MIPS: Enable dead code elimination (c0436b50) · Commits · 戴 / test

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 <paul.burton@mips.com> Patchwork: https://patchwork.linux-mips.org/patch/21187/ Cc: linux-mips@linux-mips.org

arch/mips/Kconfig

+1 −0

Original line number	Diff line number	Diff line
		@@ -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

arch/mips/kernel/vmlinux.lds.S

+2 −2

Original line number	Diff line number	Diff line
		@@ -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 = .;
		}

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