[cleanup][bigint] Compare maps instead of instance type

... when the latter is not already available.

Bug: v8:8834
Change-Id: Ib45b0e04c35a797e2d36a96b891ff1f82d4de02c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1505574Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60059}

src/compiler/effect-control-linearizer.cc

@@ -1281,10 +1281,7 @@ void EffectControlLinearizer::TruncateTaggedPointerToBit(
             &if_heapnumber);
 
   // Check if {value} is a BigInt.
-  Node* value_instance_type =
-      __ LoadField(AccessBuilder::ForMapInstanceType(), value_map);
-  __ GotoIf(__ Word32Equal(value_instance_type, __ Int32Constant(BIGINT_TYPE)),
-            &if_bigint);
+  __ GotoIf(__ WordEqual(value_map, __ BigIntMapConstant()), &if_bigint);
 
   // All other values that reach here are true.
   __ Goto(done, __ Int32Constant(1));
@@ -2478,10 +2475,7 @@ Node* EffectControlLinearizer::LowerObjectIsBigInt(Node* node) {
   Node* check = ObjectIsSmi(value);
   __ GotoIf(check, &if_smi);
   Node* value_map = __ LoadField(AccessBuilder::ForMap(), value);
-  Node* value_instance_type =
-      __ LoadField(AccessBuilder::ForMapInstanceType(), value_map);
-  Node* vfalse =
-      __ Word32Equal(value_instance_type, __ Uint32Constant(BIGINT_TYPE));
+  Node* vfalse = __ WordEqual(value_map, __ BigIntMapConstant());
   __ Goto(&done, vfalse);
 
   __ Bind(&if_smi);

src/compiler/graph-assembler.h

@@ -92,6 +92,7 @@ namespace compiler {
   V(TrueConstant)                          \
   V(FalseConstant)                         \
   V(NullConstant)                          \
+  V(BigIntMapConstant)                     \
   V(BooleanMapConstant)                    \
   V(HeapNumberMapConstant)                 \
   V(NoContextConstant)                     \

src/compiler/js-graph.cc

@@ -134,6 +134,8 @@ DEFINE_GETTER(AllocateInOldSpaceStubConstant,
 DEFINE_GETTER(ArrayConstructorStubConstant,
               HeapConstant(BUILTIN_CODE(isolate(), ArrayConstructorImpl)))
 
+DEFINE_GETTER(BigIntMapConstant, HeapConstant(factory()->bigint_map()))
+
 DEFINE_GETTER(BooleanMapConstant, HeapConstant(factory()->boolean_map()))
 
 DEFINE_GETTER(ToNumberBuiltinConstant,

src/compiler/js-graph.h

@@ -84,6 +84,7 @@ class V8_EXPORT_PRIVATE JSGraph : public MachineGraph {
   V(AllocateInNewSpaceStubConstant) \
   V(AllocateInOldSpaceStubConstant) \
   V(ArrayConstructorStubConstant)   \
+  V(BigIntMapConstant)              \
   V(BooleanMapConstant)             \
   V(ToNumberBuiltinConstant)        \
   V(EmptyFixedArrayConstant)        \