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Date: Wed, 08 Feb 2023 18:18:00 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: x86@...nel.org, jpoimboe@...hat.com, linux@...ssschuh.net
Cc: linux-kernel@...r.kernel.org, peterz@...radead.org
Subject: [PATCH 04/10] objtool: Shrink instruction::{type,visited}
Since we don't have that many types in enum insn_type, force it into a
u8 and re-arrange member to get rid of the holes, saves another 8
bytes.
struct instruction {
struct list_head list; /* 0 16 */
struct hlist_node hash; /* 16 16 */
struct list_head call_node; /* 32 16 */
struct section * sec; /* 48 8 */
long unsigned int offset; /* 56 8 */
/* --- cacheline 1 boundary (64 bytes) --- */
- unsigned int len; /* 64 4 */
- enum insn_type type; /* 68 4 */
- long unsigned int immediate; /* 72 8 */
- u16 dead_end:1; /* 80: 0 2 */
- u16 ignore:1; /* 80: 1 2 */
- u16 ignore_alts:1; /* 80: 2 2 */
- u16 hint:1; /* 80: 3 2 */
- u16 save:1; /* 80: 4 2 */
- u16 restore:1; /* 80: 5 2 */
- u16 retpoline_safe:1; /* 80: 6 2 */
- u16 noendbr:1; /* 80: 7 2 */
- u16 entry:1; /* 80: 8 2 */
+ long unsigned int immediate; /* 64 8 */
+ unsigned int len; /* 72 4 */
+ u8 type; /* 76 1 */
- /* XXX 7 bits hole, try to pack */
+ /* Bitfield combined with previous fields */
- s8 instr; /* 82 1 */
- u8 visited; /* 83 1 */
+ u16 dead_end:1; /* 76: 8 2 */
+ u16 ignore:1; /* 76: 9 2 */
+ u16 ignore_alts:1; /* 76:10 2 */
+ u16 hint:1; /* 76:11 2 */
+ u16 save:1; /* 76:12 2 */
+ u16 restore:1; /* 76:13 2 */
+ u16 retpoline_safe:1; /* 76:14 2 */
+ u16 noendbr:1; /* 76:15 2 */
+ u16 entry:1; /* 78: 0 2 */
+ u16 visited:4; /* 78: 1 2 */
- /* XXX 4 bytes hole, try to pack */
+ /* XXX 3 bits hole, try to pack */
+ /* Bitfield combined with next fields */
- struct alt_group * alt_group; /* 88 8 */
- struct symbol * call_dest; /* 96 8 */
- struct instruction * jump_dest; /* 104 8 */
- struct instruction * first_jump_src; /* 112 8 */
- struct reloc * jump_table; /* 120 8 */
+ s8 instr; /* 79 1 */
+ struct alt_group * alt_group; /* 80 8 */
+ struct symbol * call_dest; /* 88 8 */
+ struct instruction * jump_dest; /* 96 8 */
+ struct instruction * first_jump_src; /* 104 8 */
+ struct reloc * jump_table; /* 112 8 */
+ struct reloc * reloc; /* 120 8 */
/* --- cacheline 2 boundary (128 bytes) --- */
- struct reloc * reloc; /* 128 8 */
- struct alternative * alts; /* 136 8 */
- struct symbol * sym; /* 144 8 */
- struct stack_op * stack_ops; /* 152 8 */
- struct cfi_state * cfi; /* 160 8 */
+ struct alternative * alts; /* 128 8 */
+ struct symbol * sym; /* 136 8 */
+ struct stack_op * stack_ops; /* 144 8 */
+ struct cfi_state * cfi; /* 152 8 */
- /* size: 168, cachelines: 3, members: 29 */
- /* sum members: 162, holes: 1, sum holes: 4 */
- /* sum bitfield members: 9 bits, bit holes: 1, sum bit holes: 7 bits */
- /* last cacheline: 40 bytes */
+ /* size: 160, cachelines: 3, members: 29 */
+ /* sum members: 158 */
+ /* sum bitfield members: 13 bits, bit holes: 1, sum bit holes: 3 bits */
+ /* last cacheline: 32 bytes */
};
pre: 5:48.86 real, 220.30 user, 128.34 sys, 24834672 mem
post: 5:48.89 real, 220.96 user, 127.55 sys, 24834672 mem
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
tools/objtool/include/objtool/check.h | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
--- a/tools/objtool/include/objtool/check.h
+++ b/tools/objtool/include/objtool/check.h
@@ -42,9 +42,9 @@ struct instruction {
struct list_head call_node;
struct section *sec;
unsigned long offset;
- unsigned int len;
- enum insn_type type;
unsigned long immediate;
+ unsigned int len;
+ u8 type;
u16 dead_end : 1,
ignore : 1,
@@ -54,11 +54,11 @@ struct instruction {
restore : 1,
retpoline_safe : 1,
noendbr : 1,
- entry : 1;
- /* 7 bit hole */
+ entry : 1,
+ visited : 4;
+ /* 3 bit hole */
s8 instr;
- u8 visited;
struct alt_group *alt_group;
struct symbol *call_dest;
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