[turbofan] Propagate word32 truncations through tagged-hole checks.

src/compiler/simplified-lowering.cc

Index: src/compiler/simplified-lowering.cc
diff --git a/src/compiler/simplified-lowering.cc b/src/compiler/simplified-lowering.cc
index ac0f53af9d0c686483d3c8d2c4d77f4a6f9e6f0a..ee1d7b7a8132c693c30a87c226fc94970e95fed6 100644
--- a/src/compiler/simplified-lowering.cc
+++ b/src/compiler/simplified-lowering.cc
@@ -1860,9 +1860,18 @@ class RepresentationSelector {
         return;
       }
       case IrOpcode::kCheckTaggedHole: {
-        ProcessInput(node, 0, UseInfo::AnyTagged());
-        ProcessRemainingInputs(node, 1);
-        SetOutput(node, MachineRepresentation::kTagged);
+        CheckTaggedHoleMode mode = CheckTaggedHoleModeOf(node->op());
+        if (truncation.TruncatesToWord32() &&
+            mode == CheckTaggedHoleMode::kConvertHoleToUndefined) {
+          ProcessInput(node, 0, UseInfo::CheckedSigned32AsWord32());
+          ProcessRemainingInputs(node, 1);
+          SetOutput(node, MachineRepresentation::kWord32);
+          if (lower()) DeferReplacement(node, node->InputAt(0));
+        } else {
+          ProcessInput(node, 0, UseInfo::AnyTagged());
+          ProcessRemainingInputs(node, 1);
+          SetOutput(node, MachineRepresentation::kTagged);
+        }
         return;
       }