Crash in ARM instruction selection for fp_round

[stephenhines]

This is one reduced crasher from android/ndk#1608. The LLVM IR input can be found at Arm82InstanceNorm-22e98b.ll.txt. Drop the .txt to get the original file that crashes with llc.

srhines@ringworld:__:~$ /disk/llvm/build/bin/llc Arm82InstanceNorm-22e98b.ll 
LLVM ERROR: Cannot select: t9: v4f16 = fp_round t43, TargetConstant:i32<0>, Arm82InstanceNorm-22e98b.ii:24:14
  t43: v4f32,i32,ch = ARMISD::VLD1_UPD<(load (s128) from %ir.lsr.iv1113, align 4, !tbaa !79)> t0, t4, Constant:i32<16>, Constant:i32<1>, Arm82InstanceNorm-22e98b.ii:24:14
    t4: i32,ch = CopyFromReg t0, Register:i32 %4, Arm82InstanceNorm-22e98b.ii:23:33
      t3: i32 = Register %4
    t21: i32 = Constant<16>
    t41: i32 = Constant<1>
  t8: i32 = TargetConstant<0>
In function: _ZN17Arm82InstanceNormC2Ev
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
Stack dump:
0.      Program arguments: /disk/llvm/build/bin/llc Arm82InstanceNorm-22e98b.ll
1.      Running pass 'Function Pass Manager' on module 'Arm82InstanceNorm-22e98b.ll'.
2.      Running pass 'ARM Instruction Selection' on function '@_ZN17Arm82InstanceNormC2Ev'
Stack dump without symbol names (ensure you have llvm-symbolizer in your PATH or set the environment var `LLVM_SYMBOLIZER_PATH` to point to it):
/disk/llvm/build/bin/llc(_ZN4llvm3sys15PrintStackTraceERNS_11raw_ostreamEi+0x3a)[0x447704a]
/disk/llvm/build/bin/llc[0x44771fb]
/disk/llvm/build/bin/llc(_ZN4llvm3sys17RunSignalHandlersEv+0x8a)[0x44758aa]
/disk/llvm/build/bin/llc[0x4477925]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x13200)[0x7f3de4bda200]
/lib/x86_64-linux-gnu/libc.so.6(gsignal+0x141)[0x7f3de466f891]
/lib/x86_64-linux-gnu/libc.so.6(abort+0x112)[0x7f3de4659536]
/disk/llvm/build/bin/llc[0x439fa4a]
/disk/llvm/build/bin/llc[0x420ff1b]
/disk/llvm/build/bin/llc(_ZN4llvm16SelectionDAGISel16SelectCodeCommonEPNS_6SDNodeEPKhj+0x653e)[0x420d51e]
/disk/llvm/build/bin/llc[0x1979559]
/disk/llvm/build/bin/llc[0x195ff1a]
/disk/llvm/build/bin/llc(_ZN4llvm16SelectionDAGISel22DoInstructionSelectionEv+0x629)[0x4201df9]
/disk/llvm/build/bin/llc(_ZN4llvm16SelectionDAGISel17CodeGenAndEmitDAGEv+0x161a)[0x4200e4a]
/disk/llvm/build/bin/llc(_ZN4llvm16SelectionDAGISel16SelectBasicBlockENS_14ilist_iteratorINS_12ilist_detail12node_optionsINS_11InstructionELb1ELb0EvEELb0ELb1EEES6_Rb+0x17d)[0x41ff81d]
/disk/llvm/build/bin/llc(_ZN4llvm16SelectionDAGISel20SelectAllBasicBlocksERKNS_8FunctionE+0x16b0)[0x41ff2b0]
/disk/llvm/build/bin/llc(_ZN4llvm16SelectionDAGISel20runOnMachineFunctionERNS_15MachineFunctionE+0x7f5)[0x41fc6d5]
/disk/llvm/build/bin/llc[0x1956225]
/disk/llvm/build/bin/llc(_ZN4llvm19MachineFunctionPass13runOnFunctionERNS_8FunctionE+0x1f7)[0x33131d7]
/disk/llvm/build/bin/llc(_ZN4llvm13FPPassManager13runOnFunctionERNS_8FunctionE+0x26e)[0x399db6e]
/disk/llvm/build/bin/llc(_ZN4llvm13FPPassManager11runOnModuleERNS_6ModuleE+0x72)[0x39a29f2]
/disk/llvm/build/bin/llc[0x399e459]
/disk/llvm/build/bin/llc(_ZN4llvm6legacy15PassManagerImpl3runERNS_6ModuleE+0x10d)[0x399dfcd]
/disk/llvm/build/bin/llc(_ZN4llvm6legacy11PassManager3runERNS_6ModuleE+0x21)[0x39a2cd1]
/disk/llvm/build/bin/llc[0xd5deb9]
/disk/llvm/build/bin/llc(main+0x53e)[0xd5c27e]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xcd)[0x7f3de465a7ed]
/disk/llvm/build/bin/llc(_start+0x2a)[0xd5ba6a]
Aborted

