On Fri, Jul 14, 2017 at 4:46 AM, H.J. Lu <hjl.to...@gmail.com> wrote: > On Fri, Jul 7, 2017 at 5:56 PM, H.J. Lu <hjl.to...@gmail.com> wrote: >> On Fri, Jul 07, 2017 at 09:58:42AM -0700, H.J. Lu wrote: >>> On Fri, Dec 20, 2013 at 8:06 AM, Jakub Jelinek <ja...@redhat.com> wrote: >>> > Hi! >>> > >>> > Honza recently changed the i?86 backend, so that it often doesn't >>> > do -maccumulate-outgoing-args by default on x86_64. >>> > Unfortunately, on some of the here included testcases this regressed >>> > quite a bit the generated code. As AVX vectors are used, the dynamic >>> > realignment code needs to assume e.g. that some of them will need to be >>> > spilled, and for -mno-accumulate-outgoing-args the code needs to set >>> > need_drap early as well. But in when emitting the prologue/epilogue, >>> > if need_drap is set, we don't perform the optimization for leaf functions >>> > which have zero size stack frame, thus we end up with uselessly doing >>> > dynamic stack realignment, setting up DRAP that nothing uses and later on >>> > restore everything back. >>> > >>> > This patch improves it, if the DRAP register isn't live at the start of >>> > entry bb successor and we aren't going to realign the stack, we don't >>> > need DRAP at all, and even if we need DRAP register, that can't be the >>> > sole >>> > reason for doing stack realignment, the prologue code is able to set up >>> > DRAP >>> > even without dynamic stack realignment. >>> > >>> > Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk? >>> > >>> > 2013-12-20 Jakub Jelinek <ja...@redhat.com> >>> > >>> > PR target/59501 >>> > * config/i386/i386.c (ix86_save_reg): Don't return true for >>> > drap_reg >>> > if !crtl->stack_realign_needed. >>> > (ix86_finalize_stack_realign_flags): If drap_reg isn't live on >>> > entry >>> > and stack_realign_needed will be false, clear drap_reg and >>> > need_drap. >>> > Optimize leaf functions that don't need stack frame even if >>> > crtl->need_drap. >>> > >>> > * gcc.target/i386/pr59501-1.c: New test. >>> > * gcc.target/i386/pr59501-1a.c: New test. >>> > * gcc.target/i386/pr59501-2.c: New test. >>> > * gcc.target/i386/pr59501-2a.c: New test. >>> > * gcc.target/i386/pr59501-3.c: New test. >>> > * gcc.target/i386/pr59501-3a.c: New test. >>> > * gcc.target/i386/pr59501-4.c: New test. >>> > * gcc.target/i386/pr59501-4a.c: New test. >>> > * gcc.target/i386/pr59501-5.c: New test. >>> > * gcc.target/i386/pr59501-6.c: New test. >>> > >>> > >>> > --- gcc/testsuite/gcc.target/i386/pr59501-4a.c.jj 2013-12-20 >>> > 12:19:20.603212859 +0100 >>> > +++ gcc/testsuite/gcc.target/i386/pr59501-4a.c 2013-12-20 >>> > 12:23:33.647881672 +0100 >>> > @@ -0,0 +1,8 @@ >>> > +/* PR target/59501 */ >>> > +/* { dg-do compile { target { ! ia32 } } } */ >>> > +/* { dg-options "-O2 -mavx -maccumulate-outgoing-args" } */ >>> > + >>> > +#include "pr59501-3a.c" >>> > + >>> > +/* Verify no dynamic realignment is performed. */ >>> > +/* { dg-final { scan-assembler-not "and\[^\n\r]*sp" { xfail *-*-* } } } >>> > */ >>> > >>> >>> Since DRAP isn't used with -maccumulate-outgoing-args, pr59501-4a.c was >>> xfailed due to stack frame access via frame pointer instead of DARP. >>> This patch finds the maximum stack alignment from the stack frame access >>> instructions and avoids stack realignment if stack alignment needed is >>> less than incoming stack boundary. >>> >>> I am testing this patch. OK for trunk if there is no regression? >>> >>> >> >> We need to keep the preferred stack alignment as the minimum stack >> alignment. Here is the updated patch. Tested on x86-64. OK for >> trunk? >> >> Thanks. > > Hi Jakub, > > This patch fixes the xfailed testcase in your patch: > > https://gcc.gnu.org/ml/gcc-patches/2013-12/msg01767.html > > Your original patch: > > https://gcc.gnu.org/ml/gcc-patches/2011-11/msg01058.html > > assumes that any instructions accessing stack require stack > realignment: > > + FOR_EACH_BB (bb) > + { > + rtx insn; > + FOR_BB_INSNS (bb, insn) > + if (NONDEBUG_INSN_P (insn) > + && requires_stack_frame_p (insn, prologue_used, > + set_up_by_prologue)) > + { > + crtl->stack_realign_needed = stack_realign; > + crtl->stack_realign_finalized = true; > + return; > + } > + } > > This patch checks the actual alignment needed for any instructions > accessing stack. It skips stack realignment if the actual stack alignment > needed is less than or equal to incoming stack alignment. > > Can you take look at it? > > Thanks. >
PING https://gcc.gnu.org/ml/gcc-patches/2017-07/msg00400.html -- H.J.