Re: [Valgrind-developers] Patch reviews and repo write access

[Alex B. <ale...@li...>]

Julian Seward <js...@ac...> writes:

> On 08/10/2019 16:06, Assad Hashmi wrote:
>> After establishing the host architecture, can the test infrastructure
>> detect CPU capabilities when deciding to execute tests?
>> For example arm64 v8.1 CPUs have the "atomics" capability, v8.2 has "fphp" etc.
>> Or is that check something each test has to implement itself?
>
> The framework can do that itself.  But you'll need to update the framework.
> You should just write the test .c file(s) without any capability checks.
>
> There are actually two different questions here:
>
> (1) can the target's assembler assemble the relevant instructions?  In
>      other words, is the test even compilable?  For an example, look at
>      "if BUILD_ARMV8_CRC_TESTS" in tests/none/arm64/Makefile.am.  You will
>      need to add a new conditional, for .._ARMV8_1.  See the top level
>      configure.ac for how BUILD_ARMV8_CRC_TESTS gets defined.
>
> (2) can the target machine run the test (is the insn actually supported)?
>      Unfortunately there is no infrastructure in none/tests/arm64 that you
>      can copy, because so far we have only supported on arm64 variant.

I appreciate that Valgrind is a host-2-host translator but does this
mean you can only support instructions when the host supports them or is
this just a limitation for tests?

>
>      The way this is done is by having a "prereq:" line in the test's
>      .vgtest file.  For example, look at none/tests/amd64/xacq_xrel.vgtest.
>      This has:
>       prereq: test -x xacq_xrel && ../../../tests/x86_amd64_features amd64-avx
>      This checks first whether the test got built (per (1)).  If so then it
>      runs tests/x86_amd64_features to ask whether the specified CPU feature
>      ("amd64-avx") is supported on this machine.
>
>      You'll need to add an arm64 equivalent to the existing
>      {mips,s390,x86_amd64}_features.c, which the .vgtest file can use to ask
>      if the relevant 8.1 features are supported.
>
> Sorry if this seems like a maze.  Just fix it as best you can and it can be
> checked over at review time.
>
> J
>
>
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--
Alex Bennée