[NVPTX][EarlyCSE] Assertion `Val && "isa<> used on a null pointer"' failed.

[XChy]

Reproducer: https://godbolt.org/z/P3exKvMsT
Testcase:

target datalayout = "e-p6:32:32-i64:64-i128:128-i256:256-v16:16-v32:32-n16:32:64"
target triple = "nvptx64-unknown-nvidiacl"

define ptr @func_64() {
entry:
  %p_1027_1 = alloca i16, align 2
  br label %for.cond2.3

for.cond2.3:                                      ; preds = %entry
  %l_171.1.3 = phi ptr [ null, %entry ]
  br i1 false, label %for.cond2.4, label %BS_LABEL_0.preheader.4

BS_LABEL_0.preheader.4:                           ; preds = %for.cond2.3
  br label %for.cond2.4

for.cond2.4:                                      ; preds = %BS_LABEL_0.preheader.4, %for.cond2.3
  %l_171.1.4 = phi ptr [ %p_1027_1, %BS_LABEL_0.preheader.4 ], [ %l_171.1.3, %for.cond2.3 ]
  ret ptr %l_171.1.4
}

Dump:

llc: /root/llvm-project/llvm/include/llvm/Support/Casting.h:109: static bool llvm::isa_impl_cl<To, const From*>::doit(const From*) [with To = llvm::PoisonValue; From = llvm::Value]: Assertion `Val && "isa<> used on a null pointer"' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace and instructions to reproduce the bug.
Stack dump:
0.	Program arguments: /opt/compiler-explorer/clang-assertions-trunk/bin/llc -o /app/output.s -x86-asm-syntax=intel -O1 <source>
1.	Running pass 'Function Pass Manager' on module '<source>'.
2.	Running pass 'Early CSE' on function '@func_64'
 #0 0x000000000421f3e8 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x421f3e8)
 #1 0x000000000421c294 SignalHandler(int, siginfo_t*, void*) Signals.cpp:0:0
 #2 0x0000712cf8642520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #3 0x0000712cf86969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
 #4 0x0000712cf8642476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
 #5 0x0000712cf86287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
 #6 0x0000712cf862871b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)
 #7 0x0000712cf8639e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
 #8 0x0000000002ba36a3 (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x2ba36a3)
 #9 0x0000000002bc87ab simplifyInstructionWithOperands(llvm::Instruction*, llvm::ArrayRef<llvm::Value*>, llvm::SimplifyQuery const&, unsigned int) InstructionSimplify.cpp:0:0
#10 0x0000000002bc89cb llvm::simplifyInstruction(llvm::Instruction*, llvm::SimplifyQuery const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x2bc89cb)
#11 0x0000000003aba91f (anonymous namespace)::EarlyCSE::processNode(llvm::DomTreeNodeBase<llvm::BasicBlock>*) EarlyCSE.cpp:0:0
#12 0x0000000003abcdc6 (anonymous namespace)::EarlyCSE::run() EarlyCSE.cpp:0:0
#13 0x0000000003abf7cb (anonymous namespace)::EarlyCSELegacyCommonPass<false>::runOnFunction(llvm::Function&) (.part.0) EarlyCSE.cpp:0:0
#14 0x00000000037503d6 llvm::FPPassManager::runOnFunction(llvm::Function&) (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x37503d6)
#15 0x0000000003750781 llvm::FPPassManager::runOnModule(llvm::Module&) (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x3750781)
#16 0x0000000003750fef llvm::legacy::PassManagerImpl::run(llvm::Module&) (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x3750fef)
#17 0x00000000008fdcc4 compileModule(char**, llvm::LLVMContext&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>&) llc.cpp:0:0
#18 0x00000000007c8139 main (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x7c8139)
#19 0x0000712cf8629d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#20 0x0000712cf8629e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#21 0x00000000008f2ec5 _start (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x8f2ec5)
Program terminated with signal: SIGSEGV
Compiler returned: 139