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Re: [PATCH] Refactor section/label init for early LTO debug
- From: Jason Merrill <jason at redhat dot com>
- To: Richard Biener <rguenther at suse dot de>
- Cc: gcc-patches List <gcc-patches at gcc dot gnu dot org>
- Date: Fri, 23 Sep 2016 14:05:53 -0400
- Subject: Re: [PATCH] Refactor section/label init for early LTO debug
- Authentication-results: sourceware.org; auth=none
- References: <alpine.LSU.2.11.1609211512420.26629@t29.fhfr.qr>
OK.
On Wed, Sep 21, 2016 at 9:19 AM, Richard Biener <rguenther@suse.de> wrote:
>
> The following patch ports a refactoring of section/label in it from
> the early LTO debug work to trunk. For early LTO debug we need to
> be able to emit two sets of debug infos into two sets of different
> sections - early LTO into .gnu.debuglto_ prefixed sections and
> regular (early + late) debug for the FAT part of the object.
>
> Thus this preparation splits out the section and label generation
> from dwarf2out_init moving the text section related stuff to
> dwarf2out_assembly_start and the rest to a new function
> init_sections_and_labels which is now called only before we start
> outputting dwarf (in dwarf2out_finish). It also removes some
> dwarf_split_debug_info checks from the macro section name defines
> (in the end I'll have up to four variants - regular, regular LTO,
> DWO, DWO LTO).
>
> And it removes an unused function.
>
> Bootstrapped on x86_64-unknown-linux-gnu, testing in progress. I've
> also bootstrapped with -O2 -g3 to exercise the .debug_macro path.
>
> Ok?
>
> Just noticed that DEBUG_STR_OFFSETS_SECTION needs similar massaging
> for its dwarf_split_debug_info condition - will followup as obvious
> if this one is approved.
>
> Thanks,
> Richard.
>
> 2016-09-21 Richard Biener <rguenther@suse.de>
>
> * dwarf2out.c (stripattributes): Remove unused function.
> (DEBUG_NORM_MACINFO_SECTION): Rename to DEBUG_MACINFO_SECTION.
> Push dwarf_split_debug_info handling into init_sections_and_labels.
> (DEBUG_NORM_MACRO_SECTION): Likewise to DEBUG_MACRO_SECTION.
> (DEBUG_MACRO_SECTION_FLAGS): Remove.
> (debug_macinfo_section_name): New global.
> (output_macinfo): Use debug_macinfo_section_name.
> (init_sections_and_labels): Split out section and label generation
> from dwarf2out_init. Set debug_macinfo_section_name.
> (dwarf2out_init): Move text section label generation and emission
> to ...
> (dwarf2out_assembly_start): ... here.
> (dwarf2out_finish): Call init_sections_and_labels before DWARF
> output starts.
>
> Index: gcc/dwarf2out.c
> ===================================================================
> --- gcc/dwarf2out.c (revision 240303)
> +++ gcc/dwarf2out.c (working copy)
> @@ -159,6 +159,7 @@ static GTY(()) section *debug_skeleton_a
> static GTY(()) section *debug_aranges_section;
> static GTY(()) section *debug_addr_section;
> static GTY(()) section *debug_macinfo_section;
> +static const char *debug_macinfo_section_name;
> static GTY(()) section *debug_line_section;
> static GTY(()) section *debug_skeleton_line_section;
> static GTY(()) section *debug_loc_section;
> @@ -265,7 +266,6 @@ static GTY(()) dw_die_ref decltype_auto_
>
> /* Forward declarations for functions defined in this file. */
>
> -static char *stripattributes (const char *);
> static void output_call_frame_info (int);
> static void dwarf2out_note_section_used (void);
>
