From here:
  http://lists.gnu.org/archive/html/tinycc-devel/2005-01/msg00013.html

Fixes a problem with sign extension in certain conversions.

diff -p tcc-0.9.22-orig/tcc.c tcc-0.9.22/tcc.c
*** tcc-0.9.22-orig/tcc.c       Mon Nov  8 12:47:16 2004
--- tcc-0.9.22/tcc.c    Tue Jan 25 14:25:33 2005
*************** void force_charshort_cast(int t)
*** 5613,5618 ****
--- 5613,5623 ----
          bits = 32 - bits;
          vpushi(bits);
          gen_op(TOK_SHL);
+       /* result must be signed or the SAR is converted to an SHL
+          This was not the case when "t" was a signed short
+          and the last value on the stack was an unsigned int
+       */
+       vtop->type.t &= (~VT_UNSIGNED);
          vpushi(bits);
          gen_op(TOK_SAR);
      }
diff -p tcc-0.9.22-orig/tcctest.c tcc-0.9.22/tcctest.c
*** tcc-0.9.22-orig/tcctest.c   Mon Nov  8 12:47:16 2004
--- tcc-0.9.22/tcctest.c        Tue Jan 25 14:17:28 2005
*************** void cast_test()
*** 1058,1063 ****
--- 1058,1065 ----
      int a;
      char c;
      char tab[10];
+     unsigned b,d;
+     short s;
  
      printf("cast_test:\n");
      a = 0xfffff;
*************** void cast_test()
*** 1081,1086 ****
--- 1083,1096 ----
      
      printf("sizeof(c) = %d, sizeof((int)c) = %d\n", sizeof(c), sizeof((int)c));
  
+     /* test cast from unsigned to signed short to int */
+     b = 0xf000;
+     d = (short)b;
+     printf("((unsigned)(short)0x%08x) = 0x%08x\n", b, d);
+     b = 0xf0f0;
+     d = (char)b;
+     printf("((unsigned)(char)0x%08x) = 0x%08x\n", b, d);
+ 
      /* test implicit int casting for array accesses */
      c = 0;
      tab[1] = 2;