[llvm] [NVPTX] support switch statement with brx.idx (PR #102400)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-nvptx64-nvidia-ubuntu` running on `as-builder-7` while building `llvm` at step 6 "test-build-unified-tree-check-llvm".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/160/builds/2999

Here is the relevant piece of the build log for the reference:
```
Step 6 (test-build-unified-tree-check-llvm) failure: test (failure)
******************** TEST 'LLVM :: CodeGen/Generic/switch-lower-feature.ll' FAILED ********************
Exit Code: 134

Command Output (stderr):
--
RUN: at line 1: /home/buildbot/worker/as-builder-7/ramdisk/llvm-nvptx64-nvidia-ubuntu/build/bin/llc < /home/buildbot/worker/as-builder-7/ramdisk/llvm-nvptx64-nvidia-ubuntu/llvm-project/llvm/test/CodeGen/Generic/switch-lower-feature.ll
+ /home/buildbot/worker/as-builder-7/ramdisk/llvm-nvptx64-nvidia-ubuntu/build/bin/llc
llc: /home/buildbot/worker/as-builder-7/ramdisk/llvm-nvptx64-nvidia-ubuntu/llvm-project/llvm/lib/CodeGen/MachineBlockPlacement.cpp:2869: void {anonymous}::MachineBlockPlacement::buildCFGChains(): Assertion `(!TII->analyzeBranch(*PrevBB, TBB, FBB, Cond) || !PrevBB->canFallThrough()) && "Unexpected block with un-analyzable fallthrough!"' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
Stack dump:
0.	Program arguments: /home/buildbot/worker/as-builder-7/ramdisk/llvm-nvptx64-nvidia-ubuntu/build/bin/llc
1.	Running pass 'Function Pass Manager' on module '<stdin>'.
2.	Running pass 'Branch Probability Basic Block Placement' on function '@test2'
 #0 0x00007fdbcb2527c0 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/home/buildbot/worker/as-builder-7/ramdisk/llvm-nvptx64-nvidia-ubuntu/build/lib/libLLVMSupport.so.20.0git+0x1dc7c0)
 #1 0x00007fdbcb24fbdf llvm::sys::RunSignalHandlers() (/home/buildbot/worker/as-builder-7/ramdisk/llvm-nvptx64-nvidia-ubuntu/build/lib/libLLVMSupport.so.20.0git+0x1d9bdf)
 #2 0x00007fdbcb24fd35 SignalHandler(int) Signals.cpp:0:0
 #3 0x00007fdbcaa42520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #4 0x00007fdbcaa969fc __pthread_kill_implementation ./nptl/pthread_kill.c:44:76
 #5 0x00007fdbcaa969fc __pthread_kill_internal ./nptl/pthread_kill.c:78:10
 #6 0x00007fdbcaa969fc pthread_kill ./nptl/pthread_kill.c:89:10
 #7 0x00007fdbcaa42476 gsignal ./signal/../sysdeps/posix/raise.c:27:6
 #8 0x00007fdbcaa287f3 abort ./stdlib/abort.c:81:7
 #9 0x00007fdbcaa2871b _nl_load_domain ./intl/loadmsgcat.c:1177:9
#10 0x00007fdbcaa39e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
#11 0x00007fdbcd10193f (anonymous namespace)::MachineBlockPlacement::buildCFGChains() MachineBlockPlacement.cpp:0:0
#12 0x00007fdbcd101d24 (anonymous namespace)::MachineBlockPlacement::runOnMachineFunction(llvm::MachineFunction&) (.part.0) MachineBlockPlacement.cpp:0:0
#13 0x00007fdbcd173ca7 llvm::MachineFunctionPass::runOnFunction(llvm::Function&) (.part.0) MachineFunctionPass.cpp:0:0
#14 0x00007fdbcb66904c llvm::FPPassManager::runOnFunction(llvm::Function&) (/home/buildbot/worker/as-builder-7/ramdisk/llvm-nvptx64-nvidia-ubuntu/build/lib/libLLVMCore.so.20.0git+0x2d404c)
#15 0x00007fdbcb669479 llvm::FPPassManager::runOnModule(llvm::Module&) (/home/buildbot/worker/as-builder-7/ramdisk/llvm-nvptx64-nvidia-ubuntu/build/lib/libLLVMCore.so.20.0git+0x2d4479)
#16 0x00007fdbcb668386 llvm::legacy::PassManagerImpl::run(llvm::Module&) (/home/buildbot/worker/as-builder-7/ramdisk/llvm-nvptx64-nvidia-ubuntu/build/lib/libLLVMCore.so.20.0git+0x2d3386)
#17 0x000062df7c3b7906 compileModule(char**, llvm::LLVMContext&) llc.cpp:0:0
#18 0x000062df7c3ad666 main (/home/buildbot/worker/as-builder-7/ramdisk/llvm-nvptx64-nvidia-ubuntu/build/bin/llc+0xf666)
#19 0x00007fdbcaa29d90 __libc_start_call_main ./csu/../sysdeps/nptl/libc_start_call_main.h:58:16
#20 0x00007fdbcaa29e40 call_init ./csu/../csu/libc-start.c:128:20
#21 0x00007fdbcaa29e40 __libc_start_main ./csu/../csu/libc-start.c:379:5
#22 0x000062df7c3ae1c5 _start (/home/buildbot/worker/as-builder-7/ramdisk/llvm-nvptx64-nvidia-ubuntu/build/bin/llc+0x101c5)
/home/buildbot/worker/as-builder-7/ramdisk/llvm-nvptx64-nvidia-ubuntu/build/test/CodeGen/Generic/Output/switch-lower-feature.ll.script: line 1: 28296 Aborted                 (core dumped) /home/buildbot/worker/as-builder-7/ramdisk/llvm-nvptx64-nvidia-ubuntu/build/bin/llc < /home/buildbot/worker/as-builder-7/ramdisk/llvm-nvptx64-nvidia-ubuntu/llvm-project/llvm/test/CodeGen/Generic/switch-lower-feature.ll

--

********************


```

https://github.com/llvm/llvm-project/pull/102400