[PATCH] D151414: [RISCV] Add Zvfhmin extension support for llvm RISCV backend.

[Michael Maitland via Phabricator via llvm-commits]

michaelmaitland added a comment.

I think that this patch and https://reviews.llvm.org/D153848 need to be committed at the same time. This will ensure that if the zvfhmin option is enabled, then we can codegen all LLVM IR.

I applied this patch and https://reviews.llvm.org/D153848, and then updated all instances of +zvfh to be +zvfhmin and re-ran the update_llc_test script for all of the files that were impacted. I found the following crash:

  llvm/utils/update_llc_test_checks.py --llc-binary=build/bin/llc llvm/test/CodeGen/RISCV/regalloc-last-chance-recoloring-failure.ll
  LLVM ERROR: Cannot select: intrinsic %llvm.riscv.vfwsub.w
  PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
  Stack dump:
  0.      Program arguments: build/bin/llc -mtriple=riscv64 -mattr=+f,+m,+zfh,+zvfhmin -riscv-enable-subreg-liveness=false
  1.      Running pass 'Function Pass Manager' on module '<stdin>'.
  2.      Running pass 'RISC-V DAG->DAG Pattern Instruction Selection' on function '@last_chance_recoloring_failure'
   #0 0x000000000178f197 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (build/bin/llc+0x178f197)
   #1 0x000000000178cebe llvm::sys::RunSignalHandlers() (build/bin/llc+0x178cebe)
   #2 0x000000000178f9af SignalHandler(int) Signals.cpp:0:0
   #3 0x00007f612c0b6cf0 __restore_rt (/lib64/libpthread.so.0+0x12cf0)
   #4 0x00007f612ab2aaff raise (/lib64/libc.so.6+0x4eaff)
   #5 0x00007f612aafdea5 abort (/lib64/libc.so.6+0x21ea5)
   #6 0x000000000170cad3 llvm::report_fatal_error(llvm::Twine const&, bool) (build/bin/llc+0x170cad3)
   #7 0x00000000015b1e3d llvm::SelectionDAGISel::CannotYetSelect(llvm::SDNode*) (build/bin/llc+0x15b1e3d)
   #8 0x00000000015b0cfb llvm::SelectionDAGISel::SelectCodeCommon(llvm::SDNode*, unsigned char const*, unsigned int) (build/bin/llc+0x15b0cfb)
   #9 0x000000000072465f llvm::RISCVDAGToDAGISel::Select(llvm::SDNode*) (build/bin/llc+0x72465f)
  #10 0x00000000015a60f5 llvm::SelectionDAGISel::DoInstructionSelection() (build/bin/llc+0x15a60f5)
  #11 0x00000000015a4fe2 llvm::SelectionDAGISel::CodeGenAndEmitDAG() (build/bin/llc+0x15a4fe2)
  #12 0x00000000015a2b71 llvm::SelectionDAGISel::SelectAllBasicBlocks(llvm::Function const&) (build/bin/llc+0x15a2b71)
  #13 0x000000000159f69c llvm::SelectionDAGISel::runOnMachineFunction(llvm::MachineFunction&) (build/bin/llc+0x159f69c)
  #14 0x0000000000be8e2c llvm::MachineFunctionPass::runOnFunction(llvm::Function&) (build/bin/llc+0xbe8e2c)
  #15 0x0000000001102e23 llvm::FPPassManager::runOnFunction(llvm::Function&) (build/bin/llc+0x1102e23)
  #16 0x000000000110aaa1 llvm::FPPassManager::runOnModule(llvm::Module&) (build/bin/llc+0x110aaa1)
  #17 0x0000000001103626 llvm::legacy::PassManagerImpl::run(llvm::Module&) (build/bin/llc+0x1103626)
  #18 0x00000000006987e8 compileModule(char**, llvm::LLVMContext&) llc.cpp:0:0
  #19 0x00000000006962bd main (build/bin/llc+0x6962bd)
  #20 0x00007f612ab16d85 __libc_start_main (/lib64/libc.so.6+0x3ad85)
  #21 0x0000000000692c6e _start (build/bin/llc+0x692c6e)

I think we need to be able to update this patch or the type promotion patch to make sure we don't get any crashes like this when we run the experiment I describe above.



================
Comment at: llvm/lib/Target/RISCV/RISCVISelLowering.cpp:911
+        setOperationAction({ISD::VP_FP_ROUND, ISD::VP_FP_EXTEND}, VT, Custom);
+        // TODO: make others promote?
+      }
----------------
Do we need this TODO still?


================
Comment at: llvm/lib/Target/RISCV/RISCVISelLowering.cpp:1092
+          setOperationAction({ISD::VP_FP_ROUND, ISD::VP_FP_EXTEND}, VT, Custom);
+          // TODO: make others promote?
+          continue;
----------------
Do we need this TODO still?


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D151414/new/

https://reviews.llvm.org/D151414