From c0436b503591f927f326457a588c461881260276 Mon Sep 17 00:00:00 2001 From: Paul Burton Date: Wed, 21 Nov 2018 21:56:36 +0000 Subject: [PATCH] MIPS: Enable dead code elimination Select CONFIG_HAVE_LD_DEAD_CODE_DATA_ELIMINATION for MIPS, allowing the user to enable dead code elimination. In order for this to work, ensure that we keep the data bus exception table & the machine list by annotating them with KEEP. This shrinks both 32r2el_defconfig & 64r6el_defconfig builds by ~6%, as shown by numbers from scripts/bloat-o-meter: | 32r2el_defconfig | 64r6el_defconfig --------|------------------|------------------ No DCE | 8919864 | 8286307 DCE | 8338988 (-6.51%) | 7741808 (-6.57%) Signed-off-by: Paul Burton Patchwork: https://patchwork.linux-mips.org/patch/21187/ Cc: linux-mips@linux-mips.org --- arch/mips/Kconfig | 1 + arch/mips/kernel/vmlinux.lds.S | 4 ++-- 2 files changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig index e83a8cce41e9..e49b5a0c8585 100644 --- a/arch/mips/Kconfig +++ b/arch/mips/Kconfig @@ -63,6 +63,7 @@ config MIPS select HAVE_IRQ_TIME_ACCOUNTING select HAVE_KPROBES select HAVE_KRETPROBES + select HAVE_LD_DEAD_CODE_DATA_ELIMINATION select HAVE_MEMBLOCK_NODE_MAP select HAVE_MOD_ARCH_SPECIFIC select HAVE_NMI diff --git a/arch/mips/kernel/vmlinux.lds.S b/arch/mips/kernel/vmlinux.lds.S index 971a504001c2..cb7e9ed7a453 100644 --- a/arch/mips/kernel/vmlinux.lds.S +++ b/arch/mips/kernel/vmlinux.lds.S @@ -72,7 +72,7 @@ SECTIONS /* Exception table for data bus errors */ __dbe_table : { __start___dbe_table = .; - *(__dbe_table) + KEEP(*(__dbe_table)) __stop___dbe_table = .; } @@ -123,7 +123,7 @@ SECTIONS . = ALIGN(4); .mips.machines.init : AT(ADDR(.mips.machines.init) - LOAD_OFFSET) { __mips_machines_start = .; - *(.mips.machines.init) + KEEP(*(.mips.machines.init)) __mips_machines_end = .; }