https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99988
Bug ID: 99988
Summary: aarch64: GCC generates excessive consecutive bti j
instructions
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: acoplan at gcc dot gnu.org
Target Milestone: ---
Created attachment 50535
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=50535&action=edit
minimal reproducer
For the attached testcase (reduced from the linux kernel), GCC generates
multiple redundant sequences of back-to-back bti j instructions, the longest of
which is 262 instructions long.
To reproduce:
$ aarch64-linux-gnu-gcc -c test.c -S -o - -O2 -mbranch-protection=standard |
uniq -c | grep "bti j" | sort -nr
262 hint 36 // bti j
7 hint 36 // bti j
6 hint 36 // bti j
4 hint 36 // bti j
4 hint 36 // bti j
3 hint 36 // bti j
2 hint 36 // bti j
2 hint 36 // bti j
2 hint 36 // bti j
2 hint 36 // bti j
2 hint 36 // bti j
2 hint 36 // bti j
2 hint 36 // bti j
