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[1/3] Check function is GC'ed

Message ID 87sikggadr.fsf@codesourcery.com
State New
Headers show

Commit Message

Yao Qi Aug. 28, 2014, 10:46 a.m. UTC
Doug Evans <dje@google.com> writes:

> I'd like to solve this for both partial syms and .gdb_index.
>
> We want to, essentially, discard the entry if address is outside the
> range of the cu (the range needn't be contiguous, but for the task
> at hand I don't think it matters).  I haven't dug into this too deeply,
> but if we have lowpc (which for example is that read_file_scope has
> before it calls handle_DW_AT_stmt_list (which calls dwarf_decode_lines),
> can we use that in the test?  Can we arrange for all callers of
> dwarf_decode_lines_1 pass lowpc down to it? [Or both lowpc,highpc
> for a more complete test, but for the task at hand we've only been
> checking, effectively, lowpc all along so I don't mind leaving it at that
> for now.]

Hi Doug,
Patch below implemented what you suggested, if I understand you correct
:)

A new argument 'lowpc' is added to both dwarf2_build_include_psymtabs
and handle_DW_AT_stmt_list, to keep the similarity between them.  I
thought about merging them into one function, but still need more
thinking.

Comments

Yao Qi Sept. 15, 2014, 8:02 a.m. UTC | #1
Yao Qi <yao@codesourcery.com> writes:

> In this patch, we choose 'lowpc' got in read_file_scope to check
> whether 'lowpc' is greater than zero.  If it isn't, address zero really
> means the function is GC'ed.  In this patch, we pass 'lowpc' in
> read_file_scope through handle_DW_AT_stmt_list and dwarf_decode_lines,
> and to dwarf_decode_lines_1 finally.
>
> This patch fixes the fail above. This patch also covers the path that
> partial symbol isn't used, which is tested by starting gdb with
> --readnow option.
>
> It is regression tested on x86-linux with
> target_board=dwarf4-gdb-index, and arm-none-eabi.  OK to apply?
>
> gdb:
>
> 2014-08-27  Yao Qi  <yao@codesourcery.com>
>
> 	* dwarf2read.c (dwarf_decode_lines): Update declaration.
> 	(handle_DW_AT_stmt_list): Add argument 'lowpc'.  Update
> 	comments.  Callers update.
> 	(dwarf_decode_lines): Likewise.
> 	(dwarf2_build_include_psymtabs): Likewise.
> 	(dwarf_decode_lines_1): Add argument 'lowpc'.  Update
> 	comments.  Skip the line table if  'lowpc' is greater than
> 	'address'.
>
> gdb/testsuite:
>
> 2014-08-27  Yao Qi  <yao@codesourcery.com>
>
> 	* gdb.base/break-on-linker-gcd-function.exp: Move test into new
> 	proc set_breakpoint_on_gcd_function.  Invoke
> 	set_breakpoint_on_gcd_function.  Restart GDB with --readnow and
> 	invoke set_breakpoint_on_gcd_function again.

Ping.  https://sourceware.org/ml/gdb-patches/2014-08/msg00595.html
diff mbox

Patch

diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
index be32309..8fdae74 100644
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -1512,7 +1512,8 @@  static struct line_header *dwarf_decode_line_header (unsigned int offset,
 						     struct dwarf2_cu *cu);
 
 static void dwarf_decode_lines (struct line_header *, const char *,
-				struct dwarf2_cu *, struct partial_symtab *);
+				struct dwarf2_cu *, struct partial_symtab *,
+				CORE_ADDR);
 
 static void dwarf2_start_subfile (const char *, const char *, const char *);
 
@@ -4436,7 +4437,8 @@  dwarf2_create_include_psymtab (const char *name, struct partial_symtab *pst,
 static void
 dwarf2_build_include_psymtabs (struct dwarf2_cu *cu,
 			       struct die_info *die,
-			       struct partial_symtab *pst)
+			       struct partial_symtab *pst,
+			       CORE_ADDR lowpc)
 {
   struct line_header *lh = NULL;
   struct attribute *attr;
@@ -4448,7 +4450,7 @@  dwarf2_build_include_psymtabs (struct dwarf2_cu *cu,
     return;  /* No linetable, so no includes.  */
 
   /* NOTE: pst->dirname is DW_AT_comp_dir (if present).  */
-  dwarf_decode_lines (lh, pst->dirname, cu, pst);
+  dwarf_decode_lines (lh, pst->dirname, cu, pst, lowpc);
 
   free_line_header (lh);
 }
@@ -5954,7 +5956,7 @@  process_psymtab_comp_unit_reader (const struct die_reader_specs *reader,
 
   /* Get the list of files included in the current compilation unit,
      and build a psymtab for each of them.  */
-  dwarf2_build_include_psymtabs (cu, comp_unit_die, pst);
+  dwarf2_build_include_psymtabs (cu, comp_unit_die, pst, pst->textlow);
 
   if (dwarf2_read_debug)
     {
@@ -8967,11 +8969,12 @@  find_file_and_directory (struct die_info *die, struct dwarf2_cu *cu,
 
