DPCT1057

Intel® DPC++ Compatibility Tool Developer Guide and Reference

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ID 768918

Date 3/22/2024

Version

Public

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DPCT1057

Message

Variable <variable name> was used in host code and device code. <variable name> type was updated to be used in SYCL device code and new <host variable name> was generated to be used in host code. You need to update the host code manually to use the new <host variable name>.

Detailed Help

If __constant__variable is used in both host code and device code (for example, the variable is included in two compilation units and they are compiled by different compilers), it will be migrated to a dpct::constant_memory object and a new host variable <host variable name>.

Suggestions to Fix

You need to update the host code manually to use the new <host variable name>.

For example, this original CUDA* code:

// h.h:
#include <cuda_runtime.h>
#include <stdio.h>

static __constant__ const float const_a = 10.f;

// a.cu:
#include "h.h"

__device__ void foo_device() {
  printf("%f\n", const_a);
}

// b.c:
#include "h.h"

void foo_host() {
  printf("%f\n", const_a);
}

is migrated using the following migration commands:

dpct --out-root out a.cu
dpct --out-root out b.c --extra-arg=-xc

which results in the following migrated SYCL* code:

// h.h:
#include <sycl/sycl.hpp>
#include <dpct/dpct.hpp>
#include <stdio.h>

/*
DPCT1057:0: Variable const_a was used in host code and device code. const_a type was
updated to be used in SYCL device code and new const_a_host_ct1 was generated to be
used in host code. You need to update the host code manually to use the new
const_a_host_ct1.
*/
static const float const_a_host_ct1 = 10.f;
static dpct::constant_memory<const float, 0> const_a(10.f);

// a.dp.cpp:
#include <sycl/sycl.hpp>
#include <dpct/dpct.hpp>
#include "h.h"

void foo_device(const sycl::stream &stream_ct1, const float const_a) {
  /*
  DPCT1015:0: Output needs adjustment.
  */
  stream_ct1 << "%f\n";
}

// b.c:
#include "h.h"

void foo_host() {
  printf("%f\n", const_a);
}

The migrated SYCL code is rewritten to address the DPCT1057 warning:

// h.h:
#include <sycl/sycl.hpp>
#include <dpct/dpct.hpp>
#include <stdio.h>

static const float const_a_host_ct1 = 10.f;
static dpct::constant_memory<const float, 0> const_a(10.f);

// a.dp.cpp:
#include <sycl/sycl.hpp>
#include <dpct/dpct.hpp>
#include "h.h"

void foo_device(const sycl::stream &stream_ct1, const float const_a) {
  stream_ct1 << const_a << "\n";
}

// b.c:
#include "h.h"

void foo_host() {
  printf("%f\n", const_a_host_ct1);
}

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Intel® DPC++ Compatibility Tool Developer Guide and Reference

DPCT1057

Message

Detailed Help

Suggestions to Fix