[MIPS] Cannot select llvm.{min,max}imum.{f32,f64}

[Urgau]

It seems that none of these intrinsics are currently working on MIPS:

• llvm.minimum.f32
• llvm.minimum.f64
• llvm.maximum.f32
• llvm.maximum.f64

Error output [godbolt]:

LLVM ERROR: Cannot select: 0x8787710: f32 = fmaximum 0x87875c0, 0x87876a0
  0x87875c0: f32,ch = CopyFromReg 0x86f0750, Register:f32 %0
    0x8787550: f32 = Register %0
  0x87876a0: f32,ch = CopyFromReg 0x86f0750, Register:f32 %1
    0x8787630: f32 = Register %1
In function: _ZN1a4test17hb60f9f6975710eeaE
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
Stack dump:
0.	Program arguments: /opt/compiler-explorer/clang-trunk/bin/llc -o /app/output.s -x86-asm-syntax=intel <source>
1.	Running pass 'Function Pass Manager' on module '<source>'.
2.	Running pass 'MIPS DAG->DAG Pattern Instruction Selection' on function '@_ZN1a4test17hb60f9f6975710eeaE'
 #0 0x0000000003066278 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-trunk/bin/llc+0x3066278)
 #1 0x0000000003063e3c SignalHandler(int) Signals.cpp:0:0
 #2 0x00007fc3f21b8420 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x14420)
 #3 0x00007fc3f1c7b00b raise (/lib/x86_64-linux-gnu/libc.so.6+0x4300b)
 #4 0x00007fc3f1c5a859 abort (/lib/x86_64-linux-gnu/libc.so.6+0x22859)
 #5 0x000000000069cfa2 llvm::RISCVISAInfo::updateImplication() (.cold) RISCVISAInfo.cpp:0:0
 #6 0x0000000002e4f044 llvm::SelectionDAGISel::CannotYetSelect(llvm::SDNode*) (/opt/compiler-explorer/clang-trunk/bin/llc+0x2e4f044)
 #7 0x0000000002e546d5 llvm::SelectionDAGISel::SelectCodeCommon(llvm::SDNode*, unsigned char const*, unsigned int) (/opt/compiler-explorer/clang-trunk/bin/llc+0x2e546d5)
 #8 0x0000000002e4c6a7 llvm::SelectionDAGISel::DoInstructionSelection() (/opt/compiler-explorer/clang-trunk/bin/llc+0x2e4c6a7)
 #9 0x0000000002e58f65 llvm::SelectionDAGISel::CodeGenAndEmitDAG() (/opt/compiler-explorer/clang-trunk/bin/llc+0x2e58f65)
#10 0x0000000002e5b9b9 llvm::SelectionDAGISel::SelectAllBasicBlocks(llvm::Function const&) (/opt/compiler-explorer/clang-trunk/bin/llc+0x2e5b9b9)
#11 0x0000000002e5e086 llvm::SelectionDAGISel::runOnMachineFunction(llvm::MachineFunction&) (.part.0) SelectionDAGISel.cpp:0:0
#12 0x00000000013a2bcb llvm::MipsDAGToDAGISel::runOnMachineFunction(llvm::MachineFunction&) (/opt/compiler-explorer/clang-trunk/bin/llc+0x13a2bcb)
#13 0x0000000002443820 llvm::MachineFunctionPass::runOnFunction(llvm::Function&) (.part.0) MachineFunctionPass.cpp:0:0
#14 0x00000000029263f2 llvm::FPPassManager::runOnFunction(llvm::Function&) (/opt/compiler-explorer/clang-trunk/bin/llc+0x29263f2)
#15 0x0000000002926571 llvm::FPPassManager::runOnModule(llvm::Module&) (/opt/compiler-explorer/clang-trunk/bin/llc+0x2926571)
#16 0x00000000029280e0 llvm::legacy::PassManagerImpl::run(llvm::Module&) (/opt/compiler-explorer/clang-trunk/bin/llc+0x29280e0)
#17 0x0000000000766170 compileModule(char**, llvm::LLVMContext&) llc.cpp:0:0
#18 0x00000000006a7ce2 main (/opt/compiler-explorer/clang-trunk/bin/llc+0x6a7ce2)
#19 0x00007fc3f1c5c083 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x24083)
#20 0x000000000075e0be _start (/opt/compiler-explorer/clang-trunk/bin/llc+0x75e0be)

Similar to #53353 which was for x86_64

[llvmbot]

@llvm/issue-subscribers-backend-mips

[Cyanoxygen]

There is a target independent implementation for llvm.fminimum and llvm.fmaximum intrinsic that is pending merge in #67301, shall we wait for that PR?

BTW I think a custom implementation for lowering FMIN and FMAX is feasible for MIPS R6, since it has native min.fmt and max.fmt FPU instructions.

[wzssyqa]

@Cyanoxygen Please go ahead of this problem.

[Cyanoxygen]

Sorry for the delay, I have to take rests because of a medical condition.