llvm dev - Mar 2009 - [LLVMdev] Consumer ARM platform suitable for LLVM development?

On Mar 12, 2009, at 8:30 AMPDT, Misha Brukman wrote:
>
> ../../../../src/llvm-gcc4.2-2.5.source/gcc/config/arm/arm.md:4788:  
> error: ‘MACHO_DYNAMIC_NO_PIC_P’ undeclared here (not in a function)
>
> This tells me there are some Darwin-specific bits in arm.md which  
> shouldn't be there (MachO is Mac OS X-specific).  I'm using the  
> attached script llvm-arm-crosstool.sh to configure/build/install  
> LLVM and LLVM-GCC from the 2.5 release.  If anyone wants to try it  
> out and see if it works for them, I'd love to hear their experiences.
>
> If any ARM/GCC experts know how to fix arm.md to not refer to Darwin- 
> specific macros, that would be great, too.
Probably the right general idea is to #define MACHO_DYNAMIC_NO_PIC_P  
to be 0 for non-Darwin targets.  Not sure where to put this so it will  
work for both targets (the Darwin definition comes from config/ 
darwin.h).

-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20090312/ccdae5d1/attachment.html>

>>
>> If any ARM/GCC experts know how to fix arm.md to not refer to  
>> Darwin-specific macros, that would be great, too.
>
> Probably the right general idea is to #define MACHO_DYNAMIC_NO_PIC_P  
> to be 0 for non-Darwin targets.  Not sure where to put this so it  
> will work for both targets (the Darwin definition comes from config/ 
> darwin.h).
I don't think so. Darwin-specific pieces of code should be guarded, as  
usual, with TARGET_MACHO define.

---
With best regards, Anton Korobeynikov
Faculty of Mathematics and Mechanics, Saint Petersburg State University

-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20090312/e56f1cd6/attachment.html>

On Thu, Mar 12, 2009 at 1:31 PM, Anton Korobeynikov <anton at
korobeynikov.info
> wrote:
> If any ARM/GCC experts know how to fix arm.md to not refer to
> Darwin-specific macros, that would be great, too.
>
> Probably the right general idea is to #define MACHO_DYNAMIC_NO_PIC_P to be
> 0 for non-Darwin targets.  Not sure where to put this so it will work for
> both targets (the Darwin definition comes from config/darwin.h).
>
> I don't think so. Darwin-specific pieces of code should be guarded, as
> usual, with TARGET_MACHO define.
>
Perhaps, but the problem is that MACHO_DYNAMIC_NO_PIC_P is so ingrained into
the machine description, that if you try to guard each use with something
like

#ifdef TARGET_MACHO
  ...
#endif

you will get unreadable code for something as simple as:

; APPLE LOCAL begin ARM pic support
(define_insn "pic_load_addr_arm"
  [(set (match_operand:SI 0 "s_register_operand" "=r")
  (unspec:SI [(match_operand:SI 1 "" "mX")
        (label_ref (match_operand 2 "" ""))]
UNSPEC_PIC_SYM))
   (use (label_ref (match_dup 2)))]
  "TARGET_ARM && (flag_pic || (TARGET_MACHO &&
MACHO_DYNAMIC_NO_PIC_P))"
  "ldr%?\\t%0, %1"
  [(set_attr "type" "load1")
   (set (attr "pool_range")     (const_int 4096))
   (set (attr "neg_pool_range") (const_int 4084))]
)

or, even more complex code sequence:

;; APPLE LOCAL begin compact switch tables
;; This pattern represents the library call for Thumb switch tables.
;; The functions' (sparse) register usage is recorded as clobbers.

(define_insn "thumb_casesi_internal"
  [(parallel [(set (pc)
         (if_then_else
    (leu (match_operand:SI 0 "s_register_operand" "l")
         (match_operand:SI 1 "const_int_operand" "i"))
    (mem:SI (plus:SI (mult:SI (match_dup 0) (const_int 2))
         (label_ref (match_operand 2 "" ""))))
    (label_ref (match_operand 3 "" ""))))
        (clobber (reg:CC CC_REGNUM))
        (clobber (reg:SI LR_REGNUM))
        (clobber (reg:SI IP_REGNUM))
        (use (reg:SI 0))
        (use (label_ref (match_dup 2)))])]
  "TARGET_COMPACT_SWITCH_TABLES"
  "*
    {
      rtx body = PATTERN (next_real_insn (insn));
      static char buf[255];
      gcc_assert (GET_CODE (body) == ADDR_DIFF_VEC);
      strcpy(buf, \"bl\\t\");
      if (flag_pic || MACHO_DYNAMIC_NO_PIC_P)
    strcat(buf, \"L\");
      if (GET_MODE (body) == QImode
    && ADDR_DIFF_VEC_FLAGS (body).offset_unsigned)
  {
    register_switchu8_libfunc ();

[... more code below ...]

If this code is purely Darwin-specific, it shouldn't even appear in
arm.md.  If this is ARM-PIC-specific, then we should use a var such as
ARM_PIC,
and darwin.h can set the common ARM_PIC variable if MACHO_DYNAMIC_* is
defined.

Adding #ifdef/#endif code to .md files will make what's already barely
readable even less comprehensible.

Misha
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20090312/44c717ee/attachment.html>