[llvmbot]

@llvm/issue-subscribers-backend-arm

[stephenhines]

I thought I had a second issue, but I realize I mistakenly ignored the first line. I suspect that this bugpoint-reduced case might be helpful too. bugpoint-reduced-simplified.ll.txt is the source file for this case, which is definitely a bit smaller.

srhines@ringworld:__:~$ /disk/llvm/build/bin/llc bugpoint-reduced-simplified.ll 
LLVM ERROR: Cannot select: t3: v4f16 = fp_round undef:v4f32, TargetConstant:i32<0>
  t1: v4f32 = undef
  t2: i32 = TargetConstant<0>
In function: _ZN17Arm82InstanceNormC2Ev
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
Stack dump:
0.      Program arguments: /disk/llvm/build/bin/llc bugpoint-reduced-simplified.ll
1.      Running pass 'Function Pass Manager' on module 'bugpoint-reduced-simplified.ll'.
2.      Running pass 'ARM Instruction Selection' on function '@_ZN17Arm82InstanceNormC2Ev'
Stack dump without symbol names (ensure you have llvm-symbolizer in your PATH or set the environment var `LLVM_SYMBOLIZER_PATH` to point to it):
/disk/llvm/build/bin/llc(_ZN4llvm3sys15PrintStackTraceERNS_11raw_ostreamEi+0x3a)[0x447704a]
/disk/llvm/build/bin/llc[0x44771fb]
/disk/llvm/build/bin/llc(_ZN4llvm3sys17RunSignalHandlersEv+0x8a)[0x44758aa]
/disk/llvm/build/bin/llc[0x4477925]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x13200)[0x7fc5f38c1200]
/lib/x86_64-linux-gnu/libc.so.6(gsignal+0x141)[0x7fc5f3356891]
/lib/x86_64-linux-gnu/libc.so.6(abort+0x112)[0x7fc5f3340536]
/disk/llvm/build/bin/llc[0x439fa4a]
/disk/llvm/build/bin/llc[0x420ff1b]
/disk/llvm/build/bin/llc(_ZN4llvm16SelectionDAGISel16SelectCodeCommonEPNS_6SDNodeEPKhj+0x653e)[0x420d51e]
/disk/llvm/build/bin/llc[0x1979559]
/disk/llvm/build/bin/llc[0x195ff1a]
/disk/llvm/build/bin/llc(_ZN4llvm16SelectionDAGISel22DoInstructionSelectionEv+0x629)[0x4201df9]
/disk/llvm/build/bin/llc(_ZN4llvm16SelectionDAGISel17CodeGenAndEmitDAGEv+0x161a)[0x4200e4a]
/disk/llvm/build/bin/llc(_ZN4llvm16SelectionDAGISel16SelectBasicBlockENS_14ilist_iteratorINS_12ilist_detail12node_optionsINS_11InstructionELb1ELb0EvEELb0ELb1EEES6_Rb+0x17d)[0x41ff81d]
/disk/llvm/build/bin/llc(_ZN4llvm16SelectionDAGISel20SelectAllBasicBlocksERKNS_8FunctionE+0x16b0)[0x41ff2b0]
/disk/llvm/build/bin/llc(_ZN4llvm16SelectionDAGISel20runOnMachineFunctionERNS_15MachineFunctionE+0x7f5)[0x41fc6d5]
/disk/llvm/build/bin/llc[0x1956225]
/disk/llvm/build/bin/llc(_ZN4llvm19MachineFunctionPass13runOnFunctionERNS_8FunctionE+0x1f7)[0x33131d7]
/disk/llvm/build/bin/llc(_ZN4llvm13FPPassManager13runOnFunctionERNS_8FunctionE+0x26e)[0x399db6e]
/disk/llvm/build/bin/llc(_ZN4llvm13FPPassManager11runOnModuleERNS_6ModuleE+0x72)[0x39a29f2]
/disk/llvm/build/bin/llc[0x399e459]
/disk/llvm/build/bin/llc(_ZN4llvm6legacy15PassManagerImpl3runERNS_6ModuleE+0x10d)[0x399dfcd]
/disk/llvm/build/bin/llc(_ZN4llvm6legacy11PassManager3runERNS_6ModuleE+0x21)[0x39a2cd1]
/disk/llvm/build/bin/llc[0xd5deb9]
/disk/llvm/build/bin/llc(main+0x53e)[0xd5c27e]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xcd)[0x7fc5f33417ed]
/disk/llvm/build/bin/llc(_start+0x2a)[0xd5ba6a]
Aborted

[ostannard]

Only triggers when the fullfp16 target feature (introduced in v8.2A, adds instructions for arithmetic on half-precision scalars and vectors) is enabled. Bisected to d16037d, which was the start of codegen support for that feature, so I don't think this has ever worked properly.

[ostannard]

Fix: https://reviews.llvm.org/D119354