http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51019
Bug #: 51019
Summary: unclear documentation on -fomit-frame-pointer default
for -Os and different platforms
Classification: Unclassified
Product: gcc
Version: 4.6.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: web
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: solar-...@openwall.com
The texinfo documentation for GCC 4.6.2 says:
Starting with GCC version 4.6, the default setting (when not
optimizing for size) for 32-bit Linux x86 and 32-bit Darwin x86
targets has been changed to `-fomit-frame-pointer'. The default
can be reverted to `-fno-omit-frame-pointer' by configuring GCC
with the `--enable-frame-pointer' configure option.
Enabled at levels `-O', `-O2', `-O3', `-Os'.
The "when not optimizing for size" comment feels contradictory to having "-Os"
listed on the "Enabled at levels" line. Also, it is not clear what the default
is on other than "32-bit Linux x86 and 32-bit Darwin x86". In practice, I
observe the following behavior with GCC 4.6.2: on Linux/x86_64,
-fomit-frame-pointer is the default at both -O2 and -Os (I did not test
others); on Linux/i386, it is the default at -O2, but not at -Os. This needs
to be documented more clearly.
