diff -ur gc-7.6.4.old/include/private/gcconfig.h gc-7.6.4/include/private/gcconfig.h

--- gc-7.6.4.old/include/private/gcconfig.h	2018-02-27 09:35:01.074561443 +0000

+++ gc-7.6.4/include/private/gcconfig.h	2018-02-27 09:35:38.571522689 +0000

@@ -603,13 +603,8 @@

 #   define mach_type_known

 # endif

 # if defined(__riscv) && defined(LINUX)

-#   if __riscv_xlen == 32

-#     define RISCV32

-#     define mach_type_known

-#   elif __riscv_xlen == 64

-#     define RISCV64

-#     define mach_type_known

-#   endif

+#   define RISCV

+#   define mach_type_known

 # endif

 /* Feel free to add more clauses here */

@@ -2659,23 +2654,10 @@

 #   endif

 # endif

-# ifdef RISCV32

-#   define CPP_WORDSZ 32

-#   define MACH_TYPE "RISC-V32"

-#   define ALIGNMENT 4

-#   ifdef LINUX

-#     define OS_TYPE "LINUX"

-      extern int __data_start[];

-#     define DATASTART ((ptr_t)__data_start)

-#     define LINUX_STACKBOTTOM

-#     define DYNAMIC_LOADING

-#   endif

-# endif /* RISCV32 */

-

-# ifdef RISCV64

-#   define CPP_WORDSZ 64

-#   define MACH_TYPE "RISC-V64"

-#   define ALIGNMENT 8

+# ifdef RISCV

+#   define MACH_TYPE "RISC-V"

+#   define CPP_WORDSZ __riscv_xlen /* 32 or 64 */

+#   define ALIGNMENT (CPP_WORDSZ/8)

 #   ifdef LINUX

 #     define OS_TYPE "LINUX"

       extern int __data_start[];

@@ -2683,7 +2665,7 @@

 #     define LINUX_STACKBOTTOM

 #     define DYNAMIC_LOADING

 #   endif

-# endif /* RISCV64 */

+# endif /* RISCV */

 #if defined(__GLIBC__) && !defined(DONT_USE_LIBC_PRIVATES)

   /* Use glibc's stack-end marker. */