> @@ -410,24 +410,6 @@ should_emit_struct_debug (tree type, enu
> return DUMP_GSTRUCT (type, usage, criterion, generic, false, false);
> }
>
> -/* Return a pointer to a copy of the section string name S with all
> - attributes stripped off, and an asterisk prepended (for assemble_name). */
> -
> -static inline char *
> -stripattributes (const char *s)
> -{
> - char *stripped = XNEWVEC (char, strlen (s) + 2);
> - char *p = stripped;
> -
> - *p++ = '*';
> -
> - while (*s && *s != ',')
> - *p++ = *s++;
> -
> - *p = '\0';
> - return stripped;
> -}
> -
> /* Switch [BACK] to eh_frame_section. If we don't have an eh_frame_section,
> switch to the data section instead, and write out a synthetic start label
> for collect2 the first time around. */
> @@ -3514,27 +3496,17 @@ new_addr_loc_descr (rtx addr, enum dtpre
> #ifndef DEBUG_ADDR_SECTION
> #define DEBUG_ADDR_SECTION ".debug_addr"
> #endif
> -#ifndef DEBUG_NORM_MACINFO_SECTION
> -#define DEBUG_NORM_MACINFO_SECTION ".debug_macinfo"
> +#ifndef DEBUG_MACINFO_SECTION
> +#define DEBUG_MACINFO_SECTION ".debug_macinfo"
> #endif
> #ifndef DEBUG_DWO_MACINFO_SECTION
> #define DEBUG_DWO_MACINFO_SECTION ".debug_macinfo.dwo"
> #endif
> -#ifndef DEBUG_MACINFO_SECTION
> -#define DEBUG_MACINFO_SECTION \
> - (!dwarf_split_debug_info \
> - ? (DEBUG_NORM_MACINFO_SECTION) : (DEBUG_DWO_MACINFO_SECTION))
> -#endif
> -#ifndef DEBUG_NORM_MACRO_SECTION
> -#define DEBUG_NORM_MACRO_SECTION ".debug_macro"
> -#endif
> #ifndef DEBUG_DWO_MACRO_SECTION
> #define DEBUG_DWO_MACRO_SECTION ".debug_macro.dwo"
> #endif
> #ifndef DEBUG_MACRO_SECTION
> -#define DEBUG_MACRO_SECTION \
> - (!dwarf_split_debug_info \
> - ? (DEBUG_NORM_MACRO_SECTION) : (DEBUG_DWO_MACRO_SECTION))
> +#define DEBUG_MACRO_SECTION ".debug_macro"
> #endif
> #ifndef DEBUG_LINE_SECTION
> #define DEBUG_LINE_SECTION ".debug_line"
> @@ -3580,10 +3552,6 @@ new_addr_loc_descr (rtx addr, enum dtpre
> #define TEXT_SECTION_NAME ".text"
> #endif
>
> -/* Section flags for .debug_macinfo/.debug_macro section. */
> -#define DEBUG_MACRO_SECTION_FLAGS \
> - (dwarf_split_debug_info ? SECTION_DEBUG | SECTION_EXCLUDE : SECTION_DEBUG)
> -
> /* Section flags for .debug_str section. */
> #define DEBUG_STR_SECTION_FLAGS \
> (HAVE_GAS_SHF_MERGE && flag_merge_debug_strings \
> @@ -25520,7 +25488,7 @@ output_macinfo (void)
> tree comdat_key = get_identifier (ref->info);
> /* Terminate the previous .debug_macinfo section. */
> dw2_asm_output_data (1, 0, "End compilation unit");
> - targetm.asm_out.named_section (DEBUG_MACRO_SECTION,
> + targetm.asm_out.named_section (debug_macinfo_section_name,
> SECTION_DEBUG
> | SECTION_LINKONCE,
> comdat_key);
> @@ -25548,53 +25516,11 @@ output_macinfo (void)
> }
> }
>
> -/* Set up for Dwarf output at the start of compilation. */
> +/* Initialize the various sections and labels for dwarf output. */
>
> static void
> -dwarf2out_init (const char *filename ATTRIBUTE_UNUSED)
> +init_sections_and_labels (void)
> {
> - /* This option is currently broken, see (PR53118 and PR46102). */
> - if (flag_eliminate_dwarf2_dups
> - && strstr (lang_hooks.name, "C++"))
> - {
> - warning (0, "-feliminate-dwarf2-dups is broken for C++, ignoring");
> - flag_eliminate_dwarf2_dups = 0;
> - }
> -
> - /* Allocate the file_table. */
> - file_table = hash_table<dwarf_file_hasher>::create_ggc (50);
> -
> -#ifndef DWARF2_LINENO_DEBUGGING_INFO
> - /* Allocate the decl_die_table. */
