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

src/x64/lithium-codegen-x64.cc

 // Copyright 2013 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 1245 matching lines @@
       // Check for (kMinInt / -1).
       if (divisor == -1 && instr->hydrogen()->CheckFlag(HValue::kCanOverflow)) {
         __ cmpl(dividend, Immediate(kMinInt));
         DeoptimizeIf(zero, instr->environment());
       }
       test_value = - divisor - 1;
       power = WhichPowerOf2(-divisor);
     }
 
     if (test_value != 0) {
-      // Deoptimize if remainder is not 0.
-      __ testl(dividend, Immediate(test_value));
-      DeoptimizeIf(not_zero, instr->environment());
-      __ sarl(dividend, Immediate(power));
+      if (instr->hydrogen()->CheckFlag(
+          HInstruction::kAllUsesTruncatingToInt32)) {
+        Label done, negative;
+        __ cmpl(dividend, Immediate(0));
+        __ j(less, &negative, Label::kNear);
+        __ sarl(dividend, Immediate(power));
+        __ jmp(&done, Label::kNear);
+
+        __ bind(&negative);
+        __ negl(dividend);
+        __ sarl(dividend, Immediate(power));
+        if (divisor > 0) __ negl(dividend);
+        __ bind(&done);
+        return;  // Don't fall through to "__ neg" below.
+      } else {
+        // Deoptimize if remainder is not 0.
+        __ testl(dividend, Immediate(test_value));
+        DeoptimizeIf(not_zero, instr->environment());
+        __ sarl(dividend, Immediate(power));
+      }
     }
 
     if (divisor < 0) __ negl(dividend);
 
     return;
   }
 
   LOperand* right = instr->right();
   ASSERT(ToRegister(instr->result()).is(rax));
   ASSERT(ToRegister(instr->left()).is(rax));
@@ skipping 26 matching lines @@
     __ j(not_zero, &left_not_min_int, Label::kNear);
     __ cmpl(right_reg, Immediate(-1));
     DeoptimizeIf(zero, instr->environment());
     __ bind(&left_not_min_int);
   }
 
   // Sign extend to rdx.
   __ cdq();
   __ idivl(right_reg);
 
-  if (!instr->is_flooring()) {
-    // Deoptimize if remainder is not 0.
-    __ testl(rdx, rdx);
-    DeoptimizeIf(not_zero, instr->environment());
-  } else {
+  if (instr->is_flooring()) {
     Label done;
     __ testl(rdx, rdx);
     __ j(zero, &done, Label::kNear);
     __ xorl(rdx, right_reg);
     __ sarl(rdx, Immediate(31));
     __ addl(rax, rdx);
     __ bind(&done);
+  } else if (!instr->hydrogen()->CheckFlag(
+      HInstruction::kAllUsesTruncatingToInt32)) {
+    // Deoptimize if remainder is not 0.
+    __ testl(rdx, rdx);
+    DeoptimizeIf(not_zero, instr->environment());
   }
 }
 
 
 void LCodeGen::DoMulI(LMulI* instr) {
   Register left = ToRegister(instr->left());
   LOperand* right = instr->right();
 
   if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
     __ movl(kScratchRegister, left);
@@ skipping 4268 matching lines @@
                                FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64