Extend ipa-pure-const pass to propagate malloc attribute.

2017-10-27  Prathamesh Kulkarni  <prathamesh.kulkarni@linaro.org>

	* cgraph.h (set_malloc_flag): Declare.
	* cgraph.c (set_malloc_flag_1): New function.
	(set_malloc_flag): Likewise.
	* ipa-fnsummary.h (ipa_call_summary): Add new field is_return_callee.
	* ipa-fnsummary.c (ipa_call_summary::reset): Set is_return_callee to
	false.
	(read_ipa_call_summary): Add support for reading is_return_callee.
	(write_ipa_call_summary): Stream is_return_callee.
	* ipa-inline.c (ipa_inline): Remove call to ipa_free_fn_summary.
	* ipa-pure-const.c: Add headers ssa.h, alloc-pool.h, symbol-summary.h,
	ipa-prop.h, ipa-fnsummary.h.
	(pure_const_names): Change to static.
	(malloc_state_e): Define.
	(malloc_state_names): Define.
	(funct_state_d): Add field malloc_state.
	(varying_state): Set malloc_state to STATE_MALLOC_BOTTOM.
	(check_retval_uses): New function.
	(malloc_candidate_p): Likewise.
	(analyze_function): Add support for malloc attribute.
	(pure_const_write_summary): Stream malloc_state.
	(pure_const_read_summary): Add support for reading malloc_state.
	(dump_malloc_lattice): New function.
	(propagate_malloc): New function.
	(warn_function_malloc): New function.
	(ipa_pure_const::execute): Call propagate_malloc and
	ipa_free_fn_summary.
	(pass_local_pure_const::execute): Add support for malloc attribute.
	* ssa-iterators.h (RETURN_FROM_IMM_USE_STMT): New macro.
	* doc/invoke.texi: Document Wsuggest-attribute=malloc.

testsuite/
	* gcc.dg/ipa/propmalloc-1.c: New test-case.
	* gcc.dg/ipa/propmalloc-2.c: Likewise.
	* gcc.dg/ipa/propmalloc-3.c: Likewise.

From-SVN: r254140

gcc/ChangeLog

+2017-10-27  Prathamesh Kulkarni  <prathamesh.kulkarni@linaro.org>
+
+	* cgraph.h (set_malloc_flag): Declare.
+	* cgraph.c (set_malloc_flag_1): New function.
+	(set_malloc_flag): Likewise.
+	* ipa-fnsummary.h (ipa_call_summary): Add new field is_return_callee.
+	* ipa-fnsummary.c (ipa_call_summary::reset): Set is_return_callee to
+	false.
+	(read_ipa_call_summary): Add support for reading is_return_callee.
+	(write_ipa_call_summary): Stream is_return_callee.
+	* ipa-inline.c (ipa_inline): Remove call to ipa_free_fn_summary.
+	* ipa-pure-const.c: Add headers ssa.h, alloc-pool.h, symbol-summary.h,
+	ipa-prop.h, ipa-fnsummary.h.
+	(pure_const_names): Change to static.
+	(malloc_state_e): Define.
+	(malloc_state_names): Define.
+	(funct_state_d): Add field malloc_state.
+	(varying_state): Set malloc_state to STATE_MALLOC_BOTTOM.
+	(check_retval_uses): New function.
+	(malloc_candidate_p): Likewise.
+	(analyze_function): Add support for malloc attribute.
+	(pure_const_write_summary): Stream malloc_state.
+	(pure_const_read_summary): Add support for reading malloc_state.
+	(dump_malloc_lattice): New function.
+	(propagate_malloc): New function.
+	(warn_function_malloc): New function.
+	(ipa_pure_const::execute): Call propagate_malloc and
+	ipa_free_fn_summary.
+	(pass_local_pure_const::execute): Add support for malloc attribute.
+	* ssa-iterators.h (RETURN_FROM_IMM_USE_STMT): New macro.
+	* doc/invoke.texi: Document Wsuggest-attribute=malloc.
+
 2017-10-27  Martin Liska  <mliska@suse.cz>
 
