[llvm] [clang] X86::LAR X86::LSL add_implicate eflags (PR #80993)

[via llvm-commits]

https://github.com/Qfrost911 created https://github.com/llvm/llvm-project/pull/80993

[@xia0ji233](https://github.com/xia0ji233) and I found that X86::LAR and X86::lSR implicit use eflags register. However, it was not been defined in LLVM, which means we will get wrong alive-result if we use these two instructions.
![T~ _81W6A}J}{AP{DF%E}KY](https://github.com/llvm/llvm-project/assets/58380176/b84e758b-2978-49e7-a11c-726fd66e1976)


>From b3133c1c8f32e8509885c1f0bf7e88b163f0e643 Mon Sep 17 00:00:00 2001
From: Qfrost <root at qfrost.com>
Date: Wed, 7 Feb 2024 22:13:10 +0800
Subject: [PATCH] X86::LAR X86::LSL add_implicate eflags

---
 llvm/lib/Target/X86/X86InstrSystem.td | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/llvm/lib/Target/X86/X86InstrSystem.td b/llvm/lib/Target/X86/X86InstrSystem.td
index a7899a2492b882..24a334d38f9261 100644
--- a/llvm/lib/Target/X86/X86InstrSystem.td
+++ b/llvm/lib/Target/X86/X86InstrSystem.td
@@ -213,6 +213,7 @@ def MOV16sm : I<0x8E, MRMSrcMem, (outs SEGMENT_REG:$dst), (ins i16mem:$src),
 let SchedRW = [WriteSystem] in {
 def SWAPGS : I<0x01, MRM_F8, (outs), (ins), "swapgs", []>, TB;
 
+let Defs = [EFLAGS] in {
 let mayLoad = 1 in
 def LAR16rm : I<0x02, MRMSrcMem, (outs GR16:$dst), (ins i16mem:$src),
                 "lar{w}\t{$src, $dst|$dst, $src}", []>, TB,
@@ -253,6 +254,7 @@ def LSL64rm : RI<0x03, MRMSrcMem, (outs GR64:$dst), (ins i16mem:$src),
                  "lsl{q}\t{$src, $dst|$dst, $src}", []>, TB;
 def LSL64rr : RI<0x03, MRMSrcReg, (outs GR64:$dst), (ins GR16orGR32orGR64:$src),
                  "lsl{q}\t{$src, $dst|$dst, $src}", []>, TB;
+}
 
 def INVLPG : I<0x01, MRM7m, (outs), (ins i8mem:$addr), "invlpg\t$addr", []>, TB;