merging branch lab2-IRGen into master

src/sysyc.cpp

@@ -9,6 +9,7 @@ using namespace antlr4;
 #include "ASTPrinter.h"
 #include "Backend.h"
 #include "SysYIRGenerator.h"
+#include "LLVMIRGenerator.h"
 using namespace sysy;
 
 static string argStopAfter;
@@ -20,7 +21,7 @@ void usage(int code = EXIT_FAILURE) {
                     "Supported options:\n"
                     "  -h \tprint help message and exit\n";
   "  -f \tpretty-format the input file\n";
-  "  -s {ast,ir,asm}\tstop after generating AST/IR/Assembly\n";
+  "  -s {ast,ir,asm,llvmir}\tstop after generating AST/IR/Assembly\n";
   cerr << msg;
   exit(code);
 }
@@ -83,6 +84,10 @@ int main(int argc, char **argv) {
   if (argStopAfter == "ir") {
     moduleIR->print(cout);
     return EXIT_SUCCESS;
+  } else if (argStopAfter == "llvmir") {
+    LLVMIRGenerator llvmirGenerator;
+    cout << llvmirGenerator.getIR();
+    return EXIT_SUCCESS;
   }
 
   // generate assembly