[PATCH v3 21/26] objtool: Use sec_offset_hash() for insn_hash

From: Peter Zijlstra
Date: Tue Mar 24 2020 - 12:12:17 EST


In preparation for find_insn_containing(), change insn_hash to use
sec_offset_hash().

This actually reduces runtime; probably because mixing in the section
index reduces the collisions due to text sections all starting their
instructions at offset 0.

Runtime on vmlinux.o from 3.1 to 2.5 seconds.

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Acked-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
---
tools/objtool/check.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -34,9 +34,10 @@ struct instruction *find_insn(struct obj
{
struct instruction *insn;

- hash_for_each_possible(file->insn_hash, insn, hash, offset)
+ hash_for_each_possible(file->insn_hash, insn, hash, sec_offset_hash(sec, offset)) {
if (insn->sec == sec && insn->offset == offset)
return insn;
+ }

return NULL;
}
@@ -276,7 +277,7 @@ static int decode_instructions(struct ob
if (ret)
goto err;

- hash_add(file->insn_hash, &insn->hash, insn->offset);
+ hash_add(file->insn_hash, &insn->hash, sec_offset_hash(sec, insn->offset));
list_add_tail(&insn->list, &file->insn_list);
nr_insns++;
}