[LLVMdev] [LLVM, llvm-diff] Question about FunctionDifferenceEngine and DiffConsumer::printValue

Stepan Dyatkovskiy stpworld at narod.ru
Fri Oct 28 02:00:53 PDT 2011

Hi all.
I found next code when switch instruction differs:

Engine.logf("right switch has extra case %r") << CaseValue;

Where CaseValue is a ConstantInt object. Looking how logf works I found 
that it invokes DiffConsumer::printValue method for CaseValue. And here 
I found that CaseValue itself will never printed. On first look how 
DiffConsumer::printValue works it seems that for all constants "object 
numbering" should be printed:

out << '%' << ctxt.RNumbering[V]; // V = CaseValue in our case.
                                   // RNumbering is instance of 

Then I look into DiffConsumer.cpp, ComputeNumbering method that fills 
RNumbering and LNumbering. Well, numbering computed for function 
arguments, basic blocks and instructions only.

It means that for Constants "%0" will be printed always. If so, I 
propose to add case for constants in DiffConsumer::printValue method, 
that will print constant itself.


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