[PATCH] RISC-V: Enable pressure-aware scheduling by default.

[PATCH] RISC-V: Enable pressure-aware scheduling by default.

[Robin Dapp]

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.

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.

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?

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.
---
 gcc/common/config/riscv/riscv-common.cc                      | 2 ++
 gcc/config/riscv/riscv.cc                                    | 5 +++++
 .../gcc.target/riscv/rvv/base/narrow_constraint-1.c          | 2 +-
 .../gcc.target/riscv/rvv/base/narrow_constraint-17.c         | 2 +-
 .../gcc.target/riscv/rvv/base/narrow_constraint-18.c         | 2 +-
 .../gcc.target/riscv/rvv/base/narrow_constraint-19.c         | 2 +-
 .../gcc.target/riscv/rvv/base/narrow_constraint-20.c         | 2 +-
 .../gcc.target/riscv/rvv/base/narrow_constraint-21.c         | 2 +-
 .../gcc.target/riscv/rvv/base/narrow_constraint-22.c         | 2 +-
 .../gcc.target/riscv/rvv/base/narrow_constraint-23.c         | 2 +-
 .../gcc.target/riscv/rvv/base/narrow_constraint-24.c         | 2 +-
 .../gcc.target/riscv/rvv/base/narrow_constraint-25.c         | 2 +-
 .../gcc.target/riscv/rvv/base/narrow_constraint-26.c         | 2 +-
 .../gcc.target/riscv/rvv/base/narrow_constraint-27.c         | 2 +-
 .../gcc.target/riscv/rvv/base/narrow_constraint-28.c         | 2 +-
 .../gcc.target/riscv/rvv/base/narrow_constraint-29.c         | 2 +-
 .../gcc.target/riscv/rvv/base/narrow_constraint-30.c         | 2 +-
 .../gcc.target/riscv/rvv/base/narrow_constraint-31.c         | 2 +-
 .../gcc.target/riscv/rvv/base/narrow_constraint-4.c          | 2 +-
 .../gcc.target/riscv/rvv/base/narrow_constraint-5.c          | 2 +-
 .../gcc.target/riscv/rvv/base/narrow_constraint-8.c          | 2 +-
 .../gcc.target/riscv/rvv/base/narrow_constraint-9.c          | 2 +-
 gcc/testsuite/gcc.target/riscv/rvv/vsetvl/vlmax_bb_prop-10.c | 2 +-
 gcc/testsuite/gcc.target/riscv/rvv/vsetvl/vlmax_bb_prop-11.c | 2 +-
 gcc/testsuite/gcc.target/riscv/rvv/vsetvl/vlmax_bb_prop-12.c | 2 +-
 gcc/testsuite/gcc.target/riscv/rvv/vsetvl/vlmax_bb_prop-3.c  | 2 +-
 gcc/testsuite/gcc.target/riscv/rvv/vsetvl/vlmax_bb_prop-9.c  | 2 +-
 27 files changed, 32 insertions(+), 25 deletions(-)

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 }
   };
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);
+
   /* Convert -march to a chunks count.  */
   riscv_vector_chunks = riscv_convert_vector_bits ();
 }
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-1.c b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-1.c
index 0cdf60cde06..02d155dc5bf 100644
--- a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-1.c
+++ b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-1.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-march=rv32gcv -mabi=ilp32d -O3" } */
+/* { dg-options "-march=rv32gcv -mabi=ilp32d -O3 -fno-sched-pressure" } */
 
 #include "riscv_vector.h"
 
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-17.c b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-17.c
index 97df21dd743..35ef18817fa 100644
--- a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-17.c
+++ b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-17.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-march=rv32gcv -mabi=ilp32d -O3" } */
+/* { dg-options "-march=rv32gcv -mabi=ilp32d -O3 -fno-sched-pressure" } */
 
 #include "riscv_vector.h"
 
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-18.c b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-18.c
index 56c95d9c884..1c17b763fab 100644
--- a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-18.c
+++ b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-18.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-march=rv32gcv -mabi=ilp32d -O3" } */
+/* { dg-options "-march=rv32gcv -mabi=ilp32d -O3 -fno-sched-pressure" } */
 
 #include "riscv_vector.h"
 
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-19.c b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-19.c
index d50e497d6c9..923bc27b36b 100644
--- a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-19.c
+++ b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-19.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-march=rv32gcv -mabi=ilp32d -O3" } */
+/* { dg-options "-march=rv32gcv -mabi=ilp32d -O3 -fno-sched-pressure" } */
 
 #include "riscv_vector.h"
 
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-20.c b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-20.c
index 4e77c51d058..6dd1b84678b 100644
--- a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-20.c
+++ b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-20.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-march=rv32gcv -mabi=ilp32d -O3" } */
+/* { dg-options "-march=rv32gcv -mabi=ilp32d -O3 -fno-sched-pressure" } */
 
 #include "riscv_vector.h"
 
