Created attachment 15638 [details]
The source file

This program was generated by csmith and compiled at -O1. While single-stepping, a line was reached that the program had not yet executed.
gcc version:9.4.0 (installed by sudo command)
gdb version:13.2
os:Ubuntu 20.04


The problem occurs on line 333.The problem occurs on line 333. This line is not a return statement in the source code.

Reading symbols from ./random_64.o...
(gdb) b func_1
Breakpoint 1 at 0x31f4: file random_64_mutated.c, line 224.
(gdb) r
Starting program: /home/hzw/experiment/mutation/mutated_files/random_64.o 

Breakpoint 1, func_1 () at random_64_mutated.c:224
224	    int32_t l_2166 = 1L;
(gdb) n
247	    g_2153[0] = func_2((func_4(func_7(g_11, l_12, g_11), (l_12 < l_12)) , ((safe_mul_func_uint8_t_u_u(0xDCL, (l_1915 = ((func_4(((*l_1908)--), l_12) , g_1630.f1) | 0UL)))) >= 6L)));
(gdb) 
248	int32_t c_61 = l_1915 * l_2166;
(gdb) 
250	int32_t c_63 = l_2166 * (*(*l_2366));
(gdb) 
256	int32_t c_69 = l_1915 * l_1915;
(gdb) 
278	g_2476[2][3][0] = c_89 - c_90;
(gdb) 
279	    if ((~(safe_div_func_uint8_t_u_u(((((254UL && (((safe_rshift_func_uint16_t_u_s((((safe_mul_func_uint32_t_u_u((safe_sub_func_int64_t_s_s((safe_rshift_func_uint64_t_u_u(((l_2166 |= (0x60DEL | (l_1915 = l_12))) , (l_2167 != l_2165[0])), 40)), (l_12 <= (safe_rshift_func_int8_t_s_s(l_12, ((*l_2170) = (((l_12 , l_1908) != l_1908) <= g_841.f0))))))), l_12)) | g_1399) , 0x5B0BL), l_12)) <= l_12) >= 0xEC13E069L)) ^ g_388) != 0x74L) , g_120.f1), l_12))))
(gdb) 
288	        (*g_105) = (safe_mod_func_int32_t_s_s((l_12 == ((safe_rshift_func_uint64_t_u_u((l_2175[0] == ((l_2176 == l_2176) , (((&g_579 != l_2177) , l_2178) , (((*g_657) , (255UL ^ 0xE6L)) , (*g_1254))))), 45)) & l_1915)), 4294967291UL));
(gdb) 
333	  return 
(gdb) 
289	        (*g_2180) = (*g_1305);
(gdb) 
321	g_1388[0][0][3] = c_119 + c_120;
(gdb) 
740	    (*l_2366) = l_2532[0];
(gdb) 
main (argc=<optimized out>, argv=<optimized out>) at random_64_mutated.c:1760
1760	    csmith_sink_ = g_11;


After that, I tried to execute it with lldb in single step. After executing the if statement, lldb went back to execute the statement of the previous basic block. It seems that some kind of optimization scheduled the instructions, causing gdb to have an error.

I attached the debugging information printed by llvm-dwarfdump, I hope it helps.