[llvm] [SystemZ] Fold i16/i32/i64 logical RMW operations into memory operands in TableGen (PR #192802)

[Ulrich Weigand via llvm-commits]

================
@@ -554,10 +554,33 @@ static bool isFoldableRMW(const Instruction *I, Type *Ty) {
   switch (Opcode) {
   case Instruction::And:
   case Instruction::Or:
-  case Instruction::Xor:
-    if (BitWidth != 8)
+  case Instruction::Xor: {
+    if (BitWidth == 8)
+      break;
+    if (BitWidth != 16 && BitWidth != 32 && BitWidth != 64)
+      return false;
+
+    auto *CI = dyn_cast<ConstantInt>(I->getOperand(1));
+    if (!CI)
       return false;
+
+    uint64_t Val = CI->getZExtValue();
+    if (Opcode == Instruction::And) {
+      if (BitWidth == 16 && (Val & 0xff00ULL) != 0xff00ULL)
+        return false;
+      if (BitWidth == 32 && (Val & 0xffffff00ULL) != 0xffffff00ULL &&
+          (Val & 0xffffff00ULL) != 0x0000ff00ULL)
----------------
uweigand wrote:

Same problem as above.

https://github.com/llvm/llvm-project/pull/192802