[turbofan] Pass Truncation::Any() for memory access indices.

For 64-bit indices it's not safe to pass Truncation::Word32() for
indices, as operations will incorrectly truncate the outputs to
32-bit integers. There's also not really a point in not passing
Truncation::Any(), but it might have performance impact (since we
misuse IsUsedAsWord32 in various places).

Bug: v8:8178
Change-Id: Ie33b8e03a82e46e314dfb3f268c74c9356653aec
Reviewed-on: https://chromium-review.googlesource.com/1230653Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56006}

src/compiler/simplified-lowering.cc

@@ -158,10 +158,6 @@ UseInfo UseInfoForBasePointer(const ElementAccess& access) {
   return access.tag() != 0 ? UseInfo::AnyTagged() : UseInfo::Word();
 }
 
-UseInfo UseInfoForIndex() {
-  return UseInfo(MachineType::PointerRepresentation(), Truncation::Word32());
-}
-
 void ReplaceEffectControlUses(Node* node, Node* effect, Node* control) {
   for (Edge edge : node->use_edges()) {
     if (NodeProperties::IsControlEdge(edge)) {
@@ -2429,11 +2425,11 @@ class RepresentationSelector {
                           MachineRepresentation::kTaggedPointer);
       }
       case IrOpcode::kStringCharCodeAt: {
-        return VisitBinop(node, UseInfo::AnyTagged(), UseInfoForIndex(),
+        return VisitBinop(node, UseInfo::AnyTagged(), UseInfo::Word(),
                           MachineRepresentation::kWord32);
       }
       case IrOpcode::kStringCodePointAt: {
-        return VisitBinop(node, UseInfo::AnyTagged(), UseInfoForIndex(),
+        return VisitBinop(node, UseInfo::AnyTagged(), UseInfo::Word(),
                           MachineRepresentation::kTaggedSigned);
       }
       case IrOpcode::kStringFromSingleCharCode: {
@@ -2567,7 +2563,7 @@ class RepresentationSelector {
       }
 
       case IrOpcode::kAllocate: {
-        ProcessInput(node, 0, UseInfoForIndex());
+        ProcessInput(node, 0, UseInfo::Word());
         ProcessRemainingInputs(node, 1);
         SetOutput(node, MachineRepresentation::kTaggedPointer);
         return;
@@ -2619,7 +2615,7 @@ class RepresentationSelector {
       case IrOpcode::kLoadElement: {
         if (truncation.IsUnused()) return VisitUnused(node);
         ElementAccess access = ElementAccessOf(node->op());
-        VisitBinop(node, UseInfoForBasePointer(access), UseInfoForIndex(),
+        VisitBinop(node, UseInfoForBasePointer(access), UseInfo::Word(),
                    access.machine_type.representation());
         return;
       }
@@ -2639,7 +2635,7 @@ class RepresentationSelector {
             access.base_is_tagged, element_representation, access.type,
             input_info->representation(), value_node);
         ProcessInput(node, 0, UseInfoForBasePointer(access));  // base
-        ProcessInput(node, 1, UseInfoForIndex());              // index
+        ProcessInput(node, 1, UseInfo::Word());                // index
         ProcessInput(node, 2,
                      TruncatingUseInfoFromRepresentation(
                          element_representation));  // value
@@ -2663,7 +2659,7 @@ class RepresentationSelector {
         Type value_type = TypeOf(node->InputAt(2));
 
         ProcessInput(node, 0, UseInfo::AnyTagged());  // array
-        ProcessInput(node, 1, UseInfoForIndex());     // index
+        ProcessInput(node, 1, UseInfo::Word());       // index
 
         if (value_type.Is(Type::SignedSmall())) {
           ProcessInput(node, 2, UseInfo::TruncatingWord32());  // value
@@ -2701,7 +2697,7 @@ class RepresentationSelector {
         ProcessInput(node, 0, UseInfo::AnyTagged());  // buffer
         ProcessInput(node, 1, UseInfo::AnyTagged());  // base pointer
         ProcessInput(node, 2, UseInfo::Word());       // external pointer
-        ProcessInput(node, 3, UseInfoForIndex());     // index
+        ProcessInput(node, 3, UseInfo::Word());       // index
         ProcessRemainingInputs(node, 4);
         SetOutput(node, rep);
         return;
@@ -2711,7 +2707,7 @@ class RepresentationSelector {
             MachineRepresentationFromArrayType(ExternalArrayTypeOf(node->op()));
         ProcessInput(node, 0, UseInfo::AnyTagged());  // buffer
         ProcessInput(node, 1, UseInfo::Word());       // external pointer
-        ProcessInput(node, 2, UseInfoForIndex());     // index
+        ProcessInput(node, 2, UseInfo::Word());       // index
         ProcessInput(node, 3, UseInfo::Bool());       // little-endian
         ProcessRemainingInputs(node, 4);
         SetOutput(node, rep);
@@ -2723,7 +2719,7 @@ class RepresentationSelector {
         ProcessInput(node, 0, UseInfo::AnyTagged());  // buffer
         ProcessInput(node, 1, UseInfo::AnyTagged());  // base pointer
         ProcessInput(node, 2, UseInfo::Word());       // external pointer
-        ProcessInput(node, 3, UseInfoForIndex());     // index
+        ProcessInput(node, 3, UseInfo::Word());       // index
         ProcessInput(node, 4,
                      TruncatingUseInfoFromRepresentation(rep));  // value
         ProcessRemainingInputs(node, 5);
@@ -2735,7 +2731,7 @@ class RepresentationSelector {
             MachineRepresentationFromArrayType(ExternalArrayTypeOf(node->op()));
         ProcessInput(node, 0, UseInfo::AnyTagged());         // buffer
         ProcessInput(node, 1, UseInfo::Word());              // external pointer
-        ProcessInput(node, 2, UseInfoForIndex());            // index
+        ProcessInput(node, 2, UseInfo::Word());              // index
         ProcessInput(node, 3,
                      TruncatingUseInfoFromRepresentation(rep));  // value
         ProcessInput(node, 4, UseInfo::Bool());  // little-endian