llvm dev - Sep 2009 - [LLVMdev] About porting llvm-gcc frontend.

I am porting llvm-gcc frontend. We have ported GCC4.2 for our target. So I move
*.h *.md and *.c to llvm-gcc.  I do not implement any LLVM MACRO, and use
default action of llvm-gcc.  I get a new llvm-gcc for our target. But I get a
bug.

/******************************/
//#include <stdio.h>
union MYunion {
  unsigned char uc ;
  int ui;
} myunion;

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

void unions() {
   myunion.ui = 0;
   vfu1(myunion);
   iequals(244, myunion.ui, 0);
}

int iequals( int line, int val1, int val2) {
    printf("in iequals: line = %d, val1 = %d, val2 = %d\n", line,
val1, val2);
    if(val1 == val2) {
       printf("val1 == val2\n");
    } else {
       printf("val1 != val2\n");
    }
    return 1;
}

int main() {
      unions();
      return 0;
}
/1. ****************I get IR from my llvm-gcc.*****************************/
        %struct.MYunion = type { i32 }
@myunion = common global %struct.MYunion zeroinitializer                ;
<%struct.MYunion*> [#uses=2]
@.str = internal constant [45 x i8] c"in iequals: line = %d, val1 = %d,
val2 = %d\0A\00"                ; <[45 x i8]*> [#uses=1]
@.str1 = internal constant [13 x i8] c"val1 == val2\00"         ;
<[13 x i8]*> [#uses=1]
@.str2 = internal constant [13 x i8] c"val1 != val2\00"         ;
<[13 x i8]*> [#uses=1]

define void @vfu1(%struct.MYunion* byval align 4 %u) nounwind {
entry:
        %0 = getelementptr %struct.MYunion* %u, i32 0, i32 0            ;
<i32*> [#uses=1]
        store i32 99, i32* %0, align 4
        br label %return

return:         ; preds = %entry
        ret void
}

define void @unions() nounwind {
entry:
        store i32 0, i32* getelementptr (%struct.MYunion* @myunion, i32 0, i32
0), align 4
        call void @vfu1(%struct.MYunion* byval align 4 @myunion) nounwind
        %0 = load i32* getelementptr (%struct.MYunion* @myunion, i32 0, i32 0),
align 4         ; <i32> [#uses=1]
        %1 = call i32 (...)* bitcast (i32 (i32, i32, i32)* @iequals to i32
(...)*)(i32 244, i32 %0, i32 0) nounwind             ; <i32> [#uses=0]
        br label %return

return:         ; preds = %entry
        ret void
}
/2. ***********After llvm optimize pass. I get *****************/
declare i32 @printf(i8*, ...) nounwind

declare i32 @puts(i8*)

define i32 @main() nounwind {
return:
        %0 = call i32 (i8*, ...)* @printf(i8* getelementptr ([45 x i8]* @.str,
i32 0, i32 0), i32 244, i32 99, i32 0) nounwind          ; <i32> [#uses=0]
        %1 = call i32 @puts(i8* getelementptr ([13 x i8]* @.str2, i32 0, i32 0))
nounwind               ; <i32> [#uses=0]
        ret i32 0
}
/3. ***********My question*********/
It  means that function "void vfu1(union MYunion  u)"  modifies global
varible myunion. But llvm-gcc of X86 will not do that. So my llvm-gcc has a bug.

1) Which function or Macro changes "vfu1" function's arguments
type?
2) Which Macro of GCC or LLVM does I implement to control this arguments type
convert?






      ___________________________________________________________ 
  好玩贺卡等你发，邮箱贺卡全新上线！ 
http://card.mail.cn.yahoo.com/
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20090923/208daa79/attachment.html>

Hi 任坤,
> 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.

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.



      ___________________________________________________________ 
  好玩贺卡等你发，邮箱贺卡全新上线！ 
http://card.mail.cn.yahoo.com/
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20090926/b82fd33d/attachment.html>