https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86828
Bug ID: 86828
Summary: [6/7 Regression] wrong-code bug with "-march=knl
-Ofast" (invalid memory reference)
Product: gcc
Version: 8.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: janus at gcc dot gnu.org
Target Milestone: ---
Fortran test case:
program knl_bug
implicit none
integer, parameter :: NN = 32
type tList
integer, dimension(:), allocatable :: list
end type
integer, dimension(1:100) :: Y = 0
type(tList) :: nb
allocate(nb%list(1:NN), source = 1)
call s(nb)
contains
subroutine s(n)
type(tList), intent(in) :: n
integer, dimension(1:NN) :: liKOB
liKOB = Y(n%list)
print *,liKOB
end subroutine
end
Compiling this with "gfortran -march=knl -Ofast -g", and then running the
executable, I get:
$ ./a.out
Program received signal SIGSEGV: Segmentation fault - invalid memory reference.
Backtrace for this error:
#0 0x7f9d495c42da in ???
#1 0x7f9d495c3503 in ???
#2 0x7f9d491f6f1f in ???
#3 0x563dd9a3dd7f in s
at test.f90:26
#4 0x563dd9a3da9a in knl_bug
at test.f90:17
#5 0x563dd9a3da9a in main
at test.f90:17
Segmentation fault (core dumped)
I see this happening with:
gcc version 6.4.0 20180727 (Ubuntu 6.4.0-19ubuntu1~18.04)
gcc version 7.3.0 (Ubuntu 7.3.0-27ubuntu1~18.04)
but not with:
gcc version 5.5.0 20171010 (Ubuntu 5.5.0-12ubuntu1)
gcc version 8.2.0 (Ubuntu 8.2.0-1ubuntu2~18.04)
gcc version 9.0.0 20180730 (experimental) [trunk revision 263059] (GCC)
Note that the segfault also happens with -march=skylake-avx512 (which is not
available with gcc 5).
Similar to PR 86735.
The CPU where I found this is an Intel(R) Core(TM) i9-7980XE.
