Fix exp gas

matter-labs · May 22, 2024 · 7047533 · 7047533
1 parent 9124b42
commit 7047533
Show file tree

Hide file tree

Showing 2 changed files with 24 additions and 14 deletions.
diff --git a/system-contracts/contracts/EvmInterpreterLoop.template.yul b/system-contracts/contracts/EvmInterpreterLoop.template.yul
@@ -116,10 +116,12 @@ for { } true { } {
 
         sp := pushStackItem(sp, exp(a, exponent))
 
-        if exponent {
-            let expSizeByte := div(add(exponent, 256), 256) // TODO: Replace with shr(8, add(exponent, 256))
-            evmGasLeft := chargeGas(evmGasLeft, mul(50, expSizeByte))
-        }
+        let to_charge := 0
+        for {} gt(exponent,0) {} { // while exponent > 0
+            to_charge := add(to_charge, 50)
+            exponent := shr(8, exponent)
+        } 
+        evmGasLeft := chargeGas(evmGasLeft, to_charge)
     }
     case 0x0B { // OP_SIGNEXTEND
         evmGasLeft := chargeGas(evmGasLeft, 5)

diff --git a/system-contracts/contracts/EvmInterpreterPreprocessed.yul b/system-contracts/contracts/EvmInterpreterPreprocessed.yul
@@ -1406,12 +1406,16 @@ object "EVMInterpreter" {
                     a, sp := popStackItem(sp)
                     exponent, sp := popStackItem(sp)
 
-                    sp := pushStackItem(sp, exp(a, exponent))
+                    let result := exp(a, exponent)
 
-                    if exponent {
-                        let expSizeByte := div(add(exponent, 256), 256) // TODO: Replace with shr(8, add(exponent, 256))
-                        evmGasLeft := chargeGas(evmGasLeft, mul(50, expSizeByte))
-                    }
+                    sp := pushStackItem(sp, result)
+
+                    let to_charge := 0
+                    for {} gt(exponent,0) {} { // while exponent > 0
+                        to_charge := add(to_charge, 50)
+                        exponent := shr(8, exponent)
+                    } 
+                    evmGasLeft := chargeGas(evmGasLeft, to_charge)
                 }
                 case 0x0B { // OP_SIGNEXTEND
                     evmGasLeft := chargeGas(evmGasLeft, 5)
@@ -3993,12 +3997,16 @@ object "EVMInterpreter" {
                     a, sp := popStackItem(sp)
                     exponent, sp := popStackItem(sp)
 
-                    sp := pushStackItem(sp, exp(a, exponent))
+                    let result := exp(a, exponent)
 
-                    if exponent {
-                        let expSizeByte := div(add(exponent, 256), 256) // TODO: Replace with shr(8, add(exponent, 256))
-                        evmGasLeft := chargeGas(evmGasLeft, mul(50, expSizeByte))
-                    }
+                    sp := pushStackItem(sp, result)
+
+                    let to_charge := 0
+                    for {} gt(exponent,0) {} { // while exponent > 0
+                        to_charge := add(to_charge, 50)
+                        exponent := shr(8, exponent)
+                    } 
+                    evmGasLeft := chargeGas(evmGasLeft, to_charge)
                 }
                 case 0x0B { // OP_SIGNEXTEND
                     evmGasLeft := chargeGas(evmGasLeft, 5)