TheRock/debug-tools/rocgdb/source/gdb/testsuite/gdb.rocm/lane-info.cpp

/* Copyright 2021-2024 Free Software Foundation, Inc.
   Copyright (C) 2021-2024 Advanced Micro Devices, Inc. All rights reserved.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include <hip/hip_runtime.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>

#define CHECK(cmd)                                                           \
  {                                                                          \
    hipError_t error = cmd;                                                  \
    if (error != hipSuccess)                                                 \
      {                                                                      \
	fprintf (stderr, "error: '%s'(%d) at %s:%d\n",                       \
		 hipGetErrorString (error), error, __FILE__, __LINE__);      \
	exit (EXIT_FAILURE);                                                 \
      }                                                                      \
  }

/* The kernel never returns, via this sleep, so that the .exp file can
   test background execution (cont&).  The volatile loop guard keeps
   the loop's observable behavior well-defined (an infinite loop
   without side effects would otherwise be UB in C++); do not mark
   the function noreturn, as that would license the compiler to
   eliminate the very behavior the volatile is preserving.  */

__device__ static void __attribute__ ((noinline))
sleep_forever ()
{
  volatile bool keep_going = true;
  while (keep_going)
    __builtin_amdgcn_s_sleep (1);
}

/* foo() and bar() are non-static so each lane has a stable call frame
   and an externally visible symbol under -O1/-O2/-O3, which the test
   relies on for "info lanes" and "lane apply" to discriminate active
   vs inactive lanes.  foo() uses optnone (which implies noinline and
   keeps the body opaque) so the call cannot be proven away.  In bar(),
   disable_tail_calls keeps the bar() frame on the stack so the sleeping
   wave appears in bar() rather than in sleep_forever().  */

__device__ void __attribute__ ((optnone))
foo ()
{
}

__device__ void __attribute__ ((noinline, disable_tail_calls))
bar ()
{
  sleep_forever ();
}

__global__ void
kernel ()
{
  int tid_x = blockIdx.x * blockDim.x + threadIdx.x;

  if (tid_x % 2)
    foo ();
  else
    bar ();
}

int
main ()
{
  alarm (30);

 /* If the wavefront size is 64 lanes, then this results in 2 waves, 1
     with 64 lanes used, and 1 with 5 lanes used.  If the wavefront
     size is 32 lanes, then this results in 3 waves, 2 with 32 lanes
     used each, and 1 with 5 lanes used.  */
  hipLaunchKernelGGL (kernel, dim3 (1), dim3 (64 + 5),
		      0 /*dynamicShared*/, 0 /*stream*/);

  CHECK (hipDeviceSynchronize ());

  return 0;
}