Shift Optimization (hyperledger#3039)

Reduce shift calculations to shifts that may have an actual result. Signed-off-by: Danno Ferrin <danno.ferrin@gmail.com>
noirgif · Nov 11, 2021 · 4170524 · 4170524
1 parent 00b81b6
commit 4170524
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Showing 3 changed files with 3 additions and 3 deletions.
diff --git a/evm/src/main/java/org/hyperledger/besu/evm/operation/SarOperation.java b/evm/src/main/java/org/hyperledger/besu/evm/operation/SarOperation.java
@@ -44,7 +44,7 @@ public Operation.OperationResult executeFixedCostOperation(
     } else {
       final int shiftAmountInt = shiftAmount.toInt();
 
-      if (shiftAmountInt >= 256) {
+      if (shiftAmountInt >= 256 || shiftAmountInt < 0) {
         frame.pushStackItem(negativeNumber ? ALL_BITS : UInt256.ZERO);
       } else {
         // first perform standard shift right.

diff --git a/evm/src/main/java/org/hyperledger/besu/evm/operation/ShlOperation.java b/evm/src/main/java/org/hyperledger/besu/evm/operation/ShlOperation.java
@@ -40,7 +40,7 @@ public Operation.OperationResult executeFixedCostOperation(
       final int shiftAmountInt = shiftAmount.toInt();
       final Bytes value = leftPad(frame.popStackItem());
 
-      if (shiftAmountInt >= 256) {
+      if (shiftAmountInt >= 256 || shiftAmountInt < 0) {
         frame.pushStackItem(UInt256.ZERO);
       } else {
         frame.pushStackItem(value.shiftLeft(shiftAmountInt));

diff --git a/evm/src/main/java/org/hyperledger/besu/evm/operation/ShrOperation.java b/evm/src/main/java/org/hyperledger/besu/evm/operation/ShrOperation.java
@@ -40,7 +40,7 @@ public Operation.OperationResult executeFixedCostOperation(
       final int shiftAmountInt = shiftAmount.toInt();
       final Bytes value = leftPad(frame.popStackItem());
 
-      if (shiftAmountInt >= 256) {
+      if (shiftAmountInt >= 256 || shiftAmountInt < 0) {
         frame.pushStackItem(UInt256.ZERO);
       } else {
         frame.pushStackItem(value.shiftRight(shiftAmountInt));