[Bug middle-end/33970] Missed optimization using unsigned char loop variable

["abnikant dot singh at atmel dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #12 from abnikant dot singh at atmel dot com  2010-09-13 12:09 -------
I have verified the attached test case and test case with other comments and
found the code generated is correct i.e. the variable is not promoted to
integer in gcc-4.3.3, gcc-4.4.3, gcc-4.5.0 and also the latest head. 
The assembly for the following piece of code:

int sub2(unsigned char); // external function

void foo(void) {
  unsigned char x;
  for(x=0;x<128; x++)
  {
   sub2(x); //x is becomes a int (16bit)
   // sub2(x+1); //x is char (8bit)
  }
}
in gcc-4.3.3 is:
foo:
    push r17
/* prologue: function */
/* frame size = 0 */
    ldi r17,lo8(0)
.L2:
    mov r24,r17
    rcall sub2
    subi r17,lo8(-(1))
    cpi r17,lo8(-128)
    brne .L2
/* epilogue start */
    pop r17
    ret
    .size   foo, .-foo


-- 

abnikant dot singh at atmel dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |abnikant dot singh at atmel
                   |                            |dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33970