486d00eca6
Summary: This patch implements support for variadic functions for NVPTX targets. The implementation here mainly follows what was done to implement it for AMDGPU in https://github.com/llvm/llvm-project/pull/93362. We change the NVPTX codegen to lower all variadic arguments to functions by-value. This creates a flattened set of arguments that the IR lowering pass converts into a struct with the proper alignment. The behavior of this function was determined by iteratively checking what the NVCC copmiler generates for its output. See examples like https://godbolt.org/z/KavfTGY93. I have noted the main methods that NVIDIA uses to lower variadic functions. 1. All arguments are passed in a pointer to aggregate. 2. The minimum alignment for a plain argument is 4 bytes. 3. Alignment is dictated by the underlying type 4. Structs are flattened and do not have their alignment changed. 5. NVPTX never passes any arguments indirectly, even very large ones. This patch passes the tests in the `libc` project currently, including support for `sprintf`.
14 KiB
14 KiB