[PATCH] D79794: Change the INLINEASM_BR MachineInstr to be a non-terminating instruction.

[Nathan Chancellor via Phabricator via llvm-commits]

nathanchance added a comment.

In D79794#2104506 <https://reviews.llvm.org/D79794#2104506>, @nickdesaulniers wrote:

> @void 's additional diff <https://reviews.llvm.org/D79794#2092123> fixes the arm64 mainline boot issue I was observing.  Maybe @nathanchance can help test with that additional diff applied atop this patch that we're in good shape?


Unfortunately, my test case is still broken. With https://gist.github.com/nathanchance/f69a0281d63d6e72a1449d2f5a98636b on top of 1cfdda57fa63dd6d770ecb4411bd4d2b59e78544 <https://reviews.llvm.org/rG1cfdda57fa63dd6d770ecb4411bd4d2b59e78544>, this kernel boots (v5.7):

  $ make -skj"$(nproc)" LLVM=1 O=out/x86_64 distclean defconfig bzImage
  ...
  
  $ ../../cbl/github/boot-utils/boot-qemu.sh -a x86_64 -k out/x86_64 -t 30s |& grep -A1 qemu-system-x86_64
  + timeout --foreground 30s unbuffer qemu-system-x86_64 -cpu host -d unimp,guest_errors -enable-kvm -smp 64 -append 'console=ttyS0 ' -display none -initrd /home/nathan/cbl/github/boot-utils/images/x86_64/rootfs.cpio -kernel /home/nathan/src/linux/out/x86_64/arch/x86_64/boot/bzImage -m 512m -nodefaults -serial mon:stdio
  [    0.000000] Linux version 5.7.0 (nathan at ubuntu-n2-xlarge-x86) (ClangBuiltLinux clang version 11.0.0 (https://github.com/llvm/llvm-project 07bde6d2c4646c888b1011aa079bbaaa250f79b8), LLD 11.0.0 (https://github.com/llvm/llvm-project 07bde6d2c4646c888b1011aa079bbaaa250f79b8)) #1 SMP Fri Jun 19 22:07:10 MST 2020

but this one does not:

  $ make -skj"$(nproc)" KCFLAGS=-march=znver2 LLVM=1 LOCALVERSION=-znver2 O=out/x86_64 distclean defconfig bzImage
  ...
  
  $ ../../cbl/github/boot-utils/boot-qemu.sh -a x86_64 -k out/x86_64 -t 30s |& grep -A1 qemu-system-x86_64
  + timeout --foreground 30s unbuffer qemu-system-x86_64 -cpu host -d unimp,guest_errors -enable-kvm -smp 64 -append 'console=ttyS0 ' -display none -initrd /home/nathan/cbl/github/boot-utils/images/x86_64/rootfs.cpio -kernel /home/nathan/src/linux/out/x86_64/arch/x86_64/boot/bzImage -m 512m -nodefaults -serial mon:stdio
  + RET=124

At 1cfdda57fa63dd6d770ecb4411bd4d2b59e78544 <https://reviews.llvm.org/rG1cfdda57fa63dd6d770ecb4411bd4d2b59e78544>, both kernels boot without any issue.

  $ make -skj"$(nproc)" LLVM=1 O=out/x86_64 distclean defconfig bzImage
  ...
  
  $ ../../cbl/github/boot-utils/boot-qemu.sh -a x86_64 -k out/x86_64 -t 30s |& grep -A1 qemu-system-x86_64
  + timeout --foreground 30s unbuffer qemu-system-x86_64 -cpu host -d unimp,guest_errors -enable-kvm -smp 64 -append 'console=ttyS0 ' -display none -initrd /home/nathan/cbl/github/boot-utils/images/x86_64/rootfs.cpio -kernel /home/nathan/src/linux/out/x86_64/arch/x86_64/boot/bzImage -m 512m -nodefaults -serial mon:stdio
  [    0.000000] Linux version 5.7.0 (nathan at ubuntu-n2-xlarge-x86) (ClangBuiltLinux clang version 11.0.0 (https://github.com/llvm/llvm-project 1cfdda57fa63dd6d770ecb4411bd4d2b59e78544), LLD 11.0.0 (https://github.com/llvm/llvm-project 1cfdda57fa63dd6d770ecb4411bd4d2b59e78544)) #1 SMP Fri Jun 19 22:02:11 MST 2020



  $ make -skj"$(nproc)" KCFLAGS=-march=znver2 LLVM=1 LOCALVERSION=-znver2 O=out/x86_64 distclean defconfig bzImage
  ...
  
  $ ../../cbl/github/boot-utils/boot-qemu.sh -a x86_64 -k out/x86_64 -t 30s |& grep -A1 qemu-system-x86_64
  + timeout --foreground 30s unbuffer qemu-system-x86_64 -cpu host -d unimp,guest_errors -enable-kvm -smp 64 -append 'console=ttyS0 ' -display none -initrd /home/nathan/cbl/github/boot-utils/images/x86_64/rootfs.cpio -kernel /home/nathan/src/linux/out/x86_64/arch/x86_64/boot/bzImage -m 512m -nodefaults -serial mon:stdio
  [    0.000000] Linux version 5.7.0-znver2 (nathan at ubuntu-n2-xlarge-x86) (ClangBuiltLinux clang version 11.0.0 (https://github.com/llvm/llvm-project 1cfdda57fa63dd6d770ecb4411bd4d2b59e78544), LLD 11.0.0 (https://github.com/llvm/llvm-project 1cfdda57fa63dd6d770ecb4411bd4d2b59e78544)) #1 SMP Fri Jun 19 22:00:23 MST 2020


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https://reviews.llvm.org/D79794