gcc/generate-csel-for-arrayref.patch

diff -uprN a/gcc/testsuite/gcc.dg/tree-ssa/pr89430-1.c b/gcc/testsuite/gcc.dg/tree-ssa/pr89430-1.c
--- a/gcc/testsuite/gcc.dg/tree-ssa/pr89430-1.c	2020-05-26 21:03:43.132721856 +0800
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr89430-1.c	2020-05-19 20:12:32.655794652 +0800
@@ -9,4 +9,4 @@ unsigned test(unsigned k, unsigned b) {
         return a[0]+a[1];
 }
 
-/* { dg-final { scan-tree-dump "Conditional store replacement" "cselim" { xfail *-*-* } } } */
+/* { dg-final { scan-tree-dump "Conditional store replacement" "cselim" } } */
diff -uprN a/gcc/testsuite/gcc.dg/tree-ssa/pr89430-2.c b/gcc/testsuite/gcc.dg/tree-ssa/pr89430-2.c
--- a/gcc/testsuite/gcc.dg/tree-ssa/pr89430-2.c	2020-05-26 21:03:43.132721856 +0800
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr89430-2.c	2020-05-19 20:12:32.667794652 +0800
@@ -11,4 +11,4 @@ unsigned test(unsigned k, unsigned b) {
         return a[0]+a[1];
 }
 
-/* { dg-final { scan-tree-dump "Conditional store replacement" "cselim" { xfail *-*-* } } } */
+/* { dg-final { scan-tree-dump "Conditional store replacement" "cselim" } } */
diff -uprN a/gcc/testsuite/gcc.dg/tree-ssa/pr89430-5.c b/gcc/testsuite/gcc.dg/tree-ssa/pr89430-5.c
--- a/gcc/testsuite/gcc.dg/tree-ssa/pr89430-5.c	2020-05-26 21:03:43.132721856 +0800
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr89430-5.c	2020-05-19 20:12:32.667794652 +0800
@@ -13,4 +13,4 @@ int test(int b, int k) {
     return a.data[0] + a.data[1];
 }
 
-/* { dg-final { scan-tree-dump "Conditional store replacement" "cselim" { xfail *-*-* } } } */
+/* { dg-final { scan-tree-dump "Conditional store replacement" "cselim" } } */
diff -uprN a/gcc/tree-ssa-phiopt.c b/gcc/tree-ssa-phiopt.c
--- a/gcc/tree-ssa-phiopt.c	2020-05-26 21:03:43.132721856 +0800
+++ b/gcc/tree-ssa-phiopt.c	2020-05-26 21:02:02.872006469 +0800
@@ -47,6 +47,7 @@ along with GCC; see the file COPYING3.
 #include "params.h"
 #include "case-cfn-macros.h"
 #include "tree-eh.h"
+#include "inchash.h"
 
 static unsigned int tree_ssa_phiopt_worker (bool, bool, bool);
 static bool two_value_replacement (basic_block, basic_block, edge, gphi *,
@@ -1984,6 +1985,18 @@ struct name_to_bb
   basic_block bb;
 };
 
+/* A hash-table of ARRAY_REF with a base of VAR_DECL and an offset of
+   SSA_NAME, and in which basic block it was seen, which would constitute
+   a no-trap region for same accessed.  */
+struct array_ref_to_bb
+{
+  unsigned int ssa_name_ver;
+  unsigned int phase;
+  HOST_WIDE_INT size;
+  tree var_decl;
+  basic_block bb;
+};
+
 /* Hashtable helpers.  */
 
 struct ssa_names_hasher : free_ptr_hash <name_to_bb>
@@ -1992,6 +2005,12 @@ struct ssa_names_hasher : free_ptr_hash
   static inline bool equal (const name_to_bb *, const name_to_bb *);
 };
 
+struct array_refs_hasher : free_ptr_hash <array_ref_to_bb>
+{
+  static inline hashval_t hash (const array_ref_to_bb *);
+  static inline bool equal (const array_ref_to_bb *, const array_ref_to_bb *);
+};
+
 /* Used for quick clearing of the hash-table when we see calls.
    Hash entries with phase < nt_call_phase are invalid.  */
 static unsigned int nt_call_phase;
@@ -2005,6 +2024,16 @@ ssa_names_hasher::hash (const name_to_bb
          ^ (n->offset << 6) ^ (n->size << 3);
 }
 
+inline hashval_t
+array_refs_hasher::hash (const array_ref_to_bb *n)
+{
+  inchash::hash hstate (0);
+  hstate.add_int (n->ssa_name_ver);
+  hstate.add_hwi (n->size);
+  hstate.add_ptr (n->var_decl);
+  return hstate.end ();
+}
+
 /* The equality function of *P1 and *P2.  */
 
 inline bool
@@ -2016,11 +2045,21 @@ ssa_names_hasher::equal (const name_to_b
          && n1->size == n2->size;
 }
 
