From 5d110fe90afcd850ea21aee6429f22edd6b1b592 Mon Sep 17 00:00:00 2001
From: Andrew MacLeod <amacleod@redhat.com>
Date: Fri, 17 Sep 2021 14:58:06 -0400
Subject: [PATCH 1/2] Make each def a new equivalency record.
Create a new equivalency set at each def point killing any equivalencies
coming into the block from back edges. Do not add equivalences for PHI
arguments defined in this block.
* value-relation.cc (equiv_oracle::register_initial_def): New.
(equiv_oracle::register_relation): Call register_initial_def.
(equiv_oracle::add_equiv_to_block): New. Split register_relation.
(relation_oracle::register_stmt): Check def block of PHI arguments.
* value-relation.h (equiv_oracle): Add new prototypes.
---
gcc/value-relation.cc | 57 +++++++++++++++++++++++++++++++++++++++++++
gcc/value-relation.h | 3 ++-
2 files changed, 59 insertions(+), 1 deletion(-)
@@ -407,6 +407,24 @@ equiv_oracle::register_equiv (basic_block bb, equiv_chain *equiv_1,
return b;
}
+// Create an equivalency set containing only SSA in its definition block.
+// This is done the first time SSA is registered in an equivalency and blocks
+// any DOM searches past the definition.
+
+void
+equiv_oracle::register_initial_def (tree ssa)
+{
+ if (SSA_NAME_IS_DEFAULT_DEF (ssa))
+ return;
+ basic_block bb = gimple_bb (SSA_NAME_DEF_STMT (ssa));
+ gcc_checking_assert (bb && !find_equiv_dom (ssa, bb));
+
+ unsigned v = SSA_NAME_VERSION (ssa);
+ bitmap_set_bit (m_equiv_set, v);
+ bitmap equiv_set = BITMAP_ALLOC (&m_bitmaps);
+ bitmap_set_bit (equiv_set, v);
+ add_equiv_to_block (bb, equiv_set);
+}
// Register an equivalence between SSA1 and SSA2 in block BB.
// The equivalence oracle maintains a vector of equivalencies indexed by basic
@@ -425,6 +443,14 @@ equiv_oracle::register_relation (basic_block bb, relation_kind k, tree ssa1,
unsigned v1 = SSA_NAME_VERSION (ssa1);
unsigned v2 = SSA_NAME_VERSION (ssa2);
+
+ // If this is the first time an ssa_name has an equivalency registered
+ // create a self-equivalency record in the def block.
+ if (!bitmap_bit_p (m_equiv_set, v1))
+ register_initial_def (ssa1);
+ if (!bitmap_bit_p (m_equiv_set, v2))
+ register_initial_def (ssa2);
+
equiv_chain *equiv_1 = find_equiv_dom (ssa1, bb);
equiv_chain *equiv_2 = find_equiv_dom (ssa2, bb);
@@ -456,6 +482,15 @@ equiv_oracle::register_relation (basic_block bb, relation_kind k, tree ssa1,
if (!equiv_set)
return;
+ add_equiv_to_block (bb, equiv_set);
+}
+
+// Add an equivalency record in block BB containing bitmap EQUIV_SET.
+// Note the internal caller is responible for allocating EQUIV_SET properly.
+
+void
+equiv_oracle::add_equiv_to_block (basic_block bb, bitmap equiv_set)
+{
equiv_chain *ptr;
// Check if this is the first time a block has an equivalence added.
@@ -786,6 +821,28 @@ relation_oracle::register_stmt (gimple *stmt, relation_kind k, tree op1,
print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
}
+ // If an equivalence is being added between a PHI and one of its arguments
+ // make sure that that argument is not defined in the same block.
+ // This can happen along back edges and the equivalence will not be
+ // applicable as it would require a use before def.
+ if (k == EQ_EXPR && is_a<gphi *> (stmt))
+ {
+ tree phi_def = gimple_phi_result (stmt);
+ gcc_checking_assert (phi_def == op1 || phi_def == op2);
+ tree arg = op2;
+ if (phi_def == op2)
+ arg = op1;
+ if (gimple_bb (stmt) == gimple_bb (SSA_NAME_DEF_STMT (arg)))
+ {
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ {
+ fprintf (dump_file, " Not registered due to ");
+ print_generic_expr (dump_file, arg, TDF_SLIM);
+ fprintf (dump_file, " being defined in the same block.\n");
+ }
+ return;
+ }
+ }
register_relation (gimple_bb (stmt), k, op1, op2);
}
@@ -146,7 +146,8 @@ private:
bitmap register_equiv (basic_block bb, unsigned v, equiv_chain *equiv_1);
bitmap register_equiv (basic_block bb, equiv_chain *equiv_1,
equiv_chain *equiv_2);
-
+ void register_initial_def (tree ssa);
+ void add_equiv_to_block (basic_block bb, bitmap equiv);
};
// Summary block header for relations.
--
2.17.2