Re: [avr-gcc-list] When does the Stack Frame Pointer (Y) get setup?

[Don Kinzer]

>You'll probably have to create a "static inline" function [...]
In my test, the stack frame setup still was not done with a call to a
static inline function.  However, removing the "static inline"
resulted in the stack frame setup being in the code for the helper
function at the expense of a call from the .init8 function.

void id_filter_init8( void ) __attribute__ ((naked))
__attribute__((section(".init8")));
void id_filter_init8( void )
{
  98:   07 d0           rcall   .+14            ; 0xa8 <bar>
  9a:   03 d0           rcall   .+6             ; 0xa2 <main>
  9c:   2a c0           rjmp    .+84            ; 0xf2 <_exit>
...
void bar(void)
{
  a8:   df 93           push    r29
  aa:   cf 93           push    r28
  ac:   cd b7           in      r28, 0x3d       ; 61
  ae:   de b7           in      r29, 0x3e       ; 62
  b0:   c0 58           subi    r28, 0x80       ; 128
  b2:   d0 40           sbci    r29, 0x00       ; 0
  b4:   0f b6           in      r0, 0x3f        ; 63
  b6:   f8 94           cli
  b8:   de bf           out     0x3e, r29       ; 62
  ba:   0f be           out     0x3f, r0        ; 63
  bc:   cd bf           out     0x3d, r28       ; 61
  be:   fe 01           movw    r30, r28
  c0:   31 96           adiw    r30, 0x01       ; 1
  uint8_t ff_u8[128U];

  /* memset() should really be used here */
  for( uint16_t idx_u16 = 0U; idx_u16 < (uint16_t) sizeof( ff_u8 ); idx_u16++)
  c2:   ce 01           movw    r24, r28
  c4:   8f 57           subi    r24, 0x7F       ; 127
  c6:   9f 4f           sbci    r25, 0xFF       ; 255
  {
    ff_u8[ idx_u16 ] = 0U;
  c8:   11 92           st      Z+, r1
void bar(void)
{
  uint8_t ff_u8[128U];

  /* memset() should really be used here */
  for( uint16_t idx_u16 = 0U; idx_u16 < (uint16_t) sizeof( ff_u8 ); idx_u16++)
  ca:   e8 17           cp      r30, r24
  cc:   f9 07           cpc     r31, r25
  ce:   e1 f7           brne    .-8             ; 0xc8 <bar+0x20>
  {
    ff_u8[ idx_u16 ] = 0U;
  }
  foo(ff_u8[ val ]);  // <-- this is to prevent the code above from
being optimized away
  d0:   80 91 00 01     lds     r24, 0x0100
  d4:   fe 01           movw    r30, r28
  d6:   e8 0f           add     r30, r24
  d8:   f1 1d           adc     r31, r1
  da:   81 81           ldd     r24, Z+1        ; 0x01
  dc:   e1 df           rcall   .-62            ; 0xa0 <foo>
}
  de:   c0 58           subi    r28, 0x80       ; 128
  e0:   df 4f           sbci    r29, 0xFF       ; 255
  e2:   0f b6           in      r0, 0x3f        ; 63
  e4:   f8 94           cli
  e6:   de bf           out     0x3e, r29       ; 62
  e8:   0f be           out     0x3f, r0        ; 63
  ea:   cd bf           out     0x3d, r28       ; 61
  ec:   cf 91           pop     r28
  ee:   df 91           pop     r29
  f0:   08 95           ret