llvm dev - Jun 2021 - When I got a Operator by iterating a Value's User, how can I got the relevant Instruction?

Hi,

I am using IR to do some dataflow analysis, and I want to get the source
location related to the dataflow. In my thought, when I iterate the Users
of a Value, there should be an corresponding instruction, then I could get
source location from dbg info.

However, in some cases, I got some Operators as the Users of a Value, such
as GEPOperator, BitCastOperator, etc.
My question is, how could I got the corresponding instruction that use this
Operator as Operand?

For example, when I got the GEPOperator as follows, how could I get the
LoadInst?

*%39 = load i32, i32* getelementptr inbounds (%struct.TTT, %struct.TTT*
@ttt, i32 0, i32 2), align 8, !dbg !971*


Sincerely,
Shulin
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Am Do., 17. Juni 2021 um 10:24 Uhr schrieb 周书林 via llvm-dev
<llvm-dev at lists.llvm.org>:
> %39 = load i32, i32* getelementptr inbounds (%struct.TTT, %struct.TTT*
@ttt, i32 0, i32 2), align 8, !dbg !971
%39 is the LoadInst, while getelementptr is its second operand. It is
inlined because it is an llvm::Constant, not an instruction. Constants
do not participate in use/user-chains and hence there is no link from
GEP to the LoadInst that is using it. The constant GEP object may be
used by an arbitrary number of other instructions, other constants in
the same or other functions.

Node that there "GEPOperator" can represent either a GetElementPtrInst
(i.e. an instruction) or a GEP constant expression (derived from
ConstantExpr)

Michael