On Fri, Nov 12, 2021 at 02:20:23PM +0100, Jakub Jelinek via Gcc-patches wrote: > This patch assumes that .shared variables are initialized to 0, > https://docs.nvidia.com/cuda/parallel-thread-execution/index.html lists > in Table 7. .shared as non-initializable. If that isn't the case, > we need to initialize it somewhere for the case of #pragma omp target > without #pragma omp teams in it, maybe in libgcc/config/nvptx/crt0.c ?
A quick look at libgcc/config/nvptx/crt0.c shows the target supports __attribute__((shared)), so perhaps either following instead, or, if .shared isn't preinitialized to zero, defining the variable in libgcc/config/nvptx/crt0.c , adding there __gomp_team_num = 0; and adding extern keyword before int __gomp_team_num __attribute__((shared)); in libgomp/config/nvptx/target.c. 2021-11-12 Jakub Jelinek <ja...@redhat.com> * config/nvptx/target.c (__gomp_team_num): Define as __attribute__((shared)) var. (GOMP_teams4): Use __gomp_team_num as the team number instead of %ctaid.x. If first, initialize it to %ctaid.x. If num_teams_lower is bigger than num_blocks, use num_teams_lower teams and arrange for bumping of __gomp_team_num if !first and returning false once we run out of teams. * config/nvptx/teams.c (__gomp_team_num): Declare as extern __attribute__((shared)) var. (omp_get_team_num): Return __gomp_team_num value instead of %ctaid.x. --- libgomp/config/nvptx/target.c.jj 2021-11-12 12:41:11.433501988 +0100 +++ libgomp/config/nvptx/target.c 2021-11-12 14:21:39.451426717 +0100 @@ -26,28 +26,41 @@ #include "libgomp.h" #include <limits.h> +int __gomp_team_num __attribute__((shared)); + bool GOMP_teams4 (unsigned int num_teams_lower, unsigned int num_teams_upper, unsigned int thread_limit, bool first) { + unsigned int num_blocks, block_id; + asm ("mov.u32 %0, %%nctaid.x;" : "=r" (num_blocks)); if (!first) - return false; + { + unsigned in team_num; + if (num_blocks > gomp_num_teams_var) + return false; + team_num = __gomp_team_num; + if (team_num > gomp_num_teams_var - num_blocks) + return false; + __gomp_team_num = team_num + num_blocks; + return true; + } if (thread_limit) { struct gomp_task_icv *icv = gomp_icv (true); icv->thread_limit_var = thread_limit > INT_MAX ? UINT_MAX : thread_limit; } - unsigned int num_blocks, block_id; - asm ("mov.u32 %0, %%nctaid.x;" : "=r" (num_blocks)); - asm ("mov.u32 %0, %%ctaid.x;" : "=r" (block_id)); - /* FIXME: If num_teams_lower > num_blocks, we want to loop multiple - times for some CTAs. */ - (void) num_teams_lower; - if (!num_teams_upper || num_teams_upper >= num_blocks) + if (!num_teams_upper) num_teams_upper = num_blocks; - else if (block_id >= num_teams_upper) + else if (num_blocks < num_teams_lower) + num_teams_upper = num_teams_lower; + else if (num_blocks < num_teams_upper) + num_teams_upper = num_blocks; + asm ("mov.u32 %0, %%ctaid.x;" : "=r" (block_id)); + if (block_id >= num_teams_upper) return false; + __gomp_team_num = block_id; gomp_num_teams_var = num_teams_upper - 1; return true; } --- libgomp/config/nvptx/teams.c.jj 2021-01-05 00:13:58.255297642 +0100 +++ libgomp/config/nvptx/teams.c 2021-11-12 14:22:06.443039863 +0100 @@ -28,6 +28,8 @@ #include "libgomp.h" +extern int __gomp_team_num __attribute__((shared)); + void GOMP_teams_reg (void (*fn) (void *), void *data, unsigned int num_teams, unsigned int thread_limit, unsigned int flags) @@ -48,9 +50,7 @@ omp_get_num_teams (void) int omp_get_team_num (void) { - int ctaid; - asm ("mov.u32 %0, %%ctaid.x;" : "=r" (ctaid)); - return ctaid; + return __gomp_team_num; } ialias (omp_get_num_teams) Jakub