re PR middle-end/56727 (Recursive call goes through the PLT unnecessarily)

2017-07-21  Yury Gribov  <tetra2005@gmail.com>

	PR middle-end/56727
	* ipa-visibility (function_and_variable_visibility): Convert
	recursive PLT call to direct call if appropriate.

	* gcc.dg/pr56727-1.c: New test.
	* gcc.dg/pr56727-2.c: New test.

From-SVN: r250442

gcc/ChangeLog

+2017-07-21  Yury Gribov  <tetra2005@gmail.com>
+
+	PR middle-end/56727
+	* ipa-visibility (function_and_variable_visibility): Convert
+	recursive PLT call to direct call if appropriate.
+
 2017-07-21  Andrew Pinski  <apinski@cavium.com>
 
 	* tree-ssa-sccvn.c (vn_nary_op_eq): Check BIT_INSERT_EXPR's

gcc/ipa-visibility.c

@@ -83,6 +83,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "cgraph.h"
 #include "calls.h"
 #include "varasm.h"
+#include "ipa-utils.h"
 
 /* Return true when NODE can not be local. Worker for cgraph_local_node_p.  */
 
@@ -617,6 +618,36 @@ function_and_variable_visibility (bool whole_program)
   /* All aliases should be procssed at this point.  */
   gcc_checking_assert (!alias_pairs || !alias_pairs->length ());
 
+  FOR_EACH_DEFINED_FUNCTION (node)
+    {
+      if (node->get_availability () != AVAIL_INTERPOSABLE
+	  || DECL_EXTERNAL (node->decl)
+	  || node->has_aliases_p ())
+	continue;
+
+      cgraph_node *alias = 0;
+      for (cgraph_edge *e = node->callees; e; e = e->next_callee)
+	{
+	  /* Recursive function calls usually can't be interposed.  */
+
+	  if (!e->recursive_p ())
+	    continue;
+
+	  if (!alias)
+	    { 
+	      alias = dyn_cast<cgraph_node *> (node->noninterposable_alias ());
+	      gcc_assert (alias && alias != node);
+	    }
+
+	  e->redirect_callee (alias);
+	  if (gimple_has_body_p (e->caller->decl))
+	    { 
+	      push_cfun (DECL_STRUCT_FUNCTION (e->caller->decl));
+	      e->redirect_call_stmt_to_callee ();
+	      pop_cfun (); 
+	    }
+	}
+    }
   FOR_EACH_FUNCTION (node)
     {
       int flags = flags_from_decl_or_type (node->decl);

gcc/testsuite/ChangeLog

+2017-07-21  Yury Gribov  <tetra2005@gmail.com>
+
+	PR middle-end/56727
+	* gcc.dg/pr56727-1.c: New test.
+	* gcc.dg/pr56727-2.c: New test.
+
 2017-07-21  Steven Munroe  <munroesj@gcc.gnu.org>
 
 	* gcc.target/powerpc/mmx-check.h: New file.

gcc/testsuite/gcc.dg/pr56727-1.c

+/* { dg-do compile { target fpic } } */
+/* { dg-options "-O2 -fPIC" } */
+/* { dg-final { scan-assembler-not "@(PLT|plt)" { target i?86-*-* x86_64-*-* powerpc*-*-* } } } */
+
+#define define_func(type) \
+  void f_ ## type (type b) { f_ ## type (0); } \
+  void __attribute__((noinline, noclone)) f_noinline_ ## type (type b) \
+  { f_noinline_ ## type (0); }
+
+define_func(char)
+define_func(short)
+define_func(int)
+define_func(long)
+
+int foo(int n)
+{
+  return (n == 1 || n == 2) ? 1 : foo(n-1) * foo(n-2);
+}
+
+int __attribute__((noinline, noclone)) foo_noinline(int n)
+{
+  return (n == 1 || n == 2) ? 1 : foo_noinline(n-1) * foo_noinline(n-2);
+}

gcc/testsuite/gcc.dg/pr56727-2.c

+/* { dg-do compile { target fpic } } */
+/* { dg-options "-O2 -fPIC" } */
+/* { dg-final { scan-assembler "@(PLT|plt)" { target i?86-*-* x86_64-*-* powerpc*-*-* } } } */
+
+__attribute__((noinline, noclone))
+void f (short b)
+{
+  f (0);
+}
+
+static void g (short) __attribute__ ((alias ("f")));
+
+void h ()
+{
+  g (0);
+}