On 7/30/2026 9:28 AM, [email protected] wrote:
From: Kyrylo Tkachov <[email protected]>
reg_last_in_use does not record every reg_last entry that contains a list.
The debug-insn path adds uses and then clears reg_pending_uses before the
normal update of reg_last_in_use. The control-use path also adds lists
without updating reg_last_in_use. free_deps only walks reg_last_in_use, so
these INSN_LIST nodes are not returned to the recycler.
Add a teardown-only reg_last_dirty regset for these entries. Merge it into
reg_last_in_use in free_deps, then release all lists in the existing loop.
Do not use reg_last_dirty for dependence generation. Adding these entries
to reg_last_in_use during analysis would make barrier handling create new
anti-dependences for debug uses and control dependences for control uses.
Add a selftest that puts a use list and a control-use list in a dirty-only
entry. It calls free_deps and verifies that the INSN_LIST recycler returns
both nodes. Ignoring the dirty-only entry makes this selftest fail.
Bootstrapped and regtested on aarch64-none-linux-gnu and x86_64-linux.
gcc/ChangeLog:
* sched-int.h (struct deps_desc): Add reg_last_dirty.
* sched-deps.cc: Include selftest.h.
(sched_analyze_insn): Record debug-insn uses and control uses in
reg_last_dirty.
(init_deps): Initialize reg_last_dirty.
(free_deps): Merge reg_last_dirty into reg_last_in_use for teardown,
then clear it.
(selftest::test_dirty_reg_last_release): New.
(selftest::sched_deps_cc_tests): New. Provide an empty definition
when INSN_SCHEDULING is not defined.
* selftest-run-tests.cc (selftest::run_tests): Call
sched_deps_cc_tests.
* selftest.h (selftest::sched_deps_cc_tests): Declare.
Signed-off-by: Kyrylo Tkachov <[email protected]>
The selftest is a bit on the fragile side in that it's dependent on a
LIFO (or nearly LIFO) implementation of the list recycling. But that's
been in place since the late 90s IIRC. So probably not a terrible
assumption to make for a selftest.
OK for the trunk.
jeff
