PR23652, Use symbols from debug bfd for _bfd_elf_find_function

Sometimes DWARF info for a function is incomplete, and the function
can be retrieved by examining symbols.  However, when separate debug
files are used it may be that the original file is completely
stripped of symbols.  This patch teaches BFD to look at symbols from
the debug file in that case.

The patch also removes arm_elf_find_function, instead implementing
elf_backend_maybe_function_sym.  arm_elf_find_function was written
before the generic _bfd_elf_find_function called maybe_function_sym.
aarch64 copied arm, so that file gets the same treatment.  There is
some chance this will speed up arm and aarch64 lookup of function/line.

	PR 23652
	* dwarf2.c (_bfd_dwarf2_stash_syms): New function.
	(_bfd_dwarf2_find_nearest_line): Use it here, passing syms to
	_bfd_elf_find_function.  Call _bfd_elf_find_function in cases
	where _bfd_elf_find_nearest_line would do so.
	* elf.c (_bfd_elf_find_nearest_line): Omit _bfd_elf_find_function
	for dwarf2.
	* elfxx-mips.c (_bfd_mips_elf_find_nearest_line): Similarly.  Tidy.
	* elf32-arm.c (elf32_arm_maybe_function_sym): New function.
	(elf_backend_maybe_function_sym): Define.
	(arm_elf_find_function, elf32_arm_find_nearest_line): Delete.
	(bfd_elf32_find_nearest_line): Don't define.
	* elfnn-aarch64.c (elfNN_aarch64_maybe_function_sym): New function.
	(elf_backend_maybe_function_sym): Define.
	(aarch64_elf_find_function, elfNN_aarch64_find_nearest_line): Delete.
	(bfd_elfNN_find_nearest_line): Don't define.

1 files changed, 30 insertions, 111 deletions

diff --git a/bfd/elf32-arm.c b/bfd/elf32-arm.c
index dca208f..37b5b64 100644
--- a/bfd/elf32-arm.c
+++ b/bfd/elf32-arm.c
@@ -16040,125 +16040,44 @@ elf32_arm_is_target_special_symbol (bfd * abfd ATTRIBUTE_UNUSED, asymbol * sym)
 					 BFD_ARM_SPECIAL_SYM_TYPE_ANY);
 }
 
-/* This is a version of _bfd_elf_find_function() from dwarf2.c except that
-   ARM mapping symbols are ignored when looking for function names
-   and STT_ARM_TFUNC is considered to a function type.  */
+/* If the ELF symbol SYM might be a function in SEC, return the
+   function size and set *CODE_OFF to the function's entry point,
+   otherwise return zero.  */
 
-static bfd_boolean
-arm_elf_find_function (bfd *	     abfd,
-		       asymbol **    symbols,
-		       asection *    section,
-		       bfd_vma	     offset,
-		       const char ** filename_ptr,
-		       const char ** functionname_ptr)
-{
-  const char * filename = NULL;
-  asymbol * func = NULL;
-  bfd_vma low_func = 0;
-  asymbol ** p;
-
-  if (symbols == NULL)
-    return FALSE;
-
-  if (bfd_get_flavour (abfd) != bfd_target_elf_flavour)
-    return FALSE;
-
-  for (p = symbols; *p != NULL; p++)
-    {
-      elf_symbol_type *q;
+static bfd_size_type
+elf32_arm_maybe_function_sym (const asymbol *sym, asection *sec,
+			      bfd_vma *code_off)
+{
+  bfd_size_type size;
 
-      q = (elf_symbol_type *) *p;
+  if ((sym->flags & (BSF_SECTION_SYM | BSF_FILE | BSF_OBJECT
+		     | BSF_THREAD_LOCAL | BSF_RELC | BSF_SRELC)) != 0
+      || sym->section != sec)
+    return 0;
 
