[LLVMdev] Passing String to an external function in llvm

[David Blaikie]

On Thu, Jul 25, 2013 at 11:07 AM, Abhinash Jain <omnia at mailinator.com> wrote:
> Thanx for the response.
>
>  %x = alloca i32, align 4
>  %y = alloca i32, align 4
>  %a = alloca i32, align 4
>  %t = alloca i32, align 4
>
> 1. %10 = load i32* %x, align 4
> 2. %11 = load i32* %y, align 4
> 3. %div = sdiv i32 %10, %11
> 4. %12 = load i32* %a, align 4
> 5. %mul4 = mul nsw i32 %div, %12
>
> 6. store i32 %mul4, i32* %t, align 4
> a.                %mul4 = mul nsw i32 %div, %12
> b.                %div = sdiv i32 %10, %11
> c.                %10 = load i32* %x, align 4
> d.                %11 = load i32* %y, align 4
> e.                %12 = load i32* %a, align 4
>
> This is a IR of       " t = x/y*a "
> The address of the "%x, %y, %a" are "0xbe4ab94, 0xbe4abd4, 0xbe4ac54"
> respectively.
> and the opcode of "*, /" are "12, 15" respectively.
>
> Point (6.a to 6.e)  are the result of use-def chain, with the help of which
> I managed to make a string as -
>
> "12_15_0xbe4ab94_0xbe4abd4_0xbe4ac54" (by converting getOpcode() and
> getOperand() to string and than concatenating it)
>
> Now I want to pass this whole string to some other external function, How
> can I do this?

It's still rather unclear what you're attempting to achieve - are you
trying to pass this string to something else within the compiler? If
so, you'd pass a string the same way you'd pass any other string in
C++ (well, in LLVM:

void func(StringRef Str);
...
std::string foo = "12_15_....";
func(foo);

If you're trying to emit this string into the compiled binary &
produce a function call in that program... that's another story, but
again - looking at simple examples of code compiled by Clang should
give you an idea of what instructions you need to emit.

>
> If you want I can show you the full code.
>
>
>
> --
> View this message in context: http://llvm.1065342.n5.nabble.com/Passing-String-to-an-external-function-in-llvm-tp59798p59807.html
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