https://gcc.gnu.org/g:1bda298251f57d8942796fe141746a23db99f56f
commit 1bda298251f57d8942796fe141746a23db99f56f
Author: Ondřej Machota <ondrejmach...@gmail.com>
Date: Mon Jul 7 23:06:56 2025 +0200
rtl-ssa-dce: improve code
Diff:
---
gcc/dce.cc | 184 +++++++++++++++++++++++++-----------------------
gcc/rtl-ssa/changes.cc | 49 ++++++++++---
gcc/rtl-ssa/functions.h | 1 +
3 files changed, 134 insertions(+), 100 deletions(-)
diff --git a/gcc/dce.cc b/gcc/dce.cc
index d564935a82f3..67fb42541d84 100644
--- a/gcc/dce.cc
+++ b/gcc/dce.cc
@@ -1324,7 +1324,8 @@ make_pass_fast_rtl_dce (gcc::context *ctxt)
}
namespace {
-// offset_bitmap is a wrapper around sbitmap that also handles negative
indices from RTL SSA
+// offset_bitmap is a wrapper around sbitmap that also handles negative indices
+// from RTL SSA
struct offset_bitmap
{
private:
@@ -1332,9 +1333,7 @@ private:
sbitmap m_bitmap;
public:
- offset_bitmap ()
- : m_offset{0}, m_bitmap{sbitmap_alloc(0)}
- {}
+ offset_bitmap () : m_offset{0}, m_bitmap{sbitmap_alloc (0)} {}
offset_bitmap (size_t size, int offset)
: m_offset{offset}, m_bitmap{sbitmap_alloc (size)}
@@ -1344,15 +1343,15 @@ public:
: offset_bitmap (size_t (max_index - min_index + 1), -min_index)
{}
- void resize(size_t size, int offset)
+ void resize (size_t size, int offset)
{
- m_bitmap = sbitmap_resize(m_bitmap, (unsigned int)size, 0);
- m_offset = offset;
+ m_bitmap = sbitmap_resize (m_bitmap, (unsigned int) size, 0);
+ m_offset = offset;
}
- void resize(int min_index, int max_index)
+ void resize (int min_index, int max_index)
{
- resize(size_t (max_index - min_index + 1), -min_index);
+ resize (size_t (max_index - min_index + 1), -min_index);
}
void clear_bit (int index) { bitmap_clear_bit (m_bitmap, index + m_offset); }
@@ -1411,13 +1410,12 @@ rtl_ssa_dce::can_delete_call (const_rtx insn)
// We cannot delete pure or const sibling calls because it is
// hard to see the result.
return !SIBLING_CALL_P (insn)
- // We can delete dead const or pure calls as long as they do not
- // infinite loop.
- && (RTL_CONST_OR_PURE_CALL_P (insn)
- && !RTL_LOOPING_CONST_OR_PURE_CALL_P (insn))
- // Don't delete calls that may throw if we cannot do so.
- && cfun->can_delete_dead_exceptions
- && insn_nothrow_p (insn);
+ // We can delete dead const or pure calls as long as they do not
+ // infinite loop.
+ && (RTL_CONST_OR_PURE_CALL_P (insn)
+ && !RTL_LOOPING_CONST_OR_PURE_CALL_P (insn))
+ // Don't delete calls that may throw if we cannot do so.
+ && cfun->can_delete_dead_exceptions && insn_nothrow_p (insn);
}
bool
@@ -1508,7 +1506,6 @@ rtl_ssa_dce::is_prelive (insn_info *insn)
return is_rtx_prelive (insn->rtl ());
}
-
// Mark SET as visited and return true if SET->insn() is not nullptr and SET
// has not been visited. Otherwise return false.
bool
@@ -1519,26 +1516,28 @@ rtl_ssa_dce::mark_if_not_visited (const set_info *set)
return false;
if (insn->is_phi ())
- {
- const phi_info *phi = static_cast<const phi_info *> (set);
- auto uid = phi->uid ();
+ {
+ const phi_info *phi = static_cast<const phi_info *> (set);
+ auto uid = phi->uid ();
- if (bitmap_bit_p (m_marked_phis, uid))
- return false;
+ if (bitmap_bit_p (m_marked_phis, uid))
+ return false;
- bitmap_set_bit (m_marked_phis, uid);
- if (dump_file)
- fprintf (dump_file, "Phi node %d:%d marked as live\n", set->regno ()
,insn->uid ());
- } else
- {
- auto uid = insn->uid ();
- if (m_marked.get_bit (uid))
- return false;
+ bitmap_set_bit (m_marked_phis, uid);
+ if (dump_file)
+ fprintf (dump_file, "Phi node %d:%d marked as live\n", set->regno (),
+ insn->uid ());
+ }
+ else
+ {
+ auto uid = insn->uid ();
+ if (m_marked.get_bit (uid))
+ return false;
- m_marked.set_bit (uid);
- if (dump_file)
- fprintf (dump_file, "Insn %d marked as live\n", insn->uid ());
- }
+ m_marked.set_bit (uid);
+ if (dump_file)
+ fprintf (dump_file, "Insn %d marked as live\n", insn->uid ());
+ }
return true;
}
@@ -1546,28 +1545,31 @@ rtl_ssa_dce::mark_if_not_visited (const set_info *set)
// For each use in USES, if use->def () is non-null and has not been visited,
// mark it as visited and append it to WORKLIST.
