The first step is to define the "def" clear. For example,
A[i] = ...
It doesn't define A or i. The value of A and i are not changed in this
statement. You should always take care about the indirect access when you
are talking about "def".
In the next, if you are working on H/VH WHIRL, you just need to traverse
the WHIRL tree and take different actions according to the operator of the
WHIRL node. For example:
void Collect_Def_Use(WN* wn) {
switch(WN_Operator(wn)) {
case OPR_BLOCK:
......
break;
case OPR_LDID:
......
break;
case OPR_STID:
......
break;
case OPR_ILOAD:
......
break;
case OPR_ISTORE:
......
default:
for (INT i = 0; i < WN_kid_count(wn); ++i) {
.......
}
}
}
2013/10/14 Kun Ling <lkun.e...@gmail.com>
> Hi Daniel,
>
> Firstly, I am also not an expert in WOPT and Open64. The following is
> just for some of clue that maybe helpful to you.
>
> 1. Whirl is AST based IR, while the in/out list used in Data-flow
> analysis is based on BB and CFG.
>
> 2. According to the Pre_Optimizer() in be/opt/opt_main.cxx. At the
> beginning of WOPT, WHIRL IR will be translated into CFG ( a different IR
> for SSA-based DFA analysis) after comp_unit->Ssa()->Construct().
>
> 3. set a breakpoint after the SSA construction using gdb, and run
> comp_unit->Ssa()->Print(), Comp_unit->Cfg()->Print(stderr,1,-1),
> Cr->Print_str(true), cr->Print_node(1,stderr), Sr->Print(stderr),
> BB_Node->Print(stderr) for object of comp_unit, CODEREP, STMTREP, BB_Node
> may help understand what is going on during the OPT, and also help you to
> get an idea of how the in/out is generated.
>
> 4. If you want to know the actual definition of in/out list of BBs in
> CFG of WOPT, looking into the code of opt_bb.cxx/h may be a good start.
>
>
> Regards,
> Kun Ling
>
>
> On Sat, Oct 12, 2013 at 6:46 AM, daniel tian <xti...@uh.edu> wrote:
>
>> hey guys:
>> I have a question about how to get the in/out variables list for a
>> block in high level whirl? I checked the def/use chain. But there is no
>> such thing in WOPT. I mean there must be a existing module to analysis a
>> input block and get the in/out list.
>>
>> For example:
>>
>> Block1:
>>
>> sum = 0;
>> for(i=0; i<n; i++)
>> {
>> A[i] = B[c] + C[c]
>> sum+=A[i];
>> }
>>
>> For here, this block require the input list"B, C, n", and the output is
>> "A, sum". And "i" is obviously defined in the block. BTW, here the block is
>> in IR, but not three address code.
>>
>> Does anyone have clue?
>> Any suggestion is appreciated.
>>
>> Thank you very much.
>> Daniel
>>
>>
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>
>
> --
> http://www.lingcc.com
>
>
> ------------------------------------------------------------------------------
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>
--
Regards,
Lai Jian-Xin
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