On January 30, 2021 10:46:17 AM GMT+01:00, Jakub Jelinek <ja...@redhat.com>
wrote:
>On Sat, Jan 30, 2021 at 09:17:45AM +0100, Richard Biener wrote:
>> >The following patch fixes it, ok for trunk if it passes
>> >bootstrap/regtest?
>>
>> Hmm, that's odd. Who relies on deferred rescan being the default?
>Finish
>> pass, via processing deferred insns also resets it back. Or is this
>> documented somewhere?
>
>Ifcvt clearly relies on non-deferred rescanning.
>And yes, df_finish_pass clears df->changeable_flags, but we don't do
>that
>for this pass anymore (removal of TODO_df_finish), as that pass didn't
>call
>df_analyze either.
>df_process_deferred_rescans temporarily clears DF_DEFER_INSN_RESCAN
>flag, but restores it to the previous state at the end.
>
>So, I think we either need what I posted (which passed
>bootstrap/regtest
>on x86_64-linux and i686-linux), or we need to restore TODO_df_finish
>for the pass.
>Given that the pass previously did call df_analyze () only
>conditionally,
>not at all in many functions, and had TODO_df_finish unconditionally,
>perhaps that needs to work even if it wasn't meant to be used that way.
OK, so I'd prefer we simply unset the flag after processing deferred rescan. I
clearly misread the function to do that.
Richard.
>> >2021-01-29 Jakub Jelinek <ja...@redhat.com>
>> >
>> > * config/i386/i386-features.c (remove_partial_avx_dependency):
>> >Remember
>> > whether DF_DEFER_INSN_RESCAN has been active before or not, and
>> > reset it to previous state.
>> >
>> > * gcc.target/i386/20051216-1.c: New test.
>> >
>> >--- gcc/config/i386/i386-features.c.jj 2021-01-29 20:39:10.561912947
>> >+0100
>> >+++ gcc/config/i386/i386-features.c 2021-01-29 20:59:06.254740315
>+0100
>> >@@ -2273,7 +2273,7 @@ remove_partial_avx_dependency (void)
>> > auto_vec<rtx_insn *> control_flow_insns;
>> >
>> > /* We create invalid RTL initially so defer rescans. */
>> >- df_set_flags (DF_DEFER_INSN_RESCAN);
>> >+ int prev_df_flags = df_set_flags (DF_DEFER_INSN_RESCAN);
>> >
>> > FOR_EACH_BB_FN (bb, cfun)
>> > {
>> >@@ -2409,6 +2409,8 @@ remove_partial_avx_dependency (void)
>> > }
>> >
>> > df_process_deferred_rescans ();
>> >+ if ((prev_df_flags & DF_DEFER_INSN_RESCAN) == 0)
>> >+ df_clear_flags (DF_DEFER_INSN_RESCAN);
>> > bitmap_obstack_release (NULL);
>> > BITMAP_FREE (convert_bbs);
>> >
>> >--- gcc/testsuite/gcc.target/i386/20051216-1.c.jj 2021-01-29
>> >21:06:20.386960652 +0100
>> >+++ gcc/testsuite/gcc.target/i386/20051216-1.c 2021-01-29
>> >21:03:17.599973093 +0100
>> >@@ -0,0 +1,5 @@
>> >+/* PR rtl-optimization/25432 */
>> >+/* { dg-do compile } */
>> >+/* { dg-options "-O1 -march=cascadelake" } */
>> >+
>> >+#include "../../gcc.c-torture/compile/20051216-1.c"
>> >
>> >
>> > Jakub
>
> Jakub
