firefox fails to build with ICE in src/gl.cc with clang-19

[stefson]

from the build log, I think this is the error:

179:48.20   cargo:warning=fatal error: error in backend: Do not know how to scalarize the result of this operator!
179:48.20   cargo:warning=
179:48.21   cargo:warning=PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
179:48.22   cargo:warning=Stack dump:
179:48.33   cargo:warning=0.	Program arguments: /usr/lib/llvm/19/bin/armv7a-unknown-linux-musleabihf-clang++-19 -O2 -ffunction-sections -fdata-sections -fPIC --target=armv7a-unknown-linux-musleabihf -I/var/tmp/portage/www-client/firefox-131.0_rc1/work/firefox_build/dist/stl_wrappers -fvisibility=hidden -fvisibility-inlines-hidden -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -fstack-protector-strong -DNDEBUG=1 -DTRIMMED=1 -I/var/tmp/portage/www-client/firefox-131.0_rc1/work/firefox_build/dist/include -I/usr/include/nspr -I/usr/include/nss -I/usr/include/nspr -I/var/tmp/portage/www-client/firefox-131.0_rc1/work/firefox_build/dist/include/nss -I/usr/include/libpng16 -I/usr/include/pixman-1 -DMOZILLA_CLIENT -include /var/tmp/portage/www-client/firefox-131.0_rc1/work/firefox_build/mozilla-config.h -mfloat-abi=hard -fno-rtti -pthread -fno-sized-deallocation -fno-aligned-new -ffunction-sections -fdata-sections -fno-math-errno -fno-exceptions -fPIC -pipe -march=armv7-a -mfpu=vfpv3-d16 -mfloat-abi=hard -fomit-frame-pointer -O2 -fomit-frame-pointer -funwind-tables -Wno-error=tautological-type-limit-compare -Wno-invalid-offsetof -Wno-range-loop-analysis -Wno-deprecated-anon-enum-enum-conversion -Wno-deprecated-enum-enum-conversion -Wno-deprecated-this-capture -Wno-inline-new-delete -Wno-error=deprecated-declarations -Wno-error=array-bounds -Wno-error=free-nonheap-object -Wno-error=atomic-alignment -Wno-error=deprecated-builtins -Wno-psabi -Wno-error=builtin-macro-redefined -Wno-vla-cxx-extension -Wno-unknown-warning-option -fno-strict-aliasing -ffp-contract=off -DMOZILLA_CONFIG_H -I /var/tmp/portage/www-client/firefox-131.0_rc1/work/firefox-131.0/gfx/wr/swgl/../webrender/res -I src -I /var/tmp/portage/www-client/firefox-131.0_rc1/work/firefox_build/armv7a-unknown-linux-musleabihf/release/build/swgl-3e66616cdca95a28/out -std=c++17 -fno-exceptions -fno-rtti -fno-math-errno -UMOZILLA_CONFIG_H -ffast-math -mrecip=none -fno-finite-math-only -D_GLIBCXX_USE_CXX11_ABI=0 -o /var/tmp/portage/www-client/firefox-131.0_rc1/work/firefox_build/armv7a-unknown-linux-musleabihf/release/build/swgl-3e66616cdca95a28/out/2e40c9e35e9506f4-gl.o -c src/gl.cc
179:48.33   cargo:warning=1.	<eof> parser at end of file
179:48.33   cargo:warning=2.	Code generation
179:48.34   cargo:warning=3.	Running pass 'Function Pass Manager' on module 'src/gl.cc'.
179:48.35   cargo:warning=4.	Running pass 'ARM Instruction Selection' on function '@_ZN25cs_blur_ALPHA_TARGET_frag15swgl_drawSpanR8Ev'
179:48.36   cargo:warning=armv7a-unknown-linux-musleabihf-clang++-19: error: clang frontend command failed with exit code 70 (use -v to see invocation)
179:48.36   cargo:warning=clang version 19.1.0
179:48.36   cargo:warning=Target: armv7a-unknown-linux-musleabihf
179:48.37   cargo:warning=Thread model: posix
179:48.37   cargo:warning=InstalledDir: /usr/lib/llvm/19/bin
179:48.38   cargo:warning=Configuration file: /etc/clang/armv7a-unknown-linux-musleabihf-clang++.cfg
179:48.38   cargo:warning=armv7a-unknown-linux-musleabihf-clang++-19: note: diagnostic msg:
179:48.39   cargo:warning=********************
179:48.39   cargo:warning=
179:48.40   cargo:warning=PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
179:48.40   cargo:warning=Preprocessed source(s) and associated run script(s) are located at:
179:48.41   cargo:warning=armv7a-unknown-linux-musleabihf-clang++-19: note: diagnostic msg: /var/tmp/portage/www-client/firefox-131.0_rc1/temp/gl-a0fb08.cpp
179:48.42   cargo:warning=armv7a-unknown-linux-musleabihf-clang++-19: note: diagnostic msg: /var/tmp/portage/www-client/firefox-131.0_rc1/temp/gl-a0fb08.sh
179:48.42   cargo:warning=armv7a-unknown-linux-musleabihf-clang++-19: note: diagnostic msg:
179:48.43   cargo:warning=
179:48.43   cargo:warning=********************
179:48.43   --- stderr

