckFlag(
+      HInstruction::kAllUsesTruncatingToInt32)) {
+    // Deoptimize if remainder is not 0.
+    __ test(edx, Operand(edx));
+    DeoptimizeIf(not_zero, instr->environment());
   }
 }
 
 
 void LCodeGen::DoMathFloorOfDiv(LMathFloorOfDiv* instr) {
   ASSERT(instr->right()->IsConstantOperand());
 
   Register dividend = ToRegister(instr->left());
   int32_t divisor = ToInteger32(LConstantOperand::cast(instr->right()));
   Register result = ToRegister(instr->result());
@@ skipping 5065 matching lines @@
                               FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32