Confusion about COMMON_FLAGS in LDFLAGS

[beastrabban]

Hi all,

In the Gentoo Wiki page for LTO, I'm confused why it recommends to add COMMON_FLAGS to LDFLAGS:

Code: Select all

LDFLAGS="${COMMON_FLAGS} ${LDFLAGS}"

In the Wiki page for GCC Optimization, it says

The Gentoo developers have already set basic, safe LDFLAGS in the base profiles, so they do not need to be changed.

Is there a reason why "-march=native -O2 -pipe -flto" should be appended to LDFLAGS when LTO is enabled? Or is the advice on the LTO page outdated?

Thanks in advance.

[sam_]

The advice on the LTO page is correct, see https://gcc.gnu.org/onlinedocs/gcc/Opti ... index-flto

To use the link-time optimizer, -flto and optimization options should be specified at compile time and during the final link. It is recommended that you compile all the files participating in the same link with the same options and also specify those options at link time.

(and some other text in that section to the same effect).

The "GCC Optimization" wiki page is saying what it does because it means you don't need to go digging through the ld(1) man page to find options to add.