From 61b04dd04ac2c64d455bc6e17f08a106305b06b3 Mon Sep 17 00:00:00 2001 From: Pedro Alves Date: Tue, 19 Jun 2018 16:30:13 +0100 Subject: Change inline frame breakpoint skipping logic (fix gdb.gdb/selftest.exp) Currently, gdb.gdb/selftest.exp fails if you build GDB with optimization (-O2, etc.). The reason is that after setting a breakpoint in captured_main, we stop at: ... Breakpoint 1, captured_main_1 (context=) at src/gdb/main.c:492 ... while selftest_setup expects a stop at captured_main. Here, captured_main_1 has been inlined into captured_main, and captured_main has been inlined into gdb_main: ... $ nm ./build/gdb/gdb | egrep ' [tT] .*captured_main|gdb_main' | c++filt 000000000061b950 T gdb_main(captured_main_args*) ... Indeed, the two inlined functions show up in the backtrace: ... (gdb) bt #0 captured_main_1 (context=) at main.c:492 #1 captured_main (data=) at main.c:1147 #2 gdb_main (args=args@entry=0x7fffffffdb80) at main.c:1173 #3 0x000000000040fea5 in main (argc=, argv=) at gdb.c:32 ... We're now stopping at captured_main_1 because commit ddfe970e6bec ("Don't elide all inlined frames") makes GDB present a stop at the innermost inlined frame if the program stopped by a user breakpoint. Now, the selftest.exp testcase explicitly asks to stop at "captured_main", not "captured_main_1", so I'm thinking that it's GDB'S behavior that should be improved. That is what this commit does, by only showing a stop at an inline frame if the user breakpoint was set in that frame's block. Before this commit: (top-gdb) b captured_main Breakpoint 1 at 0x792f99: file src/gdb/main.c, line 492. (top-gdb) r Starting program: build/gdb/gdb Breakpoint 1, captured_main_1 (context=) at src/gdb/main.c:492 492 lim_at_start = (char *) sbrk (0); (top-gdb) After this commit, we now instead get: (top-gdb) b captured_main Breakpoint 1 at 0x791339: file src/gdb/main.c, line 492. (top-gdb) r Starting program: build/gdb/gdb Breakpoint 1, captured_main (data=) at src/gdb/main.c:1147 1147 captured_main_1 (context); (top-gdb) and: (top-gdb) b captured_main_1 Breakpoint 2 at 0x791339: file src/gdb/main.c, line 492. (top-gdb) r Starting program: build/gdb/gdb Breakpoint 2, captured_main_1 (context=) at src/gdb/main.c:492 492 lim_at_start = (char *) sbrk (0); (top-gdb) Note that both captured_main and captured_main_1 resolved to the same address, 0x791339. That is necessary to trigger the issue in question. The gdb.base/inline-break.exp testcase currently does not exercise that, but the new test added by this commit does. That new test fails without the GDB fix and passes with the fix. No regressions on x86-64 GNU/Linux. While at it, the THIS_PC comparison in stopped_by_user_bp_inline_frame is basically a nop, so just remove it -- if a software or hardware breakpoint explains the stop, then it must be that it was installed at the current PC. gdb/ChangeLog: 2018-06-19 Pedro Alves * inline-frame.c (stopped_by_user_bp_inline_frame): Replace PC parameter with a block parameter. Compare location's block symbol with the frame's block instead of addresses. (skip_inline_frames): Pass the current block instead of the frame's address. Break out as soon as we determine the frame should not be skipped. gdb/testsuite/ChangeLog: 2018-06-19 Pedro Alves * gdb.opt/inline-break.c (func_inline_callee, func_inline_caller) (func_extern_caller): New. (main): Call func_extern_caller. * gdb.opt/inline-break.exp: Add tests for inline frame skipping logic change. --- gdb/inline-frame.c | 23 +++++++++++------------ 1 file changed, 11 insertions(+), 12 deletions(-) (limited to 'gdb/inline-frame.c') diff --git a/gdb/inline-frame.c b/gdb/inline-frame.c index 1ac5835..3edd5b2 100644 --- a/gdb/inline-frame.c +++ b/gdb/inline-frame.c @@ -286,11 +286,10 @@ block_starting_point_at (CORE_ADDR pc, const struct block *block) } /* Loop over the stop chain and determine if execution stopped in an - inlined frame because of a user breakpoint. THIS_PC is the current - frame's PC. */ + inlined frame because of a user breakpoint set at FRAME_BLOCK. */ static bool -stopped_by_user_bp_inline_frame (CORE_ADDR this_pc, bpstat stop_chain) +stopped_by_user_bp_inline_frame (const block *frame_block, bpstat stop_chain) { for (bpstat s = stop_chain; s != NULL; s = s->next) { @@ -301,9 +300,9 @@ stopped_by_user_bp_inline_frame (CORE_ADDR this_pc, bpstat stop_chain) bp_location *loc = s->bp_location_at; enum bp_loc_type t = loc->loc_type; - if (loc->address == this_pc - && (t == bp_loc_software_breakpoint - || t == bp_loc_hardware_breakpoint)) + if ((t == bp_loc_software_breakpoint + || t == bp_loc_hardware_breakpoint) + && frame_block == SYMBOL_BLOCK_VALUE (loc->symbol)) return true; } } @@ -340,12 +339,12 @@ skip_inline_frames (ptid_t ptid, bpstat stop_chain) { /* Do not skip the inlined frame if execution stopped in an inlined frame because of a user - breakpoint. */ - if (!stopped_by_user_bp_inline_frame (this_pc, stop_chain)) - { - skip_count++; - last_sym = BLOCK_FUNCTION (cur_block); - } + breakpoint for this inline function. */ + if (stopped_by_user_bp_inline_frame (cur_block, stop_chain)) + break; + + skip_count++; + last_sym = BLOCK_FUNCTION (cur_block); } else break; -- cgit v1.1