AcoSail/kernel_optimize_test
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MIPS: Enable dead code elimination

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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
This commit is contained in:
Paul Burton 2018-11-21 21:56:36 +00:00
parent 1feba8df94
commit c0436b5035
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GPG Key ID: 3EA79FACB57500DD
2 changed files with 3 additions and 2 deletions
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1
arch/mips/Kconfig
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@ -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

4
arch/mips/kernel/vmlinux.lds.S
View File

@ -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 = .;
}