[PATCH, Pointer Bounds Checker 14/x] Passes [12/n] Optimize string functions

[Ilya Enkovich <enkovich dot gnu at gmail dot com>]

Hi,

This patch introduces simple optimization of string function calls using variants with no checks and/or bounds copy when possible.

Thanks,
Ilya
--
2014-10-08  Ilya Enkovich  <ilya.enkovich@intel.com>

	* tree-chkp.c (check_infos): New.
	(chkp_get_nobnd_fndecl): New.
	(chkp_get_nochk_fndecl): New.
	(chkp_optimize_string_function_calls): New.
	(chkp_opt_init): New.
	(chkp_opt_fini): New.
	(chkp_opt_execute): New.
	(chkp_opt_gate): New.
	(pass_data_chkp_opt): New.
	(pass_chkp_opt): New.
	(make_pass_chkp_opt): New.


diff --git a/gcc/tree-chkp.c b/gcc/tree-chkp.c
index aae9681..5230d14 100644
--- a/gcc/tree-chkp.c
+++ b/gcc/tree-chkp.c
@@ -399,6 +399,8 @@ static void chkp_parse_array_and_component_ref (tree node, tree *ptr,
 #define chkp_extract_upper_fndecl \
   (targetm.builtin_chkp_function (BUILT_IN_CHKP_EXTRACT_UPPER))
 
+static vec<struct bb_checks, va_heap, vl_ptr> check_infos = vNULL;
+
 static GTY (()) tree chkp_uintptr_type;
 
 static GTY (()) tree chkp_zero_bounds_var;
@@ -4567,8 +4569,315 @@ chkp_fill_check_info (gimple stmt, struct check_info *ci)
   ci->stmt = stmt;
 }
 