here is the full compressed build log: build.log.gz

and here is the preprocessed sources, and the reproducer: preprocess.tar.gz

[stefson]

there were some reports of musttail errors in various issues over the last week, ccing @ostannard as he is working on them.

I'm happy to test any patches

[llvmbot]

@llvm/issue-subscribers-backend-arm

Author: None (stefson)

from the build log, I think this is the error:

179:48.20   cargo:warning=fatal error: error in backend: Do not know how to scalarize the result of this operator!
179:48.20   cargo:warning=
179:48.21   cargo:warning=PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
179:48.22   cargo:warning=Stack dump:
179:48.33   cargo:warning=0.	Program arguments: /usr/lib/llvm/19/bin/armv7a-unknown-linux-musleabihf-clang++-19 -O2 -ffunction-sections -fdata-sections -fPIC --target=armv7a-unknown-linux-musleabihf -I/var/tmp/portage/www-client/firefox-131.0_rc1/work/firefox_build/dist/stl_wrappers -fvisibility=hidden -fvisibility-inlines-hidden -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -fstack-protector-strong -DNDEBUG=1 -DTRIMMED=1 -I/var/tmp/portage/www-client/firefox-131.0_rc1/work/firefox_build/dist/include -I/usr/include/nspr -I/usr/include/nss -I/usr/include/nspr -I/var/tmp/portage/www-client/firefox-131.0_rc1/work/firefox_build/dist/include/nss -I/usr/include/libpng16 -I/usr/include/pixman-1 -DMOZILLA_CLIENT -include /var/tmp/portage/www-client/firefox-131.0_rc1/work/firefox_build/mozilla-config.h -mfloat-abi=hard -fno-rtti -pthread -fno-sized-deallocation -fno-aligned-new -ffunction-sections -fdata-sections -fno-math-errno -fno-exceptions -fPIC -pipe -march=armv7-a -mfpu=vfpv3-d16 -mfloat-abi=hard -fomit-frame-pointer -O2 -fomit-frame-pointer -funwind-tables -Wno-error=tautological-type-limit-compare -Wno-invalid-offsetof -Wno-range-loop-analysis -Wno-deprecated-anon-enum-enum-conversion -Wno-deprecated-enum-enum-conversion -Wno-deprecated-this-capture -Wno-inline-new-delete -Wno-error=deprecated-declarations -Wno-error=array-bounds -Wno-error=free-nonheap-object -Wno-error=atomic-alignment -Wno-error=deprecated-builtins -Wno-psabi -Wno-error=builtin-macro-redefined -Wno-vla-cxx-extension -Wno-unknown-warning-option -fno-strict-aliasing -ffp-contract=off -DMOZILLA_CONFIG_H -I /var/tmp/portage/www-client/firefox-131.0_rc1/work/firefox-131.0/gfx/wr/swgl/../webrender/res -I src -I /var/tmp/portage/www-client/firefox-131.0_rc1/work/firefox_build/armv7a-unknown-linux-musleabihf/release/build/swgl-3e66616cdca95a28/out -std=c++17 -fno-exceptions -fno-rtti -fno-math-errno -UMOZILLA_CONFIG_H -ffast-math -mrecip=none -fno-finite-math-only -D_GLIBCXX_USE_CXX11_ABI=0 -o /var/tmp/portage/www-client/firefox-131.0_rc1/work/firefox_build/armv7a-unknown-linux-musleabihf/release/build/swgl-3e66616cdca95a28/out/2e40c9e35e9506f4-gl.o -c src/gl.cc
179:48.33   cargo:warning=1.	<eof> parser at end of file
179:48.33   cargo:warning=2.	Code generation
179:48.34   cargo:warning=3.	Running pass 'Function Pass Manager' on module 'src/gl.cc'.
179:48.35   cargo:warning=4.	Running pass 'ARM Instruction Selection' on function '@<!-- -->_ZN25cs_blur_ALPHA_TARGET_frag15swgl_drawSpanR8Ev'
179:48.36   cargo:warning=armv7a-unknown-linux-musleabihf-clang++-19: error: clang frontend command failed with exit code 70 (use -v to see invocation)
179:48.36   cargo:warning=clang version 19.1.0
179:48.36   cargo:warning=Target: armv7a-unknown-linux-musleabihf
179:48.37   cargo:warning=Thread model: posix
179:48.37   cargo:warning=InstalledDir: /usr/lib/llvm/19/bin
179:48.38   cargo:warning=Configuration file: /etc/clang/armv7a-unknown-linux-musleabihf-clang++.cfg
179:48.38   cargo:warning=armv7a-unknown-linux-musleabihf-clang++-19: note: diagnostic msg:
179:48.39   cargo:warning=********************
179:48.39   cargo:warning=
179:48.40   cargo:warning=PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
179:48.40   cargo:warning=Preprocessed source(s) and associated run script(s) are located at:
179:48.41   cargo:warning=armv7a-unknown-linux-musleabihf-clang++-19: note: diagnostic msg: /var/tmp/portage/www-client/firefox-131.0_rc1/temp/gl-a0fb08.cpp
179:48.42   cargo:warning=armv7a-unknown-linux-musleabihf-clang++-19: note: diagnostic msg: /var/tmp/portage/www-client/firefox-131.0_rc1/temp/gl-a0fb08.sh
179:48.42   cargo:warning=armv7a-unknown-linux-musleabihf-clang++-19: note: diagnostic msg:
179:48.43   cargo:warning=
179:48.43   cargo:warning=********************
179:48.43   --- stderr

here is the full compressed build log: build.log.gz

and here is the preprocessed sources, and the reproducer: preprocess.tar.gz

[ostannard]

fatal error: error in backend: Do not know how to scalarize the result of this operator!

This error doesn't look obviously related to the musttail bugs I have been working on, but if you think it's relevant then you could test with #109943.

[stefson]

yeah I think you're right, the only part of firefox using clang::musttail is skia

I could need some help with reducing, never had an issue like that before with llvm - is there a guide somewhere on what to do?

