llvm dev - Apr 2014 - [LLVMdev] how to identify basic blocks added for switch instruction without default?

Hi,

    I just notice that front-end will add an extra block for switch 
instruction without default. How could I identify basic blocks added due 
to this reason?

    The added codes looks like:

sw.default.i625:                                  ; preds = %if.end512
   tail call void @fancy_abort(i8* getelementptr inbounds ([38 x i8]* 
@.str, i64 0, i64 0), i32 3045, i8* getelementptr inbounds ([23 x i8]* 
@__FUNCTION__.compcode_to_comparison, i64 0, i64 0)) #7, !dbg !8046
   unreachable, !dbg !8046

    Could I get "unreachable" information from metadata?

    Thanks a lot!

    Best,

                                                                          
                Linhai

I suspect pattern matching "sw.default" will identify these blocks
with a
reasonable accuracy. The code in clang adding these blocks is in
lib/CodeGen/CGStmt.cpp.

Jingyue


On Mon, Apr 28, 2014 at 8:06 PM, songlh <songlh at cs.wisc.edu> wrote:
> Hi,
>
>    I just notice that front-end will add an extra block for switch
> instruction without default. How could I identify basic blocks added due to
> this reason?
>
>    The added codes looks like:
>
> sw.default.i625:                                  ; preds = %if.end512
>   tail call void @fancy_abort(i8* getelementptr inbounds ([38 x i8]*
> @.str, i64 0, i64 0), i32 3045, i8* getelementptr inbounds ([23 x i8]*
> @__FUNCTION__.compcode_to_comparison, i64 0, i64 0)) #7, !dbg !8046
>   unreachable, !dbg !8046
>
>    Could I get "unreachable" information from metadata?
>
>    Thanks a lot!
>
>    Best,
>
>
>               Linhai
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
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Thanks a lot for the suggestion! Let me try the pattern matching 
firstly.

Best

Linhai


On 2014-04-28 22:12, Jingyue Wu wrote:
> I suspect pattern matching "sw.default" will identify these
blocks
> with a reasonable accuracy. The code in clang adding these blocks is
> in lib/CodeGen/CGStmt.cpp. 
> 
> Jingyue
> 
> On Mon, Apr 28, 2014 at 8:06 PM, songlh <songlh at cs.wisc.edu>
wrote:
> 
>> Hi,
>> 
>>    I just notice that front-end will add an extra block for
>> switch instruction without default. How could I identify basic
>> blocks added due to this reason?
>> 
>>    The added codes looks like:
>> 
>> sw.default.i625:                                
>>  ; preds = %if.end512
>>   tail call void @fancy_abort(i8* getelementptr inbounds ([38 x
>> i8]* @.str, i64 0, i64 0), i32 3045, i8* getelementptr inbounds ([23
>> x i8]* @__FUNCTION__.compcode_to_comparison, i64 0, i64 0)) #7, !dbg
>> !8046
>>   unreachable, !dbg !8046
>> 
>>    Could I get "unreachable" information from metadata?
>> 
>>    Thanks a lot!
>> 
>>    Best,
>> 
>>                                            
>>                                            
>> Linhai
>> _______________________________________________
>> LLVM Developers mailing list
>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu [1]
>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev [2]
> 
> 
> 
> Links:
> ------
> [1] http://llvm.cs.uiuc.edu
> [2] http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev