| Message ID | 20211109111521.361580-2-aldyh@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | Dump details of an attempt to register a jump threading path. | expand |
On 11/9/2021 4:15 AM, Aldy Hernandez wrote: > The goal with these sets of patches is to improve the detailed dumps for > the threader, as I hope we eventually reach the point when I'm not > the only one looking at these dumps ;-). > > This patch adds candidate paths to the detailed threading dumps to make it > easier to see the decisions the threader makes. With it we can now > grep for the discovery logic in action: > > $ grep ^path: a.ii.*thread* > a.ii.034t.ethread:path: 4->5->xx REJECTED > a.ii.034t.ethread:path: 3->5->8 SUCCESS > a.ii.034t.ethread:path: 4->5->6 SUCCESS > a.ii.034t.ethread:path: 0->2->xx REJECTED > a.ii.034t.ethread:path: 0->2->xx REJECTED > ... > ... > a.ii.111t.threadfull1:path: 14->22->23->xx REJECTED (unreachable) > a.ii.111t.threadfull1:path: 15->22->23->xx REJECTED (unreachable) > a.ii.111t.threadfull1:path: 16->22->23->xx REJECTED (unreachable) > > In addition to this, if --param=threader-debug=all is used, one can see > the entire chain of events leading up to the ultimate threading > decision: > > ============================================== > path_range_query: compute_ranges for path: 2->5 > Registering killing_def (path_oracle) _3 > Registering killing_def (path_oracle) _1 > range_defined_in_block (BB2) for _1 is _Bool VARYING > Registering killing_def (path_oracle) _2 > range_defined_in_block (BB2) for _2 is _Bool VARYING > range_defined_in_block (BB2) for _3 is _Bool VARYING > outgoing_edge_range_p for b_10(D) on edge 2->5 is int VARYING > ... > ... [BBs and gimple along path] > ... > path: 2->5->xx REJECTED > > Tested on x86-64 Linux. > > OK? > > gcc/ChangeLog: > > * tree-ssa-threadbackward.c > (back_threader::maybe_register_path_dump): New. > (back_threader::maybe_register_path): Call maybe_register_path_dump. OK jeff
diff --git a/gcc/tree-ssa-threadbackward.c b/gcc/tree-ssa-threadbackward.c index 84249544760..74b5f361f45 100644 --- a/gcc/tree-ssa-threadbackward.c +++ b/gcc/tree-ssa-threadbackward.c @@ -89,6 +89,7 @@ private: void find_paths (basic_block bb, tree name); bool debug_counter (); edge maybe_register_path (); + void maybe_register_path_dump (edge taken_edge); void find_paths_to_names (basic_block bb, bitmap imports); bool resolve_def (tree name, bitmap interesting, vec<tree> &worklist); void resolve_phi (gphi *phi, bitmap imports); @@ -186,6 +187,35 @@ back_threader::debug_counter () return true; } +// Dump details of an attempt to register a path. + +void +back_threader::maybe_register_path_dump (edge taken) +{ + if (m_path.is_empty ()) + return; + + fprintf (dump_file, "path: "); + + for (unsigned i = m_path.length (); i > 0; --i) + { + basic_block bb = m_path[i - 1]; + fprintf (dump_file, "%d", bb->index); + if (i > 1) + fprintf (dump_file, "->"); + } + fprintf (dump_file, "->"); + + if (taken == UNREACHABLE_EDGE) + fprintf (dump_file, "xx REJECTED (unreachable)\n"); + else if (taken) + fprintf (dump_file, "%d SUCCESS\n", taken->dest->index); + else + fprintf (dump_file, "xx REJECTED\n"); +} + +// If an outgoing edge can be determined out of the current path, +// register it for jump threading and return the taken edge. // // Return NULL if it is unprofitable to thread this path, or the // outgoing edge is unknown. Return UNREACHABLE_EDGE if the path is @@ -220,6 +250,10 @@ back_threader::maybe_register_path () taken_edge = NULL; } } + + if (dump_file && (dump_flags & TDF_DETAILS)) + maybe_register_path_dump (taken_edge); + return taken_edge; }