gcc-inline-regressions-2.patch

From 9638ad02a052fa44eb32e7b2d624caa520c4f0a2 Mon Sep 17 00:00:00 2001
From: Vaisakh Murali <[email protected]>
Date: Sat, 20 Jun 2020 12:55:37 +0600
Subject: [PATCH] Makefile: Restore GCC 9.3 inline param logic

* This is a follow up commit to 6cbcf0181d09
* Based on the advice by arter97 to restore the inline params
* This overcomes the regressions introduced in GCC 10

Signed-off-by: Vaisakh Murali <[email protected]>
---
 Makefile | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index d0ce3b8117c2..7580ba5d1690 100644
--- a/Makefile
+++ b/Makefile
@@ -638,7 +638,11 @@ endif
 ifdef CONFIG_LTO
 LTO_CFLAGS    := -flto -flto=jobserver -fno-fat-lto-objects \
                  -fuse-linker-plugin -fwhole-program
-KBUILD_CFLAGS += $(LTO_CFLAGS) --param=max-inline-insns-auto=1000
+KBUILD_CFLAGS += $(LTO_CFLAGS) --param=max-inline-insns-auto=1000 \
+		 --param=inline-min-speedup=15 \
+		 --param=max-inline-insns-single=200 \
+		 --param=early-inlining-insns=14
 LTO_LDFLAGS   := $(LTO_CFLAGS) -Wno-lto-type-mismatch -Wno-psabi \
                  -Wno-stringop-overflow -flinker-output=nolto-rel
 LDFINAL       := $(CONFIG_SHELL) $(srctree)/scripts/gcc-ld $(LTO_LDFLAGS)

gcc-inline-regressions.patch

From 4216f1147e141312ea124d7619f56154b76e963f Mon Sep 17 00:00:00 2001
From: Sultan Alsawaf <[email protected]>
Date: Tue, 12 May 2020 12:00:08 -0700
Subject: [PATCH] kbuild: Increase GCC automatic inline instruction limit to
 1000 for LTO

GCC 10 updated its interprocedural optimizer's logic to have it make
more conservative inlining decisions, resulting in worse syscall and
hackbench performance compared to GCC 9. Although the max-inline-insns-
auto parameter's value was not altered, increasing it from the -O3
default of 30 to 1000 instructions yields improved performance with LTO,
surpassing GCC 9.

Do this only for LTO though because for non-LTO builds, this causes GCC
to produce mountains of spurious -Wmaybe-used-uninitialized warnings.

Signed-off-by: Sultan Alsawaf <[email protected]>
---
 Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 13b0a417889c..84d6e990417c 100644
--- a/Makefile
+++ b/Makefile
@@ -628,7 +628,7 @@ endif
 ifdef CONFIG_LTO_GCC
 LTO_CFLAGS	:= -flto -flto=jobserver -fno-fat-lto-objects \
 		   -fuse-linker-plugin -fwhole-program
-KBUILD_CFLAGS	+= $(LTO_CFLAGS)
+KBUILD_CFLAGS	+= $(LTO_CFLAGS) --param=max-inline-insns-auto=1000
 LTO_LDFLAGS	:= $(LTO_CFLAGS) -Wno-lto-type-mismatch -Wno-psabi \
 		   -Wno-stringop-overflow -flinker-output=nolto-rel
 LDFINAL		:= $(CONFIG_SHELL) $(srctree)/scripts/gcc-ld $(LTO_LDFLAGS)

Will eva boot with these?

It should, even though this didn't give any advantage.