openmp: Add support for the 'indirect' clause in C/C++

This adds support for the 'indirect' clause in the 'declare target'
directive.  Functions declared as indirect may be called via function
pointers passed from the host in offloaded code.

Virtual calls to member functions via the object pointer in C++ are
currently not supported in target regions.

2023-11-07  Kwok Cheung Yeung  <kcy@codesourcery.com>

gcc/c-family/
	* c-attribs.cc (c_common_attribute_table): Add attribute for
	indirect functions.
	* c-pragma.h (enum parma_omp_clause): Add entry for indirect clause.

gcc/c/
	* c-decl.cc (c_decl_attributes): Add attribute for indirect
	functions.
	* c-lang.h (c_omp_declare_target_attr): Add indirect field.
	* c-parser.cc (c_parser_omp_clause_name): Handle indirect clause.
	(c_parser_omp_clause_indirect): New.
	(c_parser_omp_all_clauses): Handle indirect clause.
	(OMP_DECLARE_TARGET_CLAUSE_MASK): Add indirect clause to mask.
	(c_parser_omp_declare_target): Handle indirect clause.  Emit error
	message if device_type or indirect clauses used alone.  Emit error
	if indirect clause used with device_type that is not 'any'.
	(OMP_BEGIN_DECLARE_TARGET_CLAUSE_MASK): Add indirect clause to mask.
	(c_parser_omp_begin): Handle indirect clause.
	* c-typeck.cc (c_finish_omp_clauses): Handle indirect clause.

gcc/cp/
	* cp-tree.h (cp_omp_declare_target_attr): Add indirect field.
	* decl2.cc (cplus_decl_attributes): Add attribute for indirect
	functions.
	* parser.cc (cp_parser_omp_clause_name): Handle indirect clause.
	(cp_parser_omp_clause_indirect): New.
	(cp_parser_omp_all_clauses): Handle indirect clause.
	(handle_omp_declare_target_clause): Add extra parameter.  Add
	indirect attribute for indirect functions.
	(OMP_DECLARE_TARGET_CLAUSE_MASK): Add indirect clause to mask.
	(cp_parser_omp_declare_target): Handle indirect clause.  Emit error
	message if device_type or indirect clauses used alone.  Emit error
	if indirect clause used with device_type that is not 'any'.
	(OMP_BEGIN_DECLARE_TARGET_CLAUSE_MASK): Add indirect clause to mask.
	(cp_parser_omp_begin): Handle indirect clause.
	* semantics.cc (finish_omp_clauses): Handle indirect clause.

gcc/
	* lto-cgraph.cc (enum LTO_symtab_tags): Add tag for indirect
	functions.
	(output_offload_tables): Write indirect functions.
	(input_offload_tables): read indirect functions.
	* lto-section-names.h (OFFLOAD_IND_FUNC_TABLE_SECTION_NAME): New.
	* omp-builtins.def (BUILT_IN_GOMP_TARGET_MAP_INDIRECT_PTR): New.
	* omp-offload.cc (offload_ind_funcs): New.
	(omp_discover_implicit_declare_target): Add functions marked with
	'omp declare target indirect' to indirect functions list.
	(omp_finish_file): Add indirect functions to section for offload
	indirect functions.
	(execute_omp_device_lower): Redirect indirect calls on target by
	passing function pointer to BUILT_IN_GOMP_TARGET_MAP_INDIRECT_PTR.
	(pass_omp_device_lower::gate): Run pass_omp_device_lower if
	indirect functions are present on an accelerator device.
	* omp-offload.h (offload_ind_funcs): New.
	* tree-core.h (omp_clause_code): Add OMP_CLAUSE_INDIRECT.
	* tree.cc (omp_clause_num_ops): Add entry for OMP_CLAUSE_INDIRECT.
	(omp_clause_code_name): Likewise.
	* tree.h (OMP_CLAUSE_INDIRECT_EXPR): New.
	* config/gcn/mkoffload.cc (process_asm): Process offload_ind_funcs
	section.  Count number of indirect functions.
	(process_obj): Emit number of indirect functions.
	* config/nvptx/mkoffload.cc (ind_func_ids, ind_funcs_tail): New.
	(process): Emit offload_ind_func_table in PTX code.  Emit indirect
	function names and count in image.
	* config/nvptx/nvptx.cc (nvptx_record_offload_symbol): Mark
	indirect functions in PTX code with IND_FUNC_MAP.

gcc/testsuite/
	* c-c++-common/gomp/declare-target-7.c: Update expected error message.
	* c-c++-common/gomp/declare-target-indirect-1.c: New.
	* c-c++-common/gomp/declare-target-indirect-2.c: New.
	* g++.dg/gomp/attrs-21.C (v12): Update expected error message.
	* g++.dg/gomp/declare-target-indirect-1.C: New.
	* gcc.dg/gomp/attrs-21.c (v12): Update expected error message.

