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

src/x64/lithium-codegen-x64.cc

Index: src/x64/lithium-codegen-x64.cc
diff --git a/src/x64/lithium-codegen-x64.cc b/src/x64/lithium-codegen-x64.cc
index 2d6e4cba33c6ebf86ea0877451657cc7325fcdd5..bb3ab770b358fa76d93690882f5ebbe4e072b76e 100644
--- a/src/x64/lithium-codegen-x64.cc
+++ b/src/x64/lithium-codegen-x64.cc
@@ -1263,10 +1263,26 @@ void LCodeGen::DoDivI(LDivI* instr) {
     }
 
     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);
@@ -1313,11 +1329,7 @@ void LCodeGen::DoDivI(LDivI* instr) {
   __ 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);
@@ -1325,6 +1337,11 @@ void LCodeGen::DoDivI(LDivI* instr) {
     __ 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());
   }
 }