[Pkg-julia-devel] Bug#974779: Bug#974779: severity - Julia: Please upgrade to llvm-toolchain-11

[Sebastian Ramacher]

Hi Norbert

On 2021-01-08 12:17:54, Norbert Preining wrote:
> Hi Sebastian,
> 
> coming back to the llvm-9 vs -10 vs -11 issue.
> 
> So, julia fails to build on ppc64el with llvm-9 because llvm-9 has bugs
> there, and we cannot use llvm-11 since this is not supported in the
> current version of julia.
> 
> There are thus the following options:
> - keep llvm-10
> - drop julia on ppc64el
> - fix llvm-9
> 
> The necessary fixes for llvm-9 are described here:
> https://github.com/JuliaLang/julia/pull/35477
> in particular in the two patches that are included in the PR

Sylvestre, could you apply the two patches to llvm-toolchain-9 so that
we can check if that fixes the julia build on ppc64el?

If that doesn't help, we can still look at droping julia from ppc64el.

> ***** deps/patches/llvm9-D71443-PPC-MC-redef-symbol.patch ******
> From 5cd52dbfa9c60cfd12676924bed97701ee9bc4ef Mon Sep 17 00:00:00 2001
> From: Fangrui Song <maskray at google.com>
> Date: Thu, 12 Dec 2019 16:18:57 -0800
> Subject: [PATCH] [MC][PowerPC] Fix a crash when redefining a symbol after .set
> 
> Fix PR44284. This is probably not valid assembly but we should not crash.
> 
> Reviewed By: luporl, #powerpc, steven.zhang
> 
> Differential Revision: https://reviews.llvm.org/D71443
> 
> (cherry picked from commit f99eedeb72644671cd584f48e4c136d47f6b0020)
> ---
>  llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCTargetDesc.cpp | 3 ++-
>  llvm/test/MC/PowerPC/ppc64-localentry-symbols.s          | 5 +++++
>  2 files changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCTargetDesc.cpp llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCTargetDesc.cpp
> index 90c3c8d20ed..71f926c265e 100644
> --- llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCTargetDesc.cpp
> +++ llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCTargetDesc.cpp
> @@ -196,7 +196,8 @@ public:
> 
>    void finish() override {
>      for (auto *Sym : UpdateOther)
> -      copyLocalEntry(Sym, Sym->getVariableValue());
> +      if (Sym->isVariable())
> +        copyLocalEntry(Sym, Sym->getVariableValue());
>    }
> 
>  private:
> diff --git llvm/test/MC/PowerPC/ppc64-localentry-symbols.s llvm/test/MC/PowerPC/ppc64-localentry-symbols.s
> index f1d5c5d0ab1..a663af57ad4 100644
> --- llvm/test/MC/PowerPC/ppc64-localentry-symbols.s
> +++ llvm/test/MC/PowerPC/ppc64-localentry-symbols.s
> @@ -32,3 +32,8 @@ func:
>    nop
>    nop
>    .localentry func, 8
> +
> +## PR44284 Don't crash if err is redefined after .set
> +.set err, _err
> +.globl err
> +err:
> --
> 2.26.0
> ******************************
> 
> 
> 
> 
> ******* deps/patches/llvm-9.0-D78196.patch ****************
> diff --git a/lib/Target/PowerPC/MCTargetDesc/PPCMCTargetDesc.cpp b/lib/Target/PowerPC/MCTargetDesc/PPCMCTargetDesc.cpp
> --- a/lib/Target/PowerPC/MCTargetDesc/PPCMCTargetDesc.cpp
> +++ b/lib/Target/PowerPC/MCTargetDesc/PPCMCTargetDesc.cpp
> @@ -210,6 +210,10 @@
>      for (auto *Sym : UpdateOther)
>        if (Sym->isVariable())
>          copyLocalEntry(Sym, Sym->getVariableValue());
> +
> +    // Clear the set of symbols that needs to be updated so the streamer can
> +    // be reused without issues.
> +    UpdateOther.clear();
>    }
> 
>  private:
> ****************************
> 
> 
> I cannot guarantee that Julia will build with these fixes applied to the
> LLVM-9 sources, but at least that is what I read out of the above PR.
> 
> In particular looking at the list of other patches applied to LLVM-9:
> ifeq ($(LLVM_VER_SHORT),9.0)
> $(eval $(call LLVM_PATCH,llvm-D27629-AArch64-large_model_6.0.1))
> $(eval $(call LLVM_PATCH,llvm8-D34078-vectorize-fdiv))
> $(eval $(call LLVM_PATCH,llvm-6.0-NVPTX-addrspaces)) # NVPTX -- warning: this fails check-llvm-codegen-nvptx
> $(eval $(call LLVM_PATCH,llvm-7.0-D44650)) # mingw32 build fix
> $(eval $(call LLVM_PATCH,llvm9-D50010-VNCoercion-ni))
> $(eval $(call LLVM_PATCH,llvm8-WASM-addrspaces)) # WebAssembly
> $(eval $(call LLVM_PATCH,llvm-exegesis-mingw)) # mingw build
> $(eval $(call LLVM_PATCH,llvm-test-plugin-mingw)) # mingw build
> $(eval $(call LLVM_PATCH,llvm7-revert-D44485))
> $(eval $(call LLVM_PATCH,llvm-8.0-D66657-codegen-degenerate)) # remove for 10.0
> $(eval $(call LLVM_PATCH,llvm-8.0-D71495-vectorize-freduce)) # remove for 10.0
> $(eval $(call LLVM_PATCH,llvm-D75072-SCEV-add-type))
> $(eval $(call LLVM_PATCH,llvm-9.0-D65174-limit-merge-stores)) # remove for 10.0
> 
> )
> 
> 
> I guess you prefer that we drop julia for ppc64el, which would of course
> be the easiest way. But I still would like to hear your opinion,
> especially since llvm-10-dev is still present as of now, in both testing
> and unstable.

FWIW, I have already added the removal hint for llvm-toolchain-10, but
removal is still blocked by julia:

trying: -llvm-toolchain-10
skipped: -llvm-toolchain-10 (61, 0, 187)
    got: 29+0: a-5:a-23:a-0:a-0:i-0:m-0:m-0:p-0:s-1
    * amd64: cantor-backend-julia, julia, libjulia-dev, libjulia1

(from https://release.debian.org/britney/update_output.txt)

So once julia is either built on or removed from ppc64el and therefore
able to migrate, llvm-toolchain-10 will be removed from testing.

Cheers
-- 
Sebastian Ramacher