RISC-V: Fix __riscv_compressed regression.

This was accidentally broken by the patch adding ELF attribute support.
The __riscv_compressed predefined macro is not being defined when the
target supports the C extension.  The fix adds testcases to verify that
all of the predefined macros are correct for various option combinations.

	gcc/
	* common/config/riscv/riscv-common.c (riscv_parse_arch_string):
	Clear MASK_RVC and then set if C subset supported.

	gcc/testsuite/
	* gcc.target/riscv/predef-1.c: New.
	* gcc.target/riscv/predef-2.c: New.
	* gcc.target/riscv/predef-3.c: New.
	* gcc.target/riscv/predef-4.c: New.
	* gcc.target/riscv/predef-5.c: New.
	* gcc.target/riscv/predef-6.c: New.
	* gcc.target/riscv/predef-7.c: New.
	* gcc.target/riscv/predef-8.c: New.

From-SVN: r270026

1 files changed, 4 insertions, 0 deletions

diff --git a/gcc/common/config/riscv/riscv-common.c b/gcc/common/config/riscv/riscv-common.c
index 72c43c6..9452bd3 100644
--- a/gcc/common/config/riscv/riscv-common.c
+++ b/gcc/common/config/riscv/riscv-common.c
@@ -564,6 +564,10 @@ riscv_parse_arch_string (const char *isa, int *flags, location_t loc)
   if (subset_list->lookup ("d"))
     *flags |= MASK_DOUBLE_FLOAT;
 
+  *flags &= ~MASK_RVC;
+  if (subset_list->lookup ("c"))
+    *flags |= MASK_RVC;
+
   if (current_subset_list)
     delete current_subset_list;