Hi all! Does anybody considered backporting this? Given https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92410#c3 "Confirmed also with r247015 (GCC 7 branch point)."
For example, we may apply it without an assertion in release branches. Roman 12.11.2019 12:11, Matthew Malcomson wrote: > In scheduling passes, notes are removed with `remove_notes` before the > scheduling is done, and added back in with `reemit_notes` once the > scheduling has been decided. > > This process leaves the notes in the RTL chain with different insn uid's > than were there before. Having different UID's (larger than the > previous ones) means that DF_INSN_INFO_GET(insn) will access outside of > the allocated array. > > This has been seen in the `regstat_bb_compute_calls_crossed` function. > This patch adds an assert to the `regstat_bb_compute_calls_crossed` > function so that bad accesses here are caught instead of going > unnoticed, and then avoids the problem. > > We avoid the problem by ensuring that new notes added by `reemit_notes` have > an > insn record given to them. This is done by adding a call to > `df_insn_create_insn_record` on each note added in `reemit_notes`. > `df_insn_create_insn_record` leaves this new record zeroed out, which appears > to be fine for notes (e.g. `df_bb_refs_record` already does not set > anything except the luid for notes, and notes have no dataflow information to > record). > > We add the testcase that Martin found here > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92410#c2 . > This testcase fails with the "regstat.c" change, and then succeeds with the > "haifa-sched.c" change. > > There is a similar problem with labels, that the `gcc_assert` catches > when running regression tests in gcc.dg/fold-eqandshift-1.c and > gcc.c-torture/compile/pr32482.c. > This is due to the `cfg_layout_finalize` call in `bb-reorder.c` emitting > new labels for the start of the newly created basic blocks. These labels are > not given a dataflow df_insn_info member. > > We solve this by manually calling `df_recompute_luids` on each basic > block once this pass has finished. > > Testing done: > Bootstrapped and regression test on aarch64-none-linux-gnu native. > > gcc/ChangeLog: > > 2019-11-12 Matthew Malcomson <matthew.malcom...@arm.com> > > PR middle-end/92410 > * bb-reorder.c (pass_reorder_blocks::execute): Recompute > dataflow luids once basic blocks have been reordered. > * haifa-sched.c (reemit_notes): Create df insn record for each > new note. > * regstat.c (regstat_bb_compute_calls_crossed): Assert every > insn has an insn record before trying to use it. > > gcc/testsuite/ChangeLog: > > 2019-11-12 Matthew Malcomson <matthew.malcom...@arm.com> > > PR middle-end/92410 > * gcc.dg/torture/pr92410.c: New test. > > > > ############### Attachment also inlined for ease of reply > ############### > > > diff --git a/gcc/bb-reorder.c b/gcc/bb-reorder.c > index > 0ac39140c6ce3db8499f99cd8f483218888de61b..4943f97a2cfccc7ab7c4834fff2c81f62fc5b738 > 100644 > --- a/gcc/bb-reorder.c > +++ b/gcc/bb-reorder.c > @@ -2662,6 +2662,8 @@ pass_reorder_blocks::execute (function *fun) > bb->aux = bb->next_bb; > cfg_layout_finalize (); > > + FOR_EACH_BB_FN (bb, fun) > + df_recompute_luids (bb); > return 0; > } > > diff --git a/gcc/haifa-sched.c b/gcc/haifa-sched.c > index > 41cf1f362e8c34d009b0a310ff5b9a9ffb613631..2e1a84f1325d54ece1cf3c6f0bab607099c71d27 > 100644 > --- a/gcc/haifa-sched.c > +++ b/gcc/haifa-sched.c > @@ -5433,6 +5433,7 @@ reemit_notes (rtx_insn *insn) > > last = emit_note_before (note_type, last); > remove_note (insn, note); > + df_insn_create_insn_record (last); > } > } > } > diff --git a/gcc/regstat.c b/gcc/regstat.c > index > 4da9b7cc523cde113df931226ea56310b659e619..c6cefb117d7330cc1b9787c37083e05e2acda2d2 > 100644 > --- a/gcc/regstat.c > +++ b/gcc/regstat.c > @@ -324,6 +324,7 @@ regstat_bb_compute_calls_crossed (unsigned int bb_index, > bitmap live) > > FOR_BB_INSNS_REVERSE (bb, insn) > { > + gcc_assert (INSN_UID (insn) < DF_INSN_SIZE ()); > struct df_insn_info *insn_info = DF_INSN_INFO_GET (insn); > unsigned int regno; > > diff --git a/gcc/testsuite/gcc.dg/torture/pr92410.c > b/gcc/testsuite/gcc.dg/torture/pr92410.c > new file mode 100644 > index > 0000000000000000000000000000000000000000..628e329782260ef36f26506bfbc0d36a93b33f41 > --- /dev/null > +++ b/gcc/testsuite/gcc.dg/torture/pr92410.c > @@ -0,0 +1,8 @@ > +/* PR middle-end/92410 */ > +/* { dg-do compile } */ > +int v; > + > +int a() { > + ; > + return v; > +} >
