On 8/18/23 07:57, Robin Dapp wrote:
Hi,
this patch enables pressure-aware scheduling for riscv. There have been
various requests for it so I figured I'd just go ahead and send
the patch.
Thanks. Your timing is good, I was pondering nominating a victim to
pick this up next week ;-)
There is some slight regression in code quality for a number of
vector tests where we spill more due to different instructions order.
The ones I looked at were a mix of bad luck and/or brittle tests.
Comparing the size of the generated assembly or the number of vsetvls
for SPECint also didn't show any immediate benefit but that's obviously
not a very fine-grained analysis.
Yea. In fact I wouldn't really expect significant changes other than
those key loops in x264.
As cost and scheduling models mature I expect the situation to improve
and for now I think it's generally favorable to enable pressure-aware
scheduling so we can work with it rather than trying to find every
possible problem in advance. Any other opinions on that?
Agreed. I wouldn't be surprised if largely turns into a set-and-forget.
Regards
Robin
This patch enables register -fsched-pressure by default and sets
the algorithm to "model". As with other backends, this helps
reduce unnecessary spills.
gcc/ChangeLog:
* common/config/riscv/riscv-common.cc: Add -fsched-pressure.
* config/riscv/riscv.cc (riscv_option_override): Set sched
pressure algorithm.
gcc/testsuite/ChangeLog:
* gcc.target/riscv/rvv/base/narrow_constraint-1.c: Add
-fno-sched-pressure.
* gcc.target/riscv/rvv/base/narrow_constraint-17.c: Ditto.
* gcc.target/riscv/rvv/base/narrow_constraint-18.c: Ditto.
* gcc.target/riscv/rvv/base/narrow_constraint-19.c: Ditto.
* gcc.target/riscv/rvv/base/narrow_constraint-20.c: Ditto.
* gcc.target/riscv/rvv/base/narrow_constraint-21.c: Ditto.
* gcc.target/riscv/rvv/base/narrow_constraint-22.c: Ditto.
* gcc.target/riscv/rvv/base/narrow_constraint-23.c: Ditto.
* gcc.target/riscv/rvv/base/narrow_constraint-24.c: Ditto.
* gcc.target/riscv/rvv/base/narrow_constraint-25.c: Ditto.
* gcc.target/riscv/rvv/base/narrow_constraint-26.c: Ditto.
* gcc.target/riscv/rvv/base/narrow_constraint-27.c: Ditto.
* gcc.target/riscv/rvv/base/narrow_constraint-28.c: Ditto.
* gcc.target/riscv/rvv/base/narrow_constraint-29.c: Ditto.
* gcc.target/riscv/rvv/base/narrow_constraint-30.c: Ditto.
* gcc.target/riscv/rvv/base/narrow_constraint-31.c: Ditto.
* gcc.target/riscv/rvv/base/narrow_constraint-4.c: Ditto.
* gcc.target/riscv/rvv/base/narrow_constraint-5.c: Ditto.
* gcc.target/riscv/rvv/base/narrow_constraint-8.c: Ditto.
* gcc.target/riscv/rvv/base/narrow_constraint-9.c: Ditto.
* gcc.target/riscv/rvv/vsetvl/vlmax_bb_prop-10.c: Ditto.
* gcc.target/riscv/rvv/vsetvl/vlmax_bb_prop-11.c: Ditto.
* gcc.target/riscv/rvv/vsetvl/vlmax_bb_prop-12.c: Ditto.
* gcc.target/riscv/rvv/vsetvl/vlmax_bb_prop-3.c: Ditto.
* gcc.target/riscv/rvv/vsetvl/vlmax_bb_prop-9.c: Ditto.
OK. Just one nit below.
diff --git a/gcc/common/config/riscv/riscv-common.cc
b/gcc/common/config/riscv/riscv-common.cc
index 4737dcd44a1..59848b21162 100644
--- a/gcc/common/config/riscv/riscv-common.cc
+++ b/gcc/common/config/riscv/riscv-common.cc
@@ -2017,9 +2017,11 @@ static const struct default_options
riscv_option_optimization_table[] =
{
{ OPT_LEVELS_1_PLUS, OPT_fsection_anchors, NULL, 1 },
{ OPT_LEVELS_2_PLUS, OPT_free, NULL, 1 },
+ { OPT_LEVELS_1_PLUS, OPT_fsched_pressure, NULL, 1 },
#if TARGET_DEFAULT_ASYNC_UNWIND_TABLES == 1
{ OPT_LEVELS_ALL, OPT_fasynchronous_unwind_tables, NULL, 1 },
{ OPT_LEVELS_ALL, OPT_funwind_tables, NULL, 1},
+ /* Enable -fsched-pressure by default when optimizing. */
#endif
{ OPT_LEVELS_NONE, 0, NULL, 0 }
};
Shouldn't the comment move up to before the OPT_fsched_pressure line?
diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
index 49062bef9fc..96c5362d2fd 100644
--- a/gcc/config/riscv/riscv.cc
+++ b/gcc/config/riscv/riscv.cc
@@ -65,6 +65,7 @@ along with GCC; see the file COPYING3. If not see
#include "cfgloop.h"
#include "cfgrtl.h"
#include "sel-sched.h"
+#include "sched-int.h"
#include "fold-const.h"
#include "gimple-iterator.h"
#include "gimple-expr.h"
@@ -7095,6 +7096,10 @@ riscv_option_override (void)
sorry (
"Current RISC-V GCC cannot support VLEN greater than 4096bit for 'V'
Extension");
+ SET_OPTION_IF_UNSET (&global_options, &global_options_set,
+ param_sched_pressure_algorithm,
+ SCHED_PRESSURE_MODEL);
+
FWIW, I tried both variants of the pressure model. They seemed roughly
on-par with each other across specint.
Jeff
