| Message ID | 1410560868-11154-1-git-send-email-andi@firstfloor.org |
|---|---|
| State | New |
| Headers | show |
On Fri, Sep 12, 2014 at 3:27 PM, Andi Kleen <andi@firstfloor.org> wrote: > From: Andi Kleen <ak@linux.intel.com> > > When compiling on opensuse 13.1, with a 4.8.1 based host compiler > and --disable-bootstrap, the generated compiler always ICEs while > compiling __builtin_cpu_supports in the cilk runtime library. > > The problem is fixed with later 4.8 releases, but at least still > happens with the opensuse compiler. > > The cilk library already had a fallback path for this function > for other compilers. Just use the fallback path when > __SSE2_MATH__ is set. This makes it work on x86_64 systems > with the buggy 4.8.1 at least, if multilib is forced to > SSE. > > libcilkrts/: > > 2014-09-12 Andi Kleen <ak@linux.intel.com> > > PR bootstrap/63235 > * runtime/config/x86/os-unix-sysdep.c (__builtin_cpu_supports): > Use fallback when __SSE2_MATH__ is set. > --- > libcilkrts/runtime/config/x86/os-unix-sysdep.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/libcilkrts/runtime/config/x86/os-unix-sysdep.c b/libcilkrts/runtime/config/x86/os-unix-sysdep.c > index b505ddf..344c31a 100644 > --- a/libcilkrts/runtime/config/x86/os-unix-sysdep.c > +++ b/libcilkrts/runtime/config/x86/os-unix-sysdep.c > @@ -96,7 +96,7 @@ COMMON_SYSDEP int __cilkrts_xchg(volatile int *ptr, int x) > * This declaration should generate an error when the Intel compiler adds > * supprt for the intrinsic. > */ > -#ifdef __INTEL_COMPILER > +#if defined(__INTEL_COMPILER) || defined(__SSE2_MATH__) > static inline int __builtin_cpu_supports(const char *feature) > { > return 1; So GCC 4.8.1 miscompiles GCC. Can we trust such GCC? Should we put a work around in GCC compiler to avoid the bad GCC? BTW, I run into another miscompilation bug https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63252 It only shows up when GCC is compiled with -O2 using GCC 5 on x32.
diff --git a/libcilkrts/runtime/config/x86/os-unix-sysdep.c b/libcilkrts/runtime/config/x86/os-unix-sysdep.c index b505ddf..344c31a 100644 --- a/libcilkrts/runtime/config/x86/os-unix-sysdep.c +++ b/libcilkrts/runtime/config/x86/os-unix-sysdep.c @@ -96,7 +96,7 @@ COMMON_SYSDEP int __cilkrts_xchg(volatile int *ptr, int x) * This declaration should generate an error when the Intel compiler adds * supprt for the intrinsic. */ -#ifdef __INTEL_COMPILER +#if defined(__INTEL_COMPILER) || defined(__SSE2_MATH__) static inline int __builtin_cpu_supports(const char *feature) { return 1;
From: Andi Kleen <ak@linux.intel.com> When compiling on opensuse 13.1, with a 4.8.1 based host compiler and --disable-bootstrap, the generated compiler always ICEs while compiling __builtin_cpu_supports in the cilk runtime library. The problem is fixed with later 4.8 releases, but at least still happens with the opensuse compiler. The cilk library already had a fallback path for this function for other compilers. Just use the fallback path when __SSE2_MATH__ is set. This makes it work on x86_64 systems with the buggy 4.8.1 at least, if multilib is forced to SSE. libcilkrts/: 2014-09-12 Andi Kleen <ak@linux.intel.com> PR bootstrap/63235 * runtime/config/x86/os-unix-sysdep.c (__builtin_cpu_supports): Use fallback when __SSE2_MATH__ is set. --- libcilkrts/runtime/config/x86/os-unix-sysdep.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)