https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61904
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution|--- |DUPLICATE
--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
Reduced set of options to reproduce with 4.9.1 are
-mno-red-zone -mcmodel=kernel -maccumulate-outgoing-args -mno-sse -g -Os
-fno-omit-frame-pointer
if you use -fno-var-tracking the bug goes away, similar if you update to
the 4.9 branch head.
If you use -fno-schedule-insns2 you see a similar pattern to the mentioned PR:
subq $424, %rsp
.LCFI427:
movl %edi, -400(%rbp)
movq %rdx, %rbx
movl %ecx, -396(%rbp)
movq %r8, -464(%rbp)
.LVL1306:
.loc 2 6489 0
movq (%rdx), %rax
movq %rax, -440(%rbp)
.LVL1307:
.LBB2616:
.loc 2 6493 0
movq $load_balance_mask, -384(%rbp)
movq -384(%rbp), %rax
.LVL1308:
#APP
# 6493 "kernel/sched/fair.c" 1
add %gs:this_cpu_off, %rax
so that spill is right before the asm and we immediately re-load it into
a register required by an asm constraint (stupid register allocator).
*** This bug has been marked as a duplicate of bug 61801 ***
