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

[Stepan D. <stp...@na...>]

Hi Borja,

In clang/lib/Basic/Targets.cpp, AVRTargetInfo::AVRTargetInfo(), I have 
changed DoubleWidth to 32 bit value. Is it legal? I mean why it was 64 
bits, doesn't it has some pitfalls? Anyway I allowed me to compile that 
large source.

 >          > typedef unsigned int uint32_t __attribute__ ((__mode__
 >         (__SI__)));

I have found the next info about it 
(http://www.delorie.com/gnu/docs/gcc/gcc_80.html):

QI --  An integer that is as wide as the smallest addressable unit, 
usually 8 bits.
HI -- An integer, twice as wide as a QI mode integer, usually 16 bits.
SI -- An integer, four times as wide as a QI mode integer, usually 32 bits.
DI -- An integer, eight times as wide as a QI mode integer, usually 64 
bits.
SF -- A floating point value, as wide as a SI mode integer, usually 32 
bits.
DF -- A floating point value, as wide as a DI mode integer, usually 64 bits.

It is implemented in clang/lib/Sema/SemaDeclAttr.cpp, in handleModeAttr 
static function.

Perhaps we just have to sort it out in AVRTargetInfo...

-Stepan.

Borja Ferrer wrote:
> Found it, the isfinite() function takes in a double, and since our
> backend treats them as 64bit types this fails in inline asm. Removing
> the function implementation and just leaving it as an extern compiles
> successfully.
>
>
> 2013/7/28 Borja Ferrer <bor...@gm...
> <mailto:bor...@gm...>>
>
>     I've tried different optimization levels and they all fail for me.
>     The interesting thing is that i've isolated the strtod function in a
>     different file and it compiles fine, so there's something in the
>     huge file that causes this.
>
>
>     2013/7/28 Stepan Dyatkovskiy <stp...@na...
>     <mailto:stp...@na...>>
>
>
>
>          > Ok this was a bit insane to reduce but I've found the
>         offending lines.
>          >
>          > The problem is how uint32_t and uint16_t are defined:
>          > typedef unsigned int uint16_t __attribute__ ((__mode__
>         (__HI__)));
>          >
>          > typedef unsigned int uint32_t __attribute__ ((__mode__
>         (__SI__)));
>          >
>          > I have no idea what this syntax is, but if you refedefine
>         those types to unsigned int / long the problem goes away.
>
>         Wow great. Never expected that wrong definition.
>
>          >
>          > Now im getting an error in llc: error: couldn't allocate
>         input reg for constraint 'r'
>          >
>
>         Hm.. May be try with O2 instead of Os?
>
>          > 2013/7/28 Borja Ferrer <bor...@gm...
>         <mailto: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...
>         <mailto: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.
>
>
>           --
>         Truly yours,
>         Stepan Dyatkovskiy
>
>
>