On Thu, Jan 14, 2021 at 3:01 PM Jakub Jelinek <ja...@redhat.com> wrote:
>
> On Thu, Jan 14, 2021 at 01:04:31PM -0800, H.J. Lu via Gcc-patches wrote:
> > If x86 libatomic isn't compiled with -march=i486 or better, append
> > -march=i486 XCFLAGS for x86 libatomic build. Set try_ifunc to yes
> > if -mcx16 isn't used to compile x86-64 libatomic or -march=i686 or
> > better isn't used to compile x86 libatomic.
> >
> > PR target/70454
> > * configure.tgt (XCFLAGS): Append -march=i486 to compile x86
> > libatomic if needed.
> > (try_ifunc): Set to yes only if needed.
> > ---
> > libatomic/configure.tgt | 73 ++++++++++++++++++++++++++++-------------
> > 1 file changed, 50 insertions(+), 23 deletions(-)
> >
> > diff --git a/libatomic/configure.tgt b/libatomic/configure.tgt
> > index 2f24817b454..1f3a3ad6c7c 100644
> > --- a/libatomic/configure.tgt
> > +++ b/libatomic/configure.tgt
> > @@ -81,32 +81,59 @@ case "${target_cpu}" in
> > ARCH=sparc
> > ;;
> >
> > - i[3456]86)
> > - case " ${CC} ${CFLAGS} " in
> > - *" -m64 "*|*" -mx32 "*)
> > - ;;
> > - *)
> > - if test -z "$with_arch"; then
> > - XCFLAGS="${XCFLAGS} -march=i486 -mtune=${target_cpu}"
> > - XCFLAGS="${XCFLAGS} -fomit-frame-pointer"
> > - fi
> > - esac
> > - ARCH=x86
> > - # ??? Detect when -march=i686 is already enabled.
> > - try_ifunc=yes
> > - ;;
> > - x86_64)
> > - case " ${CC} ${CFLAGS} " in
> > - *" -m32 "*)
> > + i[3456]86 | x86_64)
> > + # Need i486 or better.
> > + cat > conftestx.c <<EOF
> > +#if defined __x86_64__ || defined __i486__ || defined __pentium__ \
> > + || defined __pentiumpro__ || defined __pentium4__ \
> > + || defined __geode__ || defined __SSE__
> > +# error Need i486 or better
> > +#endif
>
> Rather than hoping we got all the defines right, wouldn't it be better to
> compile with -S a testcase like:
> int
> foo (int *p, int x, int y)
> {
> return __sync_val_compare_and_swap (p, x, y);
> }
> and if there is __sync_val_compare_and_swap_4 in the assembly assume
> -march=i486 needs to be added?
> I.e. test for what exactly we need (working atomics).
>
> Jakub
>
Here is the updated patch. OK for master?
Thanks.
--
H.J.
From f847185c4faa94b6dbb52327c13d5d5bfec9b259 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.to...@gmail.com>
Date: Mon, 2 May 2016 09:44:07 -0700
Subject: [PATCH] Build x86 libatomic with -march=i486 or better
If x86 libatomic isn't compiled with -march=i486 or better, append
-march=i486 XCFLAGS for x86 libatomic build. Set try_ifunc to yes
if -mcx16 isn't used to compile x86-64 libatomic or -march=i686 or
better isn't used to compile x86 libatomic.
PR target/70454
* configure.tgt (XCFLAGS): Append -march=i486 to compile x86
libatomic if needed.
(try_ifunc): Set to yes only if needed.
---
libatomic/configure.tgt | 74 ++++++++++++++++++++++++++++-------------
1 file changed, 51 insertions(+), 23 deletions(-)
diff --git a/libatomic/configure.tgt b/libatomic/configure.tgt
index 2f24817b454..3530c992264 100644
--- a/libatomic/configure.tgt
+++ b/libatomic/configure.tgt
@@ -81,32 +81,60 @@ case "${target_cpu}" in
ARCH=sparc
;;
- i[3456]86)
- case " ${CC} ${CFLAGS} " in
- *" -m64 "*|*" -mx32 "*)
- ;;
- *)
- if test -z "$with_arch"; then
- XCFLAGS="${XCFLAGS} -march=i486 -mtune=${target_cpu}"
- XCFLAGS="${XCFLAGS} -fomit-frame-pointer"
- fi
- esac
- ARCH=x86
- # ??? Detect when -march=i686 is already enabled.
- try_ifunc=yes
- ;;
- x86_64)
- case " ${CC} ${CFLAGS} " in
- *" -m32 "*)
+ i[3456]86 | x86_64)
+ # Need i486 or better.
+ cat > conftestx.c <<EOF
+int
+foo (int *p, int x, int y)
+{
+ return __sync_val_compare_and_swap (p, x, y);
+}
+EOF
+ if ${CC} ${CFLAGS} -S conftestx.c > /dev/null 2>&1 \
+ && grep -q __sync_val_compare_and_swap conftestx.s /dev/null; then
+ if test "${target_cpu}" = x86_64; then
XCFLAGS="${XCFLAGS} -march=i486 -mtune=generic"
XCFLAGS="${XCFLAGS} -fomit-frame-pointer"
- ;;
- *)
- ;;
- esac
+ else
+ XCFLAGS="${XCFLAGS} -march=i486 -mtune=${target_cpu}"
+ XCFLAGS="${XCFLAGS} -fomit-frame-pointer"
+ fi
+ fi
+ # Detect if -march=i686/-mcx16 is already enabled.
+ cat > conftestx.c <<EOF
+#if defined __x86_64__
+__int128_t v = 0;
+__int128_t expected = 0;
+__int128_t max = ~0;
+__int128_t desired = ~0;
+__int128_t zero = 0;
+
+int
+foo (void)
+{
+ return !__atomic_compare_exchange_n (&v, &expected, max, 0,
+ __ATOMIC_RELAXED,
+ __ATOMIC_RELAXED);
+}
+#else
+# if defined __pentiumpro__ || defined __pentium4__ || defined __SSE__
+asm ("# has i686");
+# endif
+#endif
+EOF
+ if ${CC} ${CFLAGS} -S -o conftestx.s conftestx.c > /dev/null 2>&1; then
+ if grep cmpxchg16b conftestx.s >/dev/null; then
+ # This is the 64-bit library.
+ try_ifunc=no
+ elif grep i686 conftestx.s >/dev/null; then
+ # This is the 32-bit library.
+ try_ifunc=no
+ else
+ try_ifunc=yes
+ fi
+ fi
+ rm -f conftestx.c conftestx.s
ARCH=x86
- # ??? Detect when -mcx16 is already enabled.
- try_ifunc=yes
;;
*) ARCH="${target_cpu}" ;;
--
2.29.2
