[PATCH] Report call site for inlined functions

[PATCH] Report call site for inlined functions

[Keith Seitz]

Currently, "info break" can show some (perhaps) unexpected results when
setting a breakpoint on an inlined function:

(gdb) list
1	#include <stdio.h>
2
3	static inline void foo()
4	{
5	        printf("Hello world\n");
6	}
7
8	int main()
9	{
10	        foo();
11	        return 0;
12	}
13
(gdb) b foo
Breakpoint 1 at 0x400434: file foo.c, line 5.
(gdb) i b
Num     Type           Disp Enb Address            What
1       breakpoint     keep y   0x0000000000400434 in main at foo.c:5

GDB reported that we understood what "foo" was, but we then report that the
breakpoint is actually set in main. While that is literally true, we can
do a little better.

This is accomplished by copying the symbol for which the breakpoint was set
into the bp_location.  From there, print_breakpoint_location can use this
information to print out symbol information (if available) instead of calling
find_pc_sect_function.

With the patch installed,

(gdb) i b
Num     Type           Disp Enb Address            What
1       breakpoint     keep y   0x0000000000400434 in foo at foo.c:5

gdb/ChangeLog:

	* breakpoint.c (print_breakpoint_location): Use the symbol saved
	in the bp_location, falling back to find_pc_sect_function when
	needed.
	(add_location_to_breakpoint): Save sal->symbol.
	* breakpoint.h (struct bp_location) <symbol>: New field.
	* symtab.c (find_function_start_sal): Save the symbol into the SaL.
	* symtab.h (struct symtab_and_line) <symbol>: New field.

gdb/testsuite/ChangeLog:

	* gdb.opt/inline-break.exp (break_info_1): New procedure.
	Test "info break" for every inlined function breakpoint.
---
 gdb/breakpoint.c                       |  8 +++-
 gdb/breakpoint.h                       |  5 +++
 gdb/testsuite/gdb.opt/inline-break.exp | 75 ++++++++++++++++++++++++++++++++++
 3 files changed, 86 insertions(+), 2 deletions(-)

diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
index 32ceea7c9b..2ede1cef96 100644
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -5956,8 +5956,11 @@ print_breakpoint_location (struct breakpoint *b,
     uiout->field_string ("what", event_location_to_string (b->location.get ()));
   else if (loc && loc->symtab)
     {
-      struct symbol *sym 
-	= find_pc_sect_function (loc->address, loc->section);
+      const struct symbol *sym = loc->symbol;
+
+      if (sym == NULL)
+	sym = find_pc_sect_function (loc->address, loc->section);
+
       if (sym)
 	{
 	  uiout->text ("in ");
@@ -8742,6 +8745,7 @@ add_location_to_breakpoint (struct breakpoint *b,
   loc->gdbarch = loc_gdbarch;
   loc->line_number = sal->line;
   loc->symtab = sal->symtab;
+  loc->symbol = sal->symbol;
 
   set_breakpoint_location_function (loc,
 				    sal->explicit_pc || sal->explicit_line);
diff --git a/gdb/breakpoint.h b/gdb/breakpoint.h
index 2b80ed9f46..2cc235c3a8 100644
--- a/gdb/breakpoint.h
+++ b/gdb/breakpoint.h
@@ -486,6 +486,11 @@ public:
      to find the corresponding source file name.  */
 
   struct symtab *symtab = NULL;
+
+  /* The symbol found by the location parser, if any.  This may be used to
+     ascertain when an event location was set at a different location than
+     the one originally selected by parsing, e.g., inlined symbols.  */
+  const struct symbol *symbol = NULL;
 };
 
 /* The possible return values for print_bpstat, print_it_normal,
diff --git a/gdb/testsuite/gdb.opt/inline-break.exp b/gdb/testsuite/gdb.opt/inline-break.exp
index 7be3a34dbc..ec9ee74ec1 100644
--- a/gdb/testsuite/gdb.opt/inline-break.exp
+++ b/gdb/testsuite/gdb.opt/inline-break.exp
@@ -24,6 +24,62 @@ if { [prepare_for_testing "failed to prepare" $testfile $srcfile \
     return -1
 }
 
+# Return a string that may be used to match the output of "info break NUM".
+#
+# Optional arguments:
+#
+# source    - the name of the source file
+# func      - the name of the function
+# disp      - the event disposition
+# enabled   - enable state
+# locs      - number of locations
+# line      - source line number (ignored without -source)
+
+proc break_info_1 {num args} {
+    global decimal
+
+    # Column delimiter
+    set c {[\t ]+}
+
+    # Row delimiter
+    set end {[\r\n \t]+}
+
+    # Table header
+    set header "[join [list Num Type Disp Enb Address What] ${c}]"
+
+    # Get/configure any optional parameters.
+    parse_args [list {source ""} {func ".*"} {disp "keep"} \
+		    {enabled "y"} {locs 1} [list line $decimal] \
+		    {type "breakpoint"}]
+
+    if {$source != ""} {
+	set source "/$source:$line"
+    }
+
+    # Result starts with the standard header.
+    set result "$header${end}"
+
+    # Set up for multi-location breakpoint marker.
+    if {$locs == 1} {
+	set multi ".*"
+    } else {
+	set multi "<MULTIPLE>${end}"
+    }
+    append result "[join [list $num $type $disp $enabled $multi] $c]"
+
+    # Add location info.
+    for {set i 1} {$i <= $locs} {incr i} {
+	if {$locs > 1} {
+	    append result "[join [list $num.$i $enabled] $c].*"
+	}
+
+	#  Add function/source file info.
+	append result "in $func at .*$source${end}"
+    }
+
+    return $result
+}
+
 #
 # func1 is a static inlined function that is called once.
 # The result should be a single-location breakpoint.
@@ -111,3 +167,22 @@ gdb_test "print func1" \
 #
 gdb_test "print func2" \
     "\\\$.* = {int \\(int\\)} .* <func2>"
+
+# Test that "info break" reports the location of the breakpoints "inside"
+# the inlined functions
+
+set results(1) [break_info_1 1 -source $srcfile -func "func1"]
+set results(2) [break_info_1 2 -locs 2 -source $srcfile -func "func2"]
+set results(3) [break_info_1 3 -source $srcfile -func "func3b"]
+set results(4) [break_info_1 4 -locs 2 -source $srcfile -func "func4b"]
+set results(5) [break_info_1 5 -locs 2 -source $srcfile -func "func5b"]
+set results(6) [break_info_1 6 -locs 3 -source $srcfile -func "func6b"]
+set results(7) [break_info_1 7 -locs 2 -source $srcfile -func "func7b"]
+set results(8) [break_info_1 8 -locs 3 -source $srcfile -func "func8b"]
+
+for {set i 1} {$i <= [array size results]} {incr i} {
+    send_log "Expecting: $results($i)\n"
+    gdb_test "info break $i" $results($i)
+}
+
+unset -nocomplain results
-- 
2.13.6

Re: [PATCH] Report call site for inlined functions

[Pedro Alves]

Is this a v2?  As general guideline, please state so in the
subject header, and also state what changed compared to v1.

E.g., what happened to showing both call site and inline location?

The subject still talks about "call site", but it's not
what the patch is doing, is it?

Thanks,
Pedro Alves

Re: [PATCH] Report call site for inlined functions

[Keith Seitz]

On 10/19/2017 10:22 AM, Pedro Alves wrote:
> Is this a v2?  As general guideline, please state so in the
> subject header, and also state what changed compared to v1.

Oh, it is. I forgot! I'll edit/resubmit.

Keith