Unverified Commit c0436b50 authored Nov 21, 2018 by Paul Burton

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

parent 1feba8df

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 = .;
		}