Gentoo Archives: gentoo-dev

From: grozin@g.o
To: gentoo-dev@l.g.o
Subject: [gentoo-dev] Should this be considered a gcc bug?
Date: Tue, 21 Apr 2015 03:57:27
1 Hello *,
3 There was a bug #526194 - dev-lisp/sbcl does not respect CFLAGS. It was
4 "fixed" by Mark Wright <gienah@g.o> on Jan 31 - Feb 1. However,
5 after this fix the upstream CFLAGS were appended to the user-supplyed
6 ${CFLAGS}. And the upstream CFLAGS contain -O3. So, is a user has, e.g.,
7 -O2 in his/her ${CFLAGS}, it was silently replaced by -O3. For some time,
8 nobody noticed this: gcc-4.8 happily compiled the C stuff in sbcl with
9 -O3.
11 However, after the upgrade to gcc-4.9 problems began (bug #544070). On
12 amd64, gcc is still happy co compile sbcl with -O3. However, on x86 this
13 leads to a crash of a freshly compiled sbcl runtime. Namely, the
14 combinations
16 -O2 -march=<something>
17 -O3
19 behave correctly, and produce a working sbcl; but
21 -O3 -march=<something>
23 lead to the crush. I have changed the above "fix" in sbcl-1.2.10 in such a
24 way that now it appends only -g -Wall -Wsign-compare to ${CFLAGS}, but
25 not -O3. This resolves the bug #544070, unless a user has -O3
26 -march=<something> in his/her ${CFLAGS}.
28 Shouldn't gcc-4.9 on x86 produce with -O3 something functionally
29 equivalent to the -O2 case, only more optimized? Should this be considered
30 a gcc-4.9 bug?
32 Andrey