nvptx: In offloading compilation, special-case certain host-setup symbol aliases...

Namely, use PTX '.alias' even for (default) '-mno-alias' if the host made the
C++ "base and complete [cd]tor aliases".

	PR target/101544
	gcc/
	* config/nvptx/nvptx.cc (nvptx_asm_output_def_from_decls)
	[ACCEL_COMPILER]: Special-case certain host-setup symbol aliases.
	* varasm.cc (do_assemble_alias) [ACCEL_COMPILER]: Adjust.

diff --git a/gcc/config/nvptx/nvptx.cc b/gcc/config/nvptx/nvptx.cc
index 5cd4b2427714775e5e86ddc1210f6ab4f68b1e24..022037f1362708754943e8aae7fb0e988ae55bfc 100644 (file)
--- a/gcc/config/nvptx/nvptx.cc
+++ b/gcc/config/nvptx/nvptx.cc
@@ -245,7 +245,7 @@ default_ptx_version_option (void)
      warp convergence.  */
   res = MAX (res, PTX_VERSION_6_0);
 
-  /* Pick at least 6.3.  */
+  /* Pick at least 6.3, to enable PTX '.alias'.  */
   res = MAX (res, PTX_VERSION_6_3);
 
   /* For sm_52+, pick at least 7.3, to enable PTX 'alloca'.  */
@@ -7713,6 +7713,30 @@ nvptx_asm_output_def_from_decls (FILE *stream, tree name,
 {
   if (nvptx_alias == 0 || !TARGET_PTX_6_3)
     {
+      /* Symbol aliases are not supported here.  */
+
+#ifdef ACCEL_COMPILER
+      if (DECL_CXX_CONSTRUCTOR_P (name)
+         || DECL_CXX_DESTRUCTOR_P (name))
+       {
+         /* ..., but symbol aliases are supported and used in the host system,
+            via 'gcc/cp/optimize.cc:can_alias_cdtor'.  */
+
+         gcc_assert (!lookup_attribute ("weak", DECL_ATTRIBUTES (name)));
+         gcc_assert (TREE_CODE (name) == FUNCTION_DECL);
+
+         /* In this specific case, use PTX '.alias', if available, even for
+            (default) '-mno-alias'.  */
+         if (TARGET_PTX_6_3)
+           {
+             DECL_ATTRIBUTES (name)
+               = tree_cons (get_identifier ("symbol alias handled"),
+                            NULL_TREE, DECL_ATTRIBUTES (name));
+             goto emit_ptx_alias;
+           }
+       }
+#endif
+
       /* Copied from assemble_alias.  */
       error_at (DECL_SOURCE_LOCATION (name),
                "alias definitions not supported in this configuration");
@@ -7744,6 +7768,8 @@ nvptx_asm_output_def_from_decls (FILE *stream, tree name,
       return;
     }
 
+ emit_ptx_alias:
+
   cgraph_node *cnode = cgraph_node::get (name);
   if (!cnode->referred_to_p ())
     /* Prevent "Internal error: reference to deleted section".  */

diff --git a/gcc/varasm.cc b/gcc/varasm.cc
index eddfb6a3524d10c02c9fdecfdfa90633dd3659f4..10c1d2e313712e5bbc9bb00c2f503d988f91bc47 100644 (file)
--- a/gcc/varasm.cc
+++ b/gcc/varasm.cc
@@ -6525,7 +6525,12 @@ do_assemble_alias (tree decl, tree target)
                  IDENTIFIER_POINTER (target));
 # endif
   /* If symbol aliases aren't actually supported...  */
-  if (!TARGET_SUPPORTS_ALIASES)
+  if (!TARGET_SUPPORTS_ALIASES
+# ifdef ACCEL_COMPILER
+      /* ..., and unless special-cased...  */
+      && !lookup_attribute ("symbol alias handled", DECL_ATTRIBUTES (decl))
+# endif
+      )
     /* ..., 'ASM_OUTPUT_DEF{,_FROM_DECLS}' better have raised an error.  */
     gcc_checking_assert (seen_error ());
 #elif defined (ASM_OUTPUT_WEAK_ALIAS) || defined (ASM_WEAKEN_DECL)