Consider the test-case small.c: ... $ cat -n small.c 1 __attribute__ ((noinline, noclone)) 2 int foo (char *c) 3 { 4 asm volatile ("" : : "r" (c) : "memory"); 5 return 1; 6 } 7 8 int main () 9 { 10 char tpl1[20] = "/tmp/test.XXX"; 11 char tpl2[20] = "/tmp/test.XXX"; 12 int fd1 = foo (tpl1); 13 int fd2 = foo (tpl2); 14 if (fd1 == -1) { 15 return 1; 16 } 17 18 return 0; 19 } ... Compiled with gcc-8 and optimization: ... $ gcc-8 -O2 -g small.c ... We step through the calls to foo, but fail to visit line 13: ... 12 int fd1 = foo (tpl1); (gdb) step foo (c=c@entry=0x7fffffffdea0 "/tmp/test.XXX") at small.c:5 5 return 1; (gdb) step foo (c=c@entry=0x7fffffffdec0 "/tmp/test.XXX") at small.c:5 5 return 1; (gdb) step main () at small.c:14 14 if (fd1 == -1) { (gdb) ... This is caused by the following. The calls to foo are implemented by these insns: .... 4003df: 0f 29 04 24 movaps %xmm0,(%rsp) 4003e3: 0f 29 44 24 20 movaps %xmm0,0x20(%rsp) 4003e8: e8 03 01 00 00 callq 4004f0 <foo> 4003ed: 48 8d 7c 24 20 lea 0x20(%rsp),%rdi 4003f2: 89 c2 mov %eax,%edx 4003f4: e8 f7 00 00 00 callq 4004f0 <foo> 4003f9: 31 c0 xor %eax,%eax ... with corresponding line table entries: ... INDEX LINE ADDRESS IS-STMT 8 12 0x00000000004003df Y 9 10 0x00000000004003df 10 11 0x00000000004003e3 11 12 0x00000000004003e8 12 13 0x00000000004003ed 13 12 0x00000000004003f2 14 13 0x00000000004003f4 Y 15 13 0x00000000004003f4 16 14 0x00000000004003f9 Y 17 14 0x00000000004003f9 ... Once we step out of the call to foo at 4003e8, we land at 4003ed, and gdb enters process_event_stop_test to figure out what to do. That entry has is-stmt=n, so it's not the start of a line, so we don't stop there. However, we do update ecs->event_thread->current_line to line 13, because the frame has changed (because we stepped out of the function). Next we land at 4003f2. Again the entry has is-stmt=n, so it's not the start of a line, so we don't stop there. However, because the frame hasn't changed, we don't update update ecs->event_thread->current_line, so it stays 13. Next we land at 4003f4. Now is-stmt=y, so it's the start of a line, and we'd like to stop here. But we don't stop because this test fails: ... if ((ecs->event_thread->suspend.stop_pc == stop_pc_sal.pc) && (ecs->event_thread->current_line != stop_pc_sal.line || ecs->event_thread->current_symtab != stop_pc_sal.symtab)) { ... because ecs->event_thread->current_line == 13 and stop_pc_sal.line == 13. Fix this by resetting ecs->event_thread->current_line to 0 if is-stmt=n and the frame has changed, such that we have: ... 12 int fd1 = foo (tpl1); (gdb) step foo (c=c@entry=0x7fffffffdbc0 "/tmp/test.XXX") at small.c:5 5 return 1; (gdb) step main () at small.c:13 13 int fd2 = foo (tpl2); (gdb) ... Tested on x86_64-linux, with gcc-7 and gcc-8. gdb/ChangeLog: 2021-01-29 Tom de Vries <tdevries@suse.de> PR breakpoints/26063 * infrun.c (process_event_stop_test): Reset ecs->event_thread->current_line to 0 if is-stmt=n and frame has changed. gdb/testsuite/ChangeLog: 2021-01-29 Tom de Vries <tdevries@suse.de> PR breakpoints/26063 * gdb.dwarf2/dw2-step-out-of-function-no-stmt.c: New test. * gdb.dwarf2/dw2-step-out-of-function-no-stmt.exp: New file.
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README for GNU development tools This directory contains various GNU compilers, assemblers, linkers, debuggers, etc., plus their support routines, definitions, and documentation. If you are receiving this as part of a GDB release, see the file gdb/README. If with a binutils release, see binutils/README; if with a libg++ release, see libg++/README, etc. That'll give you info about this package -- supported targets, how to use it, how to report bugs, etc. It is now possible to automatically configure and build a variety of tools with one command. To build all of the tools contained herein, run the ``configure'' script here, e.g.: ./configure make To install them (by default in /usr/local/bin, /usr/local/lib, etc), then do: make install (If the configure script can't determine your type of computer, give it the name as an argument, for instance ``./configure sun4''. You can use the script ``config.sub'' to test whether a name is recognized; if it is, config.sub translates it to a triplet specifying CPU, vendor, and OS.) If you have more than one compiler on your system, it is often best to explicitly set CC in the environment before running configure, and to also set CC when running make. For example (assuming sh/bash/ksh): CC=gcc ./configure make A similar example using csh: setenv CC gcc ./configure make Much of the code and documentation enclosed is copyright by the Free Software Foundation, Inc. See the file COPYING or COPYING.LIB in the various directories, for a description of the GNU General Public License terms under which you can copy the files. REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info on where and how to report problems.
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