https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97065
Bug ID: 97065
Summary: Support -fprofile-update=set (boolean counters)
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: gcov-profile
Assignee: unassigned at gcc dot gnu.org
Reporter: i at maskray dot me
CC: marxin at gcc dot gnu.org
Target Milestone: ---
I can understand that defaulting -fprofile-update=prefer-atomic in GCC 7 and
using atomic counters when -pthread is specified is for very good reasons that
imprecise line execution counts can be very confusing.
However, atomic counters can lead to very drastic performance degradation when
the contention is large (e.g. bug 80952)
Sometimes users just need to know whether a statement is executed or not. For
example lcov does not really need to know the number. A boolean mode
-fprofile-update=set may be useful. 'set' is the name used by Go -covermode=set
