RISC-V/libgcc: Use `-fasynchronous-unwind-tables' for LIB2_DIVMOD_FUNCS

Use `-fasynchronous-unwind-tables' rather than `-fexceptions
-fnon-call-exceptions' in LIB2_DIVMOD_FUNCS compilation flags so as to
provide unwind tables for the affected functions while not pulling the
unwinder proper, which is not required here.

Beyond saving program space it fixes a RISC-V glibc build error due to
unsatisfied `malloc' and `free' references from the unwinder causing
link errors with `ld.so' where libgcc has been built at -O0.

	libgcc/
	* config/riscv/t-elf (LIB2_DIVMOD_EXCEPTION_FLAGS): New
	variable.

diff --git a/libgcc/config/riscv/t-elf b/libgcc/config/riscv/t-elf
index dbc8f85dfc5ca5abf057229d7a7b79472e0f5dd2..415e1fffbe710ab678f17ebadba3b15966adcf8e 100644 (file)
--- a/libgcc/config/riscv/t-elf
+++ b/libgcc/config/riscv/t-elf
@@ -4,3 +4,5 @@ LIB2ADD += $(srcdir)/config/riscv/save-restore.S \
           $(srcdir)/config/riscv/div.S \
           $(srcdir)/config/riscv/atomic.c \
 
+# Avoid the full unwinder being pulled along with the division libcalls.
+LIB2_DIVMOD_EXCEPTION_FLAGS := -fasynchronous-unwind-tables