commit 5c3fc5093aaf7d9422459d295eb4eb769abcbaa4
Author: Kamlesh Kumar <kamleshbhalui@gmail.com>
Date:   Wed Mar 3 04:32:47 2021 +0530

    [libunwind] [risc-v] This patch is for fixing
    immediate build failure when Cross Unwinding enabled.
    Follow up patch will cleanup some Macros handling.
    
    Differential Revision: https://reviews.llvm.org/D97762

diff --git a/libunwind/src/Registers.hpp b/libunwind/src/Registers.hpp
index 1d23f97aedfb..aea84cc22721 100644
--- a/libunwind/src/Registers.hpp
+++ b/libunwind/src/Registers.hpp
@@ -3731,26 +3731,35 @@ inline const char *Registers_hexagon::getRegisterName(int regNum) {
 /// Registers_riscv holds the register state of a thread in a RISC-V
 /// process.
 
-# if __riscv_xlen == 32
+// This check makes it safe when LIBUNWIND_ENABLE_CROSS_UNWINDING enabled.
+# ifdef __riscv
+#  if __riscv_xlen == 32
 typedef uint32_t reg_t;
-# elif __riscv_xlen == 64
+#  elif __riscv_xlen == 64
 typedef uint64_t reg_t;
-# else
-#  error "Unsupported __riscv_xlen"
-# endif
+#  else
+#   error "Unsupported __riscv_xlen"
+#  endif
 
-# if defined(__riscv_flen)
-#  if __riscv_flen == 64
+#  if defined(__riscv_flen)
+#   if __riscv_flen == 64
 typedef double fp_t;
-#  elif __riscv_flen == 32
+#   elif __riscv_flen == 32
 typedef float fp_t;
+#   else
+#    error "Unsupported __riscv_flen"
+#   endif
 #  else
-#   error "Unsupported __riscv_flen"
+// This is just for supressing undeclared error of fp_t.
+typedef double fp_t;
 #  endif
 # else
-// This is just for supressing undeclared error of fp_t.
+// Use Max possible width when cross unwinding
+typedef uint64_t reg_t;
 typedef double fp_t;
-# endif
+# define __riscv_xlen 64
+# define __riscv_flen 64
+#endif
 
 /// Registers_riscv holds the register state of a thread.
 class _LIBUNWIND_HIDDEN Registers_riscv {