https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78087
Bug ID: 78087
Summary: gcc 6.2.0 fails to link temacs from emacs-25.1 with
-O0 -flto
Product: gcc
Version: 6.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: lto
Assignee: unassigned at gcc dot gnu.org
Reporter: howarth.at.gcc at gmail dot com
Target Milestone: ---
The gcc 6.2.0 compiler fails to link temacs in a build of emacs 25.1 when the
"-O0 -flto" flag is passed on CFLAGS and "-flto" on LDFLAGS. This issue occurs
on x86_64-apple-darwin15 where the failure appears as...
CCLD temacs
/var/folders/vh/xthx1f251nqfj804049zl1wm0000gn/T//cc5Viitn.s:288358:1: error:
assembler local symbol 'L1' not defined
...
/var/folders/vh/xthx1f251nqfj804049zl1wm0000gn/T//cc5Viitn.s:288358:1: error:
assembler local symbol 'L174' not defined
and on x86_64 linux using a build gcc 6.2.0 with configure edited to set
build_lto_plugin=no on ELF to use the same code LTO code generation path on
linux as darwin...
CCLD temacs
/tmp/cc7ZBmmQ.ltrans0.ltrans.o:(.rodata+0x135a0): undefined reference to `.L1'
...
/tmp/cc7ZBmmQ.ltrans0.ltrans.o:(.rodata+0x13bc8): more undefined references to
`.L174' follow
collect2: fatal error: ld returned 1 exit status
On x86_64 linux, the issue is suppressed when the -O1 optimization level or
higher is used.
On x86_64 darwin, the linker failure in PR78077 occurs when the -O1
optimization level or higher is used.
