gcc/testsuite/gcc.target/avr/progmem.h

#define PROGMEM __attribute__((progmem))

#define PSTR(s)                                             \
    (__extension__({                                        \
            static const char __c[] PROGMEM = (s);          \
            &__c[0];}))

#ifdef __AVR_HAVE_LPMX__
#define pgm_read_char(addr)                                 \
    (__extension__({                                        \
            unsigned int __addr16 = (unsigned int)(addr);   \
            char __result;                                  \
            __asm__ ("lpm %0, %a1"                          \
                     : "=r" (__result) : "z" (__addr16));   \
            __result; }))
#elif defined (__AVR_TINY__)
/* PR71948 auto-adds 0x4000 as needed, hance just a plain read. */
#define pgm_read_char(addr)                                 \
  (*(addr))
#else
#define pgm_read_char(addr)                                 \
    (__extension__({                                        \
            unsigned int __addr16 = (unsigned int)(addr);   \
            char __result;                                  \
            __asm__ ("lpm" "\n\t"                           \
                     "mov %0, r0"                           \
                     : "=r" (__result) : "z" (__addr16));   \
            __result; }))
#endif