linux-kernel - [tip: objtool/core] objtool: Optimize layout of struct symbol

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Date:   Sat, 04 Feb 2023 10:17:11 -0000
From:   tip-bot2 for Thomas Weißschuh 
        <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     linux@...ssschuh.net, Josh Poimboeuf <jpoimboe@...nel.org>,
        x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [tip: objtool/core] objtool: Optimize layout of struct symbol

The following commit has been merged into the objtool/core branch of tip:

Commit-ID:     21a899f9fc78be6b289ee4627bccadf560930eb5
Gitweb:        https://git.kernel.org/tip/21a899f9fc78be6b289ee4627bccadf560930eb5
Author:        Thomas Weißschuh <linux@...ssschuh.net>
AuthorDate:    Tue, 27 Dec 2022 16:01:02 
Committer:     Josh Poimboeuf <jpoimboe@...nel.org>
CommitterDate: Wed, 01 Feb 2023 09:15:24 -08:00

objtool: Optimize layout of struct symbol

Reduce the size of struct symbol on x86_64 from 208 to 200 bytes.
This structure is allocated a lot and never freed.

This reduces maximum memory usage while processing vmlinux.o from
2919716 KB to 2917988 KB (-0.5%) on my notebooks "localmodconfig".

Signed-off-by: Thomas Weißschuh <linux@...ssschuh.net>
Link: https://lore.kernel.org/r/20221216-objtool-memory-v2-6-17968f85a464@weissschuh.net
Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
---
 tools/objtool/include/objtool/elf.h | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index 1c90f0a..ad0024d 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -50,12 +50,11 @@ struct symbol {
 	GElf_Sym sym;
 	struct section *sec;
 	char *name;
-	unsigned int idx;
-	unsigned char bind, type;
+	unsigned int idx, len;
 	unsigned long offset;
-	unsigned int len;
 	unsigned long __subtree_last;
 	struct symbol *pfunc, *cfunc, *alias;
+	unsigned char bind, type;
 	u8 uaccess_safe      : 1;
 	u8 static_call_tramp : 1;
 	u8 retpoline_thunk   : 1;