[PATCH 03/25] Improve TARGET_MANGLE_DECL_ASSEMBLER_NAME.

[<ams at codesourcery dot com>]

The HSA GPU drivers can't cope with binaries that have the same symbol defined
multiple times, even though the names are not exported.  This happens whenever
there are file-scope static variables with matching names.  I believe it's also
an issue with switch tables.

This is a bug, but outside our control, so we must work around it when multiple
translation units have the same symbol defined.

Therefore, we've implemented name mangling via
TARGET_MANGLE_DECL_ASSEMBLER_NAME, but found some places where the middle-end
assumes that the decl name matches the name in the source.

This patch fixes up those cases by falling back to comparing the unmangled
name, when a lookup fails.

2018-09-05  Julian Brown  <julian@codesourcery.com>

	gcc/
	* cgraphunit.c (handle_alias_pairs): Scan for aliases by DECL_NAME if
	decl assembler name doesn't match.

	gcc/c-family/
	* c-pragma.c (maye_apply_pending_pragma_weaks): Scan for aliases with
	DECL_NAME if decl assembler name doesn't match.
---
 gcc/c-family/c-pragma.c | 14 ++++++++++++++
 gcc/cgraphunit.c        | 15 +++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/gcc/c-family/c-pragma.c b/gcc/c-family/c-pragma.c
index 84e4341..1c0be0c 100644
--- a/gcc/c-family/c-pragma.c
+++ b/gcc/c-family/c-pragma.c
@@ -323,6 +323,20 @@ maybe_apply_pending_pragma_weaks (void)
 	continue;
 
       target = symtab_node::get_for_asmname (id);
+
+      /* Try again if ID didn't match an assembler name by looking through
+	 decl names.  */
+      if (!target)
+	{
+	  symtab_node *node;
+	  FOR_EACH_SYMBOL (node)
+	    if (strcmp (IDENTIFIER_POINTER (id), node->name ()) == 0)
+	      {
+	        target = node;
+		break;
+	      }
+	}
+
       decl = build_decl (UNKNOWN_LOCATION,
 			 target ? TREE_CODE (target->decl) : FUNCTION_DECL,
 			 alias_id, default_function_type);
diff --git a/gcc/cgraphunit.c b/gcc/cgraphunit.c
index ec490d7..fc3f34e 100644
--- a/gcc/cgraphunit.c
+++ b/gcc/cgraphunit.c
@@ -1393,6 +1393,21 @@ handle_alias_pairs (void)
     {
       symtab_node *target_node = symtab_node::get_for_asmname (p->target);
 
+      /* If the alias target didn't match a symbol's assembler name (e.g.
+	 because it has been mangled by TARGET_MANGLE_DECL_ASSEMBLER_NAME),
+	 try again with the unmangled decl name.  */
+      if (!target_node)
+	{
+	  symtab_node *node;
+	  FOR_EACH_SYMBOL (node)
+	    if (strcmp (IDENTIFIER_POINTER (p->target),
+			node->name ()) == 0)
+	      {
+		target_node = node;
+		break;
+	      }
+	}
+
       /* Weakrefs with target not defined in current unit are easy to handle:
 	 they behave just as external variables except we need to note the
 	 alias flag to later output the weakref pseudo op into asm file.  */