[avr-gcc-list] string initialization using "" and { }

[Zoran Rilak]

Hello,

more noobisms your way, I'm afraid.  I can't find an explanation
elsewhere why there should be a difference in the generated code for
string vs. array-of-chars initializers.  Compiling the following code:

/* ... */

int main() {
  char test1[] = "abd";
  char test2[] = { 'a', 'b', 'd', '\0' };
  /* ... */

}

using avr-gcc 4.3.2, invoked with

avr-gcc -g -mmcu=atmega168 main.c -o main.o  -lm

and disassembled with

avr-objdump -S main.o

shows this:

  char test1[] = "abd";
     8c0:       80 91 00 01     lds     r24, 0x0100
     8c4:       90 91 01 01     lds     r25, 0x0101
     8c8:       a0 91 02 01     lds     r26, 0x0102
     8cc:       b0 91 03 01     lds     r27, 0x0103
     8d0:       8f 87           std     Y+15, r24       ; 0x0f
     8d2:       98 8b           std     Y+16, r25       ; 0x10
     8d4:       a9 8b           std     Y+17, r26       ; 0x11
     8d6:       ba 8b           std     Y+18, r27       ; 0x12
  char test2[] = { 'a', 'b', 'd', '\0' };
     8d8:       81 e6           ldi     r24, 0x61       ; 97
     8da:       8b 8b           std     Y+19, r24       ; 0x13
     8dc:       82 e6           ldi     r24, 0x62       ; 98
     8de:       8c 8b           std     Y+20, r24       ; 0x14
     8e0:       83 e6           ldi     r24, 0x64       ; 100
     8e2:       8d 8b           std     Y+21, r24       ; 0x15
     8e4:       1e 8a           std     Y+22, r1        ; 0x16

Why the difference?

Thanks,
Zoran