qemu: update to 9.1.0

[heljkon]

see https://wiki.qemu.org/ChangeLog/9.1

[heljkon]

For the clang64 build failure: https://gitlab.com/qemu-project/qemu/-/issues/2476

[heljkon]

@lazka @Biswa96 @jeremyd2019
Based on ticket Regression 9.1.0-rc0: Msys2/Clang64 build fails in QEMU repository a discussion came up about the fitness of CLANG64/CLANGARM64 for QEMU.

thuth, a core QEMU developer stated:

Ok, so Clang does not support gcc_struct yet. You should not use it to build QEMU on MSYS2. While 95% of such a build might work fine, there are likely some emulated devices where this gcc_struct attribute makes a difference and those won't work in such a build.

As I am only contributing to msys2, I ask you the members of msys2 for discussion and decision.

[lazka]

If upstream doesn't want to fix their struct packing to not depend on gcc_struct there is not much we can do I guess.

Not sure, your call.

I looked at why they added it in the first place: https://lists.gnu.org/archive/html/qemu-devel/2011-08/msg01877.html

[jeremyd2019]

thuth, a core QEMU developer stated:

Ok, so Clang does not support gcc_struct yet. You should not use it to build QEMU on MSYS2. While 95% of such a build might work fine, there are likely some emulated devices where this gcc_struct attribute makes a difference and those won't work in such a build.

@mstorsjo are you aware of this limitation? I figured clang has to support both struct packing styles, since it emulates both gcc and msvc frontends, but I guess maybe not both on the same target?

[mstorsjo]

thuth, a core QEMU developer stated:

Ok, so Clang does not support gcc_struct yet. You should not use it to build QEMU on MSYS2. While 95% of such a build might work fine, there are likely some emulated devices where this gcc_struct attribute makes a difference and those won't work in such a build.

@mstorsjo are you aware of this limitation? I figured clang has to support both struct packing styles, since it emulates both gcc and msvc frontends, but I guess maybe not both on the same target?

Yes, I'm aware of this. It's indeed a case where Clang does support both, it just doesn't support the attribute. It does IIRC support ms_struct for opting in to the MS struct layout when building for a target that otherwise uses the default layout, but it doesn't yet support gcc_struct for requesting the reverse, when building in a configuration where the MS layout is the default. See llvm/llvm-project#24757 for the general tracking issue, and llvm/llvm-project#71148 for a recent PR that attempts to implement this.

[heljkon]

@lazka @Biswa96 @jeremyd2019 @mstorsjo
Upstream has added a compiler test to make sure, CLANG64 is not build. I don't want to patch this, so I've disabled clang builds.

==> Starting build()...
...
../qemu-9.1.0-rc3/meson.build:321:4: ERROR: Problem encountered: Your compiler does not support __attribute__((gcc_struct)) - please use GCC instead of Clang

A full log can be found at .../mingw-w64-qemu/src/build-CLANG64/meson-logs/meson-log.txt

ERROR: meson setup failed

==> ERROR: A failure occurred in build().
    Aborting...

.../mingw-w64-qemu/src/build-CLANG64/meson-logs/meson-log.txt:

-----------
Command line: `clang++ -m64 ../tmpud8icv9j/testfile.cpp -o ../tmpud8icv9j/output.obj -c -march=nocona -msahf -mtune=generic -O2 -pipe -Wp,-D_FORTIFY_SOURCE=2 -fstack-protector-strong -D_FILE_OFFSET_BITS=64 -O0 -fpermissive -Werror=implicit-function-declaration -Werror=unknown-warning-option -Werror=unused-command-line-argument -Werror=ignored-optimization-argument -std=gnu++11` -> 0
Running compile:
Working directory:  ./
Code:
struct x { int y; } __attribute__((gcc_struct));
-----------
Command line: `clang++ -m64 ../tmpoo9iwq6a/testfile.cpp -o ../tmpoo9iwq6a/output.obj -c -march=nocona -msahf -mtune=generic -O2 -pipe -Wp,-D_FORTIFY_SOURCE=2 -fstack-protector-strong -D_FILE_OFFSET_BITS=64 -O0 -fpermissive -Werror=implicit-function-declaration -Werror=unknown-warning-option -Werror=unused-command-line-argument -Werror=ignored-optimization-argument -std=gnu++11 -Werror` -> 1
stderr:
../tmpoo9iwq6a/testfile.cpp:1:36: error: unknown attribute 'gcc_struct' ignored [-Werror,-Wunknown-attributes]
    1 | struct x { int y; } __attribute__((gcc_struct));
      |                                    ^~~~~~~~~~
1 error generated.
-----------

../qemu-9.1.0-rc3/meson.build:321:4: ERROR: Problem encountered: Your compiler does not support __attribute__((gcc_struct)) - please use GCC instead of Clang

[jeremyd2019]

That's too bad - my "default" has been using CLANG64 qemu, generally with whpx but sometimes with tcg for arm64 target. I suppose I'll have to switch to UCRT64 until clang gains support for gcc_struct.

[heljkon]

@lazka @jeremyd2019 @Biswa96
Please review!

As already discussed, QEMU packages for clang weren't build, because upstream has introduced a test which currently results in failing clang builds:

ERROR: Problem encountered: Your compiler does not support attribute((gcc_struct)) - please use GCC instead of Clang

[heljkon]

@lazka @jeremyd2019 @Biswa96 @MehdiChinoune
Just a reminder: still waiting for review.