include/
	* gomp-constants.h (GOMP_VERSION): Increment to 3.
	(GOMP_VERSION_SUPPORTS_INDIRECT_FUNCS): New.

libgcc/
	* offloadstuff.c (OFFLOAD_IND_FUNC_TABLE_SECTION_NAME): New.
	(__offload_ind_func_table): New.
	(__offload_ind_funcs_end): New.
	(__OFFLOAD_TABLE__): Add entries for indirect functions.

libgomp/
	* Makefile.am (libgomp_la_SOURCES): Add target-indirect.c.
	* Makefile.in: Regenerate.
	* libgomp-plugin.h (GOMP_INDIRECT_ADDR_MAP): New define.
	(GOMP_OFFLOAD_load_image): Add extra argument.
	* libgomp.h (struct indirect_splay_tree_key_s): New.
	(indirect_splay_tree_node, indirect_splay_tree,
	indirect_splay_tree_key): New.
	(indirect_splay_compare): New.
	* libgomp.map (GOMP_5.1.1): Add GOMP_target_map_indirect_ptr.
	* libgomp.texi (OpenMP 5.1): Update documentation on indirect
	calls in target region and on indirect clause.
	(Other new OpenMP 5.2 features): Add entry for virtual function calls.
	* libgomp_g.h (GOMP_target_map_indirect_ptr): Add prototype.
	* oacc-host.c (host_load_image): Add extra argument.
	* target.c (gomp_load_image_to_device): If the GOMP_VERSION is high
	enough, read host indirect functions table and pass to
	load_image_func.
	* config/accel/target-indirect.c: New.
	* config/linux/target-indirect.c: New.
	* config/gcn/team.c (build_indirect_map): Add prototype.
	(gomp_gcn_enter_kernel): Initialize support for indirect
	function calls on GCN target.
	* config/nvptx/team.c (build_indirect_map): Add prototype.
	(gomp_nvptx_main): Initialize support for indirect function
	calls on NVPTX target.
	* plugin/plugin-gcn.c (struct gcn_image_desc): Add field for
	indirect functions count.
	(GOMP_OFFLOAD_load_image): Add extra argument.  If the GOMP_VERSION
	is high enough, build address translation table and copy it to target
	memory.
	* plugin/plugin-nvptx.c (nvptx_tdata): Add field for indirect
	functions count.
	(GOMP_OFFLOAD_load_image): Add extra argument.  If the GOMP_VERSION
	is high enough, Build address translation table and copy it to target
	memory.
	* testsuite/libgomp.c-c++-common/declare-target-indirect-1.c: New.
	* testsuite/libgomp.c-c++-common/declare-target-indirect-2.c: New.
	* testsuite/libgomp.c++/declare-target-indirect-1.C: New.

2 files changed, 148 insertions, 3 deletions

diff --git a/libgomp/plugin/plugin-gcn.c b/libgomp/plugin/plugin-gcn.c
index 4328d3de14e..7e7e2d6edfe 100644
--- a/libgomp/plugin/plugin-gcn.c
+++ b/libgomp/plugin/plugin-gcn.c
@@ -365,6 +365,7 @@ struct gcn_image_desc
   } *gcn_image;
   const unsigned kernel_count;
   struct hsa_kernel_description *kernel_infos;
+  const unsigned ind_func_count;
   const unsigned global_variable_count;
 };
 
@@ -3366,7 +3367,8 @@ GOMP_OFFLOAD_init_device (int n)
 int
 GOMP_OFFLOAD_load_image (int ord, unsigned version, const void *target_data,
 			 struct addr_pair **target_table,
-			 uint64_t **rev_fn_table)
+			 uint64_t **rev_fn_table,
+			 uint64_t *host_ind_fn_table)
 {
   if (GOMP_VERSION_DEV (version) != GOMP_VERSION_GCN)
     {
@@ -3382,6 +3384,8 @@ GOMP_OFFLOAD_load_image (int ord, unsigned version, const void *target_data,
   struct module_info *module;
   struct kernel_info *kernel;
   int kernel_count = image_desc->kernel_count;
+  unsigned ind_func_count = GOMP_VERSION_SUPPORTS_INDIRECT_FUNCS (version)
+			      ? image_desc->ind_func_count : 0;
   unsigned var_count = image_desc->global_variable_count;
   /* Currently, "others" is a struct of ICVS.  */
   int other_count = 1;
@@ -3400,6 +3404,7 @@ GOMP_OFFLOAD_load_image (int ord, unsigned version, const void *target_data,
     return -1;
 
