Re: [testsuite][ARM target attributes] Fix effective_target tests

[Christophe Lyon <christophe dot lyon at linaro dot org>]

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On 27 November 2015 at 14:00, Christophe Lyon
<christophe.lyon@linaro.org> wrote:
> Hi,
>
> After the recent commits from Christian adding target attributes
> support for ARM FPU settings,  I've noticed that some of the tests
> were failing because of incorrect assumptions wrt to the default
> cpu/fpu/float-abi of the compiler.
>
> This patch fixes the problems I've noticed in the following way:
> - do not force -mfloat-abi=softfp in dg-options, to avoid conflicts
> when gcc is configured --with-float=hard
>
> - change arm_vfp_ok such that it tries several -mfpu/-mfloat-abi
> flags, checks that __ARM_FP is defined and __ARM_NEON_FP is not
> defined
>
> - introduce arm_fp_ok, which is similar but does not enforce fpu setting
>
> - add a new effective_target: arm_crypto_pragma_ok to check that
> setting this fpu via a pragma is actually supported by the current
> "multilib". This is different from checking the command-line option
> because the pragma might conflict with the command-line options in
> use.
>
> The updates in the testcases are as follows:
> - attr-crypto.c, we have to make sure that the defaut fpu does not
> conflict with the one forced by pragma. That's why I use the arm_vfp
> options/effective_target. This is needed if gcc has been configured
> --with-fpu=neon-fp16, as the pragma fpu=crypto-neon-fp-armv8 would
> conflict.
>
> - attr-neon-builtin-fail.c: use arm_fp to force the appropriate
> float-abi setting. Enforcing fpu is not needed here.
>
> - attr-neon-fp16.c: similar, I also removed arm_neon_ok since it was
> not necessary to make the test pass in my testing. On second thought,
> I'm wondering whether I should leave it and make the test unsupported
> in more cases (such as when forcing -march=armv5t, although it does
> pass with this patch)
>
> - attr-neon2.c: use arm_vfp to force the appropriate float-abi
> setting. Enforcing mfpu=vfp is needed to avoid conflict with the
> pragma target fpu=neon (for instance if the toolchain default is
> neon-fp16)
>
> - attr-neon3.c: similar
>
> Tested on a variety of configurations, see:
> http://people.linaro.org/~christophe.lyon/cross-validation/gcc-test-patches/230929-target-attr/report-build-info.html
>
> Note that the regressions reported fall into 3 categories:
> - when forcing march=armv5t: tests are now unsupported because I
> modified arm_crypto_ok to require arm_v8_neon_ok instead of arm32.
>
> - the warning reported by attr-neon-builtin-fail.c moved from line 12
> to 14 and is thus seen as a regression + one improvement
>
> - finally, attr-neon-fp16.c causes an ICE on armeb compilers, for
> which I need to post a bugzilla.
>
I've created https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68620 for this.

>
> TBH, I'm a bit concerned by the complexity of all these multilib-like
> conditions. I'm confident that I'm still missing some combinations :-)
>
> And with new target attributes coming, new architectures etc... all
> this logic is likely to become even more complex.
>
> That being said, OK for trunk?
>
> Christophe
>
>
> 2015-11-27  Christophe Lyon  <christophe.lyon@linaro.org>
>
>     * lib/target-supports.exp
>     (check_effective_target_arm_vfp_ok_nocache): New.
>     (check_effective_target_arm_vfp_ok): Call the new
>     check_effective_target_arm_vfp_ok_nocache function.
>     (check_effective_target_arm_fp_ok_nocache): New.
>     (check_effective_target_arm_fp_ok): New.
>     (add_options_for_arm_fp): New.
>     (check_effective_target_arm_crypto_ok_nocache): Require
>     target_arm_v8_neon_ok instead of arm32.
>     (check_effective_target_arm_crypto_pragma_ok_nocache): New.
>     (check_effective_target_arm_crypto_pragma_ok): New.
>     (add_options_for_arm_vfp): New.
>     * gcc.target/arm/attr-crypto.c: Use arm_crypto_pragma_ok effective
>     target. Do not force -mfloat-abi=softfp, use arm_vfp effective
>     target instead.
>     * gcc.target/arm/attr-neon-builtin-fail.c: Do not force
>     -mfloat-abi=softfp, use arm_fp effective target instead.
>     * gcc.target/arm/attr-neon-fp16.c: Likewise. Remove arm_neon_ok
>     dependency.
>     * gcc.target/arm/attr-neon2.c: Do not force -mfloat-abi=softfp,
>     use arm_vfp effective target instead.
>     * gcc.target/arm/attr-neon3.c: Likewise.