> - decl_die_table = hash_table<decl_die_hasher>::create_ggc (10);
> -
> - /* Allocate the decl_loc_table. */
> - decl_loc_table = hash_table<decl_loc_hasher>::create_ggc (10);
> -
> - /* Allocate the cached_dw_loc_list_table. */
> - cached_dw_loc_list_table = hash_table<dw_loc_list_hasher>::create_ggc (10);
> -
> - /* Allocate the initial hunk of the decl_scope_table. */
> - vec_alloc (decl_scope_table, 256);
> -
> - /* Allocate the initial hunk of the abbrev_die_table. */
> - abbrev_die_table = ggc_cleared_vec_alloc<dw_die_ref>
> - (ABBREV_DIE_TABLE_INCREMENT);
> - abbrev_die_table_allocated = ABBREV_DIE_TABLE_INCREMENT;
> - /* Zero-th entry is allocated, but unused. */
> - abbrev_die_table_in_use = 1;
> -
> - /* Allocate the dwarf_proc_stack_usage_map. */
> - dwarf_proc_stack_usage_map = new hash_map<dw_die_ref, int>;
> -
> - /* Allocate the pubtypes and pubnames vectors. */
> - vec_alloc (pubname_table, 32);
> - vec_alloc (pubtype_table, 32);
> -
> - vec_alloc (incomplete_types, 64);
> -
> - vec_alloc (used_rtx_array, 32);
> -
> if (!dwarf_split_debug_info)
> {
> debug_info_section = get_section (DEBUG_INFO_SECTION,
> @@ -25603,6 +25529,10 @@ dwarf2out_init (const char *filename ATT
> SECTION_DEBUG, NULL);
> debug_loc_section = get_section (DEBUG_LOC_SECTION,
> SECTION_DEBUG, NULL);
> + debug_macinfo_section_name
> + = dwarf_strict ? DEBUG_MACINFO_SECTION : DEBUG_MACRO_SECTION;
> + debug_macinfo_section = get_section (debug_macinfo_section_name,
> + SECTION_DEBUG, NULL);
> }
> else
> {
> @@ -25623,8 +25553,8 @@ dwarf2out_init (const char *filename ATT
> /* Somewhat confusing detail: The skeleton_[abbrev|info] sections stay in
> the main .o, but the skeleton_line goes into the split off dwo. */
> debug_skeleton_line_section
> - = get_section (DEBUG_DWO_LINE_SECTION,
> - SECTION_DEBUG | SECTION_EXCLUDE, NULL);
> + = get_section (DEBUG_DWO_LINE_SECTION,
> + SECTION_DEBUG | SECTION_EXCLUDE, NULL);
> ASM_GENERATE_INTERNAL_LABEL (debug_skeleton_line_section_label,
> DEBUG_SKELETON_LINE_SECTION_LABEL, 0);
> debug_str_offsets_section = get_section (DEBUG_STR_OFFSETS_SECTION,
> @@ -25636,13 +25566,14 @@ dwarf2out_init (const char *filename ATT
> SECTION_DEBUG | SECTION_EXCLUDE, NULL);
> debug_str_dwo_section = get_section (DEBUG_STR_DWO_SECTION,
> DEBUG_STR_DWO_SECTION_FLAGS, NULL);
> + debug_macinfo_section_name
> + = dwarf_strict ? DEBUG_DWO_MACINFO_SECTION : DEBUG_DWO_MACRO_SECTION;
> + debug_macinfo_section = get_section (debug_macinfo_section_name,
> + SECTION_DEBUG | SECTION_EXCLUDE,
> + NULL);
> }
> debug_aranges_section = get_section (DEBUG_ARANGES_SECTION,
> SECTION_DEBUG, NULL);
> - debug_macinfo_section = get_section (dwarf_strict
> - ? DEBUG_MACINFO_SECTION
> - : DEBUG_MACRO_SECTION,
> - DEBUG_MACRO_SECTION_FLAGS, NULL);
> debug_line_section = get_section (DEBUG_LINE_SECTION,
> SECTION_DEBUG, NULL);
> debug_pubnames_section = get_section (DEBUG_PUBNAMES_SECTION,
> @@ -25656,14 +25587,8 @@ dwarf2out_init (const char *filename ATT
> debug_frame_section = get_section (DEBUG_FRAME_SECTION,
> SECTION_DEBUG, NULL);
>
> - ASM_GENERATE_INTERNAL_LABEL (text_end_label, TEXT_END_LABEL, 0);
> ASM_GENERATE_INTERNAL_LABEL (abbrev_section_label,
> DEBUG_ABBREV_SECTION_LABEL, 0);
> - ASM_GENERATE_INTERNAL_LABEL (text_section_label, TEXT_SECTION_LABEL, 0);
> - ASM_GENERATE_INTERNAL_LABEL (cold_text_section_label,
> - COLD_TEXT_SECTION_LABEL, 0);