[ostannard]

There's a tool called creduce which is very useful for reducing compiler test cases: https://github.com/csmith-project/creduce. Unfortunately it's documentation site has been down for a while, but archive.org has it: https://web.archive.org/web/20201204141133/https://embed.cs.utah.edu/creduce/using/

[Endilll]

One thing creduce tutorials typically don't speak of is how to preserve original identifiers. Single-character identifiers make it hard to read any snippet longer than 5 lines. Here are creduce arguments you need to pass:

--remove-pass pass_clang rename-fun --remove-pass pass_clang rename-param --remove-pass pass_clang rename-var --remove-pass pass_clang rename-class --remove-pass pass_clang rename-cxx-method --remove-pass pass_clex rename-toks

[davemgreen]

That looks like a really big case that might take a while to reduce from C. With a mixture of -emit-llvm, running it through llc and isolating the function that was going wrong I managed to get it down to this:
https://godbolt.org/z/Th63E5cqr

It fails with ScalarizeVectorResult #0: t98: v1i16 = AssertZext t96, ValueType:ch:i8. It obviously shouldn't be failing, but I believe it might come from a mismatch between using vector types (template <typename T, int N> using VectorType = T __attribute__((ext_vector_type(N)));) and having Neon disabled. The AssertZext should be able to scalarize without any legal vector types.

[stefson]

I've compiled a llvm-20 toolchain to check if the error was fixed recently, and it fails as before:

