diff options
| -rw-r--r-- | gcc/ChangeLog | 4 | ||||
| -rw-r--r-- | gcc/explow.c | 14 |
2 files changed, 16 insertions, 2 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index c404eb8..0864266 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,5 +1,9 @@ 2017-11-14 Jeff Law <law@redhat.com> + * explow.c (anti_adjust_stack_and_probe_stack_clash): Avoid probing + the red zone for stack_clash_protection_final_dynamic_probe targets + when the total dynamic stack size is zero bytes. + * tree-ssa-threadupdate.c (thread_through_all_blocks): Thread blocks is post order. diff --git a/gcc/explow.c b/gcc/explow.c index 662865d..96334b2 100644 --- a/gcc/explow.c +++ b/gcc/explow.c @@ -1999,6 +1999,13 @@ anti_adjust_stack_and_probe_stack_clash (rtx size) if (size != CONST0_RTX (Pmode) && targetm.stack_clash_protection_final_dynamic_probe (residual)) { + /* SIZE could be zero at runtime and in that case *sp could hold + live data. Furthermore, we don't want to probe into the red + zone. + + Go ahead and just guard a probe at *sp on SIZE != 0 at runtime + if SIZE is not a compile time constant. */ + /* Ideally we would just probe at *sp. However, if SIZE is not a compile-time constant, but is zero at runtime, then *sp might hold live data. So probe at *sp if we know that @@ -2011,9 +2018,12 @@ anti_adjust_stack_and_probe_stack_clash (rtx size) } else { - emit_stack_probe (plus_constant (Pmode, stack_pointer_rtx, - -GET_MODE_SIZE (word_mode))); + rtx label = gen_label_rtx (); + emit_cmp_and_jump_insns (size, CONST0_RTX (GET_MODE (size)), + EQ, NULL_RTX, Pmode, 1, label); + emit_stack_probe (stack_pointer_rtx); emit_insn (gen_blockage ()); + emit_label (label); } } } |