> On Thu, Dec 19, 2019 at 04:01:31PM +0100, Jan Hubicka wrote:
> > I now get build failure of Firefox with LTO due to:
> >
> > movabsq $.LC12, %rax
> >
> > which is output by:
> >
> > (insn:TI 468 3 849 2 (parallel [
> >
> > (set (mem/v/f/c:DI (plus:DI (reg/f:DI 6 bp)
> >
> > (const_int -56 [0xffffffffffffffc8])) [1 D.22910+0
> > S8 A64])
> > (unspec:DI [
> >
> > (mem/v/f:DI (const_int 40 [0x28]) [0
> > MEM[(<address-space-1> long unsigned int *)40B]+0 S8 A64 AS1])
> > ] UNSPEC_SP_SET))
> >
> > (set (reg:DI 0 ax [157])
> >
> > (symbol_ref/f:DI ("*.LC12") [flags 0x2] <var_decl
> > 0x7ffff56ac870 *.LC12>))
> > (clobber (reg:CC 17 flags))
> >
> > ]) 1042 {*stack_protect_set_3}
> >
> > (expr_list:REG_UNUSED (reg:CC 17 flags)
> >
> > (nil)))
> >
> >
> > I suppose we need to be more careful about the symbolic operands for
> > movabs?
>
> Is that -fPIC or -fPIE or -fno-pic?
> What were the two insns before peephole2?
It is -fPIC transforming
(insn 9 7 12 2 (parallel [
(set (mem/v/f/c:DI (plus:DI (reg/f:DI 6 bp)
(const_int -56 [0xffffffffffffffc8])) [1 D.22910+0 S8
A64])
(unspec:DI [
(mem/v/f:DI (const_int 40 [0x28]) [0
MEM[(<address-space-1> long unsigned int *)40B]+0 S8 A64 AS1])
] UNSPEC_SP_SET))
(set (reg:DI 0 ax [157])
(const_int 0 [0]))
(clobber (reg:CC 17 flags))
])
"/aux/hubicka/firefox2019-trunktest/dist/include/testing/gtest/include/gtest/gtest.h":1538:17
1039 {stack_protect_set_1_di}
(expr_list:REG_UNUSED (reg:CC 17 flags)
(expr_list:REG_UNUSED (reg:DI 0 ax [157])
(nil))))
(note 12 9 13 2 NOTE_INSN_DELETED)
(insn 13 12 426 2 (set (reg:DI 0 ax [159])
(symbol_ref/f:DI ("*.LC12") [flags 0x2] <var_decl 0x7ffff56ac870
*.LC12>)) 66 {*movdi_internal}
(nil))
to
(insn 468 7 426 2 (parallel [
(set (mem/v/f/c:DI (plus:DI (reg/f:DI 6 bp)
(const_int -56 [0xffffffffffffffc8])) [1 D.22910+0 S8
A64])
(unspec:DI [
(mem/v/f:DI (const_int 40 [0x28]) [0
MEM[(<address-space-1> long unsigned int *)40B]+0 S8 A64 AS1])
] UNSPEC_SP_SET))
(set (reg:DI 0 ax [157])
(symbol_ref/f:DI ("*.LC12") [flags 0x2] <var_decl
0x7ffff56ac870 *.LC12>))
(clobber (reg:CC 17 flags))
]) -1
(nil))
Outputting the move as RIP relative movq would work.
LC12 is string "s" and has nothing to do with stack protecting.