/usr/lib/llvm/20/bin/armv7a-unknown-linux-musleabihf-clang++-20 -O2 -ffunction-sections -fdata-sections -fPIC --target=armv7a-unknown-linux-musleabihf -I/var/tmp/portage/www-client/firefox-132.0.1-r2/work/firefox_build/dist/stl_wrappers -fvisibility=hidden -fvisibility-inlines-hidden -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -fstack-protector-strong -fstrict-flex-arrays=1 -DNDEBUG=1 -DTRIMMED=1 -I/var/tmp/portage/www-client/firefox-132.0.1-r2/work/firefox_build/dist/include -I/usr/include/nspr -I/usr/include/nss -I/usr/include/nspr -I/var/tmp/portage/www-client/firefox-132.0.1-r2/work/firefox_build/dist/include/nss -I/usr/include/libpng16 -I/usr/include/pixman-1 -DMOZILLA_CLIENT -include /var/tmp/portage/www-client/firefox-132.0.1-r2/work/firefox_build/mozilla-config.h -mfloat-abi=hard -fno-rtti -pthread -fno-sized-deallocation -fno-aligned-new -ffunction-sections -fdata-sections -fno-math-errno -fno-exceptions -fPIC -pipe -march=armv7-a -mfpu=vfpv3-d16 -mfloat-abi=hard -fomit-frame-pointer -O2 -fomit-frame-pointer -funwind-tables -Wno-error=tautological-type-limit-compare -Wno-invalid-offsetof -Wno-range-loop-analysis -Wno-deprecated-anon-enum-enum-conversion -Wno-deprecated-enum-enum-conversion -Wno-deprecated-this-capture -Wno-inline-new-delete -Wno-error=deprecated-declarations -Wno-error=array-bounds -Wno-error=free-nonheap-object -Wno-error=atomic-alignment -Wno-error=deprecated-builtins -Wno-psabi -Wno-error=builtin-macro-redefined -Wno-vla-cxx-extension -Wno-unknown-warning-option -fno-strict-aliasing -ffp-contract=off -DMOZILLA_CONFIG_H -I /var/tmp/portage/www-client/firefox-132.0.1-r2/work/firefox-132.0.1/gfx/wr/swgl/../webrender/res -I src -I /var/tmp/portage/www-client/firefox-132.0.1-r2/work/firefox_build/armv7a-unknown-linux-musleabihf/release/build/swgl-029fb04aeb3e0fe7/out -std=c++17 -fno-exceptions -fno-rtti -fno-math-errno -UMOZILLA_CONFIG_H -ffast-math -mrecip=none -fno-finite-math-only -D_GLIBCXX_USE_CXX11_ABI=0 -o /var/tmp/portage/www-client/firefox-132.0.1-r2/work/firefox_build/armv7a-unknown-linux-musleabihf/release/build/swgl-029fb04aeb3e0fe7/out/2e40c9e35e9506f4-gl.o -c src/gl.cc -v
clang version 20.0.0git0e907c17
Target: armv7a-unknown-linux-musleabihf
Thread model: posix
InstalledDir: /usr/lib/llvm/20/bin
Configuration file: /etc/clang/armv7a-unknown-linux-musleabihf-clang++.cfg
System configuration file directory: /etc/clang
Selected GCC installation: /usr/lib/gcc/armv7a-unknown-linux-musleabihf/13
Candidate multilib: .;@m32
Selected multilib: .;@m32
 (in-process)
