[turbofan][64] Remove Smi Untagging extra nodes for 31 bit smis

There are some cases where we can ignore some truncations or
change nodes for Smi Untagging, when we are using 31 bit smis
in 64 bit architectures.

Updated DecompressionOptimizer to match the new pattern.

Change-Id: I89d34407e6f780ec0399cd427cf9d3e24ee5669a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1889877
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64909}

src/compiler/decompression-optimizer.cc

@@ -80,6 +80,7 @@ void DecompressionOptimizer::MarkNodeInputs(Node* node) {
     case IrOpcode::kUint32LessThanOrEqual:
     case IrOpcode::kWord32And:
     case IrOpcode::kWord32Equal:
+    case IrOpcode::kWord32Shl:
       DCHECK_EQ(node->op()->ValueInputCount(), 2);
       MaybeMarkAndQueueForRevisit(node->InputAt(0),
                                   State::kOnly32BitsObserved);  // value_0

src/compiler/effect-control-linearizer.cc

@@ -4369,8 +4369,7 @@ Node* EffectControlLinearizer::AllocateHeapNumberWithValue(Node* value) {
 Node* EffectControlLinearizer::ChangeIntPtrToSmi(Node* value) {
   // Do shift on 32bit values if Smis are stored in the lower word.
   if (machine()->Is64() && SmiValuesAre31Bits()) {
-    return __ ChangeInt32ToInt64(
-        __ Word32Shl(__ TruncateInt64ToInt32(value), SmiShiftBitsConstant()));
+    return __ Word32Shl(value, SmiShiftBitsConstant());
   }
   return __ WordShl(value, SmiShiftBitsConstant());
 }
@@ -4392,7 +4391,7 @@ Node* EffectControlLinearizer::ChangeIntPtrToInt32(Node* value) {
 Node* EffectControlLinearizer::ChangeInt32ToSmi(Node* value) {
   // Do shift on 32bit values if Smis are stored in the lower word.
   if (machine()->Is64() && SmiValuesAre31Bits()) {
-    return __ ChangeInt32ToInt64(__ Word32Shl(value, SmiShiftBitsConstant()));
+    return __ Word32Shl(value, SmiShiftBitsConstant());
   }
   return ChangeIntPtrToSmi(ChangeInt32ToIntPtr(value));
 }
@@ -4412,7 +4411,7 @@ Node* EffectControlLinearizer::ChangeUint32ToUintPtr(Node* value) {
 Node* EffectControlLinearizer::ChangeUint32ToSmi(Node* value) {
   // Do shift on 32bit values if Smis are stored in the lower word.
   if (machine()->Is64() && SmiValuesAre31Bits()) {
-    return __ ChangeUint32ToUint64(__ Word32Shl(value, SmiShiftBitsConstant()));
+    return __ Word32Shl(value, SmiShiftBitsConstant());
   } else {
     return __ WordShl(ChangeUint32ToUintPtr(value), SmiShiftBitsConstant());
   }

test/unittests/compiler/decompression-optimizer-unittest.cc

@@ -195,13 +195,10 @@ TEST_F(DecompressionOptimizerTest, Word32ShlSmiTag) {
   // Create the graph.
   Node* load = graph()->NewNode(machine()->Load(MachineType::AnyTagged()),
                                 object, index, effect, control);
-  Node* truncation = graph()->NewNode(machine()->TruncateInt64ToInt32(), load);
   Node* smi_shift_bits =
       graph()->NewNode(common()->Int32Constant(kSmiShiftSize + kSmiTagSize));
-  Node* word32_shl =
-      graph()->NewNode(machine()->Word32Shl(), truncation, smi_shift_bits);
   graph()->SetEnd(
-      graph()->NewNode(machine()->ChangeInt32ToInt64(), word32_shl));
+      graph()->NewNode(machine()->Word32Shl(), load, smi_shift_bits));
   // Change the nodes, and test the change.
   Reduce();
   EXPECT_EQ(LoadMachRep(load), CompressedMachRep(MachineType::AnyTagged()));