 	PR gcov-profile/82457

gcc/cgraph.c

@@ -2530,6 +2530,53 @@ cgraph_node::set_nothrow_flag (bool nothrow)
   return changed;
 }
 
+/* Worker to set malloc flag.  */
+static void
+set_malloc_flag_1 (cgraph_node *node, bool malloc_p, bool *changed)
+{
+  if (malloc_p && !DECL_IS_MALLOC (node->decl))
+    {
+      DECL_IS_MALLOC (node->decl) = true;
+      *changed = true;
+    }
+
+  ipa_ref *ref;
+  FOR_EACH_ALIAS (node, ref)
+    {
+      cgraph_node *alias = dyn_cast<cgraph_node *> (ref->referring);
+      if (!malloc_p || alias->get_availability () > AVAIL_INTERPOSABLE)
+	set_malloc_flag_1 (alias, malloc_p, changed);
+    }
+
+  for (cgraph_edge *e = node->callers; e; e = e->next_caller)
+    if (e->caller->thunk.thunk_p
+	&& (!malloc_p || e->caller->get_availability () > AVAIL_INTERPOSABLE))
+      set_malloc_flag_1 (e->caller, malloc_p, changed);
+}
+
+/* Set DECL_IS_MALLOC on NODE's decl and on NODE's aliases if any.  */
+
+bool
+cgraph_node::set_malloc_flag (bool malloc_p)
+{
+  bool changed = false;
+
+  if (!malloc_p || get_availability () > AVAIL_INTERPOSABLE)
+    set_malloc_flag_1 (this, malloc_p, &changed);
+  else
+    {
+      ipa_ref *ref;
+
+      FOR_EACH_ALIAS (this, ref)
+	{
+	  cgraph_node *alias = dyn_cast<cgraph_node *> (ref->referring);
+	  if (!malloc_p || alias->get_availability () > AVAIL_INTERPOSABLE)
+	    set_malloc_flag_1 (alias, malloc_p, &changed);
+	}
+    }
+  return changed;
+}
+
 /* Worker to set_const_flag.  */
 
 static void

gcc/cgraph.h

@@ -1151,6 +1151,10 @@ public:
      if any to NOTHROW.  */
   bool set_nothrow_flag (bool nothrow);
 
+  /* SET DECL_IS_MALLOC on cgraph_node's decl and on aliases of the node
+     if any.  */
+  bool set_malloc_flag (bool malloc_p);
+
   /* If SET_CONST is true, mark function, aliases and thunks to be ECF_CONST.
     If SET_CONST if false, clear the flag.
 

gcc/common.opt

@@ -741,6 +741,10 @@ Wsuggest-attribute=noreturn
 Common Var(warn_suggest_attribute_noreturn) Warning
 Warn about functions which might be candidates for __attribute__((noreturn)).
 
+Wsuggest-attribute=malloc
+Common Var(warn_suggest_attribute_malloc) Warning
+Warn about functions which might be candidates for __attribute__((malloc)).
+
 Wsuggest-final-types
 Common Var(warn_suggest_final_types) Warning
 Warn about C++ polymorphic types where adding final keyword would improve code quality.

gcc/doc/invoke.texi

@@ -315,7 +315,7 @@ Objective-C and Objective-C++ Dialects}.
 -Wstack-protector  -Wstack-usage=@var{len}  -Wstrict-aliasing @gol
 -Wstrict-aliasing=n  -Wstrict-overflow  -Wstrict-overflow=@var{n} @gol
 -Wstringop-overflow=@var{n} @gol
--Wsuggest-attribute=@r{[}pure@r{|}const@r{|}noreturn@r{|}format@r{]} @gol
+-Wsuggest-attribute=@r{[}pure@r{|}const@r{|}noreturn@r{|}format@r{|}malloc@r{]} @gol
 -Wsuggest-final-types @gol  -Wsuggest-final-methods  -Wsuggest-override @gol
 -Wmissing-format-attribute  -Wsubobject-linkage @gol
 -Wswitch  -Wswitch-bool  -Wswitch-default  -Wswitch-enum @gol
@@ -5204,7 +5204,7 @@ whether to issue a warning.  Similarly to @option{-Wstringop-overflow=3} this
 setting of the option may result in warnings for benign code.
 @end table
 
-@item -Wsuggest-attribute=@r{[}pure@r{|}const@r{|}noreturn@r{|}format@r{|}cold@r{]}
+@item -Wsuggest-attribute=@r{[}pure@r{|}const@r{|}noreturn@r{|}format@r{|}cold@r{|}malloc@r{]}
 @opindex Wsuggest-attribute=
 @opindex Wno-suggest-attribute=
 Warn for cases where adding an attribute may be beneficial. The
@@ -5214,21 +5214,25 @@ attributes currently supported are listed below.
 @item -Wsuggest-attribute=pure
 @itemx -Wsuggest-attribute=const
 @itemx -Wsuggest-attribute=noreturn
+@itemx -Wsuggest-attribute=malloc
 @opindex Wsuggest-attribute=pure
 @opindex Wno-suggest-attribute=pure
 @opindex Wsuggest-attribute=const
 @opindex Wno-suggest-attribute=const
 @opindex Wsuggest-attribute=noreturn
 @opindex Wno-suggest-attribute=noreturn
+@opindex Wsuggest-attribute=malloc
+@opindex Wno-suggest-attribute=malloc
 
 Warn about functions that might be candidates for attributes
-@code{pure}, @code{const} or @code{noreturn}.  The compiler only warns for
-functions visible in other compilation units or (in the case of @code{pure} and
-@code{const}) if it cannot prove that the function returns normally. A function
-returns normally if it doesn't contain an infinite loop or return abnormally
-by throwing, calling @code{abort} or trapping.  This analysis requires option
-@option{-fipa-pure-const}, which is enabled by default at @option{-O} and
-higher.  Higher optimization levels improve the accuracy of the analysis.
+@code{pure}, @code{const} or @code{noreturn} or @code{malloc}. The compiler
+only warns for functions visible in other compilation units or (in the case of
+@code{pure} and @code{const}) if it cannot prove that the function returns
+normally. A function returns normally if it doesn't contain an infinite loop or
+return abnormally by throwing, calling @code{abort} or trapping.  This analysis
+requires option @option{-fipa-pure-const}, which is enabled by default at
+@option{-O} and higher.  Higher optimization levels improve the accuracy
+of the analysis.
 
 @item -Wsuggest-attribute=format
 @itemx -Wmissing-format-attribute

gcc/ipa-fnsummary.c

@@ -542,6 +542,7 @@ void
 ipa_call_summary::reset ()
 {
   call_stmt_size = call_stmt_time = 0;
+  is_return_callee_uncaptured = false;
   if (predicate)
     edge_predicate_pool.remove (predicate);
   predicate = NULL;
@@ -3204,6 +3205,10 @@ read_ipa_call_summary (struct lto_input_block *ib, struct cgraph_edge *e)
   es->call_stmt_size = streamer_read_uhwi (ib);
   es->call_stmt_time = streamer_read_uhwi (ib);
   es->loop_depth = streamer_read_uhwi (ib);
+
+  bitpack_d bp = streamer_read_bitpack (ib);
+  es->is_return_callee_uncaptured = bp_unpack_value (&bp, 1);
+
   p.stream_in (ib);
   edge_set_predicate (e, &p);
   length = streamer_read_uhwi (ib);
@@ -3360,6 +3365,11 @@ write_ipa_call_summary (struct output_block *ob, struct cgraph_edge *e)
   streamer_write_uhwi (ob, es->call_stmt_size);
   streamer_write_uhwi (ob, es->call_stmt_time);
   streamer_write_uhwi (ob, es->loop_depth);
+
+  bitpack_d bp = bitpack_create (ob->main_stream);
+  bp_pack_value (&bp, es->is_return_callee_uncaptured, 1);
+  streamer_write_bitpack (&bp);
+
   if (es->predicate)
     es->predicate->stream_out (ob);
   else

