[Bug target/79430] [7/8 Regression] action of statement incorrectly optimised away

[tkoenig at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79430

--- Comment #73 from Thomas Koenig <tkoenig at gcc dot gnu.org> ---
Created attachment 41265
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=41265&action=edit
Difference in assembly with and without the patch

This is the difference in assembly generated.  *.withpatch is the
version with https://gcc.gnu.org/bugzilla/attachment.cgi?id=41260
applied, which corresponds to r244920. The diff is rather
longish; if there was an --ignore-changes-in-label-names option
to diff, I would have used it :-)

Options to gfortran were (via libtool)

gfortran -I../basics -I../utilities -I../testing -I../system -I../combinatorics
-I../parsing -I../rng -I../physics -I../qft -I../expr_base -I../particles
-I../types -I../variables -I../model_features -I../muli -I../events -I../beams
-I../tauola -I../../vamp/src -I../fastjet -I../lhapdf -I ../pdf_builtin
-I../tauola -I../../pythia6 -g -O2 -save-temps -c shower_core.f90  -fPIC -o
.libs/shower_core.o

System is x86_64-pc-linux-gnu, version 7.0.1 20170419, latest
revision r247002 .

The translation unit in question is shower_core.f90.