void
-rtl_ssa_dce::append_not_visited_sets (auto_vec<set_info *>& worklist,
use_array& uses) {
+rtl_ssa_dce::append_not_visited_sets (auto_vec<set_info *> &worklist,
+ use_array &uses)
+{
for (use_info *use : uses)
- {
- // This seems to be a good idea, however there is a problem is
process_uses_of_deleted_def
- if (use->only_occurs_in_notes())
- continue;
+ {
+ // This seems to be a good idea, however there is a problem is
+ // process_uses_of_deleted_def
+ if (use->only_occurs_in_notes ())
+ continue;
- set_info *parent_set = use->def ();
- if (!parent_set)
- continue;
+ set_info *parent_set = use->def ();
+ if (!parent_set)
+ continue;
- if (!mark_if_not_visited (parent_set))
- continue;
+ if (!mark_if_not_visited (parent_set))
+ continue;
- // mark_if_not_visited will return false if insn is nullptr
- // insn_info *insn = parent_set->insn ();
- // gcc_checking_assert (insn);
+ // mark_if_not_visited will return false if insn is nullptr
+ // insn_info *insn = parent_set->insn ();
+ // gcc_checking_assert (insn);
- // if (dump_file)
- // fprintf (dump_file, "Adding insn %d to worklist\n", insn->uid
());
- worklist.safe_push (parent_set);
- }
+ // if (dump_file)
+ // fprintf (dump_file, "Adding insn %d to worklist\n", insn->uid ());
+ worklist.safe_push (parent_set);
+ }
}
// Mark INSN and add its uses to WORKLIST if INSN is not a debug instruction
@@ -1578,9 +1580,9 @@ rtl_ssa_dce::mark_prelive_insn (insn_info *insn,
auto_vec<set_info *> &worklist)
fprintf (dump_file, "Insn %d marked as prelive\n", insn->uid ());
// A phi node will never be prelive.
- m_marked.set_bit(insn->uid ());
- // Debug instruction are not added to worklist. They would wake up possibly
dead
- // instructions
+ m_marked.set_bit (insn->uid ());
+ // Debug instruction are not added to worklist. They would wake up possibly
+ // dead instructions
if (insn->is_debug_insn ())
return;
@@ -1627,7 +1629,7 @@ rtl_ssa_dce::mark ()
uses = phi->inputs ();
}
- append_not_visited_sets(worklist, uses);
+ append_not_visited_sets (worklist, uses);
}
}
@@ -1659,23 +1661,27 @@ rtl_ssa_dce::reset_dead_debug ()
for (use_info *use : insn->uses ())
{
- def_info *def = use->def ();
+ def_info *def = use->def ();
insn_info *parent_insn = def->insn ();
- if (parent_insn == nullptr)
- continue;
- // If we depend on a dead instruction, clear current instruction uses.
- bool is_parent_marked = false;
- if (parent_insn->is_phi ()) {
- auto phi = static_cast<phi_info *> (def);
- is_parent_marked = bitmap_bit_p (m_marked_phis, phi->uid ());
- } else {
- is_parent_marked = m_marked.get_bit (parent_insn->uid ());
- }
+ if (parent_insn == nullptr)
+ continue;
+ // If we depend on a dead instruction, clear current instruction uses.