-      switch (ELF_ST_TYPE (q->internal_elf_sym.st_info))
-	{
-	default:
-	  break;
-	case STT_FILE:
-	  filename = bfd_asymbol_name (&q->symbol);
-	  break;
+  if (!(sym->flags & BSF_SYNTHETIC))
+    switch (ELF_ST_TYPE (((elf_symbol_type *) sym)->internal_elf_sym.st_info))
+      {
 	case STT_FUNC:
 	case STT_ARM_TFUNC:
 	case STT_NOTYPE:
-	  /* Skip mapping symbols.  */
-	  if ((q->symbol.flags & BSF_LOCAL)
-	      && bfd_is_arm_special_symbol_name (q->symbol.name,
-		    BFD_ARM_SPECIAL_SYM_TYPE_ANY))
-	    continue;
-	  /* Fall through.  */
-	  if (bfd_asymbol_section (&q->symbol) == section
-	      && q->symbol.value >= low_func
-	      && q->symbol.value <= offset)
-	    {
-	      func = (asymbol *) q;
-	      low_func = q->symbol.value;
-	    }
 	  break;
-	}
-    }
-
-  if (func == NULL)
-    return FALSE;
-
-  if (filename_ptr)
-    *filename_ptr = filename;
-  if (functionname_ptr)
-    *functionname_ptr = bfd_asymbol_name (func);
-
-  return TRUE;
-}
-
-
-/* Find the nearest line to a particular section and offset, for error
-   reporting.   This code is a duplicate of the code in elf.c, except
-   that it uses arm_elf_find_function.  */
-
-static bfd_boolean
-elf32_arm_find_nearest_line (bfd *	    abfd,
-			     asymbol **	    symbols,
-			     asection *	    section,
-			     bfd_vma	    offset,
-			     const char **  filename_ptr,
-			     const char **  functionname_ptr,
-			     unsigned int * line_ptr,
-			     unsigned int * discriminator_ptr)
-{
-  bfd_boolean found = FALSE;
-
-  if (_bfd_dwarf2_find_nearest_line (abfd, symbols, NULL, section, offset,
-				     filename_ptr, functionname_ptr,
-				     line_ptr, discriminator_ptr,
-				     dwarf_debug_sections,
-				     & elf_tdata (abfd)->dwarf2_find_line_info))
-    {
-      if (!*functionname_ptr)
-	arm_elf_find_function (abfd, symbols, section, offset,
-			       *filename_ptr ? NULL : filename_ptr,
-			       functionname_ptr);
-
-      return TRUE;
-    }
-
-  /* Skip _bfd_dwarf1_find_nearest_line since no known ARM toolchain
-     uses DWARF1.  */
-
-  if (! _bfd_stab_section_find_nearest_line (abfd, symbols, section, offset,
-					     & found, filename_ptr,
-					     functionname_ptr, line_ptr,
-					     & elf_tdata (abfd)->line_info))
-    return FALSE;
-
-  if (found && (*functionname_ptr || *line_ptr))
-    return TRUE;
-
-  if (symbols == NULL)
-    return FALSE;
+	default:
+	  return 0;
+      }
 
-  if (! arm_elf_find_function (abfd, symbols, section, offset,
-			       filename_ptr, functionname_ptr))
-    return FALSE;
+  if ((sym->flags & BSF_LOCAL)
+      && bfd_is_arm_special_symbol_name (sym->name,
+					 BFD_ARM_SPECIAL_SYM_TYPE_ANY))
+    return 0;
 
-  *line_ptr = 0;
-  return TRUE;
+  *code_off = sym->value;
+  size = 0;
+  if (!(sym->flags & BSF_SYNTHETIC))
+    size = ((elf_symbol_type *) sym)->internal_elf_sym.st_size;
+  if (size == 0)
+    size = 1;
+  return size;
 }
 
 static bfd_boolean
@@ -20488,7 +20407,6 @@ elf32_arm_backend_symbol_processing (bfd *abfd, asymbol *sym)
 #define bfd_elf32_bfd_link_hash_table_create	elf32_arm_link_hash_table_create
 #define bfd_elf32_bfd_reloc_type_lookup		elf32_arm_reloc_type_lookup
 #define bfd_elf32_bfd_reloc_name_lookup		elf32_arm_reloc_name_lookup
-#define bfd_elf32_find_nearest_line		elf32_arm_find_nearest_line
 #define bfd_elf32_find_inliner_info		elf32_arm_find_inliner_info
 #define bfd_elf32_new_section_hook		elf32_arm_new_section_hook
 #define bfd_elf32_bfd_is_target_special_symbol	elf32_arm_is_target_special_symbol
@@ -20496,6 +20414,7 @@ elf32_arm_backend_symbol_processing (bfd *abfd, asymbol *sym)
 #define bfd_elf32_get_synthetic_symtab	elf32_arm_get_synthetic_symtab
 
 #define elf_backend_get_symbol_type		elf32_arm_get_symbol_type
+#define elf_backend_maybe_function_sym		elf32_arm_maybe_function_sym
 #define elf_backend_gc_mark_hook		elf32_arm_gc_mark_hook
 #define elf_backend_gc_mark_extra_sections	elf32_arm_gc_mark_extra_sections
 #define elf_backend_check_relocs		elf32_arm_check_relocs