openmp, c++: Fix up OpenMP/OpenACC handling in C++ modules [PR119102]

modules.cc has apparently support for extensions and attempts to ensure
that if a module is compiled with those extensions enabled, sources which
use the module are compiled with the same extensions.
The only extension supported is SE_OPENMP right now.
And the use of the extension is keyed on streaming out or in OMP_CLAUSE
tree.
This is undesirable for several reasons.
OMP_CLAUSE is the only tree which can appear in the IL even without
-fopenmp/-fopenmp-simd/-fopenacc (when simd ("notinbranch") or
simd ("inbranch") attributes are used), and it can appear also in all
the 3 modes mentioned above.  On the other side, with the exception of
arguments of attributes added e.g. for declare simd where no harm should
be done if -fopenmp/-fopenmp-simd isn't enabled later on, OMP_CLAUSE appears
in OMP_*_CLAUSES of OpenMP/OpenACC construct trees.  And those construct
trees often have no clauses at all, so keying the extension on OMP_CLAUSE
doesn't catch many cases that should be caught.
Furthermore, for OpenMP we have 2 modes, -fopenmp-simd which parses some
OpenMP but constructs from that mostly OMP_SIMD and a few other cases,
and -fopenmp which includes that and far more on top of that; and there is
also -fopenacc.

So, this patch stops setting/requesting the extension on OMP_CLAUSE,
introduces 3 extensions rather than one (SE_OPENMP_SIMD, SE_OPENMP and
SE_OPENACC) and keyes those on OpenMP constructs from the -fopenmp-simd
subset, other OpenMP constructs and OpenACC constructs.

2025-03-05  Jakub Jelinek  <jakub@redhat.com>

	PR c++/119102
gcc/cp/
	* module.cc (enum streamed_extensions): Add SE_OPENMP_SIMD
	and SE_OPENACC, change value of SE_OPENMP and SE_BITS.
	(CASE_OMP_SIMD_CODE, CASE_OMP_CODE, CASE_OACC_CODE): Define.
	(trees_out::start): Don't set SE_OPENMP extension for OMP_CLAUSE.
	Set SE_OPENMP_SIMD extension for CASE_OMP_SIMD_CODE, SE_OPENMP
	for CASE_OMP_CODE and SE_OPENACC for CASE_OACC_CODE.
	(trees_in::start): Don't fail for OMP_CLAUSE with missing
	SE_OPENMP extension.  Do fail for CASE_OMP_SIMD_CODE and missing
	SE_OPENMP_SIMD extension, or CASE_OMP_CODE and missing SE_OPENMP
	extension, or CASE_OACC_CODE and missing SE_OPENACC extension.
	(module_state::write_readme): Write all of SE_OPENMP_SIMD, SE_OPENMP
	and SE_OPENACC extensions.
	(module_state::read_config): Diagnose missing -fopenmp, -fopenmp-simd
	and/or -fopenacc depending on extensions used.
gcc/testsuite/
	* g++.dg/modules/pr119102_a.H: New test.
	* g++.dg/modules/pr119102_b.C: New test.
	* g++.dg/modules/omp-3_a.C: New test.
	* g++.dg/modules/omp-3_b.C: New test.
	* g++.dg/modules/omp-3_c.C: New test.
	* g++.dg/modules/omp-3_d.C: New test.
	* g++.dg/modules/oacc-1_a.C: New test.
	* g++.dg/modules/oacc-1_b.C: New test.
	* g++.dg/modules/oacc-1_c.C: New test.

gcc/cp/module.cc

@@ -3613,8 +3613,10 @@ void slurping::release_macros ()
 /* Flags for extensions that end up being streamed.  */
 
 enum streamed_extensions {
-  SE_OPENMP = 1 << 0,
-  SE_BITS = 1
+  SE_OPENMP_SIMD = 1 << 0,
+  SE_OPENMP = 1 << 1,
+  SE_OPENACC = 1 << 2,
+  SE_BITS = 3
 };
 
