From c3b7b696c231416ac90fd9cb7d5ce735b3683356 Mon Sep 17 00:00:00 2001 From: Yao Qi Date: Mon, 4 Aug 2014 14:57:22 +0800 Subject: [PATCH] Check function is GC'ed I see the following fail on arm-none-eabi target, (gdb) b 24^M Breakpoint 1 at 0x4: file ../../../../git/gdb/testsuite/gdb.base/break-on-linker-gcd-function.cc, line 24.^M (gdb) FAIL: gdb.base/break-on-linker-gcd-function.exp: b 24 Currently, we are using flag has_section_at_zero to determine whether address zero in debug info means the corresponding code has been GC'ed, like this: case DW_LNE_set_address: address = read_address (abfd, line_ptr, cu, &bytes_read); if (address == 0 && !dwarf2_per_objfile->has_section_at_zero) { /* This line table is for a function which has been GCd by the linker. Ignore it. PR gdb/12528 */ However, this is incorrect on some bare metal targets, as .text section is located at 0x0, so dwarf2_per_objfile->has_section_at_zero is true. If a function is GC'ed by linker, the address is zero. GDB thinks address zero is a function's address rather than this function is GC'ed. 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: 2014-09-19 Yao Qi * dwarf2read.c (dwarf_decode_lines): Update declaration. (handle_DW_AT_stmt_list): Add argument 'lowpc'. Update comments. Callers update. (dwarf_decode_lines): Likewise. (dwarf_decode_lines_1): Add argument 'lowpc'. Update comments. Skip the line table if 'lowpc' is greater than 'address'. Don't check dwarf2_per_objfile->has_section_at_zero. gdb/testsuite: 2014-09-19 Yao Qi * 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. --- gdb/ChangeLog | 11 ++++++++ gdb/dwarf2read.c | 33 ++++++++++++++-------- gdb/testsuite/ChangeLog | 7 +++++ .../gdb.base/break-on-linker-gcd-function.exp | 24 ++++++++++++---- 4 files changed, 59 insertions(+), 16 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 3fbc13e..3757708 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,14 @@ +2014-09-19 Yao Qi + + * dwarf2read.c (dwarf_decode_lines): Update declaration. + (handle_DW_AT_stmt_list): Add argument 'lowpc'. Update + comments. Callers update. + (dwarf_decode_lines): Likewise. + (dwarf_decode_lines_1): Add argument 'lowpc'. Update + comments. Skip the line table if 'lowpc' is greater than + 'address'. Don't check + dwarf2_per_objfile->has_section_at_zero. + 2014-09-18 Doug Evans * NEWS: Mention new "producer" attribute of gdb.Symtab. diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c index be32309..9d0ee13 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 *); @@ -4448,7 +4449,7 @@ 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, pst->textlow); free_line_header (lh); } @@ -8967,11 +8968,12 @@ 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 +8990,7 @@ 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 +9041,7 @@ 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 +17254,8 @@ 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 +17378,12 @@ 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 < lowpc then it's not a usable value, it's + outside the pc range of the CU. However, we restrict + the test to only address values of zero to preserve + GDB's previous behaviour which is to handle the specific + case of a function being GC'd by the linker. */ + if (address == 0 && address < lowpc) { /* This line table is for a function which has been GCd by the linker. Ignore it. PR gdb/12528 */ @@ -17595,17 +17603,20 @@ 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/ChangeLog b/gdb/testsuite/ChangeLog index a4b03dc..c421904 100644 --- a/gdb/testsuite/ChangeLog +++ b/gdb/testsuite/ChangeLog @@ -1,3 +1,10 @@ +2014-09-19 Yao Qi + + * 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. + 2014-09-18 Doug Evans * gdb.dwarf2/symtab-producer.exp: New file. 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 +} -- 2.7.4