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-21.c b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-21.c
index 4f7efd508b1..ecf6d267fdb 100644
--- a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-21.c
+++ b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-21.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-march=rv32gcv -mabi=ilp32d -O3" } */
+/* { dg-options "-march=rv32gcv -mabi=ilp32d -O3 -fno-sched-pressure" } */
 
 #include "riscv_vector.h"
 
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-22.c b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-22.c
index 92084be99b2..20186079593 100644
--- a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-22.c
+++ b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-22.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-march=rv32gcv -mabi=ilp32d -O3" } */
+/* { dg-options "-march=rv32gcv -mabi=ilp32d -O3 -fno-sched-pressure" } */
 
 #include "riscv_vector.h"
 
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-23.c b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-23.c
index f9817caca1e..847d27cc760 100644
--- a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-23.c
+++ b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-23.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-march=rv64gcv -mabi=lp64d -O3" } */
+/* { dg-options "-march=rv64gcv -mabi=lp64d -O3 -fno-sched-pressure" } */
 
 #include "riscv_vector.h"
 
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-24.c b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-24.c
index 62d1f6dddd5..603bfa20f82 100644
--- a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-24.c
+++ b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-24.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-march=rv64gcv -mabi=lp64d -O3" } */
+/* { dg-options "-march=rv64gcv -mabi=lp64d -O3 -fno-sched-pressure" } */
 
 #include "riscv_vector.h"
 
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-25.c b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-25.c
index 250c3fdb89a..4f295ecaaaf 100644
--- a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-25.c
+++ b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-25.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-march=rv64gcv -mabi=lp64d -O3" } */
+/* { dg-options "-march=rv64gcv -mabi=lp64d -O3 -fno-sched-pressure" } */
 
 #include "riscv_vector.h"
 
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-26.c b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-26.c
index 72e2d210c05..1a652399f87 100644
--- a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-26.c
+++ b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-26.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-march=rv64gcv -mabi=lp64d -O3" } */
+/* { dg-options "-march=rv64gcv -mabi=lp64d -O3 -fno-sched-pressure" } */
 
 #include "riscv_vector.h"
 
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-27.c b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-27.c
index 0842700475c..4d70a4c39fd 100644
--- a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-27.c
+++ b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-27.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-march=rv32gcv -mabi=ilp32d -O3" } */
+/* { dg-options "-march=rv32gcv -mabi=ilp32d -O3 -fno-sched-pressure" } */
 
 #include "riscv_vector.h"
 
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-28.c b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-28.c
index 9c1eddfac7e..c625d96a94c 100644
--- a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-28.c
+++ b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-28.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-march=rv32gcv -mabi=ilp32d -O3" } */
+/* { dg-options "-march=rv32gcv -mabi=ilp32d -O3 -fno-sched-pressure" } */
 
 #include "riscv_vector.h"
 
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-29.c b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-29.c
index 6988c24bd92..109ebc84112 100644
--- a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-29.c
+++ b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-29.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-march=rv32gcv -mabi=ilp32d -O3" } */
+/* { dg-options "-march=rv32gcv -mabi=ilp32d -O3 -fno-sched-pressure" } */
 
 #include "riscv_vector.h"
 
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-30.c b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-30.c
index fe181de4d56..b993e480765 100644
--- a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-30.c
+++ b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-30.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-march=rv32gcv -mabi=ilp32d -O3" } */
+/* { dg-options "-march=rv32gcv -mabi=ilp32d -O3 -fno-sched-pressure" } */
 
 #include "riscv_vector.h"
 
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-31.c b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-31.c
index ae5b4ed6913..d0bf4a80c9e 100644
--- a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-31.c
+++ b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-31.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-march=rv32gcv -mabi=ilp32d -O3" } */
+/* { dg-options "-march=rv32gcv -mabi=ilp32d -O3 -fno-sched-pressure" } */
 
 #include "riscv_vector.h"
 
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-4.c b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-4.c
index 28971a0aad8..273f15a21ab 100644
--- a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-4.c
+++ b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-4.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-march=rv32gcv -mabi=ilp32d -O3" } */
+/* { dg-options "-march=rv32gcv -mabi=ilp32d -O3 -fno-sched-pressure" } */
 
 #include "riscv_vector.h"
 
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-5.c b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-5.c
index 26675bcc87c..d75dc778638 100644
--- a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-5.c
+++ b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-5.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-march=rv32gcv -mabi=ilp32d -O3" } */
+/* { dg-options "-march=rv32gcv -mabi=ilp32d -O3 -fno-sched-pressure" } */
 
 #include "riscv_vector.h"
 
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-8.c b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-8.c
index 0dac85a3203..c96ab598883 100644
--- a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-8.c
+++ b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-8.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-march=rv32gcv -mabi=ilp32d -O3" } */
+/* { dg-options "-march=rv32gcv -mabi=ilp32d -O3 -fno-sched-pressure" } */
 
 #include "riscv_vector.h"
 