 /* Counter indices.  */
@@ -5276,6 +5278,53 @@ trees_in::tree_list (bool has_purpose)
 
   return res;
 }
+
+#define CASE_OMP_SIMD_CODE \
+    case OMP_SIMD:			\
+    case OMP_STRUCTURED_BLOCK:		\
+    case OMP_LOOP:			\
+    case OMP_ORDERED:			\
+    case OMP_TILE:			\
+    case OMP_UNROLL
+#define CASE_OMP_CODE \
+    case OMP_PARALLEL:			\
+    case OMP_TASK:			\
+    case OMP_FOR:			\
+    case OMP_DISTRIBUTE:		\
+    case OMP_TASKLOOP:			\
+    case OMP_TEAMS:			\
+    case OMP_TARGET_DATA:		\
+    case OMP_TARGET:			\
+    case OMP_SECTIONS:			\
+    case OMP_CRITICAL:			\
+    case OMP_SINGLE:			\
+    case OMP_SCOPE:			\
+    case OMP_TASKGROUP:			\
+    case OMP_MASKED:			\
+    case OMP_DISPATCH:			\
+    case OMP_INTEROP:			\
+    case OMP_MASTER:			\
+    case OMP_TARGET_UPDATE:		\
+    case OMP_TARGET_ENTER_DATA:		\
+    case OMP_TARGET_EXIT_DATA:		\
+    case OMP_METADIRECTIVE:		\
+    case OMP_ATOMIC:			\
+    case OMP_ATOMIC_READ:		\
+    case OMP_ATOMIC_CAPTURE_OLD:	\
+    case OMP_ATOMIC_CAPTURE_NEW
+#define CASE_OACC_CODE \
+    case OACC_PARALLEL:			\
+    case OACC_KERNELS:			\
+    case OACC_SERIAL:			\
+    case OACC_DATA:			\
+    case OACC_HOST_DATA:		\
+    case OACC_LOOP:			\
+    case OACC_CACHE:			\
+    case OACC_DECLARE:			\
+    case OACC_ENTER_DATA:		\
+    case OACC_EXIT_DATA:		\
+    case OACC_UPDATE
+
 /* Start tree write.  Write information to allocate the receiving
    node.  */
 
@@ -5311,10 +5360,21 @@ trees_out::start (tree t, bool code_streamed)
       break;
 
     case OMP_CLAUSE:
-      state->extensions |= SE_OPENMP;
       u (OMP_CLAUSE_CODE (t));
       break;
 
+    CASE_OMP_SIMD_CODE:
+      state->extensions |= SE_OPENMP_SIMD;
+      break;
+
+    CASE_OMP_CODE:
+      state->extensions |= SE_OPENMP;
+      break;
+
+    CASE_OACC_CODE:
+      state->extensions |= SE_OPENACC;
+      break;
+
     case STRING_CST:
       str (TREE_STRING_POINTER (t), TREE_STRING_LENGTH (t));
       break;
@@ -5383,13 +5443,25 @@ trees_in::start (unsigned code)
       break;
 
     case OMP_CLAUSE:
-      {
-	if (!(state->extensions & SE_OPENMP))
-	  goto fail;
+      t = build_omp_clause (UNKNOWN_LOCATION, omp_clause_code (u ()));
+      break;
 
-	unsigned omp_code = u ();
-	t = build_omp_clause (UNKNOWN_LOCATION, omp_clause_code (omp_code));
-      }
+    CASE_OMP_SIMD_CODE:
+      if (!(state->extensions & SE_OPENMP_SIMD))
+	goto fail;
+      t = make_node (tree_code (code));
+      break;
+
+    CASE_OMP_CODE:
+      if (!(state->extensions & SE_OPENMP))
+	goto fail;
+      t = make_node (tree_code (code));
+      break;
+
+    CASE_OACC_CODE:
+      if (!(state->extensions & SE_OPENACC))
+	goto fail;
+      t = make_node (tree_code (code));
       break;
 
     case STRING_CST:
@@ -15402,8 +15474,13 @@ module_state::write_readme (elf_out *to, cpp_reader *reader, const char *dialect
   readme.printf ("source: %s", main_input_filename);
   readme.printf ("dialect: %s", dialect);
   if (extensions)
-    readme.printf ("extensions: %s",
-		   extensions & SE_OPENMP ? "-fopenmp" : "");
+    readme.printf ("extensions: %s%s%s",
+		   extensions & SE_OPENMP ? "-fopenmp"
+		   : extensions & SE_OPENMP_SIMD ? "-fopenmp-simd" : "",
+		   (extensions & SE_OPENACC)
+		   && (extensions & (SE_OPENMP | SE_OPENMP_SIMD))
+		   ? " " : "",
+		   extensions & SE_OPENACC ? "-fopenacc" : "");
 