gcc/ipa-fnsummary.h

@@ -197,7 +197,9 @@ struct ipa_call_summary
   int call_stmt_time;
   /* Depth of loop nest, 0 means no nesting.  */
   unsigned int loop_depth;
-  
+  /* Indicates whether the caller returns the value of it's callee.  */
+  bool is_return_callee_uncaptured;
+
   /* Keep all field empty so summary dumping works during its computation.
      This is useful for debugging.  */
   ipa_call_summary ()

gcc/ipa-inline.c

@@ -2526,9 +2526,6 @@ ipa_inline (void)
 
   if (dump_file)
     ipa_dump_fn_summaries (dump_file);
-  /* In WPA we use inline summaries for partitioning process.  */
-  if (!flag_wpa)
-    ipa_free_fn_summary ();
   return remove_functions ? TODO_remove_functions : 0;
 }
 

gcc/ssa-iterators.h

@@ -93,6 +93,12 @@ struct imm_use_iterator
      break;							\
    }
 
+/* Similarly for return.  */
+#define RETURN_FROM_IMM_USE_STMT(ITER, VAL)			\
+  {								\
+    end_imm_use_stmt_traverse (&(ITER));			\
+    return (VAL);						\
+  }
 
 /* Use this iterator in combination with FOR_EACH_IMM_USE_STMT to
    get access to each occurrence of ssavar on the stmt returned by

gcc/testsuite/ChangeLog

+2017-10-27  Prathamesh Kulkarni  <prathamesh.kulkarni@linaro.org>
+
+	* gcc.dg/ipa/propmalloc-1.c: New test-case.
+	* gcc.dg/ipa/propmalloc-2.c: Likewise.
+	* gcc.dg/ipa/propmalloc-3.c: Likewise.
+
 2017-10-27  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/71385

gcc/testsuite/gcc.dg/ipa/propmalloc-1.c

+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-ipa-pure-const-details" } */
+
+__attribute__((noinline, no_icf, used))
+static void *f(__SIZE_TYPE__ n)
+{
+  void *p = __builtin_malloc (n);
+  if (p == 0)
+    __builtin_abort ();
+  return p;
+}
+
+__attribute__((noinline, no_icf, used))
+static void *bar(__SIZE_TYPE__ n)
+{
+  void *p = f (n);
+  return p;
+}
+
+/* { dg-final { scan-ipa-dump "Function f found to be malloc" "pure-const" } } */
+/* { dg-final { scan-ipa-dump "Function bar found to be malloc" "pure-const" } } */

gcc/testsuite/gcc.dg/ipa/propmalloc-2.c

+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-ipa-pure-const-details" } */
+
+__attribute__((noinline, used, no_icf))
+static void *foo (__SIZE_TYPE__ n)
+{
+  return __builtin_malloc (n * 10);
+}
+
+__attribute__((noinline, used, no_icf))
+static void *bar(__SIZE_TYPE__ n, int cond)
+{
+  void *p;
+  if (cond)
+    p = foo (n);
+  else
+    p = __builtin_malloc (n);
+
+  return p;
+}
+
+/* { dg-final { scan-ipa-dump "Function foo found to be malloc" "pure-const" } } */
+/* { dg-final { scan-ipa-dump "Function bar found to be malloc" "pure-const" } } */

gcc/testsuite/gcc.dg/ipa/propmalloc-3.c

+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-ipa-pure-const-details" } */
+
+static void *foo(__SIZE_TYPE__, int) __attribute__((noinline, no_icf, used));
+
+__attribute__((noinline, used, no_icf))
+static void *bar(__SIZE_TYPE__ n, int m)
+{
+  return foo (n, m);
+}
+
+static void *foo(__SIZE_TYPE__ n, int m)
+{
+  void *p;
+  if (m > 0)
+    p = bar (n, --m);
+  else
+    p = __builtin_malloc (n);
+
+  return p;
+}
+
+/* { dg-final { scan-ipa-dump "Function foo found to be malloc" "pure-const" } } */
+/* { dg-final { scan-ipa-dump "Function bar found to be malloc" "pure-const" } } */