As described in - depth in rule DCL34-C. Use volatile for data that cannot be cached, a volatile-qualified variable "shall be evaluated strictly according to the rules of the abstract machine" [ISO/IEC 9899:2011]. In other words, the volatile qualifier is used to instruct the compiler to not make caching optimizations about a variable.
...
Rule | Severity | Likelihood | Remediation Cost | Priority | Level |
|---|---|---|---|---|---|
DCL17-C | medium | probable | high | P4 | L3 |
Bibliography
| [Eide and Regehr] | "Volatiles Are Miscompiled, and What to Do about It" |
| [ISO/IEC 9899:2011] | Section 6.7.3, "Type Qualifiers" |
...