> - ASM_GENERATE_INTERNAL_LABEL (cold_end_label, COLD_END_LABEL, 0);
> -
> ASM_GENERATE_INTERNAL_LABEL (debug_info_section_label,
> DEBUG_INFO_SECTION_LABEL, 0);
> ASM_GENERATE_INTERNAL_LABEL (debug_line_section_label,
> @@ -25677,12 +25602,57 @@ dwarf2out_init (const char *filename ATT
> ? DEBUG_MACINFO_SECTION_LABEL
> : DEBUG_MACRO_SECTION_LABEL, 0);
> ASM_GENERATE_INTERNAL_LABEL (loc_section_label, DEBUG_LOC_SECTION_LABEL, 0);
> +}
> +
> +/* Set up for Dwarf output at the start of compilation. */
> +
> +static void
> +dwarf2out_init (const char *filename ATTRIBUTE_UNUSED)
> +{
> + /* This option is currently broken, see (PR53118 and PR46102). */
> + if (flag_eliminate_dwarf2_dups
> + && strstr (lang_hooks.name, "C++"))
> + {
> + warning (0, "-feliminate-dwarf2-dups is broken for C++, ignoring");
> + flag_eliminate_dwarf2_dups = 0;
> + }
> +
> + /* Allocate the file_table. */
> + file_table = hash_table<dwarf_file_hasher>::create_ggc (50);
> +
> +#ifndef DWARF2_LINENO_DEBUGGING_INFO
> + /* Allocate the decl_die_table. */
> + decl_die_table = hash_table<decl_die_hasher>::create_ggc (10);
> +
> + /* Allocate the decl_loc_table. */
> + decl_loc_table = hash_table<decl_loc_hasher>::create_ggc (10);
> +
> + /* Allocate the cached_dw_loc_list_table. */
> + cached_dw_loc_list_table = hash_table<dw_loc_list_hasher>::create_ggc (10);
> +
> + /* Allocate the initial hunk of the decl_scope_table. */
> + vec_alloc (decl_scope_table, 256);
> +
> + /* Allocate the initial hunk of the abbrev_die_table. */
> + abbrev_die_table = ggc_cleared_vec_alloc<dw_die_ref>
> + (ABBREV_DIE_TABLE_INCREMENT);
> + abbrev_die_table_allocated = ABBREV_DIE_TABLE_INCREMENT;
> + /* Zero-th entry is allocated, but unused. */
> + abbrev_die_table_in_use = 1;
> +
> + /* Allocate the dwarf_proc_stack_usage_map. */
> + dwarf_proc_stack_usage_map = new hash_map<dw_die_ref, int>;
> +
> + /* Allocate the pubtypes and pubnames vectors. */
> + vec_alloc (pubname_table, 32);
> + vec_alloc (pubtype_table, 32);
> +
> + vec_alloc (incomplete_types, 64);
> +
> + vec_alloc (used_rtx_array, 32);
>
> if (debug_info_level >= DINFO_LEVEL_VERBOSE)
> vec_alloc (macinfo_table, 64);
> -
> - switch_to_section (text_section);
> - ASM_OUTPUT_LABEL (asm_out_file, text_section_label);
> #endif
>
> /* Make sure the line number table for .text always exists. */
> @@ -25705,6 +25675,17 @@ dwarf2out_init (const char *filename ATT
> static void
> dwarf2out_assembly_start (void)
> {
> +#ifndef DWARF2_LINENO_DEBUGGING_INFO
> + ASM_GENERATE_INTERNAL_LABEL (text_section_label, TEXT_SECTION_LABEL, 0);
> + ASM_GENERATE_INTERNAL_LABEL (text_end_label, TEXT_END_LABEL, 0);
> + ASM_GENERATE_INTERNAL_LABEL (cold_text_section_label,
> + COLD_TEXT_SECTION_LABEL, 0);
> + ASM_GENERATE_INTERNAL_LABEL (cold_end_label, COLD_END_LABEL, 0);
> +
> + switch_to_section (text_section);
> + ASM_OUTPUT_LABEL (asm_out_file, text_section_label);
> +#endif
> +
> if (HAVE_GAS_CFI_SECTIONS_DIRECTIVE
> && dwarf2out_do_cfi_asm ()
> && (!(flag_unwind_tables || flag_exceptions)
> @@ -27858,6 +27839,9 @@ dwarf2out_finish (const char *)
> if (flag_eliminate_dwarf2_dups)
> break_out_includes (comp_unit_die ());
>
> + /* Initialize sections and labels used for actual assembler output. */
> + init_sections_and_labels ();
> +
> /* Traverse the DIE's and add sibling attributes to those DIE's that
> have children. */
> add_sibling_attributes (comp_unit_die ());