Currently the second lower-subreg pass is run right before RA. This
is much too late to be very useful. At least for targets that do not
have RTL patterns for operations on multi-register modes it is a lot
better to split patterns earlier, before combine and all related
passes.
This adds an option -fsplit-wide-types-early that does that, and
enables it by default for rs6000.
2019-07-07 Segher Boessenkool <seg...@kernel.crashing.org>
PR rtl-optimization/88233
* common.opt (fsplit-wide-types-early): New option.
* common/config/rs6000/rs6000-common.c
(rs6000_option_optimization_table): Add OPT_fsplit_wide_types_early for
OPT_LEVELS_ALL.
* doc/invoke.texi (Optimization Options): Add -fsplit-wide-types-early.
* lower-subreg.c (pass_lower_subreg2::gate): Add test for
flag_split_wide_types_early.
(pass_data_lower_subreg3): New.
(pass_lower_subreg3): New.
(make_pass_lower_subreg3): New.
* passes.def (pass_lower_subreg2): Move after the loop passes.
(pass_lower_subreg3): New, inserted where pass_lower_subreg2 was.
* tree-pass.h (make_pass_lower_subreg2): Move up, to its new place in
the pass pipeline; its previous place is taken by ...
(make_pass_lower_subreg3): ... this.
---
gcc/common.opt | 4 +++
gcc/common/config/rs6000/rs6000-common.c | 2 ++
gcc/doc/invoke.texi | 8 +++++-
gcc/lower-subreg.c | 46 +++++++++++++++++++++++++++++++-
gcc/passes.def | 3 ++-
gcc/tree-pass.h | 3 ++-
6 files changed, 62 insertions(+), 4 deletions(-)
diff --git a/gcc/common.opt b/gcc/common.opt
index 41514df..b998b25 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -2430,6 +2430,10 @@ fsplit-wide-types
Common Report Var(flag_split_wide_types) Optimization
Split wide types into independent registers.
+fsplit-wide-types-early
+Common Report Var(flag_split_wide_types_early) Optimization
+Split wide types into independent registers earlier.
+
fssa-backprop
Common Report Var(flag_ssa_backprop) Init(1) Optimization
Enable backward propagation of use properties at the SSA level.
diff --git a/gcc/common/config/rs6000/rs6000-common.c
b/gcc/common/config/rs6000/rs6000-common.c
index 9857b54..4b0c205 100644
--- a/gcc/common/config/rs6000/rs6000-common.c
+++ b/gcc/common/config/rs6000/rs6000-common.c
@@ -31,6 +31,8 @@
/* Implement TARGET_OPTION_OPTIMIZATION_TABLE. */
static const struct default_options rs6000_option_optimization_table[] =
{
+ /* Split multi-word types early. */
+ { OPT_LEVELS_ALL, OPT_fsplit_wide_types_early, NULL, 1 },
/* Enable -fsched-pressure for first pass instruction scheduling. */
{ OPT_LEVELS_1_PLUS, OPT_fsched_pressure, NULL, 1 },
{ OPT_LEVELS_NONE, 0, NULL, 0 }
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 73d16b5..6349d4c 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -467,7 +467,7 @@ Objective-C and Objective-C++ Dialects}.
-fsignaling-nans @gol
-fsingle-precision-constant -fsplit-ivs-in-unroller -fsplit-loops@gol
-fsplit-paths @gol
--fsplit-wide-types -fssa-backprop -fssa-phiopt @gol
+-fsplit-wide-types -fsplit-wide-types-early -fssa-backprop -fssa-phiopt @gol
-fstdarg-opt -fstore-merging -fstrict-aliasing @gol
-fthread-jumps -ftracer -ftree-bit-ccp @gol
-ftree-builtin-call-dce -ftree-ccp -ftree-ch @gol
@@ -8731,6 +8731,12 @@ but may make debugging more difficult.
Enabled at levels @option{-O}, @option{-O2}, @option{-O3},
@option{-Os}.
+@item -fsplit-wide-types-early
+@opindex fsplit-wide-types-early
+Fully split wide types early, instead of very late.
+
+This is the default on some targets.