+/* Return fast version of string function FNCODE.  */
+tree
+chkp_get_nobnd_fndecl (enum built_in_function fncode)
+{
+  /* Check if we are allowed to use fast string functions.  */
+  if (!flag_chkp_use_fast_string_functions)
+    return NULL_TREE;
+
+  switch (fncode)
+    {
+    case BUILT_IN_MEMCPY:
+      return builtin_decl_implicit (BUILT_IN_CHKP_MEMCPY_NOBND);
+
+    case BUILT_IN_MEMPCPY:
+      return builtin_decl_implicit (BUILT_IN_CHKP_MEMPCPY_NOBND);
+
+    case BUILT_IN_MEMMOVE:
+      return builtin_decl_implicit (BUILT_IN_CHKP_MEMMOVE_NOBND);
+
+    case BUILT_IN_MEMSET:
+      return builtin_decl_implicit (BUILT_IN_CHKP_MEMSET_NOBND);
+
+    case BUILT_IN_CHKP_MEMCPY_NOCHK:
+      return builtin_decl_implicit (BUILT_IN_CHKP_MEMCPY_NOBND_NOCHK);
+
+    case BUILT_IN_CHKP_MEMPCPY_NOCHK:
+      return builtin_decl_implicit (BUILT_IN_CHKP_MEMPCPY_NOBND_NOCHK);
+
+    case BUILT_IN_CHKP_MEMMOVE_NOCHK:
+      return builtin_decl_implicit (BUILT_IN_CHKP_MEMMOVE_NOBND_NOCHK);
+
+    case BUILT_IN_CHKP_MEMSET_NOCHK:
+      return builtin_decl_implicit (BUILT_IN_CHKP_MEMSET_NOBND_NOCHK);
+
+    default:
+      return NULL_TREE;
+    }
+}
+
+
+/* Return no-check version of string function FNCODE.  */
+tree
+chkp_get_nochk_fndecl (enum built_in_function fncode)
+{
+  /* Check if we are allowed to use fast string functions.  */
+  if (!flag_chkp_use_nochk_string_functions)
+    return NULL_TREE;
+
+  switch (fncode)
+    {
+    case BUILT_IN_MEMCPY:
+      return builtin_decl_implicit (BUILT_IN_CHKP_MEMCPY_NOCHK);
+
+    case BUILT_IN_MEMPCPY:
+      return builtin_decl_implicit (BUILT_IN_CHKP_MEMPCPY_NOCHK);
+
+    case BUILT_IN_MEMMOVE:
+      return builtin_decl_implicit (BUILT_IN_CHKP_MEMMOVE_NOCHK);
+
+    case BUILT_IN_MEMSET:
+      return builtin_decl_implicit (BUILT_IN_CHKP_MEMSET_NOCHK);
+
+    case BUILT_IN_CHKP_MEMCPY_NOBND:
+      return builtin_decl_implicit (BUILT_IN_CHKP_MEMCPY_NOBND_NOCHK);
+
+    case BUILT_IN_CHKP_MEMPCPY_NOBND:
+      return builtin_decl_implicit (BUILT_IN_CHKP_MEMPCPY_NOBND_NOCHK);
+
+    case BUILT_IN_CHKP_MEMMOVE_NOBND:
+      return builtin_decl_implicit (BUILT_IN_CHKP_MEMMOVE_NOBND_NOCHK);
+
+    case BUILT_IN_CHKP_MEMSET_NOBND:
+      return builtin_decl_implicit (BUILT_IN_CHKP_MEMSET_NOBND_NOCHK);
+
+    default:
+      return NULL_TREE;
+    }
+}
+
+/* Find memcpy, mempcpy, memmove and memset calls, perform
+   checks before call and then call no_chk version of
+   functions.  We do it on O2 to enable inlining of these
+   functions during expand.
+
+   Also try to find memcpy, mempcpy, memmove and memset calls
+   which are known to not write pointers to memory and use
+   faster function versions for them.  */
+void
+chkp_optimize_string_function_calls (void)
+{
+  basic_block bb;
+
+  if (dump_file && (dump_flags & TDF_DETAILS))
+    fprintf (dump_file, "Searching for replacable string function calls...\n");
+
+  FOR_EACH_BB_FN (bb, cfun)
+    {
+      gimple_stmt_iterator i;
+
+      for (i = gsi_start_bb (bb); !gsi_end_p (i); gsi_next (&i))
+        {
+	  gimple stmt = gsi_stmt (i);
+	  tree fndecl;
+
+	  if (gimple_code (stmt) != GIMPLE_CALL
+	      || !gimple_call_with_bounds_p (stmt))
+	    continue;
+
+	  fndecl = gimple_call_fndecl (stmt);
+
+	  if (!fndecl || DECL_BUILT_IN_CLASS (fndecl) != BUILT_IN_NORMAL)
+	    continue;
+
+	  if (DECL_FUNCTION_CODE (fndecl) == BUILT_IN_MEMCPY
+	      || DECL_FUNCTION_CODE (fndecl) == BUILT_IN_MEMPCPY
+	      || DECL_FUNCTION_CODE (fndecl) == BUILT_IN_MEMMOVE
+	      || DECL_FUNCTION_CODE (fndecl) == BUILT_IN_MEMSET)
+	    {
+	      tree dst = gimple_call_arg (stmt, 0);
+	      tree dst_bnd = gimple_call_arg (stmt, 1);
+	      bool is_memset = DECL_FUNCTION_CODE (fndecl) == BUILT_IN_MEMSET;
+	      tree size = gimple_call_arg (stmt, is_memset ? 3 : 4);
+	      tree fndecl_nochk;
+	      gimple_stmt_iterator j;
+	      basic_block check_bb;
+	      edge fall;
+	      address_t size_val;
+	      int sign;
+	      bool known;
+
+	      /* We may replace call with corresponding __chkp_*_nobnd
+		 call in case destination pointer base type is not
+		 void or pointer.  */
+	      if (POINTER_TYPE_P (TREE_TYPE (dst))
+		  && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (dst)))
+		  && !chkp_type_has_pointer (TREE_TYPE (TREE_TYPE (dst))))
+		{
+		  tree fndecl_nobnd
+		    = chkp_get_nobnd_fndecl (DECL_FUNCTION_CODE (fndecl));
+
+		  if (fndecl_nobnd)
+		    fndecl = fndecl_nobnd;
+		}
+
+	      fndecl_nochk = chkp_get_nochk_fndecl (DECL_FUNCTION_CODE (fndecl));
+
+	      if (fndecl_nochk)
+		fndecl = fndecl_nochk;
+
+	      gimple_call_set_fndecl (stmt, fndecl);
+
+	      /* If there is no nochk version of function then
+		 do nothing.  Otherwise insert checks before
+		 the call.  */
+	      if (!fndecl_nochk)
+		continue;
+
+	      /* If size passed to call is known and > 0
+		 then we may insert checks unconditionally.  */
+	      size_val.pol.create (0);
+	      chkp_collect_value (size, size_val);
+	      known = chkp_is_constant_addr (size_val, &sign);
+	      size_val.pol.release ();
+
+	      /* If we are not sure size is not zero then we have
+		 to perform runtiome check for size and perform
+		 checks only when size is not zero.  */
+	      if (!known)
+		{
+		  gimple check = gimple_build_cond (NE_EXPR,
+						    size,
+						    size_zero_node,
+						    NULL_TREE,
+						    NULL_TREE);
+
+		  /* Split block before string function call.  */
+		  j = i;
+		  gsi_prev (&j);
+		  fall = split_block (bb, gsi_stmt (j));
+		  bb = fall->src;
+
+		  /* Add size check.  */
+		  j = gsi_last_bb (bb);
+		  if (gsi_end_p (j))
+		    gsi_insert_before (&j, check, GSI_SAME_STMT);
+		  else
+		    gsi_insert_after (&j, check, GSI_SAME_STMT);
+
+		  /* Create basic block for checks.  */
+		  check_bb = create_empty_bb (bb);
+		  make_edge (bb, check_bb, EDGE_TRUE_VALUE);
+		  make_single_succ_edge (check_bb, fall->dest, EDGE_FALLTHRU);
+
+		  /* Fix edge for splitted bb.  */
+		  fall->flags = EDGE_FALSE_VALUE;
+		  fall->count = bb->count;
+		  fall->probability = REG_BR_PROB_BASE;
+
+		  /* Update dominance info.  */
+		  if (dom_info_available_p (CDI_DOMINATORS))
+		    {
+		      set_immediate_dominator (CDI_DOMINATORS, check_bb, bb);
+		      set_immediate_dominator (CDI_DOMINATORS, fall->dest, bb);
+		    }
+
+		  /* Update loop info.  */
+		  if (current_loops)
+		    add_bb_to_loop (check_bb, bb->loop_father);
+
+		  /* Set position for checks.  */
+		  j = gsi_last_bb (check_bb);
+
+		  /* The block was splitted and therefore we
+		     need to set iterator to its end.  */
+		  i = gsi_last_bb (bb);
+		}
+	      /* If size is known to be zero then no checks
+		 should be performed.  */
+	      else if (!sign)
+		continue;
+	      else
+		j = i;
+
+	      size = size_binop (MINUS_EXPR, size, size_one_node);
+	      if (!is_memset)
+		{
+		  tree src = gimple_call_arg (stmt, 2);
+		  tree src_bnd = gimple_call_arg (stmt, 3);
+
+		  chkp_check_mem_access (src, fold_build_pointer_plus (src, size),
+					 src_bnd, j, gimple_location (stmt),
+					 integer_zero_node);
+		}
+
+	      chkp_check_mem_access (dst, fold_build_pointer_plus (dst, size),
+				     dst_bnd, j, gimple_location (stmt),
+				     integer_one_node);
+
+	    }
+	}
+    }
+}
+
+/* Initilize checker optimization pass.  */
+void
+chkp_opt_init (void)
+{
+  check_infos.create (0);
+
+  calculate_dominance_info (CDI_DOMINATORS);
+  calculate_dominance_info (CDI_POST_DOMINATORS);
+
+  /* With LTO constant bounds vars may be not initialized by now.
+     Get constant bounds vars to handle their assignments during
+     optimizations.  */
+  chkp_get_zero_bounds_var ();
+  chkp_get_none_bounds_var ();
+}
+
+/* Finalise checker optimization  pass.  */
+void
+chkp_opt_fini (void)
+{
+  chkp_fix_cfg ();
+
+  free_dominance_info (CDI_DOMINATORS);
+  free_dominance_info (CDI_POST_DOMINATORS);
+}
+
+/* Checker optimization pass function.  */
+unsigned int
+chkp_opt_execute (void)
+{
+  chkp_opt_init();
+
+  /* This optimization may introduce new checks
+     and thus we put it before checks search.  */
+  chkp_optimize_string_function_calls ();
+
+  chkp_opt_fini ();
+
+  return 0;
+}
+
+/* Pass gate.  */
+bool
+chkp_opt_gate (void)
+{
+  return chkp_function_instrumented_p (cfun->decl)
+    && (flag_chkp_optimize > 0
+	|| (flag_chkp_optimize == -1 && optimize > 0));
+}
+
 namespace {
 
