Editing Optimizing compiler (section)

===Local vs. global scope===
[[Scope (computer science)|Scope]] describes how much of the input code is considered to apply optimizations.

Local scope optimizations use information local to a [[basic block]].<ref name="Cooper_2003">{{cite book|author-first1=Keith D.|author-last1=Cooper|author-link1=Keith D. Cooper|author-first2=Linda|author-last2=Torczon|title=Engineering a Compiler|publisher=[[Morgan Kaufmann]]|date=2003|orig-date=2002-01-01|pages=404, 407|isbn=978-1-55860-698-2}}</ref> Since basic blocks contain no control flow statements, these optimizations require minimal analysis, reducing time and storage requirements. However, no information is retained across jumps.

Global scope optimizations, also known as intra-procedural optimizations, operate on individual functions.<ref name="Cooper_2003"/> This gives them more information to work with but often makes expensive computations necessary. Worst-case assumptions need to be made when function calls occur or global variables are accessed because little information about them is available.