+
@item -fcse-follow-jumps
@opindex fcse-follow-jumps
In common subexpression elimination (CSE), scan through jump instructions
diff --git a/gcc/lower-subreg.c b/gcc/lower-subreg.c
index 4f68a73..e1418e5 100644
--- a/gcc/lower-subreg.c
+++ b/gcc/lower-subreg.c
@@ -1801,7 +1801,8 @@ public:
{}
/* opt_pass methods: */
- virtual bool gate (function *) { return flag_split_wide_types != 0; }
+ virtual bool gate (function *) { return flag_split_wide_types
+ && flag_split_wide_types_early; }
virtual unsigned int execute (function *)
{
decompose_multiword_subregs (true);
@@ -1817,3 +1818,46 @@ make_pass_lower_subreg2 (gcc::context *ctxt)
{
return new pass_lower_subreg2 (ctxt);
}
+
+/* Implement third lower subreg pass. */
+
+namespace {
+
+const pass_data pass_data_lower_subreg3 =
+{
+ RTL_PASS, /* type */
+ "subreg3", /* name */
+ OPTGROUP_NONE, /* optinfo_flags */
+ TV_LOWER_SUBREG, /* tv_id */
+ 0, /* properties_required */
+ 0, /* properties_provided */
+ 0, /* properties_destroyed */
+ 0, /* todo_flags_start */
+ TODO_df_finish, /* todo_flags_finish */
+};
+
+class pass_lower_subreg3 : public rtl_opt_pass
+{
+public:
+ pass_lower_subreg3 (gcc::context *ctxt)
+ : rtl_opt_pass (pass_data_lower_subreg3, ctxt)
+ {}
+
+ /* opt_pass methods: */
+ virtual bool gate (function *) { return flag_split_wide_types
+ && !flag_split_wide_types_early; }
+ virtual unsigned int execute (function *)
+ {
+ decompose_multiword_subregs (true);
+ return 0;
+ }
+
+}; // class pass_lower_subreg3
+
+} // anon namespace
+
+rtl_opt_pass *
+make_pass_lower_subreg3 (gcc::context *ctxt)
+{
+ return new pass_lower_subreg3 (ctxt);
+}
diff --git a/gcc/passes.def b/gcc/passes.def
index 9a5b0cd..1a7fd14 100644
--- a/gcc/passes.def
+++ b/gcc/passes.def
@@ -427,6 +427,7 @@ along with GCC; see the file COPYING3. If not see
NEXT_PASS (pass_rtl_doloop);
NEXT_PASS (pass_rtl_loop_done);
POP_INSERT_PASSES ()
+ NEXT_PASS (pass_lower_subreg2);
NEXT_PASS (pass_web);
NEXT_PASS (pass_rtl_cprop);
NEXT_PASS (pass_cse2);
@@ -440,7 +441,7 @@ along with GCC; see the file COPYING3. If not see
NEXT_PASS (pass_partition_blocks);
NEXT_PASS (pass_outof_cfg_layout_mode);
NEXT_PASS (pass_split_all_insns);
- NEXT_PASS (pass_lower_subreg2);
+ NEXT_PASS (pass_lower_subreg3);
NEXT_PASS (pass_df_initialize_no_opt);
NEXT_PASS (pass_stack_ptr_mod);
NEXT_PASS (pass_mode_switching);
diff --git a/gcc/tree-pass.h b/gcc/tree-pass.h
index b27dbdd..7b83293 100644
--- a/gcc/tree-pass.h
+++ b/gcc/tree-pass.h
@@ -552,6 +552,7 @@ extern rtl_opt_pass *make_pass_rtl_unroll_loops
(gcc::context *ctxt);
extern rtl_opt_pass *make_pass_rtl_doloop (gcc::context *ctxt);
extern rtl_opt_pass *make_pass_rtl_loop_done (gcc::context *ctxt);
+extern rtl_opt_pass *make_pass_lower_subreg2 (gcc::context *ctxt);
extern rtl_opt_pass *make_pass_web (gcc::context *ctxt);
extern rtl_opt_pass *make_pass_cse2 (gcc::context *ctxt);
extern rtl_opt_pass *make_pass_df_initialize_opt (gcc::context *ctxt);
@@ -567,7 +568,7 @@ extern rtl_opt_pass *make_pass_partition_blocks
(gcc::context *ctxt);
extern rtl_opt_pass *make_pass_match_asm_constraints (gcc::context *ctxt);
extern rtl_opt_pass *make_pass_split_all_insns (gcc::context *ctxt);
extern rtl_opt_pass *make_pass_fast_rtl_byte_dce (gcc::context *ctxt);
-extern rtl_opt_pass *make_pass_lower_subreg2 (gcc::context *ctxt);
+extern rtl_opt_pass *make_pass_lower_subreg3 (gcc::context *ctxt);
extern rtl_opt_pass *make_pass_mode_switching (gcc::context *ctxt);
extern rtl_opt_pass *make_pass_sms (gcc::context *ctxt);
extern rtl_opt_pass *make_pass_sched (gcc::context *ctxt);
--
1.8.3.1