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-9.c b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-9.c
index 448ca859dbb..53130d32606 100644
--- a/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-9.c
+++ b/gcc/testsuite/gcc.target/riscv/rvv/base/narrow_constraint-9.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-march=rv32gcv -mabi=ilp32d -O3" } */
+/* { dg-options "-march=rv32gcv -mabi=ilp32d -O3 -fno-sched-pressure" } */
 
 #include "riscv_vector.h"
 
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/vlmax_bb_prop-10.c b/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/vlmax_bb_prop-10.c
index cf6470cea0d..fba44d999b6 100644
--- a/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/vlmax_bb_prop-10.c
+++ b/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/vlmax_bb_prop-10.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-march=rv32gcv -mabi=ilp32 -fno-tree-vectorize" } */
+/* { dg-options "-march=rv32gcv -mabi=ilp32 -fno-sched-pressure -fno-tree-vectorize" } */
 
 #include "riscv_vector.h"
 
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/vlmax_bb_prop-11.c b/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/vlmax_bb_prop-11.c
index 4e2a717197b..5aabdef4aca 100644
--- a/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/vlmax_bb_prop-11.c
+++ b/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/vlmax_bb_prop-11.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-march=rv32gcv -mabi=ilp32 -fno-tree-vectorize" } */
+/* { dg-options "-march=rv32gcv -mabi=ilp32 -fno-sched-pressure -fno-tree-vectorize" } */
 
 #include "riscv_vector.h"
 
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/vlmax_bb_prop-12.c b/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/vlmax_bb_prop-12.c
index 026b40944c5..6db0f0b1c51 100644
--- a/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/vlmax_bb_prop-12.c
+++ b/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/vlmax_bb_prop-12.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-march=rv32gcv -mabi=ilp32 -fno-tree-vectorize" } */
+/* { dg-options "-march=rv32gcv -mabi=ilp32 -fno-sched-pressure -fno-tree-vectorize" } */
 
 #include "riscv_vector.h"
 
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/vlmax_bb_prop-3.c b/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/vlmax_bb_prop-3.c
index ca57ecad7cf..5e5e07b37c2 100644
--- a/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/vlmax_bb_prop-3.c
+++ b/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/vlmax_bb_prop-3.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-march=rv32gcv -mabi=ilp32 -fno-tree-vectorize" } */
+/* { dg-options "-march=rv32gcv -mabi=ilp32 -fno-sched-pressure -fno-tree-vectorize" } */
 
 #include "riscv_vector.h"
 
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/vlmax_bb_prop-9.c b/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/vlmax_bb_prop-9.c
index a01b3918404..119e41e23b8 100644
--- a/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/vlmax_bb_prop-9.c
+++ b/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/vlmax_bb_prop-9.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-march=rv32gcv -mabi=ilp32 -fno-tree-vectorize" } */
+/* { dg-options "-march=rv32gcv -mabi=ilp32 -fno-sched-pressure -fno-tree-vectorize" } */
 
 #include "riscv_vector.h"
 
-- 
2.41.0

Re: [PATCH] RISC-V: Enable pressure-aware scheduling by default.

[Jeff Law]

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

Re: [PATCH] RISC-V: Enable pressure-aware scheduling by default.

[Vineet Gupta]

On 8/18/23 16:08, Jeff Law wrote:
>> 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.

Care to elaborate a bit more please. I've seen severe reg pressure / 
spills in a bunch of others: cactu, lbm, exchange2. Is there something 
specific to x264 spills ?

>
>>
>> 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 },

Nit2: maybe move this 1 line up to keep LEVEL_1 together, at least the 
new ones being added.

>>   #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?

Yep I had the exact same first though but then thought it was something 
deeper.
Turned out to be Occam's Razor after all :-)

Thx,
-Vineet

Re: [PATCH] RISC-V: Enable pressure-aware scheduling by default.

[Jeff Law]

On 8/18/23 17:24, Vineet Gupta wrote:
> 
> 
> On 8/18/23 16:08, Jeff Law wrote:
>>> 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.
> 
> Care to elaborate a bit more please. I've seen severe reg pressure / 
> spills in a bunch of others: cactu, lbm, exchange2. Is there something 
> specific to x264 spills ?
The only thing that's particularly interesting about the x264 spills is 
they're caused by scheduling.

In simplest terms GCC's scheduler tries to minimize the latency of the 
critical path in a block.  For x264 we've got a loop that we unrolled 8 
times with 8 byte sized loads per loop iteration.  So 64 byte loads, all 
higher from a critical path latency standpoint than anything else.

Naturally there's no way we can hold 64 values live as we only have 32 
registers and thus we blow out the register file.

By turning on pressure sensitive scheduling, as register pressure 
approaches the threshold, the scheduler will select a lower priority 
instruction (say computing the difference of two previously loaded 
values) that reduces register pressure.  So it's not critical path 
optimal, but it keep us from blowing out the register file and 
ultimately we get better performance as a result.

jeff