[turbofan] Allow truncating minus zero in add, sub, mul if we have word32 truncation.

Review-Url: https://codereview.chromium.org/2080093002
Cr-Commit-Position: refs/heads/master@{#37080}

src/compiler/simplified-lowering.cc

@@ -1056,7 +1056,7 @@ class RepresentationSelector {
     }
 
     // Use truncation if available.
-    if (BothInputsAre(node, type_cache_.kAdditiveSafeInteger) &&
+    if (BothInputsAre(node, type_cache_.kAdditiveSafeIntegerOrMinusZero) &&
         truncation.TruncatesToWord32()) {
       // safe-int + safe-int = x (truncated to int32)
       // => signed Int32Add/Sub (truncated)
@@ -1282,7 +1282,8 @@ class RepresentationSelector {
           // => signed Int32Add/Sub
           VisitInt32Binop(node);
           if (lower()) NodeProperties::ChangeOp(node, Int32Op(node));
-        } else if (BothInputsAre(node, type_cache_.kAdditiveSafeInteger) &&
+        } else if (BothInputsAre(node,
+                                 type_cache_.kAdditiveSafeIntegerOrMinusZero) &&
                    truncation.TruncatesToWord32()) {
           // safe-int + safe-int = x (truncated to int32)
           // => signed Int32Add/Sub (truncated)
@@ -1305,7 +1306,8 @@ class RepresentationSelector {
             return;
           }
           if (truncation.TruncatesToWord32() &&
-              NodeProperties::GetType(node)->Is(type_cache_.kSafeInteger)) {
+              NodeProperties::GetType(node)->Is(
+                  type_cache_.kSafeIntegerOrMinusZero)) {
             // Multiply reduces to Int32Mul if the inputs are integers,
             // the uses are truncating and the result is in the safe
             // integer range.

src/type-cache.h

@@ -57,6 +57,10 @@ class TypeCache final {
   Type* const kAdditiveSafeInteger =
       CreateRange(-4503599627370496.0, 4503599627370496.0);
   Type* const kSafeInteger = CreateRange(-kMaxSafeInteger, kMaxSafeInteger);
+  Type* const kAdditiveSafeIntegerOrMinusZero =
+      Type::Union(kAdditiveSafeInteger, Type::MinusZero(), zone());
+  Type* const kSafeIntegerOrMinusZero =
+      Type::Union(kSafeInteger, Type::MinusZero(), zone());
   Type* const kPositiveSafeInteger = CreateRange(0.0, kMaxSafeInteger);
 
   Type* const kUntaggedUndefined =