re PR tree-optimization/83648 (missing -Wsuggest-attribute=malloc on a trivial malloc-like function)

2018-05-15  Prathamesh Kulkarni  <prathamesh.kulkarni@linaro.org>

	PR tree-optimization/83648
	* ipa-pure-const.c (malloc_candidate_p): Allow function with NULL
	return value as malloc candidate.

testsuite/
	* gcc.dg/tree-ssa/pr83648.c: New test.
	* gcc.dg/tree-ssa/pr83648-2.c: Likewise.

From-SVN: r260250

5 files changed, 56 insertions, 6 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 294a937..17f2cfd 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,11 @@
 2018-05-15  Prathamesh Kulkarni  <prathamesh.kulkarni@linaro.org>
 
+	PR tree-optimization/83648
+	* ipa-pure-const.c (malloc_candidate_p): Allow function with NULL
+	return value as malloc candidate.
+
+2018-05-15  Prathamesh Kulkarni  <prathamesh.kulkarni@linaro.org>
+
 	PR ipa/85734
 	* ipa-pure-const.c (warn_function_malloc): Pass value of known_finite param
 	as true in call to suggest_attribute.
diff --git a/gcc/ipa-pure-const.c b/gcc/ipa-pure-const.c
index 7665358..567b615 100644
--- a/gcc/ipa-pure-const.c
+++ b/gcc/ipa-pure-const.c
@@ -919,11 +919,13 @@ malloc_candidate_p (function *fun, bool ipa)
 #define DUMP_AND_RETURN(reason)  \
 {  \
   if (dump_file && (dump_flags & TDF_DETAILS))  \
-    fprintf (dump_file, "%s", (reason));  \
+    fprintf (dump_file, "\n%s is not a malloc candidate, reason: %s\n", \
+	     (node->name()), (reason));  \
   return false;  \
 }
 
-  if (EDGE_COUNT (exit_block->preds) == 0)
+  if (EDGE_COUNT (exit_block->preds) == 0
+      || !flag_delete_null_pointer_checks)
     return false;
 
   FOR_EACH_EDGE (e, ei, exit_block->preds)
@@ -938,6 +940,9 @@ malloc_candidate_p (function *fun, bool ipa)
       if (!retval)
 	DUMP_AND_RETURN("No return value.")
 
+      if (integer_zerop (retval))
+	continue;
+
       if (TREE_CODE (retval) != SSA_NAME
 	  || TREE_CODE (TREE_TYPE (retval)) != POINTER_TYPE)
 	DUMP_AND_RETURN("Return value is not SSA_NAME or not a pointer type.")
@@ -970,11 +975,14 @@ malloc_candidate_p (function *fun, bool ipa)
 	for (unsigned i = 0; i < gimple_phi_num_args (phi); ++i)
 	  {
 	    tree arg = gimple_phi_arg_def (phi, i);
+	    if (integer_zerop (arg))
+	      continue;
+
 	    if (TREE_CODE (arg) != SSA_NAME)
-	      DUMP_AND_RETURN("phi arg is not SSA_NAME.")
-	    if (!(arg == null_pointer_node || check_retval_uses (arg, phi)))
-	      DUMP_AND_RETURN("phi arg has uses outside phi"
-			      " and comparisons against 0.")
+	      DUMP_AND_RETURN ("phi arg is not SSA_NAME.");
+	    if (!check_retval_uses (arg, phi))
+	      DUMP_AND_RETURN ("phi arg has uses outside phi"
+			       " and comparisons against 0.")
 
 	    gimple *arg_def = SSA_NAME_DEF_STMT (arg);
 	    gcall *call_stmt = dyn_cast<gcall *> (arg_def);
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 452e6a2..90839ae 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2018-05-15  Prathamesh Kulkarni  <prathamesh.kulkarni@linaro.org>
+
+	PR tree-optimization/83648
+	* gcc.dg/tree-ssa/pr83648.c: New test.
+	* gcc.dg/tree-ssa/pr83648-2.c: Likewise.
+
 2018-05-14  Prathamesh Kulkarni  <prathamesh.kulkarni@linaro.org>
 
 	PR ipa/85734
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr83648-2.c b/gcc/testsuite/gcc.dg/tree-ssa/pr83648-2.c
new file mode 100644
index 0000000..ffa7e46
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr83648-2.c
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fno-delete-null-pointer-checks -fdump-tree-local-pure-const-details" } */
+
+void *g(unsigned n)
+{
+  return n ? __builtin_malloc (n) : 0;
+}
+
+void *h()
+{
+  return 0;
+}
+
+/* { dg-final { scan-tree-dump-not "Function found to be malloc: g" "local-pure-const1" } } */
+/* { dg-final { scan-tree-dump-not "Function found to be malloc: h" "local-pure-const1" } } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr83648.c b/gcc/testsuite/gcc.dg/tree-ssa/pr83648.c
new file mode 100644
index 0000000..febfd7d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr83648.c
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-local-pure-const-details" } */
+
+void *g(unsigned n)
+{
+  return n ? __builtin_malloc (n) : 0;
+}
+
+void *h()
+{
+  return 0;
+}
+
+/* { dg-final { scan-tree-dump "Function found to be malloc: g" "local-pure-const1" } } */
+/* { dg-final { scan-tree-dump "Function found to be malloc: h" "local-pure-const1" } } */