Update execute.cpp

Author: MichaelJSr

sim/simx/execute.cpp

@@ -657,7 +657,7 @@ void Emulator::execute(const Instr &instr, uint32_t wid, instr_trace_t *trace) {
     // RV32I: J
     trace->fu_type = FUType::ALU;
     trace->alu_type = AluType::BRANCH;
-    next_pc = immsrc;
+    next_pc = warp.PC + (immsrc >> 1);
     trace->fetch_stall = true;
     rd_write = true;
     break;