C-SKY: Add -msim option

gcc/ChangeLog:

	* config/csky/csky.opt (msim): New.
	* doc/invoke.texi (C-SKY Options): Document -msim.
	* config/csky/csky-elf.h (LIB_SPEC): Add simulator runtime.

gcc/config/csky/csky-elf.h

@@ -70,8 +70,14 @@
  %{EL:-EL} -X"
 
 #undef	LIB_SPEC
-#define LIB_SPEC \
-  "%{pthread:-lpthread} -lc %{mccrt:-lcc-rt}"
+#define LIB_SPEC "\
+%{pthread:-lpthread} \
+--start-group \
+-lc \
+%{msim:-lsemi}%{!msim:-lnosys} \
+--end-group \
+%{mccrt:-lcc-rt} \
+"
 /* FIXME add this to LIB_SPEC when need */
 /*   %{!shared:%{profile:-lc_p}%{!profile:-lc}}" */
 

gcc/config/csky/csky.opt

@@ -192,3 +192,7 @@ Set the branch costs to roughly the specified number of instructions.
 msched-prolog
 Target Report Var(flag_sched_prolog) Init(0)
 Permit scheduling of function prologue and epilogue sequences.
+
+msim
+Target
+Use the simulator runtime.

gcc/doc/invoke.texi

@@ -829,7 +829,7 @@ Objective-C and Objective-C++ Dialects}.
 -mdsp  -medsp  -mvdsp @gol
 -mdiv  -msmart  -mhigh-registers  -manchor @gol
 -mpushpop  -mmultiple-stld  -mconstpool  -mstack-size  -mccrt @gol
--mbranch-cost=@var{n}  -mcse-cc  -msched-prolog}
+-mbranch-cost=@var{n}  -mcse-cc  -msched-prolog -msim}
 
 @emph{Darwin Options}
 @gccoptlist{-all_load  -allowable_client  -arch  -arch_errors_fatal @gol
@@ -20835,6 +20835,11 @@ this option can result in code that is not compliant with the C-SKY V2 ABI
 prologue requirements and that cannot be debugged or backtraced.
 It is disabled by default.
 
+@item -msim
+@opindex msim
+Links the library libsemi.a which is in compatible with simulator. Applicable
+to ELF compiler only.
+
 @end table
 
 @node Darwin Options