[compiler] Avoid code duplication in LowerTruncateTagged*ToBit.

This refactors EffectControlLinearizer's LowerTruncateTaggedToBit and
LowerTruncateTaggedPointerToBit such that they share the common code.
This common code will grow further when supporting bigints in a future
CL.

R=jarin@chromium.org

Bug: 
Change-Id: I881d705de327243121b73e12fb93f2cd96f315f2
Reviewed-on: https://chromium-review.googlesource.com/771391
Commit-Queue: Georg Neis <neis@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49403}

src/compiler/effect-control-linearizer.cc

@@ -1062,44 +1062,40 @@ Node* EffectControlLinearizer::LowerChangeTaggedToBit(Node* node) {
   return __ WordEqual(value, __ TrueConstant());
 }
 
-Node* EffectControlLinearizer::LowerTruncateTaggedToBit(Node* node) {
+void EffectControlLinearizer::TruncateTaggedPointerToBit(
+    Node* node, GraphAssemblerLabel<1>* done) {
   Node* value = node->InputAt(0);
 
-  auto if_smi = __ MakeDeferredLabel();
   auto if_heapnumber = __ MakeDeferredLabel();
-  auto done = __ MakeLabel(MachineRepresentation::kBit);
 
   Node* zero = __ Int32Constant(0);
   Node* fzero = __ Float64Constant(0.0);
 
   // Check if {value} is false.
-  __ GotoIf(__ WordEqual(value, __ FalseConstant()), &done, zero);
-
-  // Check if {value} is a Smi.
-  Node* check_smi = ObjectIsSmi(value);
-  __ GotoIf(check_smi, &if_smi);
+  __ GotoIf(__ WordEqual(value, __ FalseConstant()), done, zero);
 
   // Check if {value} is the empty string.
-  __ GotoIf(__ WordEqual(value, __ EmptyStringConstant()), &done, zero);
+  __ GotoIf(__ WordEqual(value, __ EmptyStringConstant()), done, zero);
 
   // Load the map of {value}.
   Node* value_map = __ LoadField(AccessBuilder::ForMap(), value);
 
   // Check if the {value} is undetectable and immediately return false.
+  // This includes undefined and null.
   Node* value_map_bitfield =
       __ LoadField(AccessBuilder::ForMapBitField(), value_map);
   __ GotoIfNot(
       __ Word32Equal(__ Word32And(value_map_bitfield,
                                   __ Int32Constant(1 << Map::kIsUndetectable)),
                      zero),
-      &done, zero);
+      done, zero);
 
   // Check if {value} is a HeapNumber.
   __ GotoIf(__ WordEqual(value_map, __ HeapNumberMapConstant()),
             &if_heapnumber);
 
   // All other values that reach here are true.
-  __ Goto(&done, __ Int32Constant(1));
+  __ Goto(done, __ Int32Constant(1));
 
   __ Bind(&if_heapnumber);
   {
@@ -1107,14 +1103,24 @@ Node* EffectControlLinearizer::LowerTruncateTaggedToBit(Node* node) {
     // NaN.
     Node* value_value =
         __ LoadField(AccessBuilder::ForHeapNumberValue(), value);
-    __ Goto(&done, __ Float64LessThan(fzero, __ Float64Abs(value_value)));
+    __ Goto(done, __ Float64LessThan(fzero, __ Float64Abs(value_value)));
   }
+}
+
+Node* EffectControlLinearizer::LowerTruncateTaggedToBit(Node* node) {
+  auto done = __ MakeLabel(MachineRepresentation::kBit);
+  auto if_smi = __ MakeDeferredLabel();
+
+  Node* value = node->InputAt(0);
+  __ GotoIf(ObjectIsSmi(value), &if_smi);
+
+  TruncateTaggedPointerToBit(node, &done);
 
   __ Bind(&if_smi);
   {
     // If {value} is a Smi, then we only need to check that it's not zero.
-    __ Goto(&done,
-            __ Word32Equal(__ WordEqual(value, __ IntPtrConstant(0)), zero));
+    __ Goto(&done, __ Word32Equal(__ WordEqual(value, __ IntPtrConstant(0)),
+                                  __ Int32Constant(0)));
   }
 
   __ Bind(&done);
@@ -1122,47 +1128,9 @@ Node* EffectControlLinearizer::LowerTruncateTaggedToBit(Node* node) {
 }
 
 Node* EffectControlLinearizer::LowerTruncateTaggedPointerToBit(Node* node) {
-  Node* value = node->InputAt(0);
-
-  auto if_heapnumber = __ MakeDeferredLabel();
   auto done = __ MakeLabel(MachineRepresentation::kBit);
 
-  Node* zero = __ Int32Constant(0);
-  Node* fzero = __ Float64Constant(0.0);
-
-  // Check if {value} is false.
-  __ GotoIf(__ WordEqual(value, __ FalseConstant()), &done, zero);
-
-  // Check if {value} is the empty string.
-  __ GotoIf(__ WordEqual(value, __ EmptyStringConstant()), &done, zero);
-
-  // Load the map of {value}.
-  Node* value_map = __ LoadField(AccessBuilder::ForMap(), value);
-
-  // Check if the {value} is undetectable and immediately return false.
-  Node* value_map_bitfield =
-      __ LoadField(AccessBuilder::ForMapBitField(), value_map);
-  __ GotoIfNot(
-      __ Word32Equal(__ Word32And(value_map_bitfield,
-                                  __ Int32Constant(1 << Map::kIsUndetectable)),
-                     zero),
-      &done, zero);
-
-  // Check if {value} is a HeapNumber.
-  __ GotoIf(__ WordEqual(value_map, __ HeapNumberMapConstant()),
-            &if_heapnumber);
-
-  // All other values that reach here are true.
-  __ Goto(&done, __ Int32Constant(1));
-
-  __ Bind(&if_heapnumber);
-  {
-    // For HeapNumber {value}, just check that its value is not 0.0, -0.0 or
-    // NaN.
-    Node* value_value =
-        __ LoadField(AccessBuilder::ForHeapNumberValue(), value);
-    __ Goto(&done, __ Float64LessThan(fzero, __ Float64Abs(value_value)));
-  }
+  TruncateTaggedPointerToBit(node, &done);
 
   __ Bind(&done);
   return done.PhiAt(0);

src/compiler/effect-control-linearizer.h

@@ -79,6 +79,7 @@ class V8_EXPORT_PRIVATE EffectControlLinearizer {
   Node* LowerCheckedTaggedToTaggedSigned(Node* node, Node* frame_state);
   Node* LowerCheckedTaggedToTaggedPointer(Node* node, Node* frame_state);
   Node* LowerChangeTaggedToFloat64(Node* node);
+  void TruncateTaggedPointerToBit(Node* node, GraphAssemblerLabel<1>* done);
   Node* LowerTruncateTaggedToBit(Node* node);
   Node* LowerTruncateTaggedPointerToBit(Node* node);
   Node* LowerTruncateTaggedToFloat64(Node* node);