https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93734
Bug ID: 93734
Summary: Invalid code generated with -O2 -march=haswell
-ftree-vectorize
Product: gcc
Version: 8.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: fortran
Assignee: unassigned at gcc dot gnu.org
Reporter: bartoldeman at users dot sourceforge.net
Target Milestone: ---
Created attachment 47837
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=47837&action=edit
Fortran code that prints 0 if correct, and -9 if miscompiled
The attached code prints -9.0000000000000000 if compiled using
gfortran -O2 -march=haswell -ftree-vectorize bug.f90 -o bug
./bug
-9.0000000000000000
using
GNU Fortran (Debian 8.3.0-6) 8.3.0
Copyright (C) 2018 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
also reproduceable on GCC 9.2.0, but not with GCC 7.3.0 and earlier.
The correct answer is 1-1=0.
(I found this issue first when compiling the reference BLAS using those options
and running the "zblat2" tests, the test is a much reduced version of ztrsv,
see
http://www.netlib.org/lapack/explore-html/dc/dc1/group__complex16__blas__level2_ga99cc66f0833474d6607e6ea7dbe2f9bd.html#ga99cc66f0833474d6607e6ea7dbe2f9bd)
