[LLVMdev] 回复： About porting llvm-gcc frontend.

[任坤]

Dear Duncan Sands:

   Yes, you are right. This IR is correct.  This bug is caused by  llvm-ld.
Edwin has fixed it. Please refer to:

 Edwin <edwintorok at gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
             Resolution|                                 |FIXED


Fixed here:
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20090921/087797.html




________________________________
发件人： Duncan Sands <baldrick at free.fr>
收件人： 任坤 <hbrenkun at yahoo.cn>
抄   送： llvm <llvmdev at cs.uiuc.edu>
已发送： 2009/9/24(周四), 下午11:24:32
主   题： Re: [LLVMdev] About porting llvm-gcc frontend.

Hi 浠诲潳,

> void vfu1(union MYunion  u) {
>     u.ui = 99;
> }

here u is passed by copy, so vfu1 has no externally
visible effect.  I think you meant: union MYunion *u

> define void @vfu1(%struct.MYunion* byval align 4 %u) nounwind {

Here "byval" means that a pointer to a temporary copy of u is being
passed, not u itself.  Thus any writes to the %u parameter have no
effect outside this function.

> /3. ***********My question*********/
> It  means that function "void vfu1(union MYunion  u)"  modifies global varible myunion.

This call
  vfu1(myunion);
does not result in myunion being modified.

Ciao,

Duncan.



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