 "/usr/lib/llvm/20/bin/clang-20" -cc1 -triple armv7-unknown-linux-musleabihf -emit-obj -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name gl.cc -mrelocation-model pic -pic-level 2 -fhalf-no-semantic-interposition -mframe-pointer=none -relaxed-aliasing -fapprox-func -funsafe-math-optimizations -fno-signed-zeros -mreassociate -freciprocal-math -ffp-contract=fast -fno-rounding-math -mrecip=none -complex-range=basic -mconstructor-aliases -funwind-tables=1 -target-cpu generic -target-feature +vfp2 -target-feature +vfp2sp -target-feature -vfp3 -target-feature +vfp3d16 -target-feature +vfp3d16sp -target-feature -vfp3sp -target-feature -fp16 -target-feature -vfp4 -target-feature -vfp4d16 -target-feature -vfp4d16sp -target-feature -vfp4sp -target-feature -fp-armv8 -target-feature -fp-armv8d16 -target-feature -fp-armv8d16sp -target-feature -fp-armv8sp -target-feature -fullfp16 -target-feature +fp64 -target-feature -d32 -target-feature -neon -target-feature -sha2 -target-feature -aes -target-feature -fp16fml -target-abi aapcs-linux -mfloat-abi hard -debugger-tuning=gdb -fdebug-compilation-dir=/var/tmp/portage/www-client/firefox-132.0.1-r2/work/firefox-132.0.1/gfx/wr/swgl -v -ffunction-sections -fdata-sections -fcoverage-compilation-dir=/var/tmp/portage/www-client/firefox-132.0.1-r2/work/firefox-132.0.1/gfx/wr/swgl -resource-dir /usr/lib/llvm/20/bin/../../../../lib/clang/20 -include /usr/include/gentoo/fortify.h -include /usr/include/gentoo/maybe-stddefs.h -include /var/tmp/portage/www-client/firefox-132.0.1-r2/work/firefox_build/mozilla-config.h -I /var/tmp/portage/www-client/firefox-132.0.1-r2/work/firefox_build/dist/stl_wrappers -U _FORTIFY_SOURCE -D _FORTIFY_SOURCE=2 -D NDEBUG=1 -D TRIMMED=1 -I /var/tmp/portage/www-client/firefox-132.0.1-r2/work/firefox_build/dist/include -I /usr/include/nspr -I /usr/include/nss -I /usr/include/nspr -I /var/tmp/portage/www-client/firefox-132.0.1-r2/work/firefox_build/dist/include/nss -I /usr/include/libpng16 -I /usr/include/pixman-1 -D MOZILLA_CLIENT -D MOZILLA_CONFIG_H -I /var/tmp/portage/www-client/firefox-132.0.1-r2/work/firefox-132.0.1/gfx/wr/swgl/../webrender/res -I src -I /var/tmp/portage/www-client/firefox-132.0.1-r2/work/firefox_build/armv7a-unknown-linux-musleabihf/release/build/swgl-029fb04aeb3e0fe7/out -U MOZILLA_CONFIG_H -D _GLIBCXX_USE_CXX11_ABI=0 -internal-isystem /usr/lib/gcc/armv7a-unknown-linux-musleabihf/13/include/g++-v13 -internal-isystem /usr/lib/gcc/armv7a-unknown-linux-musleabihf/13/include/g++-v13/armv7a-unknown-linux-musleabihf -internal-isystem /usr/lib/gcc/armv7a-unknown-linux-musleabihf/13/include/g++-v13/backward -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/armv7a-unknown-linux-musleabihf/13/../../../../armv7a-unknown-linux-musleabihf/include -internal-externc-isystem /include -internal-externc-isystem /usr/include -internal-isystem /usr/lib/llvm/20/bin/../../../../lib/clang/20/include -O2 -Wno-error=tautological-type-limit-compare -Wno-invalid-offsetof -Wno-range-loop-analysis -Wno-deprecated-anon-enum-enum-conversion -Wno-deprecated-enum-enum-conversion -Wno-deprecated-this-capture -Wno-inline-new-delete -Wno-error=deprecated-declarations -Wno-error=array-bounds -Wno-error=free-nonheap-object -Wno-error=atomic-alignment -Wno-error=deprecated-builtins -Wno-psabi -Wno-error=builtin-macro-redefined -Wno-vla-cxx-extension -Wno-unknown-warning-option -std=c++17 -fdeprecated-macro -ferror-limit 19 -fvisibility=hidden -fvisibility-inlines-hidden -fstrict-flex-arrays=1 -pthread -stack-protector 2 -fno-rtti -fno-signed-char -fgnuc-version=4.2.1 -fskip-odr-check-in-gmf -fno-sized-deallocation -fno-aligned-allocation -fcolor-diagnostics -vectorize-loops -vectorize-slp -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /var/tmp/portage/www-client/firefox-132.0.1-r2/work/firefox_build/armv7a-unknown-linux-musleabihf/release/build/swgl-029fb04aeb3e0fe7/out/2e40c9e35e9506f4-gl.o -x c++ src/gl.cc
clang -cc1 version 20.0.0git0e907c17 based upon LLVM 20.0.0git0e907c17 default target armv7a-unknown-linux-musleabihf
ignoring nonexistent directory "/usr/local/include"
ignoring nonexistent directory "/usr/lib/gcc/armv7a-unknown-linux-musleabihf/13/../../../../armv7a-unknown-linux-musleabihf/include"
ignoring nonexistent directory "/include"
ignoring duplicate directory "/usr/include/nspr"
#include "..." search starts here:
#include <...> search starts here:
 /var/tmp/portage/www-client/firefox-132.0.1-r2/work/firefox_build/dist/stl_wrappers
 /var/tmp/portage/www-client/firefox-132.0.1-r2/work/firefox_build/dist/include
 /usr/include/nspr
 /usr/include/nss
 /var/tmp/portage/www-client/firefox-132.0.1-r2/work/firefox_build/dist/include/nss
 /usr/include/libpng16
 /usr/include/pixman-1
 /var/tmp/portage/www-client/firefox-132.0.1-r2/work/firefox-132.0.1/gfx/wr/swgl/../webrender/res
 src
 /var/tmp/portage/www-client/firefox-132.0.1-r2/work/firefox_build/armv7a-unknown-linux-musleabihf/release/build/swgl-029fb04aeb3e0fe7/out
 /usr/lib/gcc/armv7a-unknown-linux-musleabihf/13/include/g++-v13
 /usr/lib/gcc/armv7a-unknown-linux-musleabihf/13/include/g++-v13/armv7a-unknown-linux-musleabihf
 /usr/lib/gcc/armv7a-unknown-linux-musleabihf/13/include/g++-v13/backward
 /usr/include
 /usr/lib/llvm/20/bin/../../../../lib/clang/20/include
End of search list.
fatal error: error in backend: Do not know how to scalarize the result of this operator!

PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.      Program arguments: /usr/lib/llvm/20/bin/armv7a-unknown-linux-musleabihf-clang++-20 -O2 -ffunction-sections -fdata-sections -fPIC --target=armv7a-unknown-linux-musleabihf -I/var/tmp/portage/www-client/firefox-132.0.1-r2/work/firefox_build/dist/stl_wrappers -fvisibility=hidden -fvisibility-inlines-hidden -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -fstack-protector-strong -fstrict-flex-arrays=1 -DNDEBUG=1 -DTRIMMED=1 -I/var/tmp/portage/www-client/firefox-132.0.1-r2/work/firefox_build/dist/include -I/usr/include/nspr -I/usr/include/nss -I/usr/include/nspr -I/var/tmp/portage/www-client/firefox-132.0.1-r2/work/firefox_build/dist/include/nss -I/usr/include/libpng16 -I/usr/include/pixman-1 -DMOZILLA_CLIENT -include /var/tmp/portage/www-client/firefox-132.0.1-r2/work/firefox_build/mozilla-config.h -mfloat-abi=hard -fno-rtti -pthread -fno-sized-deallocation -fno-aligned-new -ffunction-sections -fdata-sections -fno-math-errno -fno-exceptions -fPIC -pipe -march=armv7-a -mfpu=vfpv3-d16 -mfloat-abi=hard -fomit-frame-pointer -O2 -fomit-frame-pointer -funwind-tables -Wno-error=tautological-type-limit-compare -Wno-invalid-offsetof -Wno-range-loop-analysis -Wno-deprecated-anon-enum-enum-conversion -Wno-deprecated-enum-enum-conversion -Wno-deprecated-this-capture -Wno-inline-new-delete -Wno-error=deprecated-declarations -Wno-error=array-bounds -Wno-error=free-nonheap-object -Wno-error=atomic-alignment -Wno-error=deprecated-builtins -Wno-psabi -Wno-error=builtin-macro-redefined -Wno-vla-cxx-extension -Wno-unknown-warning-option -fno-strict-aliasing -ffp-contract=off -DMOZILLA_CONFIG_H -I /var/tmp/portage/www-client/firefox-132.0.1-r2/work/firefox-132.0.1/gfx/wr/swgl/../webrender/res -I src -I /var/tmp/portage/www-client/firefox-132.0.1-r2/work/firefox_build/armv7a-unknown-linux-musleabihf/release/build/swgl-029fb04aeb3e0fe7/out -std=c++17 -fno-exceptions -fno-rtti -fno-math-errno -UMOZILLA_CONFIG_H -ffast-math -mrecip=none -fno-finite-math-only -D_GLIBCXX_USE_CXX11_ABI=0 -o /var/tmp/portage/www-client/firefox-132.0.1-r2/work/firefox_build/armv7a-unknown-linux-musleabihf/release/build/swgl-029fb04aeb3e0fe7/out/2e40c9e35e9506f4-gl.o -c src/gl.cc -v
1.      <eof> parser at end of file
2.      Code generation
3.      Running pass 'Function Pass Manager' on module 'src/gl.cc'.
4.      Running pass 'ARM Instruction Selection' on function '@_ZN25cs_blur_ALPHA_TARGET_frag15swgl_drawSpanR8Ev'
armv7a-unknown-linux-musleabihf-clang++-20: error: clang frontend command failed with exit code 70 (use -v to see invocation)
clang version 20.0.0git0e907c17
Target: armv7a-unknown-linux-musleabihf
Thread model: posix
InstalledDir: /usr/lib/llvm/20/bin
Configuration file: /etc/clang/armv7a-unknown-linux-musleabihf-clang++.cfg
armv7a-unknown-linux-musleabihf-clang++-20: note: diagnostic msg: 
********************

PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
Preprocessed source(s) and associated run script(s) are located at:
armv7a-unknown-linux-musleabihf-clang++-20: note: diagnostic msg: /tmp/gl-ffed9e.cpp
armv7a-unknown-linux-musleabihf-clang++-20: note: diagnostic msg: /tmp/gl-ffed9e.sh
armv7a-unknown-linux-musleabihf-clang++-20: note: diagnostic msg: 

[stefson]

I've compiled weekly snapshots of the 19.x branch for the last days, and have the regression range down to one week:

https://github.com/llvm/llvm-project/compare/0b9f2847da79298ed09c29493245113f02b32d9f..1bad7024561bc64ed4bfda0772b16376b475eba5