Using LLVM 3.3 backend to compile OpenCL for AMD

Question

How exactly does one use the new R600 backend inside LLVM 3.3 to generate a binary suitable for passing to the OpenCL clCreateProgramWithBinary API on an AMD card? Are there any code samples for how to do this?

I have seen a clang command line for how to compile for AMD, but I havent seen anywhere how to use the output with the driver.

Thanks very much.

Answer 1

You can read the test cases in the llvm/test/CodeGen/R600.

For example: add.ll

;RUN: llc < %s -march=r600 -mcpu=redwood | FileCheck %s

;CHECK: ADD_INT T{{[0-9]+\.[XYZW], T[0-9]+\.[XYZW], T[0-9]+\.[XYZW]}}

;CHECK: ADD_INT * T{{[0-9]+\.[XYZW], T[0-9]+\.[XYZW], T[0-9]+\.[XYZW]}}

;CHECK: ADD_INT * T{{[0-9]+\.[XYZW], T[0-9]+\.[XYZW], T[0-9]+\.[XYZW]}}

;CHECK: ADD_INT * T{{[0-9]+\.[XYZW], T[0-9]+\.[XYZW], T[0-9]+\.[XYZW]}}

define void @test(<4 x i32> addrspace(1)* %out, <4 x i32> addrspace(1)* %in) {

  %b_ptr = getelementptr <4 x i32> addrspace(1)* %in, i32 1

  %a = load <4 x i32> addrspace(1) * %in

  %b = load <4 x i32> addrspace(1) * %b_ptr

  %result = add <4 x i32> %a, %b

  store <4 x i32> %result, <4 x i32> addrspace(1)* %out

  ret void
}

Then you can just directly use the output through clCreateProgramWithBinary.