[AVR] make the AVR ABI Swift compatible

This patch is needed to add support to clang's AVR ABI for the Swift language. It is a pre-requisite for upstreaming AVR patches to the Swift compiler itself. @benshi001 @rjmccall

Author: carlos4242

clang/lib/CodeGen/Targets/AVR.cpp

@@ -112,7 +112,10 @@ class AVRABIInfo : public DefaultABIInfo {
 class AVRTargetCodeGenInfo : public TargetCodeGenInfo {
 public:
  AVRTargetCodeGenInfo(CodeGenTypes &CGT, unsigned NPR, unsigned NRR)
- : TargetCodeGenInfo(std::make_unique<AVRABIInfo>(CGT, NPR, NRR)) {}
+ : TargetCodeGenInfo(std::make_unique<AVRABIInfo>(CGT, NPR, NRR)) {
+ SwiftInfo =
+ std::make_unique<SwiftABIInfo>(CGT, /*SwiftErrorInRegister=*/true);
+ }
 
  LangAS getGlobalVarAddressSpace(CodeGenModule &CGM,
  const VarDecl *D) const override {