perf annotate: Fix source code annotate with objdump

Recently it uses llvm and capstone to speed up annotation or disassembly
of instructions. But they don't support source code view yet. Until it
fixed, we can force to use objdump for source code annotation.

To prevent performance loss, it's disabled by default and turned it on
when user requests it in TUI by pressing 's' key.

Acked-by: Ian Rogers <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Reported-by: Ingo Molnar <[e-mail]>
Signed-off-by: Namhyung Kim <[e-mail]>

tools/perf/ui/browsers/annotate.c

···
 	browser->curr_hot = rb_last(&browser->entries);
 }
 
+static struct annotation_line *annotate_browser__find_new_asm_line(
+					struct annotate_browser *browser,
+					int idx_asm)
+{
+	struct annotation_line *al;
+	struct list_head *head = browser->b.entries;
+
+	/* find an annotation line in the new list with the same idx_asm */
+	list_for_each_entry(al, head, node) {
+		if (al->idx_asm == idx_asm)
+			return al;
+	}
+
+	/* There are no asm lines */
+	return NULL;
+}
+
 static struct annotation_line *annotate_browser__find_next_asm_line(
 					struct annotate_browser *browser,
 					struct annotation_line *al)
···
 	return NULL;
 }
 
-static bool annotate_browser__toggle_source(struct annotate_browser *browser)
+static bool annotation__has_source(struct annotation *notes)
+{
+	struct annotation_line *al;
+	bool found_asm = false;
+
+	/* Let's skip the first non-asm lines which present regardless of source. */
+	list_for_each_entry(al, &notes->src->source, node) {
+		if (al->offset >= 0) {
+			found_asm = true;
+			break;
+		}
+	}
+
+	if (found_asm) {
+		/* After assembly lines, any line without offset means source. */
+		list_for_each_entry_continue(al, &notes->src->source, node) {
+			if (al->offset == -1)
+				return true;
+		}
+	}
+	return false;
+}
+
+static bool annotate_browser__toggle_source(struct annotate_browser *browser,
+					    struct evsel *evsel)
 {
 	struct annotation *notes = browser__annotation(&browser->b);
 	struct annotation_line *al;
···
 
 	browser->b.seek(&browser->b, offset, SEEK_CUR);
 	al = list_entry(browser->b.top, struct annotation_line, node);
+
+	if (!annotate_opts.annotate_src)
+		annotate_opts.annotate_src = true;
+
+	/*
+	 * It's about to get source code annotation for the first time.
+	 * Drop the existing annotation_lines and get the new one with source.
+	 * And then move to the original line at the same asm index.
+	 */
+	if (annotate_opts.hide_src_code && !notes->src->tried_source) {
+		struct map_symbol *ms = browser->b.priv;
+		int orig_idx_asm = al->idx_asm;
+
+		/* annotate again with source code info */
+		annotate_opts.hide_src_code = false;
+		annotated_source__purge(notes->src);
+		symbol__annotate2(ms, evsel, &browser->arch);
+		annotate_opts.hide_src_code = true;
+
+		/* should be after annotated_source__purge() */
+		notes->src->tried_source = true;
+
+		if (!annotation__has_source(notes))
+			ui__warning("Annotation has no source code.");
+
+		browser->b.entries = &notes->src->source;
+		al = annotate_browser__find_new_asm_line(browser, orig_idx_asm);
+		if (unlikely(al == NULL)) {
+			al = list_first_entry(&notes->src->source,
+					      struct annotation_line, node);
+		}
+		browser->b.seek(&browser->b, al->idx_asm, SEEK_SET);
+	}
 
 	if (annotate_opts.hide_src_code) {
 		if (al->idx_asm < offset)
···
 			nd = browser->curr_hot;
 			break;
 		case 's':
-			if (annotate_browser__toggle_source(browser))
+			if (annotate_browser__toggle_source(browser, evsel))
 				ui_helpline__puts(help);
 			annotate__scnprintf_title(hists, title, sizeof(title));
 			annotate_browser__show(&browser->b, title, help);
···
 			ui__error("Couldn't annotate %s:\n%s", sym->name, msg);
 			return -1;
 		}
+
+		if (!annotate_opts.hide_src_code) {
+			notes->src->tried_source = true;
+			if (!annotation__has_source(notes))
+				ui__warning("Annotation has no source code.");
+		}
 	}
 
 	ui_helpline__push("Press ESC to exit");
···
 
 	ret = annotate_browser__run(&browser, evsel, hbt);
 
-	if(not_annotated)
+	if (not_annotated && !notes->src->tried_source)
 		annotated_source__purge(notes->src);
 
 	return ret;

tools/perf/util/annotate.c

···
 		list_del_init(&al->node);
 		disasm_line__free(disasm_line(al));
 	}
+	as->tried_source = false;
 }
 
 static size_t disasm_line__fprintf(struct disasm_line *dl, FILE *fp)
···
 	opt->annotate_src = true;
 	opt->offset_level = ANNOTATION__OFFSET_JUMP_TARGETS;
 	opt->percent_type = PERCENT_PERIOD_LOCAL;
+	opt->hide_src_code = true;
 	opt->hide_src_code_on_title = true;
 }
 

tools/perf/util/annotate.h

···
 	int			nr_entries;
 	int			nr_asm_entries;
 	int			max_jump_sources;
+	bool			tried_source;
 	u64			start;
 	struct {
 		u8		addr;

tools/perf/util/disasm.c

···
 		}
 	}
 
+	/* FIXME: LLVM and CAPSTONE should support source code */
+	if (options->annotate_src && !options->hide_src_code) {
+		err = symbol__disassemble_objdump(symfs_filename, sym, args);
+		if (err == 0)
+			goto out_remove_tmp;
+	}
+
 	err = -1;
 	for (u8 i = 0; i < ARRAY_SIZE(options->disassemblers) && err != 0; i++) {
 		enum perf_disassembler dis = options->disassemblers[i];