[clang] Define SwiftInfo for RISCVTargetCodeGenInfo (llvm#82152)

For Embedded Swift, let's unblock building for RISC-V boards (e.g.
ESP32-C6). This isn't trying to add full RISC-V support to Swift /
Embedded Swift, it's just fixing the immediate blocker (not having
SwiftInfo defined blocks all compilations).

Author: kubamracek

clang/lib/CodeGen/Targets/RISCV.cpp

@@ -500,7 +500,10 @@ class RISCVTargetCodeGenInfo : public TargetCodeGenInfo {
 public:
   RISCVTargetCodeGenInfo(CodeGen::CodeGenTypes &CGT, unsigned XLen,
                          unsigned FLen)
-      : TargetCodeGenInfo(std::make_unique<RISCVABIInfo>(CGT, XLen, FLen)) {}
+      : TargetCodeGenInfo(std::make_unique<RISCVABIInfo>(CGT, XLen, FLen)) {
+    SwiftInfo =
+        std::make_unique<SwiftABIInfo>(CGT, /*SwiftErrorInRegister=*/false);
+  }
 
   void setTargetAttributes(const Decl *D, llvm::GlobalValue *GV,
                            CodeGen::CodeGenModule &CGM) const override {

clang/test/CodeGenCXX/arm-swiftcall.cpp

@@ -1,5 +1,9 @@
 // RUN: %clang_cc1 -triple armv7-apple-darwin9 -emit-llvm -o - %s -Wno-return-type-c-linkage -std=c++03 | FileCheck %s -check-prefixes=CHECK
 
+// For now just check that the RISC-V triples are accepted, but don't check the IR, as swiftcall is not yet supported.
+// RUN: %clang_cc1 -triple riscv32-unknown-linux-gnu -emit-llvm -o - %s -Wno-return-type-c-linkage -std=c++03
+// RUN: %clang_cc1 -triple riscv64-unknown-linux-gnu -emit-llvm -o - %s -Wno-return-type-c-linkage -std=c++03
+
 // This isn't really testing anything ARM-specific; it's just a convenient
 // 32-bit platform.