[ptr-compr] Add int comparison cases in DecompressionOptimizer

There is at least one case where a Load output flows into an
In32LessThanOrEqual node without any bitcasts or truncations in the
middle. We have to consider these cases in the reducer.

Bug: v8:7703
Change-Id: I1ed9c41e80c0603fd287d096c3050c5ae27c2b3e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1879945
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64811}

src/compiler/decompression-optimizer.cc

@@ -74,6 +74,10 @@ void DecompressionOptimizer::MarkNodeInputs(Node* node) {
                                   State::kOnly32BitsObserved);  // value
       break;
     // BINOPS.
+    case IrOpcode::kInt32LessThan:
+    case IrOpcode::kInt32LessThanOrEqual:
+    case IrOpcode::kUint32LessThan:
+    case IrOpcode::kUint32LessThanOrEqual:
     case IrOpcode::kWord32And:
     case IrOpcode::kWord32Equal:
       DCHECK_EQ(node->op()->ValueInputCount(), 2);

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

@@ -461,6 +461,34 @@ TEST_F(DecompressionOptimizerTest, PhiWithOneCompressedAndOneTagged) {
   }
 }
 
+// -----------------------------------------------------------------------------
+// Int cases.
+
+TEST_F(DecompressionOptimizerTest, Int32LessThanOrEqualFromSpeculative) {
+  // This case tests for what SpeculativeNumberLessThanOrEqual is lowered to.
+  // Skip test if decompression elimination is enabled.
+  if (FLAG_turbo_decompression_elimination) {
+    return;
+  }
+
+  // Define variables.
+  Node* const control = graph()->start();
+  Node* object = Parameter(Type::Any(), 0);
+  Node* effect = graph()->start();
+  Node* index = Parameter(Type::UnsignedSmall(), 1);
+
+  // Test only for AnyTagged, since TaggedPointer can't be a Smi.
+  // Create the graph.
+  Node* load = graph()->NewNode(machine()->Load(MachineType::AnyTagged()),
+                                object, index, effect, control);
+  Node* constant = graph()->NewNode(common()->Int64Constant(5));
+  graph()->SetEnd(
+      graph()->NewNode(machine()->Int32LessThanOrEqual(), load, constant));
+  // Change the nodes, and test the change.
+  Reduce();
+  EXPECT_EQ(LoadMachRep(load), CompressedMachRep(MachineType::AnyTagged()));
+}
+
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8