Re: [avr-llvm-devel] Inline assembly.

[Borja F. <bor...@gm...>]

I've compiled the file you attached, ignoring all warnings i get from clang
about the unknown attributes like progmem, i'm getting the assertion
"multibyte index is out of range."


2013/7/28 Borja Ferrer <bor...@gm...>

> Hello Stepan,
>
> 1) It seems clang mangles assembly functions names by prefixing a \01
> character. I haven't found yet the code that does this depending on the
> target used.
>
> 2) About the code above, I'm assuming you got that inline asm code from
> the __LPM_dword_classic__ macro. This is what I'm getting for the following
> C code:
> typedef unsigned int uint16_t;
> typedef unsigned long uint32_t;
>
> #define __LPM_dword_classic__(addr)         \
> (__extension__({                            \
>
>     uint16_t __addr16 = (uint16_t)(addr);   \
>     uint32_t __result;                      \
>     __asm__ __volatile__                    \
>     (                                       \
>         "lpm"           "\n\t"              \
>         "mov %A0, r0"   "\n\t"              \
>         "adiw r30, 1"   "\n\t"              \
>         "lpm"           "\n\t"              \
>         "mov %B0, r0"   "\n\t"              \
>         "adiw r30, 1"   "\n\t"              \
>         "lpm"           "\n\t"              \
>         "mov %C0, r0"   "\n\t"              \
>         "adiw r30, 1"   "\n\t"              \
>         "lpm"           "\n\t"              \
>         "mov %D0, r0"   "\n\t"              \
>         : "=r" (__result), "=z" (__addr16)  \
>         : "1" (__addr16)                    \
>         : "r0"                              \
>     );                                      \
>     __result;                               \
> }))
> unsigned long inlineasm(unsigned int addr)
> {
>     return __LPM_dword_classic__(addr);
> }
>
> clang produces:
>
> define i32 @inlineasm(i16 %addr) #0 {
> entry:
>   %0 = tail call { i32, i16 } asm sideeffect "lpm\0A\09mov ${0:A},
> r0\0A\09adiw r30, 1\0A\09lpm\0A\09mov ${0:B}, r0\0A\09adiw r30,
> 1\0A\09lpm\0A\09mov ${0:C}, r0\0A\09adiw r30, 1\0A\09lpm\0A\09mov ${0:D},
> r0\0A\09", "=r,=z,1,~{r0}"(i16 %addr) #2, !srcloc !4
>   %asmresult = extractvalue { i32, i16 } %0, 0
>   ret i32 %asmresult
> }
>
> No truncations here as far i can tell. Try this code and see what you get.
>