diff options
| -rw-r--r-- | ChangeLog | 7 | ||||
| -rw-r--r-- | tapsets.cxx | 81 |
2 files changed, 65 insertions, 23 deletions
@@ -1,3 +1,10 @@ +2005-12-06 Frank Ch. Eigler <fche@elastic.org> + + PR 1934. + * tapsets.cxx (resolve_prologue_endings2): Add new heuristic for + tail-call optimized functions. + (query_func_info): Make somewhat less verbose. + 2005-12-06 Graydon Hoare <graydon@redhat.com> * translate.cxx (visit_print_format): Explicitly Cast int64_t diff --git a/tapsets.cxx b/tapsets.cxx index 5bfe4427..b6a218db 100644 --- a/tapsets.cxx +++ b/tapsets.cxx @@ -751,12 +751,22 @@ dwflpp // This heuristic attempts to pick the first address that has a // source line distinct from the function declaration's (entrypc's). // This should be the first statement *past* the prologue. + // + // However, for some tail-call optimized functions + // ("sys_exit_group" in linux 2.6), there might be only a single + // line record for the function. We guess at this situation if + // the "next" line record refers to an address past the + // dwarf_highpc of the current function. In this case, we back + // down to the address from the previous line record. + // assert(module); assert(cu); - size_t nlines; - Dwarf_Lines *lines; - Dwarf_Addr last_function_entrypc; + size_t nlines = 0; + Dwarf_Lines *lines = NULL; + func_info* last_function = NULL; + Dwarf_Addr last_function_entrypc = 0; + Dwarf_Addr last_function_highpc = 0; int choose_next_line_otherthan = -1; // XXX: ideally, there would be a dwarf_getfile(line) routine, @@ -778,36 +788,72 @@ dwflpp Dwarf_Addr addr; Dwarf_Line * line_rec = dwarf_onesrcline(lines, i); dwarf_lineaddr (line_rec, &addr); - int this_lineno; + // If this next line goes past the current function, we have + // a probable tail call, and must go back the entrypc + if (choose_next_line_otherthan >= 0 && + addr >= last_function_highpc) // NB: >= ; highpc is exclusive + { + addr = last_function_entrypc; // go back to entrypc + Dwarf_Addr addr0 = last_function->prologue_end; + if (addr0 != addr) + { + last_function->prologue_end = addr; + if (sess.verbose) + clog << "prologue disagreement (tail call): " + << last_function->name + << " heur0=" << hex << addr0 + << " heur1=" << addr << dec + << endl; + } + choose_next_line_otherthan = -1; + continue; + } + + // If this next line maps to a line number beyond the + // first one, but still within the same function, pick it! + int this_lineno; dwfl_assert ("dwarf_lineno", dwarf_lineno(line_rec, &this_lineno)); if (choose_next_line_otherthan >= 0 && this_lineno != choose_next_line_otherthan) { - map<Dwarf_Addr, func_info>::iterator i = - funcs.find (last_function_entrypc); - assert (i != funcs.end()); - Dwarf_Addr addr0 = i->second.prologue_end; + Dwarf_Addr addr0 = last_function->prologue_end; if (addr0 != addr) { - i->second.prologue_end = addr; + last_function->prologue_end = addr; if (sess.verbose) - clog << "prologue disagreement: " << i->second.name + clog << "prologue disagreement: " << last_function->name << " heur0=" << hex << addr0 << " heur1=" << addr << dec << endl; } choose_next_line_otherthan = -1; + continue; } - map<Dwarf_Addr, func_info>::const_iterator i = funcs.find (addr); + // Else ... see if this line record refers to the entrypc of + // yet another probe-targeted function. Stash away its entrypc + // etc., for the other branches of this loop to process. + map<Dwarf_Addr, func_info>::iterator i = funcs.find (addr); if (i != funcs.end()) { dwfl_assert ("dwarf_lineno", - dwarf_lineno(line_rec, &choose_next_line_otherthan)); + dwarf_lineno (line_rec, &choose_next_line_otherthan)); + assert (choose_next_line_otherthan >= 0); + last_function = & i->second; last_function_entrypc = addr; + dwfl_assert ("dwarf_highpc", + dwarf_highpc (& last_function->die, + & last_function_highpc)); + + if (sess.verbose) + clog << "finding prologue for '" + << last_function->name + << "' entrypc=0x" << hex << addr + << " highpc=0x" << last_function_highpc + << endl; } } @@ -1887,9 +1933,6 @@ query_func_info (Dwarf_Addr entrypc, { // NB. dwarf_derived_probe::emit_registrations will emit a // kretprobe based on the entrypc in this case. - if (q->sess.verbose) - clog << "querying entrypc of function '" - << fi.name << "' for return probe" << endl; query_statement (fi.name, fi.decl_file, fi.decl_line, &fi.die, entrypc, q); } @@ -1898,21 +1941,13 @@ query_func_info (Dwarf_Addr entrypc, #ifdef __ia64__ // In IA64 platform function probe point is set at its // entry point rather than prologue end pointer - if (q->sess.verbose) - clog << "querying entrypc of function '" - << fi.name << "'" << endl; query_statement (fi.name, fi.decl_file, fi.decl_line, &fi.die, entrypc, q); #else - if (q->sess.verbose) - clog << "querying prologue-end of function '" - << fi.name << "'" << endl; - if (fi.prologue_end == 0) throw semantic_error("could not find prologue-end " "for probed function '" + fi.name + "'"); - query_statement (fi.name, fi.decl_file, fi.decl_line, &fi.die, fi.prologue_end, q); #endif |