[clang] [llvm] [LoongArch] Support amcas[_db].{b/h/w/d} instructions. (PR #114189)

[WÁNG Xuěruì via cfe-commits]

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@@ -1562,7 +1562,9 @@ unsigned LoongArchAsmParser::checkTargetMatchPredicate(MCInst &Inst) {
   unsigned Opc = Inst.getOpcode();
   switch (Opc) {
   default:
-    if (Opc >= LoongArch::AMADD_D && Opc <= LoongArch::AMXOR_W) {
+    // amcas[_db].{b/h/w/d} didn't need this judgement
+    if ((Opc >= LoongArch::AMADD_B && Opc <= LoongArch::AMAND__DB_W) ||
+        (Opc >= LoongArch::AMMAX_D && Opc <= LoongArch::AMXOR__DB_W)) {
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xen0n wrote:

Ah. This is very prone to breakage as correct operation relies on the order of insn definitions in the TableGen files.

For now it may be okay to merge as-is, but let me try refactoring this piece of logic to hopefully make it elegant and future-proof.

https://github.com/llvm/llvm-project/pull/114189