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.
> >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
