[gcc/devel/omp/gcc-12] GCN: libgomp+mkoffload.cc: Prepare for reverse offload fn lookup

[gcc/devel/omp/gcc-12] GCN: libgomp+mkoffload.cc: Prepare for reverse offload fn lookup

[Tobias Burnus]

https://gcc.gnu.org/g:b2e6dfc8090a957155a9242e720d50dd0d90ba03

commit b2e6dfc8090a957155a9242e720d50dd0d90ba03
Author: Tobias Burnus <tobias@codesourcery.com>
Date:   Mon Sep 12 09:14:50 2022 +0200

    GCN: libgomp+mkoffload.cc: Prepare for reverse offload fn lookup
    
    Add support to GCN for reverse lookup of function name to prepare for
    'omp target device(ancestor:1)'.
    
    gcc/ChangeLog:
    
            * config/gcn/mkoffload.cc (process_asm): Create .offload_func_table,
            similar to pre-existing .offload_var_table.
    
    libgomp/ChangeLog:
    
            * plugin/plugin-gcn.c (GOMP_OFFLOAD_load_image): Read
            .offload_func_table to populate rev_fn_table when requested.
    
    (cherry picked from commit dfd75bf7e9017e92b59be650fca97d2b4b331a82)

Diff:
---
 gcc/ChangeLog.omp           |  8 ++++++++
 gcc/config/gcn/mkoffload.cc | 11 ++++++++++-
 libgomp/ChangeLog.omp       |  8 ++++++++
 libgomp/plugin/plugin-gcn.c | 26 +++++++++++++++++++++++++-
 4 files changed, 51 insertions(+), 2 deletions(-)

diff --git a/gcc/ChangeLog.omp b/gcc/ChangeLog.omp
index 0ad8f78103c..a0d14efef57 100644
--- a/gcc/ChangeLog.omp
+++ b/gcc/ChangeLog.omp
@@ -1,3 +1,11 @@
+2022-09-12  Tobias Burnus  <tobias@codesourcery.com>
+
+	Backport from mainline:
+	2022-09-09  Tobias Burnus  <tobias@codesourcery.com>
+
+	* config/gcn/mkoffload.cc (process_asm): Create .offload_func_table,
+	similar to pre-existing .offload_var_table.
+
 2022-09-09  Tobias Burnus  <tobias@codesourcery.com>
 
 	Backport from mainline:
diff --git a/gcc/config/gcn/mkoffload.cc b/gcc/config/gcn/mkoffload.cc
index 2f9ee883022..2c7a1feafd2 100644
--- a/gcc/config/gcn/mkoffload.cc
+++ b/gcc/config/gcn/mkoffload.cc
@@ -564,6 +564,7 @@ process_asm (FILE *in, FILE *out, FILE *cfile)
 	    char *funcname;
 	    if (sscanf (buf, "\t.8byte\t%ms\n", &funcname))
 	      {
+		fputs (buf, out);
 		obstack_ptr_grow (&fns_os, funcname);
 		fn_count++;
 		continue;
@@ -587,7 +588,15 @@ process_asm (FILE *in, FILE *out, FILE *cfile)
 		 out);
 	}
       else if (sscanf (buf, " .section .gnu.offload_funcs%c", &dummy) > 0)
-	state = IN_FUNCS;
+	{
+	  state = IN_FUNCS;
+	  /* Likewise for .gnu.offload_vars; used for reverse offload. */
+	  fputs (buf, out);
+	  fputs ("\t.global .offload_func_table\n"
+		 "\t.type .offload_func_table, @object\n"
+		 ".offload_func_table:\n",
+		 out);
+	}
       else if (sscanf (buf, " .amdgpu_metadata%c", &dummy) > 0)
 	{
 	  state = IN_METADATA;
diff --git a/libgomp/ChangeLog.omp b/libgomp/ChangeLog.omp
index 943e872aecf..93e288a2e0c 100644
--- a/libgomp/ChangeLog.omp
+++ b/libgomp/ChangeLog.omp
@@ -1,3 +1,11 @@
+2022-09-12  Tobias Burnus  <tobias@codesourcery.com>
+
+	Backport from mainline:
+	2022-09-09  Tobias Burnus  <tobias@codesourcery.com>
+
+	* plugin/plugin-gcn.c (GOMP_OFFLOAD_load_image): Read
+	.offload_func_table to populate rev_fn_table when requested.
+
 2022-09-12  Tobias Burnus  <tobias@codesourcery.com>
 
 	Backport from mainline:
diff --git a/libgomp/plugin/plugin-gcn.c b/libgomp/plugin/plugin-gcn.c
index a051c2a9b2b..dd493f63912 100644
--- a/libgomp/plugin/plugin-gcn.c
+++ b/libgomp/plugin/plugin-gcn.c
@@ -3355,7 +3355,7 @@ 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 __attribute__((unused)))
+			 uint64_t **rev_fn_table)
 {
   if (GOMP_VERSION_DEV (version) != GOMP_VERSION_GCN)
     {
@@ -3527,6 +3527,30 @@ GOMP_OFFLOAD_load_image (int ord, unsigned version, const void *target_data,
   if (module->fini_array_func)
     kernel_count--;
 
+  if (rev_fn_table != NULL && kernel_count == 0)
+    *rev_fn_table = NULL;
+  else if (rev_fn_table != NULL)
+    {
+      hsa_status_t status;
+      hsa_executable_symbol_t var_symbol;
+      status = hsa_fns.hsa_executable_get_symbol_fn (agent->executable, NULL,
+						     ".offload_func_table",
+						     agent->id, 0, &var_symbol);
+      if (status != HSA_STATUS_SUCCESS)
+	hsa_fatal ("Could not find symbol for variable in the code object",
+		   status);
+      uint64_t fn_table_addr;
+      status = hsa_fns.hsa_executable_symbol_get_info_fn
+	(var_symbol, HSA_EXECUTABLE_SYMBOL_INFO_VARIABLE_ADDRESS,
+	 &fn_table_addr);
+      if (status != HSA_STATUS_SUCCESS)
+	hsa_fatal ("Could not extract a variable from its symbol", status);
+      *rev_fn_table = GOMP_PLUGIN_malloc (kernel_count * sizeof (uint64_t));
+      GOMP_OFFLOAD_dev2host (agent->device_id, *rev_fn_table,
+			     (void*) fn_table_addr,
+			     kernel_count * sizeof (uint64_t));
+    }
+
   return kernel_count + var_count + other_count;
 }