+const pass_data pass_data_chkp_opt =
+{
+  GIMPLE_PASS, /* type */
+  "chkpopt", /* name */
+  OPTGROUP_NONE, /* optinfo_flags */
+  TV_NONE, /* tv_id */
+  PROP_ssa | PROP_cfg, /* properties_required */
+  0, /* properties_provided */
+  0, /* properties_destroyed */
+  0, /* todo_flags_start */
+  TODO_verify_il
+  | TODO_update_ssa /* todo_flags_finish */
+};
+
 const pass_data pass_data_chkp =
 {
   GIMPLE_PASS, /* type */
@@ -4608,6 +4917,31 @@ public:
 
 }; // class pass_chkp
 
+class pass_chkp_opt : public gimple_opt_pass
+{
+public:
+  pass_chkp_opt (gcc::context *ctxt)
+    : gimple_opt_pass (pass_data_chkp_opt, ctxt)
+  {}
+
+  /* opt_pass methods: */
+  virtual opt_pass * clone ()
+    {
+      return new pass_chkp_opt (m_ctxt);
+    }
+
+  virtual bool gate (function *)
+    {
+      return chkp_opt_gate ();
+    }
+
+  virtual unsigned int execute (function *)
+    {
+      return chkp_opt_execute ();
+    }
+
+}; // class pass_chkp_opt
+
 } // anon namespace
 
 gimple_opt_pass *
@@ -4616,4 +4950,10 @@ make_pass_chkp (gcc::context *ctxt)
   return new pass_chkp (ctxt);
 }
 
+gimple_opt_pass *
+make_pass_chkp_opt (gcc::context *ctxt)
+{
+  return new pass_chkp_opt (ctxt);
+}
+
 #include "gt-tree-chkp.h"