Refactor: Simplify static offset calculation in ProgramBuilder

This is possible after commit cb77273,
which added support for random index generation for small integer
ranges.

Change-Id: Iebc491eb860fcdf29f4fa6e4d65cbecff5cd831d
Reviewed-on: https://chrome-internal-review.googlesource.com/c/v8/fuzzilli/+/8447076
Reviewed-by: Matthias Liedtke <[email protected]>
Commit-Queue: Dominik Klemba <[email protected]>

Author: Dominik Klemba

Sources/Fuzzilli/Base/ProgramBuilder.swift

@@ -3877,12 +3877,7 @@ public class ProgramBuilder {
         // Generate an in-bounds offset (dynamicOffset + staticOffset) into the memory.
         let dynamicOffsetValue = self.randomNonNegativeIndex(upTo: memSize)
         let dynamicOffset = function.memoryArgument(dynamicOffsetValue, memoryTypeInfo)
-        var staticOffset: Int64
-        if (dynamicOffsetValue == memSize) {
-            staticOffset = 0
-        } else {
-            staticOffset = self.randomNonNegativeIndex(upTo: memSize) % (memSize - dynamicOffsetValue)
-        }
+        let staticOffset = self.randomNonNegativeIndex(upTo: memSize - dynamicOffsetValue)
 
         return (dynamicOffset, staticOffset)
     }