Implement __builtin_eh_return_data_regno for SystemZ

[slavek-kucera]

Summary

Implement __builtin_eh_return_data_regno for SystemZ. Match behavior of GCC.

[uweigand]

LGTM with the format fixes.

[slavek-kucera]

I addressed the code formatting. As I don't have commit access, could you commit the change for me?

clang/lib/Basic/Targets/SystemZ.h

StringRef getABI() const override {
     if (HasVector)
       return "vector";
     return "";
   }
 
   const char *getLongDoubleMangling() const override { return "g"; }
 
   bool hasExtIntType() const override { return true; }
+
+  int getEHDataRegisterNumber(unsigned RegNo) const override {
+    return RegNo < 4 ? 6 + RegNo : -1;
+  }
 };
 } // namespace targets
 } // namespace clang
 #endif // LLVM_CLANG_LIB_BASIC_TARGETS_SYSTEMZ_H

clang/test/CodeGen/builtins-systemz.c

// CHECK: call i32 @llvm.s390.etnd()
   result = __TM_is_footprint_exceeded (tdb);
   result = __TM_is_nested_too_deep (tdb);
   result = __TM_is_conflict (tdb);
   result = __TM_is_failure_persistent (result);
   result = __TM_failure_address (tdb);
   result = __TM_failure_code (tdb);
 }
 
+void test_eh_return_data_regno() {
+  volatile int res;
+  res = __builtin_eh_return_data_regno(0); // CHECK: store volatile i32 6
+  res = __builtin_eh_return_data_regno(1); // CHECK: store volatile i32 7
+  res = __builtin_eh_return_data_regno(2); // CHECK: store volatile i32 8
+  res = __builtin_eh_return_data_regno(3); // CHECK: store volatile i32 9
+}