[turbofan] Avoid -0 checks for truncating word32 uses.

The CheckBounds operator identifies zeros, but we ignore these bits in
the representation selector, which generates unnecessary -0 checks for
array accesses.

R=jarin@chromium.org
BUG=v8:5267

Review-Url: https://codereview.chromium.org/2823203002
Cr-Commit-Position: refs/heads/master@{#44680}

src/compiler/representation-change.cc

@@ -654,7 +654,7 @@ Node* RepresentationChanger::GetWord32RepresentationFor(
                use_info.type_check() == TypeCheckKind::kSigned32) {
       op = simplified()->CheckedFloat64ToInt32(
           output_type->Maybe(Type::MinusZero())
-              ? CheckForMinusZeroMode::kCheckForMinusZero
+              ? use_info.minus_zero_check()
               : CheckForMinusZeroMode::kDontCheckForMinusZero);
     } else if (output_type->Is(Type::Unsigned32())) {
       op = machine()->ChangeFloat64ToUint32();
@@ -686,7 +686,7 @@ Node* RepresentationChanger::GetWord32RepresentationFor(
     } else if (use_info.type_check() == TypeCheckKind::kSigned32) {
       op = simplified()->CheckedTaggedToInt32(
           output_type->Maybe(Type::MinusZero())
-              ? CheckForMinusZeroMode::kCheckForMinusZero
+              ? use_info.minus_zero_check()
               : CheckForMinusZeroMode::kDontCheckForMinusZero);
     } else if (output_type->Is(Type::Unsigned32())) {
       op = simplified()->ChangeTaggedToUint32();

src/compiler/representation-change.h

@@ -198,8 +198,8 @@ class UseInfo {
                    TypeCheckKind::kSignedSmall);
   }
   static UseInfo CheckedSigned32AsWord32(IdentifyZeros identify_zeros) {
-    return UseInfo(MachineRepresentation::kWord32, Truncation::Any(),
-                   TypeCheckKind::kSigned32);
+    return UseInfo(MachineRepresentation::kWord32,
+                   Truncation::Any(identify_zeros), TypeCheckKind::kSigned32);
   }
   static UseInfo CheckedNumberAsFloat64() {
     return UseInfo(MachineRepresentation::kFloat64, Truncation::Float64(),