[HIPIFY][#2340][feature] Add implicit CUDA header inclusion to mimic nvcc behavior

[ranapratap55]

Purpose

Add implicit CUDA header pre-inclusion to hipify-clang to mimic nvcc's automatic header inclusion behavior.

Problem Statement

nvcc automatically pre-includes cuda_runtime.h at the beginning of any CUDA compilation unit. This allows CUDA code to compile without explicit #include directives.

hipify-clang uses clang for parsing, which does not perform this implicit inclusion. This causes hipification to fail for some of the source files that rely on nvcc's implicit behavior.

Solution

Introduce implicit CUDA header inclusion by adding -include cuda_runtime.h to clang's argument list during hipification. cuda_runtime.h is nvcc's single implicit entry point which transitively includes all necessary headers such as

• crt/host_config.h (System check)
• builtin_types.h (Basic types)
• device_types.h (enums and structs)
• host_defines.h (Macro definitions)

Fixes #2340

[emankov]

Hi @ranapratap55,

Perhaps the last question here. Have you had a chance to try this change on the examples that were going to be "fixed" by your previous PR #2275?

[ranapratap55]

Hi @ranapratap55,

Perhaps the last question here. Have you had a chance to try this change on the examples that were going to be "fixed" by your previous PR #2275?

Hi @emankov,

Yes, I have tested this change against the examples from #2275 and changes from the #2349(this PR) alone did not fix that issue.

CudaMath.h Fails helper_math.h (float3 +=, -, * operators)
fastWalshTransform_kernel.cuh Fails helper_cuda.h (getLastCudaError macro)
bicubicTexture_kernel.cuh Fails helper_math.h (lerp, uchar)
MonteCarlo_reduction.cuh Fails MonteCarlo_common.h (project-specific __TOptionValue type)

Additionally, I also tested cuda-samples in 0_Introduction (46 samples, 66 source files), 1_Utilities (3 samples), and 5_Domain_Specific. The implicit cuda_runtime.h inclusion is working on all of them and no existing passing test is broken.

In summary:
PR #2349(this PR) solves the nvcc implicitly pre-inclusion errors, even for source files that don't explicitly include them. This is the fix for the root cause you identified.

PR #2275 solves the non-self-contained headers that depend on project-specific includes (like helper_math.h, helper_cuda.h). These are provided by the specific project. The --local-headers header injection addresses this by injecting the preceding system includes from the main source file when hipifying individual local headers.

[emankov]

Thank you, @ranapratap55 , for your research and explanations. So let's ship this one.

[emankov]

LGTM, Thanks! Please add a couple of (synthetic) tests on this feature in a separate PR.