[LLVMdev] Figuring out the parameters of the Call Instruction

shankha shankhabanerjee at gmail.com
Thu Jul 15 10:27:53 PDT 2010

Hi Duncan,

Thanks for pointing out my mistake. I will reword my  questions.

//C code
int var1; //global

int a, b;
foo(a, b);
 generates following

%1 = load a;
%2 = load b;
call foo(%1, %2)
call bar(@var1)

CallInst.getOperand(1).getNameStr() on foo, returns null,
but on bar returns var1.

Similarly, for
call void @p_ptr(i64 ptrtoint (%struct.my_struct* @abc to i64))
nounwind, !dbg !31

CallInst.getOperand(1).getNameStr(),  return abc and type returns i64,
How do I figure the operand is a const expression and a cast operator
was used to generate it.

More generally, When I use Instruction iterator on BasicBlock, I get
the RHS of instruction
but not  the LHS. How do I get name of nameless LHS registers(%1, %2).

C Code :    p_ptr ((unsigned long) &abc);
LLVM IR : call void @p_ptr(i64 ptrtoint (%struct.my_struct* @abc to
i64)) nounwind, !dbg !52
I think by the call CI->getArgOperand(0) you mean CI->getOperand(0).
That doesn't return the ptrtoint constant expression. The CI instruction
has shows two operands.  The first operand is the function name. The
second operand
prints NULL.

thank you,
Shankha Banerjee

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