Minor Mulmod v2 refactor

ethereum/core/src/jmh/java/org/hyperledger/besu/ethereum/vm/operations/v2/MulModOperationBenchmarkV2.java

@@ -167,6 +167,6 @@ public void setUp() {
 
   @Override
   protected Operation.OperationResult invoke(final MessageFrame frame) {
-    return MulModOperationV2.staticOperation(frame, frame.stackDataV2());
+    return MulModOperationV2.staticOperation(frame);
   }
 }

evm/src/main/java/org/hyperledger/besu/evm/EVM.java

@@ -489,7 +489,7 @@ private void runToHaltV2(final MessageFrame frame, final OperationTracer tracing
         result =
             switch (opcode) {
               case 0x01 -> AddOperationV2.staticOperation(frame, frame.stackDataV2());
-              case 0x09 -> MulModOperationV2.staticOperation(frame, frame.stackDataV2());
+              case 0x09 -> MulModOperationV2.staticOperation(frame);
               case 0x1b ->
                   enableConstantinople
                       ? ShlOperationV2.staticOperation(frame)

evm/src/main/java/org/hyperledger/besu/evm/v2/operation/MulModOperationV2.java

@@ -23,7 +23,7 @@
 /** The Mul mod operation. */
 public class MulModOperationV2 extends AbstractFixedCostOperationV2 {
 
-  private static final OperationResult mulModSuccess = new OperationResult(8, null);
+  private static final OperationResult MUL_MOD_SUCCESS = new OperationResult(8, null);
 
   /**
    * Instantiates a new Mul mod operation.
@@ -37,49 +37,40 @@ public MulModOperationV2(final GasCalculator gasCalculator) {
   @Override
   public Operation.OperationResult executeFixedCostOperation(
       final MessageFrame frame, final EVM evm) {
-    return staticOperation(frame, frame.stackDataV2());
+    return staticOperation(frame);
   }
 
   /**
-   * Performs MulMod operation.
+   * Performs MULMOD operation.
+   *
+   * <p>mulmod(a, b, m) = (a * b) mod m
    *
    * @param frame the frame
-   * @param stack the v2 operand stack ({@code long[]} in big-endian limb order)
    * @return the operation result
    */
-  public static OperationResult staticOperation(final MessageFrame frame, final long[] stack) {
+  public static OperationResult staticOperation(final MessageFrame frame) {
     if (!frame.stackHasItems(3)) return UNDERFLOW_RESPONSE;
     int top = frame.stackTopV2();
-    mulMod(stack, top);
-    // consumed three items and produced one item
-    frame.setTopV2(top - 2);
-    return mulModSuccess;
-  }
+    final int aOffset = (--top) << 2;
+    final int bOffset = (--top) << 2;
+    final int mOffset = (--top) << 2;
 
-  /**
-   * Performs EVM MULMOD (modular multiplication) on the three top stack items.
-   *
-   * <p>MULMOD: mulmod(a,b,m) = (a * b) mod m
-   *
-   * <p>MULMOD: stack[top-3] = (stack[top-1] * stack[top-2]) mod stack[top-3].
-   *
-   * @param stack the flat limb array
-   * @param top current stack-top (item count)
-   */
-  private static void mulMod(final long[] stack, final int top) {
-    final int aOffset = (top - 1) << 2;
-    final int bOffset = (top - 2) << 2;
-    final int mOffset = (top - 3) << 2;
+    final long[] stack = frame.stackDataV2();
     final UInt256 valueA =
         new UInt256(stack[aOffset], stack[aOffset + 1], stack[aOffset + 2], stack[aOffset + 3]);
     final UInt256 valueB =
         new UInt256(stack[bOffset], stack[bOffset + 1], stack[bOffset + 2], stack[bOffset + 3]);
     final UInt256 modulus =
         new UInt256(stack[mOffset], stack[mOffset + 1], stack[mOffset + 2], stack[mOffset + 3]);
+
     final UInt256 r = modulus.isZero() ? UInt256.ZERO : valueA.mulMod(valueB, modulus);
+
     stack[mOffset] = r.u3();
     stack[mOffset + 1] = r.u2();
     stack[mOffset + 2] = r.u1();
     stack[mOffset + 3] = r.u0();
+
+    frame.setTopV2(++top);
+    return MUL_MOD_SUCCESS;
   }
 }

evm/src/test/java/org/hyperledger/besu/evm/v2/operation/MulModOperationV2Test.java

@@ -15,6 +15,7 @@
 package org.hyperledger.besu.evm.v2.operation;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.hyperledger.besu.evm.v2.testutils.TestMessageFrameBuilderV2.getV2StackItem;
 
 import org.hyperledger.besu.evm.UInt256;
 import org.hyperledger.besu.evm.frame.ExceptionalHaltReason;
@@ -88,16 +89,15 @@ void mulModOperation(
         expectedResult.equals("0x") || expectedResult.equals("0x0")
             ? UInt256.ZERO
             : UInt256.fromBytesBE(Bytes32.fromHexStringLenient(expectedResult).toArrayUnsafe());
-    assertThat(getStackItem(frame, 0)).isEqualTo(expected);
+    assertThat(getV2StackItem(frame, 0)).isEqualTo(expected);
   }
 
   @Test
   void mulModOperationUnderflowNoItems() {
     final MessageFrame frame = new TestMessageFrameBuilderV2().build();
     assertThat(frame.stackTopV2()).isEqualTo(0);
 
-    final Operation.OperationResult result =
-        MulModOperationV2.staticOperation(frame, frame.stackDataV2());
+    final Operation.OperationResult result = MulModOperationV2.staticOperation(frame);
 
     assertThat(result.getHaltReason()).isEqualTo(ExceptionalHaltReason.INSUFFICIENT_STACK_ITEMS);
     assertThat(frame.stackTopV2()).isEqualTo(0);
@@ -112,16 +112,9 @@ void mulModOperationUnderflowOnlyTwoItems() {
             .build();
     assertThat(frame.stackTopV2()).isEqualTo(2);
 
-    final Operation.OperationResult result =
-        MulModOperationV2.staticOperation(frame, frame.stackDataV2());
+    final Operation.OperationResult result = MulModOperationV2.staticOperation(frame);
 
     assertThat(result.getHaltReason()).isEqualTo(ExceptionalHaltReason.INSUFFICIENT_STACK_ITEMS);
     assertThat(frame.stackTopV2()).isEqualTo(2);
   }
-
-  private static UInt256 getStackItem(final MessageFrame frame, final int offset) {
-    final long[] s = frame.stackDataV2();
-    final int idx = (frame.stackTopV2() - 1 - offset) << 2;
-    return new UInt256(s[idx], s[idx + 1], s[idx + 2], s[idx + 3]);
-  }
 }

evm/src/test/java/org/hyperledger/besu/evm/v2/testutils/TestMessageFrameBuilderV2.java

@@ -184,6 +184,19 @@ public MessageFrame build() {
     return frame;
   }
 
+  /**
+   * Reads a 256-bit word from the V2 stack at the given depth below the current top.
+   *
+   * @param frame the message frame with a V2 stack
+   * @param offset 0 for the topmost item, 1 for the item below, etc.
+   * @return the value as a {@link UInt256}
+   */
+  public static UInt256 getV2StackItem(final MessageFrame frame, final int offset) {
+    final long[] s = frame.stackDataV2();
+    final int idx = (frame.stackTopV2() - 1 - offset) << 2;
+    return new UInt256(s[idx], s[idx + 1], s[idx + 2], s[idx + 3]);
+  }
+
   private WorldUpdater createDefaultWorldUpdater() {
     return new ToyWorld();
   }