+inline bool
+array_refs_hasher::equal (const array_ref_to_bb *n1, const array_ref_to_bb *n2)
+{
+  return n1->ssa_name_ver == n2->ssa_name_ver
+	 && n1->size == n2->size
+	 && n1->var_decl == n2->var_decl;
+}
+
 class nontrapping_dom_walker : public dom_walker
 {
 public:
   nontrapping_dom_walker (cdi_direction direction, hash_set<tree> *ps)
-    : dom_walker (direction), m_nontrapping (ps), m_seen_ssa_names (128) {}
+    : dom_walker (direction), m_nontrapping (ps),
+      m_seen_ssa_names (128), m_seen_array_refs (128)
+	{}
 
   virtual edge before_dom_children (basic_block);
   virtual void after_dom_children (basic_block);
@@ -2028,16 +2067,18 @@ public:
 private:
 
   /* We see the expression EXP in basic block BB.  If it's an interesting
-     expression (an MEM_REF through an SSA_NAME) possibly insert the
-     expression into the set NONTRAP or the hash table of seen expressions.
-     STORE is true if this expression is on the LHS, otherwise it's on
-     the RHS.  */
+     expression (an MEM_REF through an SSA_NAME or an ARRAY_REF with a base
+     of VAR_DECL and an offset of SSA_NAME) possibly insert the expression
+     into the set NONTRAP or the hash table of seen expressions.  STORE
+     is true if this expression is on the LHS, otherwise it's on the RHS.  */
   void add_or_mark_expr (basic_block, tree, bool);
+  void add_or_mark_array_ref (basic_block, tree);
 
   hash_set<tree> *m_nontrapping;
 
   /* The hash table for remembering what we've seen.  */
   hash_table<ssa_names_hasher> m_seen_ssa_names;
+  hash_table<array_refs_hasher> m_seen_array_refs;
 };
 
 /* Called by walk_dominator_tree, when entering the block BB.  */
@@ -2071,7 +2112,9 @@ nontrapping_dom_walker::before_dom_child
       else if (gimple_assign_single_p (stmt) && !gimple_has_volatile_ops (stmt))
 	{
 	  add_or_mark_expr (bb, gimple_assign_lhs (stmt), true);
+	  add_or_mark_array_ref (bb, gimple_assign_lhs (stmt));
 	  add_or_mark_expr (bb, gimple_assign_rhs1 (stmt), false);
+	  add_or_mark_array_ref (bb, gimple_assign_rhs1 (stmt));
 	}
     }
   return NULL;
@@ -2148,6 +2191,74 @@ nontrapping_dom_walker::add_or_mark_expr
 	    }
 	}
     }
+}
+
+/* We see the expression EXP in basic block BB.  If it's an interesting
+   expression (an ARRAY_REF with a base of VAR_DECL and an offset of
+   SSA_NAME) possibly insert the expression into the set NONTRAP or the
+   hash table of seen expressions.  */
+void
+nontrapping_dom_walker::add_or_mark_array_ref (basic_block bb, tree exp)
+{
+  if (TREE_CODE (exp) == ARRAY_REF
+      && TREE_CODE (TREE_OPERAND (exp, 1)) == SSA_NAME
+      && int_size_in_bytes (TREE_TYPE (exp)) > 0)
+    {
+      HOST_WIDE_INT size = int_size_in_bytes (TREE_TYPE (exp));
+      tree base = get_base_address (exp);
+      /* if BASE is a local variable without address-taken, which can't be
+	 read-only, a dominating load can constitute a no-trap region for
+	 a store as well.  */
+      if (TREE_CODE (base) == VAR_DECL
+	  && auto_var_p (base) && !TREE_ADDRESSABLE (base))
+	{
+	  struct array_ref_to_bb array_map;
+	  basic_block found_array_bb = 0;
+
+	  /* Try to find the last seen ARRAY_REF with the same base and
+	     offset, which can trap.  */
+	  array_map.ssa_name_ver = SSA_NAME_VERSION (TREE_OPERAND (exp, 1));
+	  array_map.phase = 0;
+	  array_map.bb = 0;
+	  array_map.size = size;
+	  array_map.var_decl = base;
+
+	  array_ref_to_bb **slot
+		= m_seen_array_refs.find_slot (&array_map, INSERT);
+	  struct array_ref_to_bb *a2bb = *slot;
+	  if (a2bb != NULL && a2bb->phase >= nt_call_phase)
+	    {
+	      found_array_bb = a2bb->bb;
+	    }
+
+	  /* If we've found a trapping MEM_REF, _and_ it dominates EXP
+	     (it's in a basic block on the path from us to the dominator root)
+	     then we can't trap.  */
+	  if (found_array_bb && (((size_t)found_array_bb->aux) & 1) == 1)
+	    {
+	      m_nontrapping->add (exp);
+	    }
+	  else
+	    {
+	      /* EXP might trap, so insert it into the hash table.  */
+	      if (a2bb != NULL)
+		{
+		  a2bb->phase = nt_call_phase;
+		  a2bb->bb = bb;
+		}
+	      else
+		{
+		  a2bb = XNEW (struct array_ref_to_bb);
+		  a2bb->ssa_name_ver = SSA_NAME_VERSION (TREE_OPERAND (exp, 1));
+		  a2bb->phase = nt_call_phase;
+		  a2bb->bb = bb;
+		  a2bb->size = size;
+		  a2bb->var_decl = base;
+		  *slot = a2bb;
+		}
+	    }
+	}
+    }
 }

 /* This is the entry point of gathering non trapping memory accesses.