HUB -> ROM lookup fix (#1640)

Author: OlivierBBB

tracer/arithmetization/src/main/java/net/consensys/linea/zktracer/module/hub/fragment/StackFragment.java

@@ -56,6 +56,7 @@ public final class StackFragment implements TraceFragment {
   private EWord hashInfoKeccak = EWord.ZERO;
   @Setter public Bytes hash;
   @Getter private final OpCode opCode;
+  @Getter private final int rawOpCode;
   @Setter private boolean jumpDestinationVettingRequired;
   @Setter private boolean validJumpDestination;
   private final State.TxState.Stamps stamps;
@@ -74,6 +75,13 @@ private StackFragment(
     this.stackOps = stackOps;
     this.exceptions = exceptions;
     this.opCode = stack.getCurrentOpcodeData().mnemonic();
+    if (this.opCode != OpCode.INVALID) {
+      this.rawOpCode = 0xff & this.opCode.byteValue();
+    } else {
+      final int codeSize = hub.messageFrame().getCode().getBytes().size();
+      final int pc = hub.messageFrame().getPC();
+      this.rawOpCode = (pc < codeSize) ? 0xff & hub.messageFrame().getCode().getBytes().get(pc) : 0;
+    }
     this.hashInfoFlag =
         switch (this.opCode) {
               case SHA3 -> true;
@@ -212,7 +220,7 @@ public Trace trace(Trace trace) {
         // Instruction details
         .pStackAlpha(UnsignedByte.of(stack.getCurrentOpcodeData().stackSettings().alpha()))
         .pStackDelta(UnsignedByte.of(stack.getCurrentOpcodeData().stackSettings().delta()))
-        .pStackInstruction(Bytes.of(stack.getCurrentOpcodeData().value()))
+        .pStackInstruction(Bytes.of(rawOpCode))
         .pStackStaticGas(staticGas)
         // Opcode families
         .pStackAccFlag(currentInstFamily == ACCOUNT)

tracer/arithmetization/src/main/java/net/consensys/linea/zktracer/opcode/OpCodeData.java

@@ -20,7 +20,10 @@
 import java.util.Objects;
 
 import net.consensys.linea.zktracer.opcode.gas.Billing;
+import net.consensys.linea.zktracer.opcode.gas.BillingRate;
+import net.consensys.linea.zktracer.opcode.gas.GasConstants;
 import net.consensys.linea.zktracer.opcode.gas.MxpType;
+import net.consensys.linea.zktracer.opcode.stack.Pattern;
 import net.consensys.linea.zktracer.opcode.stack.StackSettings;
 
 /**
@@ -46,6 +49,28 @@ public Billing billing() {
     return Objects.requireNonNullElse(billing, Billing.DEFAULT);
   }
 
+  public static OpCodeData forNonOpCodes(int value) {
+    return new OpCodeData(
+        OpCode.INVALID,
+        value,
+        INVALID,
+        new StackSettings(
+            Pattern.ZERO_ZERO,
+            0,
+            0,
+            GasConstants.G_ZERO,
+            false,
+            false,
+            false,
+            false,
+            false,
+            false,
+            false,
+            false),
+        new RamSettings(DataLocation.NONE, DataLocation.NONE),
+        new Billing(GasConstants.G_ZERO, BillingRate.NONE, MxpType.NONE));
+  }
+
   /**
    * A method singling out <code>PUSHx</code> instructions.
    *

tracer/arithmetization/src/main/java/net/consensys/linea/zktracer/opcode/OpCodes.java

@@ -70,7 +70,7 @@ public static OpCodeData of(final int value) {
       throw new IllegalArgumentException("No OpCode with value %s is defined.".formatted(value));
     }
 
-    return valueToOpCodeDataMap.getOrDefault(value, of(OpCode.INVALID));
+    return valueToOpCodeDataMap.getOrDefault(value, OpCodeData.forNonOpCodes(value));
   }
 
   /**