On Fri, Aug 23, 2024 at 5:38 AM Richard Biener <rguent...@suse.de> wrote: > > Complex lowering generally replaces existing complex defs with > COMPLEX_EXPRs but those might be dead when it can always refer to > components from the lattice. This in turn can pessimize followup > transforms like forwprop and reassoc, the following makes sure to > get rid of dead COMPLEX_EXPRs generated by using > simple_dce_from_worklist.
Just an FYI, I had noticed this also when looking into PR 115544, 2 months ago and I was thinking about implementing then. It also fixes that issue without the change to the _BitInt lower. Thanks, Andrew Pinski > > Bootstrapped and tested on x86_64-unknown-linux-gnu, this will cause > the following fallout which is similar to the aarch64 fallout in > PR116463, complex SLP recognition being somewhat fragile. I'll track > this there. Pushed. > > FAIL: gcc.target/i386/avx512fp16-vector-complex-float.c scan-assembler-not > vfma > dd[123]*ph[ \\\\t] > FAIL: gcc.target/i386/avx512fp16-vector-complex-float.c > scan-assembler-times vf > maddcph[ \\\\t] 1 > FAIL: gcc.target/i386/part-vect-complexhf.c scan-assembler-times > vfmaddcph[ \\\\t] 1 > > > PR tree-optimization/116463 > * tree-complex.cc: Include tree-ssa-dce.h. > (dce_worklist): New global. > (update_complex_assignment): Add SSA def to the DCE worklist. > (tree_lower_complex): Perform DCE. > --- > gcc/tree-complex.cc | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/gcc/tree-complex.cc b/gcc/tree-complex.cc > index dfb45b9d91c..7480c07640e 100644 > --- a/gcc/tree-complex.cc > +++ b/gcc/tree-complex.cc > @@ -46,6 +46,7 @@ along with GCC; see the file COPYING3. If not see > #include "case-cfn-macros.h" > #include "builtins.h" > #include "optabs-tree.h" > +#include "tree-ssa-dce.h" > > /* For each complex ssa name, a lattice value. We're interested in finding > out whether a complex number is degenerate in some way, having only real > @@ -88,6 +89,9 @@ static vec<gphi *> phis_to_revisit; > /* BBs that need EH cleanup. */ > static bitmap need_eh_cleanup; > > +/* SSA defs we should try to DCE. */ > +static bitmap dce_worklist; > + > /* Lookup UID in the complex_variable_components hashtable and return the > associated tree. */ > static tree > @@ -731,6 +735,7 @@ update_complex_assignment (gimple_stmt_iterator *gsi, > tree r, tree i) > update_stmt (stmt); > if (maybe_clean_or_replace_eh_stmt (old_stmt, stmt)) > bitmap_set_bit (need_eh_cleanup, gimple_bb (stmt)->index); > + bitmap_set_bit (dce_worklist, SSA_NAME_VERSION (gimple_assign_lhs (stmt))); > > update_complex_components (gsi, gsi_stmt (*gsi), r, i); > } > @@ -1962,6 +1967,7 @@ tree_lower_complex (void) > complex_propagate.ssa_propagate (); > > need_eh_cleanup = BITMAP_ALLOC (NULL); > + dce_worklist = BITMAP_ALLOC (NULL); > > complex_variable_components = new int_tree_htab_type (10); > > @@ -2008,6 +2014,9 @@ tree_lower_complex (void) > > gsi_commit_edge_inserts (); > > + simple_dce_from_worklist (dce_worklist, need_eh_cleanup); > + BITMAP_FREE (dce_worklist); > + > unsigned todo > = gimple_purge_all_dead_eh_edges (need_eh_cleanup) ? TODO_cleanup_cfg : > 0; > BITMAP_FREE (need_eh_cleanup); > -- > 2.43.0
