RE: 0006-Part-6.-Add-x86-tests-for-Intel-CET-implementation

["Tsimbalist, Igor V" <igor.v.tsimbalist@intel.com>]

> -----Original Message-----
> From: gcc-patches-owner@gcc.gnu.org [mailto:gcc-patches-
> owner@gcc.gnu.org] On Behalf Of Uros Bizjak
> Sent: Monday, September 18, 2017 12:17 PM
> To: gcc-patches@gcc.gnu.org
> Cc: Tsimbalist, Igor V <igor.v.tsimbalist@intel.com>; Tsimbalist, Igor V
> <igor.v.tsimbalist@intel.com>
> Subject: Re: 0006-Part-6.-Add-x86-tests-for-Intel-CET-implementation
> 
> Hello!
> 
> > gcc/testsuite/
> >
> > * g++.dg/cet-notrack-1.C: New test.
> > * gcc.target/i386/cet-intrin-1.c: Likewise.
> > * gcc.target/i386/cet-intrin-10.c: Likewise.
> > * gcc.target/i386/cet-intrin-2.c: Likewise.
> > * gcc.target/i386/cet-intrin-3.c: Likewise.
> > * gcc.target/i386/cet-intrin-4.c: Likewise.
> > * gcc.target/i386/cet-intrin-5.c: Likewise.
> > * gcc.target/i386/cet-intrin-6.c: Likewise.
> > * gcc.target/i386/cet-intrin-7.c: Likewise.
> > * gcc.target/i386/cet-intrin-8.c: Likewise.
> > * gcc.target/i386/cet-intrin-9.c: Likewise.
> > * gcc.target/i386/cet-label.c: Likewise.
> > * gcc.target/i386/cet-notrack-1a.c: Likewise.
> > * gcc.target/i386/cet-notrack-1b.c: Likewise.
> > * gcc.target/i386/cet-notrack-2a.c: Likewise.
> > * gcc.target/i386/cet-notrack-2b.c: Likewise.
> > * gcc.target/i386/cet-notrack-3.c: Likewise.
> > * gcc.target/i386/cet-notrack-4a.c: Likewise.
> > * gcc.target/i386/cet-notrack-4b.c: Likewise.
> > * gcc.target/i386/cet-notrack-5a.c: Likewise.
> > * gcc.target/i386/cet-notrack-5b.c: Likewise.
> > * gcc.target/i386/cet-notrack-6a.c: Likewise.
> > * gcc.target/i386/cet-notrack-6b.c: Likewise.
> > * gcc.target/i386/cet-notrack-7.c: Likewise.
> > * gcc.target/i386/cet-property-1.c: Likewise.
> > * gcc.target/i386/cet-property-2.c: Likewise.
> > * gcc.target/i386/cet-rdssp-1.c: Likewise.
> > * gcc.target/i386/cet-sjlj-1.c: Likewise.
> > * gcc.target/i386/cet-sjlj-2.c: Likewise.
> > * gcc.target/i386/cet-sjlj-3.c: Likewise.
> > * gcc.target/i386/cet-switch-1.c: Likewise.
> > * gcc.target/i386/cet-switch-2.c: Likewise.
> > * lib/target-supports.exp (check_effective_target_cet): New proc.
> 
> A couple of questions:
> 
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -mcet" } */
> +/* { dg-final { scan-assembler-times "setssbsy" 2 } } */
> +
> +#include <immintrin.h>
> +
> +void f1 (void)
> +{
> +  __builtin_ia32_setssbsy ();
> +}
> +
> +void f2 (void)
> +{
> +  _setssbsy ();
> +}
> 
> Is there a reason that both, __builtin and intrinsic versions are tested in a
> couple of places? The intrinsic version is just a wrapper for __builtin, so IMO
> testing intrinsic version should be enough.
No strong reason. Just to check that intrinsic names are recognized and processed correctly.
The implementation could change and the test will catch inconsistency. I would also assume
a user will use intrinsics that's why I add intrinsic check. Should I remove it?

> 
> diff --git a/gcc/testsuite/gcc.target/i386/cet-rdssp-1.c
> b/gcc/testsuite/gcc.target/i386/cet-rdssp-1.c
> new file mode 100644
> index 0000000..f9223a5
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/cet-rdssp-1.c
> @@ -0,0 +1,39 @@
> +/* { dg-do run { target cet } } */
> +/* { dg-options "-O2 -finstrument-control-flow -mcet" } */
> 
> The "target cet" directive just checks that CET instructions can be compiled.
> The test will (probably?) fail on targets with binutils that can compile CET
> instructions, but the target itself doesn't support CET. If this is the case, then
> check header has to be introduced, so the test can be bypassed on targets
> without runtime support.
The test will not fail even if a target doesn't support CET as 'rdssp' instruction is a
NOP on such target and further usage of CET instruction is bypassed. In this case
the code

+  ssp = rdssp (ssp);

Will keep ssp as 0.

Thanks,
Igor

> Uros.