https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80155
--- Comment #20 from Richard Biener <rguenth at gcc dot gnu.org> --- (In reply to Thomas Preud'homme from comment #19) > (In reply to Richard Biener from comment #18) > > (In reply to Thomas Preud'homme from comment #17) > > > (In reply to rguent...@suse.de from comment #16) > > > > On Thu, 23 Mar 2017, thopre01 at gcc dot gnu.org wrote: > > > > > > > > > > Funnily this led back to the Cortex-M0+ reduced testcase. With the > > > > > patch in > > > > > comment #13 applied we can still see a difference in the push (one > > > > > register > > > > > pushed Vs 0). > > > > > > > > I can't reproduce zero pushes here I get three with/without > > > > -fno-code-hoisting. code hoisting hoists the two loads inside > > > > the switch before it so we have > > > > > > Ooops my apologize, it needs more flags indeed. -O2 -funroll-all-loops > > > shows > > > 2 registers pushed Vs 1 when -fno-code-hoisting is added. > > > > Still can't reproduce. I've configured with > > > > /space/rguenther/src/svn/gcc-7-branch/configure > > --target=arm-suse-linux-gnueabi --disable-libstdcxx-pch > > --enable-languages=c,c++ > > > > and am using > > > > ./cc1 -quiet cortex-m0plus_reproducer.c -O2 -mcpu=cortex-m0plus -mthumb -I > > include -fdump-tree-pre-details -fdump-tree-crited -fdump-tree-all > > -funroll-all-loops -fno-code-hoisting > > Oh my bad, I was still not clear enough. I meant using the Cortex-M0+ > testcase but build it for Cortex-M7. Hopefully with -mcpu=cortex-m7 you > should see a difference between with and without code hoisting. I do. Two pushes with code hoisting and three without. Changed -mcpu above to -mcpu=cortex-m7.
