[Rd] Matrix issues when building R with znver3 architecture under GCC 11

[Kieran Short]

Hi Henrik,

It produces the same result.

Regards,
Kieran

On Tue, 12 Apr 2022, 23:13 Henrik Bengtsson, <henrik.bengtsson using gmail.com>
wrote:

> Shooting from the hip: What happens if you compile with -O2 instead of -O3?
>
> Henrik
>
> On Mon, Apr 11, 2022, 18:27 Kieran Short <kieran.short using gmail.com> wrote:
>
>> Hello,
>>
>> I'm new to this list, and have subscribed particularly because I've come
>> across an issue with building R from source with an AMD-based Zen
>> architecture under GCC11. Please don't attack me for my linux operating
>> system choice, but it is Ubuntu 20.04 with Linux Kernel 5.10.102.1 -
>> microsoft-standard-WSL2. I've built GCC11 using GCC8 (the standard GCC
>> under Ubuntu20.04 WSL release), under Windows11 with wslg. WSL2/g runs as
>> a
>> hypervisor with ports to all system resources including display, GPU
>> (cuda,
>> etc).
>>
>> The reason why I am posting this email is that I am trying to compile R
>> using the AMD Zen3 platform architecture rather than x86/64, because it
>> has
>> processor-specific optimizations that improve performance over the
>> standard
>> x86/64 in benchmarks. The Zen3 architecture optimizations are not
>> available
>> in earlier versions of GCC (actually, they have possibly been backported
>> to
>> GCC10 now). Since Ubuntu 20.04 doesn't have GCC11, I compiled the GCC11
>> compiler using the native GCC8.
>>
>> The GCC11 I have built can build R 4.1.3 with a standard x86-64
>> architecture and pass all tests with "make check-all".
>> I configured that with:
>> > ~/R/R-4.1.3/configure CC=gcc-11.2 CXX=g++-11.2 FC=gfortran-11.2
>> CXXFLAGS="-O3 -march=x86-64" CFLAGS="-O3 -march=x86-64" FFLAGS="-O3
>> -march=x86-64" --enable-memory-profiling --enable-R-shlib
>> and built with
>> > make -j 32 -O
>> > make check-all
>> ## PASS.
>>
>> So I can build R in my environment with GCC11.
>> In configure, I am using references to "gcc-11.2" "gfortran-11.2" and
>> "g++-11.2" because I compiled GCC11 compilers with these suffixes.
>>
>> Now, I'm using a 32 thread (16 core) AMD Zen3 CPU (a 5950x), and want to
>> use it to its full potential. Zen3 optimizations are available as a
>> -march=znver3 option n GCC11. The znver3 optimizations improve performance
>> in Phoronix Test Suite benchmarks (I'm not aware of anyone that has
>> compiled R with them). See:
>> https://www.phoronix.com/scan.php?page=article&item=amd-5950x-gcc11
>>
>> However, the R 4.1.3 build (made with "make -j 32 -O"), configured with
>> -march=znver3, produces an R that fails "make check-all".
>>
>> > ~/R/R-4.1.3/configure CC=gcc-11.2 CXX=g++-11.2 FC=gfortran-11.2
>> CXXFLAGS="-O2 -march=znver3" CFLAGS="-O2 -march=znver3" FFLAGS="-O2
>> -march=znver3" --enable-memory-profiling --enable-R-shlib
>> or
>> > ~/R/R-4.1.3/configure CC=gcc-11.2 CXX=g++-11.2 FC=gfortran-11.2
>> CXXFLAGS="-O3 -march=znver3" CFLAGS="-O3 -march=znver3" FFLAGS="-O3
>> -march=znver3" --enable-memory-profiling --enable-R-shlib
>>
>> The fail is always in the factorizing.R Matrix.R tests, and in particular,
>> there are a number of errors and a fatal error.
>> I have attached the output because I cannot really understand what is
>> going
>> wrong. But results returned from matrix calculations are obviously odd
>> with
>> -march=znver3 in GCC 11. There is another backwards-compatible
>> architecture
>> option "znver2" and this has EXACTLY the same result.
>>
>> While there are other warrnings and errors (many in assert.EQ() ), the
>> factorizing.R script continues. The fatal error (at line 2662 in the
>> attached factorizing.Rout.fail text file) is:
>>
>> > ## problematic rank deficient rankMatrix() case -- only seen in large
>> cases ??
>> > Z. <- readRDS(system.file("external", "Z_NA_rnk.rds", package="Matrix"))
>> > tools::assertWarning(rnkZ. <- rankMatrix(Z., method = "qr")) # gave
>> errors
>> Error in assertCondition(expr, classes, .exprString = d.expr) :
>>   Failed to get warning in evaluating rnkZ. <- rankMatrix(Z., method  ...
>> Calls: <Anonymous> -> assertCondition
>> Execution halted
>>
>> Can anybody shed light on what might be going on here? 'make check-all'
>> passes all the other checks. It is just factorizing.R in Matrix that fails
>> (other matrix tests run ok).
>> Sorry this is a bit long-winded, but I thought details might be important.
>>
>> best regards,
>> Kieran
>> ______________________________________________
>> R-devel using r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-devel
>>
>

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