libm: riscv support

issue #4312

repos/libports/lib/mk/spec/riscv/libm.mk

@@ -0,0 +1,10 @@
+LIBM_LD128 = yes
+
+include $(REP_DIR)/lib/mk/libm.inc
+
+#
+# RISC-V specific
+#
+SRC_C += msun/riscv/fenv.c
+
+vpath msun/riscv/fenv.c $(LIBC_DIR)/lib

repos/libports/lib/symbols/libm

@@ -175,12 +175,15 @@ fabsl T
 fdim T
 fdimf T
 fdiml T
+feclearexcept T
 fedisableexcept T
 feenableexcept T
 fegetenv T
 feholdexcept T
 feraiseexcept T
 fesetexceptflag T
+fesetround T
+fetestexcept T
 feupdateenv T
 floor T
 floorf T

repos/libports/ports/libc.hash

@@ -1 +1 @@
-130633868713e5f3e0dac32775bfcb8a1731f6ad
+392389f9e1323249c044ba6b7fea6ea3d73100c5

repos/libports/src/lib/libc/patches/fpmath_riscv.patch

@@ -0,0 +1,27 @@
+Enable PREC 113 for RISC-V
+
+--- src/lib/libc/lib/libc/riscv/_fpmath.h
++++ src/lib/libc/lib/libc/riscv/_fpmath.h
+@@ -46,6 +46,7 @@ union IEEEl2bits {
+ #define	LDBL_IMPLICIT_NBIT
+ #define	mask_nbit_l(u)	((void)0)
+ 
++#if 0
+ #define	LDBL_MANH_SIZE	20
+ #define	LDBL_MANL_SIZE	32
+ 
+@@ -53,12 +54,13 @@ union IEEEl2bits {
+ 	(a)[0] = (uint32_t)(u).bits.manl;		\
+ 	(a)[1] = (uint32_t)(u).bits.manh;		\
+ } while(0)
++#endif
+ 
+ /*
+  * TODO: Due to compiler problem we are temporary using
+  * LDBL_PREC == 53. Use code below for LDBL_PREC == 113
+  */
+-#if 0
++#if 1
+ #define	LDBL_MANH_SIZE	48
+ #define	LDBL_MANL_SIZE	64
+