https://gcc.gnu.org/g:92e2b2fd496403a8d82b20b1fcefb265d1bf9e68
commit 92e2b2fd496403a8d82b20b1fcefb265d1bf9e68
Author: Ondřej Machota <ondrejmach...@gmail.com>
Date: Sun May 11 19:08:12 2025 +0200
rtl-ssa-dce: debugize insns
Diff:
---
gcc/dce.cc | 143 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 143 insertions(+)
diff --git a/gcc/dce.cc b/gcc/dce.cc
index f12269f5dc97..5b8648be5859 100644
--- a/gcc/dce.cc
+++ b/gcc/dce.cc
@@ -17,6 +17,8 @@ You should have received a copy of the GNU General Public
License
along with GCC; see the file COPYING3. If not see
<http://www.gnu.org/licenses/>. */
+#include "bitmap.h"
+#include "sbitmap.h"
#include <iostream>
#include <ostream>
#define INCLUDE_ALGORITHM
@@ -1896,6 +1898,147 @@ replace_dead_reg(rtx x, const_rtx old_rtx
ATTRIBUTE_UNUSED, void *data)
return NULL_RTX;
}
+// visit every marked instruction in INSN dependency tree and unmark it
+static void
+unmark_debugizable(const insn_info& insn, auto_sbitmap &debugizable)
+{
+ auto_vec<insn_info *> worklist;
+ bitmap_set_bit (debugizable, insn.uid ());
+ worklist.safe_push (&insn);
+
+ while (!worklist.empty ()) {
+ insn_info *current = worklist.pop ();
+ int current_uid = current->uid ();
+
+ // skip instruction that are not marked
+ if (!bitmap_bit_p(debugizable, current_uid))
+ continue;
+
+ bitmap_clear_bit(debugizable, current_uid);
+ // add all marked dependencies to the worklist
+ for (def_info *def : current.defs())
+ {
+ if (def->kind() != access_kind::SET)
+ continue;
+
+ set_info *set = static_cast<set_info *>(def);
+ for (use_info *use : set->all_uses())
+ {
+ insn_info *use_insn = use->insn();
+ if (bitmap_bit_p(debugizable, use_insn->uid()))
+ worklist.safe_push (use_insn);
+ }
+ }
+ }
+}
+
+static auto_sbitmap
+find_debugizable(const std::unordered_set<insn_info *> &depends_on_dead_phi)
+{
+ // only real instructions
+ auto_sbitmap debugizable(get_max_uid () + 1);
+ bitmap_clear(debugizable);
+
+ for (insn_info *insn : crtl->ssa->reverse_all_insns ()) {
+ if (insn->is_artificial () ||
+ (m_marked.get_bit (insn->uid ()) && !insn->is_debug_insn()))
+ continue;
+
+ // TODO: reset dead debug instructions - those that are dependend on a
dead phi
+ if (depends_on_dead_phi.count (insn) > 0) {
+ if (insn->is_debug_insn ())
+ reset_dead_debug_insn (insn);
+ continue;
+ }
+
+ // this insn might have some debugizable dependencies and if we find that
+ // current insn is not debugizable, we have to reset those dependencies
+ gcc_checking_assert(insn->is_real ());
+
+ rtx_insn *rtl = insn->rtl ();
+ def_array defs = insn->defs ();
+ rtx rtx_set;
+
+ // If insn has debug uses and will be deleted, signalize it
+ if (!MAY_HAVE_DEBUG_BIND_INSNS ||
+ (rtx_set = single_set (rtl)) == NULL_RTX ||
+ side_effects_p (SET_SRC (rtx_set)) ||
+ asm_noperands (PATTERN (rtl)) >= 0)
+ {
+ unmark_debugizable(*insn, debugizable);
+ continue; // TODO: call unmark_debugizable
+ }
+
+ // some of the checks might be duplicate:
+ if (insn->num_defs () != 1)
+ {
+ if (insn->num_defs() > 1)
+ unmark_debugizable(*insn, debugizable);
+ continue; // TODO: call unmark_debugizable if num_defs>1
+ }
+
+ def_info *def = *defs.begin ();
+ if (def->kind () != access_kind::SET)
+ continue;
+
+ set_info *set = static_cast<set_info *> (def);
+ // this is a problem a bit
+ // TODO: check instruction dependencies and their debugizability
+ if (!set->has_nondebug_insn_uses ())
+ continue;
+
+ bitmap_set_bit (debugizable, insn->uid ());
+ }
+
+ return debugizable;
+}
+
+static void
+bruh(const auto_sbitmap& debugizable)
+{
+ for (insn_info *insn : crtl->ssa->reverse_all_insns ())
+ {
+ if (insn->is_artificial () || !bitmap_bit_p(debugizable, insn->uid ()))
+ continue;
+
+ rtx_insn *rtl = insn->rtl ();
+ def_array defs = insn->defs ();
+ rtx rtx_set = single_set (rtl);
+ def_info *def = *defs.begin ();
+ gcc_checking_assert (def->kind () != access_kind::SET);
+
+ set_info *set = static_cast<set_info *> (def);
+
+ // turn instruction into debug
+ rtx dval = make_debug_expr_from_rtl (SET_DEST (rtx_set));
+
+ /* Emit a debug bind insn before the insn in which
+ reg dies. */
+ rtx bind_var_loc =
+ gen_rtx_VAR_LOCATION (GET_MODE (SET_DEST (rtx_set)),
+ DEBUG_EXPR_TREE_DECL (dval),
+ SET_SRC (rtx_set),
+ VAR_INIT_STATUS_INITIALIZED);
+
+ obstack_watermark watermark = crtl->ssa->new_change_attempt();
+ insn_info *debug_insn = crtl->ssa->create_insn(watermark, DEBUG_INSN,
bind_var_loc);
+ insn_change change(debug_insn);
+ change.new_uses = insn->uses();
+ change.move_range = insn_range_info(insn);
+
+ rtx_insn *bind = emit_debug_insn_before (bind_var_loc, rtl);
+
+ register_replacement replacement;
+ for (use_info *u : set->all_uses ()) {
+ // TODO: transform dependent insns
+ replacement.regno = u->regno();
+ replacement.expr = dval;
+
+ simplify_replace_fn_rtx(INSN_VAR_LOCATION_LOC(rtl), NULL_RTX,
replace_dead_reg, &replacement);
+ }
+ }
+}
+
void
rtl_ssa_dce::debugize_insns (const std::unordered_set<insn_info *>
&depends_on_dead_phi)
{
