What does CallInst::Create() return in LLVM? - c++

Question

Considering
static CallInst *Create(Value *Func,
ArrayRef<Value *> Args,
const Twine &NameStr = "",
Instruction *InsertBefore = 0)
this function, I wonder what the return value of this function means.
For example, in following code,
int foo(int a);
...
Function *foo_ptr = ~~;//say, foo is refered through getOrInsertFunction()
CallInst *ptr = CallInst::Create(foo_ptr, .../* properly set */);
the CallInst *ptr is the return value. Abstractly, does ptr mean
an integer value returned by int foo(int);
or CALL instruction
I thought number 2 was the answer, but started to get confused looking at some codes.

Answer 1

Both 1 and 2 are "true". It returns the call instruction, whose "value", when we execute the code, will be the return value of the function.
To illustrate, take this little Pascal program:
program p;
function f: integer;
begin
f := 42;
end; { f }
begin
writeln(f);
end.
Which translates to this LLVM-IR:
; ModuleID = 'TheModule'
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
%text = type { i32, i8*, i32, i32 }
#input = global %text zeroinitializer, align 8
#output = global %text zeroinitializer, align 8
#UnitIniList = constant [1 x i8*] zeroinitializer
define i32 #P.f() #0 {
entry:
%f = alloca i32, align 4
store i32 42, i32* %f
%0 = load i32, i32* %f
ret i32 %0
}
define void #__PascalMain() #0 {
entry:
%calltmp = call i32 #P.f()
call void #__write_int(%text* #output, i32 %calltmp, i32 0)
call void #__write_nl(%text* #output)
ret void
}
declare void #__write_int(%text*, i32, i32)
declare void #__write_nl(%text*)
attributes #0 = { "no-frame-pointer-elim"="true" }
The call i32 #P.f() is generated by:
inst = builder.CreateCall(calleF, argsV, "calltmp");
The contents of inst is %calltmp = call i32 #P.f() - and that is a CallInst 'value'.
and inst is returned to the evaluation of the expression for the argument to writeln.