[clang] [llvm] [clang] Support the Swift calling convention on 32-bit PowerPC (PR #205457)

[Yuta Saito via cfe-commits]

================
@@ -433,6 +433,17 @@ class LLVM_LIBRARY_VISIBILITY PPC32TargetInfo : public PPCTargetInfo {
   std::pair<unsigned, unsigned> hardwareInterferenceSizes() const override {
     return std::make_pair(32, 32);
   }
+
+  CallingConvCheckResult checkCallingConvention(CallingConv CC) const override {
+    switch (CC) {
+    case CC_Swift:
+      return CCCR_OK;
+    case CC_SwiftAsync:
+      return CCCR_Error;
----------------
kateinoigakukun wrote:

(same as MIPS) Would you mind sharing the rationale on why we cannot enable swiftasynccc for PowerPC? I suppose it has everything needed to implement tail call?

https://github.com/llvm/llvm-project/pull/205457