[llvm] [X86][MC] Teach disassembler to recognize apx instructions which ignores W bit (PR #82747)

[Shengchen Kan via llvm-commits]

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@@ -967,6 +967,7 @@ class ITy<bits<8> o, Format f, X86TypeInfo t, dag outs, dag ins, string m,
       !strconcat(m, "{", t.InstrSuffix, "}\t", args), p>, NoCD8 {
   let hasSideEffects = 0;
   let hasREX_W  = t.HasREX_W;
+  let IgnoresW = !if(!eq(t.VT, i8), 1, 0);
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KanRobert wrote:

“IGNORED” means that the W bit in the EVEX payload is ignored.
Would this change make REX2.W is ignored too?

https://github.com/llvm/llvm-project/pull/82747