+ bool is_parent_marked = false;
+ if (parent_insn->is_phi ())
+ {
+ auto phi = static_cast<phi_info *> (def);
+ is_parent_marked = bitmap_bit_p (m_marked_phis, phi->uid ());
+ }
+ else
+ {
+ is_parent_marked = m_marked.get_bit (parent_insn->uid ());
+ }
- if (!is_parent_marked) {
- reset_dead_debug_insn (insn);
- break;
- }
+ if (!is_parent_marked)
+ {
+ reset_dead_debug_insn (insn);
+ break;
+ }
}
}
}
@@ -1717,27 +1723,27 @@ rtl_ssa_dce::sweep ()
unsigned int
rtl_ssa_dce::execute (function *fn)
{
- auto_timevar timer(TV_RTL_SSA_DCE);
+ auto_timevar timer (TV_RTL_SSA_DCE);
calculate_dominance_info (CDI_DOMINATORS);
crtl->ssa = new rtl_ssa::function_info (fn);
int real_max = 0, artificial_min = 0;
std::size_t count = 0;
- for (insn_info *insn : crtl->ssa->all_insns ())
- {
- artificial_min = std::min (artificial_min, insn->uid ());
- real_max = std::max (real_max, insn->uid ());
- count++;
- }
+ for (insn_info *insn : crtl->ssa->all_insns ())
+ {
+ artificial_min = std::min (artificial_min, insn->uid ());
+ real_max = std::max (real_max, insn->uid ());
+ count++;
+ }
- m_marked.resize(artificial_min, real_max + 1);
+ m_marked.resize (artificial_min, real_max + 1);
unsigned int phi_node_max = 0;
for (ebb_info *ebb : crtl->ssa->ebbs ())
for (phi_info *phi : ebb->phis ())
phi_node_max = std::max (phi_node_max, phi->uid ());
- m_marked_phis = sbitmap_alloc(phi_node_max + 1);
- bitmap_clear(m_marked_phis);
+ m_marked_phis = sbitmap_alloc (phi_node_max + 1);
+ bitmap_clear (m_marked_phis);
mark ();
if (MAY_HAVE_DEBUG_BIND_INSNS)
@@ -1748,21 +1754,21 @@ rtl_ssa_dce::execute (function *fn)
if (crtl->ssa->perform_pending_updates ())
cleanup_cfg (0);
- sbitmap_free(m_marked_phis);
+ sbitmap_free (m_marked_phis);
delete crtl->ssa;
crtl->ssa = nullptr;
return 0;
}
const pass_data pass_data_rtl_ssa_dce = {
- RTL_PASS, /* type */
- "rtl_ssa_dce", /* name */
- OPTGROUP_NONE, /* optinfo_flags */
- TV_RTL_SSA_DCE, /* tv_id */
- 0, /* properties_required */
- 0, /* properties_provided */
- 0, /* properties_destroyed */
- 0, /* todo_flags_start */
+ RTL_PASS, /* type */
+ "rtl_ssa_dce", /* name */
+ OPTGROUP_NONE, /* optinfo_flags */
+ TV_RTL_SSA_DCE, /* tv_id */
+ 0, /* properties_required */
+ 0, /* properties_provided */
+ 0, /* properties_destroyed */
+ 0, /* todo_flags_start */
TODO_df_finish, /* todo_flags_finish */
};
diff --git a/gcc/rtl-ssa/changes.cc b/gcc/rtl-ssa/changes.cc
index a9b1a00475dd..f99c95a87fbf 100644
--- a/gcc/rtl-ssa/changes.cc
+++ b/gcc/rtl-ssa/changes.cc
@@ -36,6 +36,7 @@
#include "cfghooks.h"
#include "cfgrtl.h"
#include "sreal.h"
+#include "rtl-iter.h"
using namespace rtl_ssa;
@@ -253,8 +254,42 @@ rtl_ssa::changes_are_worthwhile (array_slice<insn_change
*const> changes,
return true;
}
+// A definition is dead. Remove REG_EQUIV and REG_EQUAL notes from
+// the instruction which uses the definition.
+void
+function_info::remove_notes_of_deleted_def (use_info *use)
+{
+ gcc_checking_assert (use->only_occurs_in_notes ());
+
+ insn_info *insn = use->insn ();
+ rtx_insn *rtl = insn->rtl ();
+ for (rtx next = REG_NOTES (rtl); next;)
+ {
+ rtx note = next;
+ next = XEXP (note, 1);
+ int kind = REG_NOTE_KIND (note);
+ if (kind != REG_EQUIV && kind != REG_EQUAL)
+ continue;
+
+ bool reg_equals = false;
+ subrtx_iterator::array_type array;
+ FOR_EACH_SUBRTX (iter, array, note, ALL)
+ {
+ if (GET_CODE (*iter) == REG && REGNO (*iter) == use->regno ())
+ {
+ reg_equals = true;
+ break;
+ }
+ }
+
+ if (reg_equals)
+ remove_note (rtl, note);
+ }
+}
+
+
// SET has been deleted. Clean up all remaining uses. Such uses are
-// either dead phis or now-redundant live-out uses.
+// either dead phis, now-redundant live-out uses or dead notes.
void
function_info::process_uses_of_deleted_def (set_info *set)
{
@@ -285,20 +320,12 @@ function_info::process_uses_of_deleted_def (set_info *set)
}
else
{
- // following assert causes crash when running rtl_ssa_dce with
- // deleting eq_notes on testsuite
if (use->only_occurs_in_notes ())
- {
- insn_info *insn = use->insn ();
- rtx_insn *rtl = insn->rtl ();
- // TODO: remove note from rtl
- }
+ remove_notes_of_deleted_def (use);
else
- {
gcc_assert (use->is_live_out_use ());
- }
- remove_use (use);
+ remove_use (use);
}
// The phi handling above might have removed multiple uses of this_set.
if (this_set->has_any_uses ())
diff --git a/gcc/rtl-ssa/functions.h b/gcc/rtl-ssa/functions.h
index 2e20f5e47d72..72b330ec8c35 100644
--- a/gcc/rtl-ssa/functions.h
+++ b/gcc/rtl-ssa/functions.h
@@ -306,6 +306,7 @@ private:
bb_info *create_bb_info (basic_block);
void append_bb (bb_info *);
+ void remove_notes_of_deleted_def (use_info *);
void process_uses_of_deleted_def (set_info *);
insn_info *add_placeholder_after (insn_info *);
void possibly_queue_changes (insn_change &);
