update compiler optimizations

src/compiler/compiler-optimizations.md

@@ -63,6 +63,7 @@ Enables special optimizations for mathematical operations.
 - Converts divisions to bit shifting if possible. Good conditions for this optimization: operands are integer, denominator is constant and power of 2.
 - Converts modulo by 2 expressions to equavalent bitwise operation.
 - Eliminates neutral binary expressions such as such as addition/subtraction with the constant-zero.
+- Eliminates runtime overflow checking for binary shifing expressions if right operand is constant.
 
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