 /* Handle DW_AT_stmt_list for a compilation unit.
    DIE is the DW_TAG_compile_unit die for CU.
-   COMP_DIR is the compilation directory.  */
+   COMP_DIR is the compilation directory.  LOWPC is passed to
+   dwarf_decode_lines.  See dwarf_decode_lines comments about it.  */
 
 static void
 handle_DW_AT_stmt_list (struct die_info *die, struct dwarf2_cu *cu,
-			const char *comp_dir) /* ARI: editCase function */
+			const char *comp_dir, CORE_ADDR lowpc) /* ARI: editCase function */
 {
   struct attribute *attr;
 
@@ -8988,7 +8991,7 @@  handle_DW_AT_stmt_list (struct die_info *die, struct dwarf2_cu *cu,
 	{
 	  cu->line_header = line_header;
 	  make_cleanup (free_cu_line_header, cu);
-	  dwarf_decode_lines (line_header, comp_dir, cu, NULL);
+	  dwarf_decode_lines (line_header, comp_dir, cu, NULL, lowpc);
 	}
     }
 }
@@ -9039,7 +9042,7 @@  read_file_scope (struct die_info *die, struct dwarf2_cu *cu)
   /* Decode line number information if present.  We do this before
      processing child DIEs, so that the line header table is available
      for DW_AT_decl_file.  */
-  handle_DW_AT_stmt_list (die, cu, comp_dir);
+  handle_DW_AT_stmt_list (die, cu, comp_dir, lowpc);
 
   /* Process all dies in compilation unit.  */
   if (die->child != NULL)
@@ -17252,7 +17255,8 @@  dwarf_finish_line (struct gdbarch *gdbarch, struct subfile *subfile,
 
 static void
 dwarf_decode_lines_1 (struct line_header *lh, const char *comp_dir,
-		      struct dwarf2_cu *cu, const int decode_for_pst_p)
+		      struct dwarf2_cu *cu, const int decode_for_pst_p,
+		      CORE_ADDR lowpc)
 {
   const gdb_byte *line_ptr, *extended_end;
   const gdb_byte *line_end;
@@ -17375,7 +17379,9 @@  dwarf_decode_lines_1 (struct line_header *lh, const char *comp_dir,
 		case DW_LNE_set_address:
 		  address = read_address (abfd, line_ptr, cu, &bytes_read);
 
-		  if (address == 0 && !dwarf2_per_objfile->has_section_at_zero)
+		  if (address == 0
+		      && (!dwarf2_per_objfile->has_section_at_zero
+			  || lowpc > address))
 		    {
 		      /* This line table is for a function which has been
 			 GCd by the linker.  Ignore it.  PR gdb/12528 */
@@ -17595,17 +17601,20 @@  dwarf_decode_lines_1 (struct line_header *lh, const char *comp_dir,
    as the corresponding symtab.  Since COMP_DIR is not used in the name of the
    symtab we don't use it in the name of the psymtabs we create.
    E.g. expand_line_sal requires this when finding psymtabs to expand.
-   A good testcase for this is mb-inline.exp.  */
+   A good testcase for this is mb-inline.exp.
+
+   LOWPC is the lowest address in CU (or 0 if not known).  */
 
 static void
 dwarf_decode_lines (struct line_header *lh, const char *comp_dir,
-		    struct dwarf2_cu *cu, struct partial_symtab *pst)
+		    struct dwarf2_cu *cu, struct partial_symtab *pst,
+		    CORE_ADDR lowpc)
 {
   struct objfile *objfile = cu->objfile;
   const int decode_for_pst_p = (pst != NULL);
   struct subfile *first_subfile = current_subfile;
 
-  dwarf_decode_lines_1 (lh, comp_dir, cu, decode_for_pst_p);
+  dwarf_decode_lines_1 (lh, comp_dir, cu, decode_for_pst_p, lowpc);
 
   if (decode_for_pst_p)
     {
diff --git a/gdb/testsuite/gdb.base/break-on-linker-gcd-function.exp b/gdb/testsuite/gdb.base/break-on-linker-gcd-function.exp
index e593b51..b8de1cd 100644
--- a/gdb/testsuite/gdb.base/break-on-linker-gcd-function.exp
+++ b/gdb/testsuite/gdb.base/break-on-linker-gcd-function.exp
@@ -41,9 +41,23 @@  if {[build_executable_from_specs $testfile.exp $testfile \
 
 clean_restart $testfile
 
-# Single hex digit
-set xd {[0-9a-f]}
+proc set_breakpoint_on_gcd_function {} {
+    # Single hex digit
+    set xd {[0-9a-f]}
+
+    # This accepts e.g. "Breakpoint 1 at 0x40968a" (fixed GDB)
+    # but rejects e.g. "Breakpoint 1 at 0x4" (broken GDB).
+    gdb_test "b [gdb_get_line_number "gdb break here"]" \
+	"Breakpoint \[0-9\] at 0x${xd}${xd}+: .*"
+}
+
+set_breakpoint_on_gcd_function
 
-# This accepts e.g. "Breakpoint 1 at 0x40968a" (fixed GDB)
-# but rejects e.g. "Breakpoint 1 at 0x4" (broken GDB).
-gdb_test "b [gdb_get_line_number "gdb break here"]" "Breakpoint \[0-9\] at 0x${xd}${xd}+: .*"
+set saved_gdbflags $GDBFLAGS
+set GDBFLAGS "$GDBFLAGS --readnow"
+clean_restart ${testfile}
+set GDBFLAGS $saved_gdbflags
+
+with_test_prefix "readnow" {
+    set_breakpoint_on_gcd_function
+}