[llvm] [AMDGPU][MC] Separate VOPC MnemonicAlias from Instruction (PR #89105)

[Jay Foad via llvm-commits]

================
@@ -1386,27 +1386,32 @@ multiclass VOPC_Real_Base<GFXGen Gen, bits<9> op> {
 
 multiclass VOPC_Real_with_name<GFXGen Gen, bits<9> op, string OpName,
                                string asm_name, string pseudo_mnemonic = ""> {
-  let AssemblerPredicate = Gen.AssemblerPredicate, DecoderNamespace = Gen.DecoderNamespace in {
-    defvar ps32 = !cast<VOPC_Pseudo>(OpName#"_e32");
-    defvar ps64 = !cast<VOP3_Pseudo>(OpName#"_e64");
+  defvar ps32 = !cast<VOPC_Pseudo>(OpName#"_e32");
+  defvar ps64 = !cast<VOP3_Pseudo>(OpName#"_e64");
+  let AssemblerPredicate = Gen.AssemblerPredicate in {
+    // MnemonicAlias and GCNPredicateControl both define the field Predicates,
+    // so GCNPredicateControl must come after MnemonicAlias because it contains
+    // the predicates we actually want.
+    def : MnemonicAlias<!if(!empty(pseudo_mnemonic), ps32.Mnemonic,
+                                                     pseudo_mnemonic),
+                        asm_name, ps32.AsmVariantName>,
+          GCNPredicateControl;
+    def : MnemonicAlias<!if(!empty(pseudo_mnemonic), ps64.Mnemonic,
+                                                     pseudo_mnemonic),
+                        asm_name, ps64.AsmVariantName>,
+          GCNPredicateControl;
+
+    let DecoderNamespace = Gen.DecoderNamespace in {
     def _e32#Gen.Suffix :
----------------
jayfoad wrote:

Nit: should indent the body of this `let`

https://github.com/llvm/llvm-project/pull/89105