[llvm] [AMDGPU][True16][MC] validate op_sel and .l/.h syntax (PR #123250)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `openmp-offload-sles-build-only` running on `rocm-worker-hw-04-sles` while building `llvm` at step 8 "Add check check-llvm".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/140/builds/15972

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 8 (Add check check-llvm) failure: test (failure)
******************** TEST 'LLVM :: MC/AMDGPU/gfx11_asm_vop3_from_vopcx.s' FAILED ********************
Exit Code: 2

Command Output (stderr):
--
RUN: at line 2: /home/botworker/bbot/builds/openmp-offload-sles-build/llvm.build/bin/llvm-mc -triple=amdgcn -mcpu=gfx1100 -mattr=+wavefrontsize32,+real-true16 -show-encoding /home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/llvm/test/MC/AMDGPU/gfx11_asm_vop3_from_vopcx.s | /home/botworker/bbot/builds/openmp-offload-sles-build/llvm.build/bin/FileCheck --check-prefixes=GFX11 /home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/llvm/test/MC/AMDGPU/gfx11_asm_vop3_from_vopcx.s
+ /home/botworker/bbot/builds/openmp-offload-sles-build/llvm.build/bin/FileCheck --check-prefixes=GFX11 /home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/llvm/test/MC/AMDGPU/gfx11_asm_vop3_from_vopcx.s
+ /home/botworker/bbot/builds/openmp-offload-sles-build/llvm.build/bin/llvm-mc -triple=amdgcn -mcpu=gfx1100 -mattr=+wavefrontsize32,+real-true16 -show-encoding /home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/llvm/test/MC/AMDGPU/gfx11_asm_vop3_from_vopcx.s
llvm-mc: /home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/llvm/include/llvm/ADT/SmallVector.h:295: const T& llvm::SmallVectorTemplateCommon<T, <template-parameter-1-2> >::operator[](llvm::SmallVectorTemplateCommon<T, <template-parameter-1-2> >::size_type) const [with T = llvm::MCOperand; <template-parameter-1-2> = void; llvm::SmallVectorTemplateCommon<T, <template-parameter-1-2> >::const_reference = const llvm::MCOperand&; llvm::SmallVectorTemplateCommon<T, <template-parameter-1-2> >::size_type = long unsigned int]: Assertion `idx < size()' 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/botworker/bbot/builds/openmp-offload-sles-build/llvm.build/bin/llvm-mc -triple=amdgcn -mcpu=gfx1100 -mattr=+wavefrontsize32,+real-true16 -show-encoding /home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/llvm/test/MC/AMDGPU/gfx11_asm_vop3_from_vopcx.s
 #0 0x00000000007b35d8 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/home/botworker/bbot/builds/openmp-offload-sles-build/llvm.build/bin/llvm-mc+0x7b35d8)
 #1 0x00000000007b0d64 SignalHandler(int) Signals.cpp:0:0
 #2 0x00007fbafe305910 __restore_rt (/lib64/libpthread.so.0+0x16910)
 #3 0x00007fbafdc33d2b raise (/lib64/libc.so.6+0x4ad2b)
 #4 0x00007fbafdc353e5 abort (/lib64/libc.so.6+0x4c3e5)
 #5 0x00007fbafdc2bc6a __assert_fail_base (/lib64/libc.so.6+0x42c6a)
 #6 0x00007fbafdc2bcf2 (/lib64/libc.so.6+0x42cf2)
 #7 0x000000000048d83e (anonymous namespace)::AMDGPUAsmParser::validateInstruction(llvm::MCInst const&, llvm::SMLoc const&, llvm::SmallVectorImpl<std::unique_ptr<llvm::MCParsedAsmOperand, std::default_delete<llvm::MCParsedAsmOperand>>> const&) AMDGPUAsmParser.cpp:0:0
 #8 0x0000000000492e9e (anonymous namespace)::AMDGPUAsmParser::matchAndEmitInstruction(llvm::SMLoc, unsigned int&, llvm::SmallVectorImpl<std::unique_ptr<llvm::MCParsedAsmOperand, std::default_delete<llvm::MCParsedAsmOperand>>>&, llvm::MCStreamer&, unsigned long&, bool) AMDGPUAsmParser.cpp:0:0
 #9 0x0000000000727fcc (anonymous namespace)::AsmParser::parseAndMatchAndEmitTargetInstruction((anonymous namespace)::ParseStatementInfo&, llvm::StringRef, llvm::AsmToken, llvm::SMLoc) AsmParser.cpp:0:0
#10 0x00000000007345ad (anonymous namespace)::AsmParser::parseStatement((anonymous namespace)::ParseStatementInfo&, llvm::MCAsmParserSemaCallback*) AsmParser.cpp:0:0
#11 0x0000000000731b91 (anonymous namespace)::AsmParser::Run(bool, bool) AsmParser.cpp:0:0
#12 0x00000000004178ef main (/home/botworker/bbot/builds/openmp-offload-sles-build/llvm.build/bin/llvm-mc+0x4178ef)
#13 0x00007fbafdc1e24d __libc_start_main (/lib64/libc.so.6+0x3524d)
#14 0x000000000041bafa _start /home/abuild/rpmbuild/BUILD/glibc-2.31/csu/../sysdeps/x86_64/start.S:122:0
FileCheck error: '<stdin>' is empty.
FileCheck command line:  /home/botworker/bbot/builds/openmp-offload-sles-build/llvm.build/bin/FileCheck --check-prefixes=GFX11 /home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/llvm/test/MC/AMDGPU/gfx11_asm_vop3_from_vopcx.s

--

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


```

</details>

https://github.com/llvm/llvm-project/pull/123250