[HADOOP-9707] Fix register lists for crc32c inline assembly

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.1.0-beta, 3.0.0-alpha1
• Fix Version/s: 2.1.0-beta
• Component/s: util
• Hadoop Flags: Reviewed
• Assignee: Todd Lipcon
• Reporter: Todd Lipcon
• Created: 08/Jul/13 17:46
• Updated: 12/May/16 18:27
• Resolved: 15/Jul/13 18:20

Description

The inline assembly used for the crc32 instructions has an incorrect clobber list: the computed CRC values are "in-out" variables and thus need to use the "matching constraint" syntax in the clobber list.

This doesn't seem to cause a problem now in Hadoop, but may break in a different compiler version which allocates registers differently, or may break when the same code is used in another context.