http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53572
Bug #: 53572
Summary: Some public symbols don't get to serialized LTO
Classification: Unclassified
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: lto
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: tetra2...@gmail.com
Created attachment 27553
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=27553
This archive includes Makefile, header and two cpps which illustrate the
problem
The attached small project builds successfully by default
ygribov@ygribov-desktop:~/test/repro-x86$ make CC=<path-to-gcc> clean all
rm -f prog main.o lib.a lib.o
gcc -O2 -DNDEBUG -frtti -c -o main.o main.cpp
gcc -O2 -DNDEBUG -frtti -c -o lib.o lib.cpp
ar rcs lib.a lib.o
gcc main.o -L. lib.a -o prog -lsupc++
but fails if I compile with LTO enabled:
ygribov@ygribov-desktop:~/test/repro-x86/jni$ make CC=<path-to-gcc> LTO=-flto
clean all
rm -f prog main.o lib.a lib.o
gcc -flto -O2 -DNDEBUG -frtti -save-temps -c -o main.o main.cpp
gcc -O2 -DNDEBUG -frtti -save-temps -c -o lib.o lib.cpp
ar rcs lib.a lib.o
gcc -flto main.o -L. lib.a -o prog -lsupc++
`_ZTI1A' referenced in section `.rodata._ZTV1A[_ZTV1A]' of lib.a(lib.o):
defined in discarded section `.text' of main.o (symbol from plugin)
collect2: error: ld returned 1 exit status
make: *** [prog] Error 1
_ZTI1A is a weak definition of vtable for class A which is defined both in
main.cpp and in lib.cpp (because they both include common.h which defines thus
class). Main.cpp is compiled with -flto and _ZTI1A then gets into main.o's LTO
symtab. As main.o is the first file in the list which declares to provide
definition for this weak symbol linker assumes that it should come from main.o.
But for some reason the actual GIMPLE tree for _ZTI1A is not stored in main.o's
LTO sections and this causes errors during linking (linker can't find symbol
promised by main.o's LTO symtab).
I tried to compile both with gcc 4.6 and gcc trunk and every time it failed in
the same way.
I have to include a tgz instead of single source file because problem manifests
itself only when I link several files.