   GCN_DEBUG ("Encountered %d kernels in an image\n", kernel_count);
+  GCN_DEBUG ("Encountered %d indirect functions in an image\n", ind_func_count);
   GCN_DEBUG ("Encountered %u global variables in an image\n", var_count);
   GCN_DEBUG ("Expect %d other variables in an image\n", other_count);
   pair = GOMP_PLUGIN_malloc ((kernel_count + var_count + other_count - 2)
@@ -3481,6 +3486,87 @@ GOMP_OFFLOAD_load_image (int ord, unsigned version, const void *target_data,
 	}
     }
 
+  if (ind_func_count > 0)
+    {
+      hsa_status_t status;
+
+      /* Read indirect function table from image.  */
+      hsa_executable_symbol_t ind_funcs_symbol;
+      status = hsa_fns.hsa_executable_get_symbol_fn (agent->executable, NULL,
+						     ".offload_ind_func_table",
+						     agent->id,
+						     0, &ind_funcs_symbol);
+
+      if (status != HSA_STATUS_SUCCESS)
+	hsa_fatal ("Could not find .offload_ind_func_table symbol in the "
+		   "code object", status);
+
+      uint64_t ind_funcs_table_addr;
+      status = hsa_fns.hsa_executable_symbol_get_info_fn
+	(ind_funcs_symbol, HSA_EXECUTABLE_SYMBOL_INFO_VARIABLE_ADDRESS,
+	 &ind_funcs_table_addr);
+      if (status != HSA_STATUS_SUCCESS)
+	hsa_fatal ("Could not extract a variable from its symbol", status);
+
+      uint64_t ind_funcs_table[ind_func_count];
+      GOMP_OFFLOAD_dev2host (agent->device_id, ind_funcs_table,
+			     (void*) ind_funcs_table_addr,
+			     sizeof (ind_funcs_table));
+
+      /* Build host->target address map for indirect functions.  */
+      uint64_t ind_fn_map[ind_func_count * 2 + 1];
+      for (unsigned i = 0; i < ind_func_count; i++)
+	{
+	  ind_fn_map[i * 2] = host_ind_fn_table[i];
+	  ind_fn_map[i * 2 + 1] = ind_funcs_table[i];
+	  GCN_DEBUG ("Indirect function %d: %lx->%lx\n",
+		     i, host_ind_fn_table[i], ind_funcs_table[i]);
+	}
+      ind_fn_map[ind_func_count * 2] = 0;
+
+      /* Write the map onto the target.  */
+      void *map_target_addr
+	= GOMP_OFFLOAD_alloc (agent->device_id, sizeof (ind_fn_map));
+      GCN_DEBUG ("Allocated indirect map at %p\n", map_target_addr);
+
+      GOMP_OFFLOAD_host2dev (agent->device_id, map_target_addr,
+			     (void*) ind_fn_map,
+			     sizeof (ind_fn_map));
+
+      /* Write address of the map onto the target.  */
+      hsa_executable_symbol_t symbol;
+
+      status
+	= hsa_fns.hsa_executable_get_symbol_fn (agent->executable, NULL,
+						XSTRING (GOMP_INDIRECT_ADDR_MAP),
+						agent->id, 0, &symbol);
+      if (status != HSA_STATUS_SUCCESS)
+	hsa_fatal ("Could not find GOMP_INDIRECT_ADDR_MAP in code object",
+		   status);
+
+      uint64_t varptr;
+      uint32_t varsize;
+
+      status = hsa_fns.hsa_executable_symbol_get_info_fn
+	(symbol, HSA_EXECUTABLE_SYMBOL_INFO_VARIABLE_ADDRESS,
+	 &varptr);
+      if (status != HSA_STATUS_SUCCESS)
+	hsa_fatal ("Could not extract a variable from its symbol", status);
+      status = hsa_fns.hsa_executable_symbol_get_info_fn
+	(symbol, HSA_EXECUTABLE_SYMBOL_INFO_VARIABLE_SIZE,
+	&varsize);
+      if (status != HSA_STATUS_SUCCESS)
+	hsa_fatal ("Could not extract a variable size from its symbol",
+		   status);
+
+      GCN_DEBUG ("Found GOMP_INDIRECT_ADDR_MAP at %lx with size %d\n",
+		 varptr, varsize);
+
+      GOMP_OFFLOAD_host2dev (agent->device_id, (void *) varptr,
+			     &map_target_addr,
+			     sizeof (map_target_addr));
+    }
+
   GCN_DEBUG ("Looking for variable %s\n", XSTRING (GOMP_ADDITIONAL_ICVS));
 
   hsa_status_t status;
diff --git a/libgomp/plugin/plugin-nvptx.c b/libgomp/plugin/plugin-nvptx.c
index 00d4241ae02..0548e7e09e5 100644
--- a/libgomp/plugin/plugin-nvptx.c
+++ b/libgomp/plugin/plugin-nvptx.c
@@ -266,6 +266,8 @@ typedef struct nvptx_tdata
 
   const struct targ_fn_launch *fn_descs;
   unsigned fn_num;
+
+  unsigned ind_fn_num;
 } nvptx_tdata_t;
 