   /* The following fields could be expected to change between
      otherwise identical compilations.  Consider a distributed build
@@ -19166,12 +19243,22 @@ module_state::read_config (module_state_config &config)
      too.  */
   {
     unsigned ext = cfg.u ();
-    unsigned allowed = (flag_openmp ? SE_OPENMP : 0);
+    unsigned allowed = (flag_openmp ? SE_OPENMP | SE_OPENMP_SIMD : 0);
+    if (flag_openmp_simd)
+      allowed |= SE_OPENMP_SIMD;
+    if (flag_openacc)
+      allowed |= SE_OPENACC;
 
     if (unsigned bad = ext & ~allowed)
       {
 	if (bad & SE_OPENMP)
 	  error_at (loc, "module contains OpenMP, use %<-fopenmp%> to enable");
+	else if (bad & SE_OPENMP_SIMD)
+	  error_at (loc, "module contains OpenMP, use %<-fopenmp%> or "
+			 "%<-fopenmp-simd%> to enable");
+	if (bad & SE_OPENACC)
+	  error_at (loc, "module contains OpenACC, use %<-fopenacc%> to "
+			 "enable");
 	cfg.set_overrun ();
 	goto done;
       }

gcc/testsuite/g++.dg/modules/oacc-1_a.C

@@ -0,0 +1,15 @@
+// { dg-additional-options "-fmodules-ts -fopenacc" }
+// { dg-require-effective-target pthread }
+
+export module foo;
+// { dg-module-cmi foo { target pthread } }
+
+export inline void frob (unsigned (&ary)[64])
+{
+  int sum, i;
+#pragma acc parallel
+#pragma acc loop gang worker vector reduction (+:sum)
+  for (i = 0; i < 64; i++)
+    sum += ary[i];
+  ary[0] += sum;
+}

gcc/testsuite/g++.dg/modules/oacc-1_b.C

@@ -0,0 +1,11 @@
+// { dg-additional-options "-fmodules-ts -fopenacc" }
+// { dg-require-effective-target pthread }
+
+import foo;
+
+unsigned ary[64];
+
+int main ()
+{
+  frob (ary);
+}

gcc/testsuite/g++.dg/modules/oacc-1_c.C

@@ -0,0 +1,9 @@
+// { dg-additional-options "-fmodules-ts" }
+// { dg-require-effective-target pthread }
+
+import foo;
+
+// { dg-regexp "In module imported at \[^\n]*oacc-1_c.C:4:1:\nfoo: error: module contains OpenACC, use '-fopenacc' to enable\n" }
+// { dg-prune-output "failed to read" }
+// { dg-prune-output "fatal error:" }
+// { dg-prune-output "compilation terminated" }

gcc/testsuite/g++.dg/modules/omp-3_a.C

@@ -0,0 +1,14 @@
+// { dg-additional-options "-fmodules-ts -fopenmp-simd" }
+// { dg-require-effective-target pthread }
+
+export module foo;
+// { dg-module-cmi foo { target pthread } }
+
+export inline void frob (unsigned (&ary)[64])
+{
+  int sum = 0;
+
+#pragma omp simd safelen(16) aligned (ary : 16)
+  for (unsigned ix = 0; ix < 64; ix++)
+    ary[ix] *= 2;
+}

gcc/testsuite/g++.dg/modules/omp-3_b.C

@@ -0,0 +1,11 @@
+// { dg-additional-options "-fmodules-ts -fopenmp-simd" }
+// { dg-require-effective-target pthread }
+
+import foo;
+
+unsigned ary[64];
+
+int main ()
+{
+  frob (ary);
+}

gcc/testsuite/g++.dg/modules/omp-3_c.C

@@ -0,0 +1,11 @@
+// { dg-additional-options "-fmodules-ts -fopenmp" }
+// { dg-require-effective-target pthread }
+
+import foo;
+
+unsigned ary[64];
+
+int main ()
+{
+  frob (ary);
+}

gcc/testsuite/g++.dg/modules/omp-3_d.C

@@ -0,0 +1,9 @@
+// { dg-additional-options "-fmodules-ts" }
+// { dg-require-effective-target pthread }
+
+import foo;
+
+// { dg-regexp "In module imported at \[^\n]*omp-3_d.C:4:1:\nfoo: error: module contains OpenMP, use '-fopenmp' or '-fopenmp-simd' to enable\n" }
+// { dg-prune-output "failed to read" }
+// { dg-prune-output "fatal error:" }
+// { dg-prune-output "compilation terminated" }

gcc/testsuite/g++.dg/modules/pr119102_a.H

@@ -0,0 +1,9 @@
+// PR c++/119102
+// { dg-additional-options "-fmodule-header" }
+// { dg-module-cmi {} }
+
+int foo (int)
+#if defined __x86_64__ || defined __aarch64__
+__attribute__((simd ("notinbranch")))
+#endif
+;

gcc/testsuite/g++.dg/modules/pr119102_b.C

@@ -0,0 +1,9 @@
+// PR c++/119102
+// { dg-additional-options "-fmodules-ts" }
+
+import "pr119102_a.H";
+
+int
+main ()
+{
+}