https://gcc.gnu.org/bugzilla/show_bug.cgi?id=128179
Bug ID: 128179
Summary: RISC-V Shadow stack support in restore_stack_nonlocal
appears broken
Product: gcc
Version: 17.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: law at gcc dot gnu.org
Target Milestone: ---
The shadow stack support in restore_stack looks broken.
First note cmp_4k_label:
/* Adjust the ssp in a loop. */
rtx cmp_4k_label = gen_label_rtx ();
emit_label (cmp_4k_label);
LABEL_NUSES (cmp_4k_label) = 1;
But nothing ever references that label.
And this fragment:
rtx cmp_ssp = gen_reg_rtx (word_mode);
cmp_ssp = expand_simple_binop (ptr_mode, MINUS,
ssp_slot, cur_ssp,
cmp_ssp, 1, OPTAB_DIRECT);
That looks like an uninitialized variable in the generated code. We construct
a register for "cmp_ssp", then we use that register in the subtraction which is
effectively ssp_slot = cur_ssp - cmp_ssp.
Am I missing something here?