 /* Descriptor of a loaded function.  */
@@ -1285,12 +1287,13 @@ nvptx_set_clocktick (CUmodule module, struct ptx_device *dev)
 int
 GOMP_OFFLOAD_load_image (int ord, unsigned version, const void *target_data,
 			 struct addr_pair **target_table,
-			 uint64_t **rev_fn_table)
+			 uint64_t **rev_fn_table,
+			 uint64_t *host_ind_fn_table)
 {
   CUmodule module;
   const char *const *var_names;
   const struct targ_fn_launch *fn_descs;
-  unsigned int fn_entries, var_entries, other_entries, i, j;
+  unsigned int fn_entries, var_entries, ind_fn_entries, other_entries, i, j;
   struct targ_fn_descriptor *targ_fns;
   struct addr_pair *targ_tbl;
   const nvptx_tdata_t *img_header = (const nvptx_tdata_t *) target_data;
@@ -1319,6 +1322,8 @@ GOMP_OFFLOAD_load_image (int ord, unsigned version, const void *target_data,
   var_names = img_header->var_names;
   fn_entries = img_header->fn_num;
   fn_descs = img_header->fn_descs;
+  ind_fn_entries = GOMP_VERSION_SUPPORTS_INDIRECT_FUNCS (version)
+		     ? img_header->ind_fn_num : 0;
 
   /* Currently, other_entries contains only the struct of ICVs.  */
   other_entries = 1;
@@ -1373,6 +1378,60 @@ GOMP_OFFLOAD_load_image (int ord, unsigned version, const void *target_data,
       targ_tbl->end = targ_tbl->start + bytes;
     }
 
+  if (ind_fn_entries > 0)
+    {
+      CUdeviceptr var;
+      size_t bytes;
+
+      /* Read indirect function table from image.  */
+      CUresult r = CUDA_CALL_NOCHECK (cuModuleGetGlobal, &var, &bytes, module,
+				      "$offload_ind_func_table");
+      if (r != CUDA_SUCCESS)
+	GOMP_PLUGIN_fatal ("cuModuleGetGlobal error: %s", cuda_error (r));
+      assert (bytes == sizeof (uint64_t) * ind_fn_entries);
+
+      uint64_t ind_fn_table[ind_fn_entries];
+      r = CUDA_CALL_NOCHECK (cuMemcpyDtoH, ind_fn_table, var, bytes);
+      if (r != CUDA_SUCCESS)
+	GOMP_PLUGIN_fatal ("cuMemcpyDtoH error: %s", cuda_error (r));
+
+      /* Build host->target address map for indirect functions.  */
+      uint64_t ind_fn_map[ind_fn_entries * 2 + 1];
+      for (unsigned k = 0; k < ind_fn_entries; k++)
+	{
+	  ind_fn_map[k * 2] = host_ind_fn_table[k];
+	  ind_fn_map[k * 2 + 1] = ind_fn_table[k];
+	  GOMP_PLUGIN_debug (0, "Indirect function %d: %lx->%lx\n",
+			     k, host_ind_fn_table[k], ind_fn_table[k]);
+	}
+      ind_fn_map[ind_fn_entries * 2] = 0;
+
+      /* Write the map onto the target.  */
+      void *map_target_addr
+	= GOMP_OFFLOAD_alloc (ord, sizeof (ind_fn_map));
+      GOMP_PLUGIN_debug (0, "Allocated indirect map at %p\n", map_target_addr);
+
+      GOMP_OFFLOAD_host2dev (ord, map_target_addr,
+			     (void*) ind_fn_map,
+			     sizeof (ind_fn_map));
+
+      /* Write address of the map onto the target.  */
+      CUdeviceptr varptr;
+      size_t varsize;
+      r = CUDA_CALL_NOCHECK (cuModuleGetGlobal, &varptr, &varsize,
+			     module, XSTRING (GOMP_INDIRECT_ADDR_MAP));
+      if (r != CUDA_SUCCESS)
+	GOMP_PLUGIN_fatal ("Indirect map variable not found in image: %s",
+			   cuda_error (r));
+
+      GOMP_PLUGIN_debug (0,
+			 "Indirect map variable found at %llx with size %ld\n",
+			 varptr, varsize);
+
+      GOMP_OFFLOAD_host2dev (ord, (void *) varptr, &map_target_addr,
+			     sizeof (map_target_addr));
+    }
+
   CUdeviceptr varptr;
   size_t varsize;
   CUresult r = CUDA_CALL_NOCHECK (cuModuleGetGlobal, &varptr, &varsize,