builtins.c (expand_builtin_init_trampoline): If -Wtrampolines make a warning.

2010-07-15  Magnus Granberg  <zorry@gentoo.org>
	    Kevin F. Quinn  <kevquinn@gentoo.org>

        * builtins.c (expand_builtin_init_trampoline): If
	-Wtrampolines make a warning.
	* common.opt:   Add -Wtrampolines.
        * doc/invoke.texi:      Add -Wtrampolines.
testsuite/
        * gcc.dg/Wtrampolines.c: New.

Co-Authored-By: Kevin F. Quinn <kevquinn@gentoo.org>

From-SVN: r162205

gcc/ChangeLog

@@ -1,3 +1,11 @@
+2010-07-15  Magnus Granberg  <zorry@gentoo.org>
+	    Kevin F. Quinn  <kevquinn@gentoo.org>
+
+        * builtins.c (expand_builtin_init_trampoline): If
+	-Wtrampolines make a warning.
+	* common.opt:   Add -Wtrampolines.
+        * doc/invoke.texi:      Add -Wtrampolines.
+
 2010-07-15  Jie Zhang  <jie@codesourcery.com>
 
 	* config/arm/cortex-a8.md (cortex_a8_load_store_2): Reserve

gcc/builtins.c

@@ -5250,6 +5250,10 @@ expand_builtin_init_trampoline (tree exp)
   targetm.calls.trampoline_init (m_tramp, t_func, r_chain);
 
   trampolines_created = 1;
+
+  warning_at (DECL_SOURCE_LOCATION (t_func), OPT_Wtrampolines,
+              "trampoline generated for nested function %qD", t_func);
+
   return const0_rtx;
 }
 

gcc/common.opt

@@ -212,6 +212,10 @@ Wsystem-headers
 Common Var(warn_system_headers) Warning
 Do not suppress warnings from system headers
 
+Wtrampolines
+Common Var(warn_trampolines) Warning
+Warn whenever a trampoline is generated
+
 Wtype-limits
 Common Var(warn_type_limits) Init(-1) Warning
 Warn if a comparison is always true or always false due to the limited range of the data type

gcc/doc/invoke.texi

@@ -260,8 +260,8 @@ Objective-C and Objective-C++ Dialects}.
 -Wstrict-overflow -Wstrict-overflow=@var{n} @gol
 -Wsuggest-attribute=@r{[}pure@r{|}const@r{|}noreturn@r{]} @gol
 -Wswitch  -Wswitch-default  -Wswitch-enum -Wsync-nand @gol
--Wsystem-headers  -Wtrigraphs  -Wtype-limits  -Wundef  -Wuninitialized @gol
--Wunknown-pragmas  -Wno-pragmas @gol
+-Wsystem-headers  -Wtrampolines  -Wtrigraphs  -Wtype-limits  -Wundef @gol
+-Wuninitialized  -Wunknown-pragmas  -Wno-pragmas @gol
 -Wunsuffixed-float-constants  -Wunused  -Wunused-function @gol
 -Wunused-label  -Wunused-parameter -Wno-unused-result -Wunused-value  -Wunused-variable @gol
 -Wunused-but-set-parameter -Wunused-but-set-variable -Wvariadic-macros -Wvla @gol
@@ -3724,6 +3724,18 @@ code.  However, note that using @option{-Wall} in conjunction with this
 option will @emph{not} warn about unknown pragmas in system
 headers---for that, @option{-Wunknown-pragmas} must also be used.
 
+@item -Wtrampolines
+@opindex Wtrampolines
+@opindex Wno-trampolines
+ Warn about trampolines generated for pointers to nested functions.
+ 
+ A trampoline is a small piece of data or code that is created at run
+ time on the stack when the address of a nested function is taken, and
+ is used to call the nested function indirectly.  For some targets, it
+ is made up of data only and thus requires no special treatment.  But,
+ for most targets, it is made up of code and thus requires the stack
+ to be made executable in order for the program to work properly.
+
 @item -Wfloat-equal
 @opindex Wfloat-equal
 @opindex Wno-float-equal

gcc/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2010-07-15  Magnus Granberg  <zorry@gentoo.org>
+	    Kevin F. Quinn  <kevquinn@gentoo.org>
+
+        * gcc.dg/Wtrampolines.c: New.
+
 2010-07-14  Jerry DeLisle  <jvdelisle@gcc.gnu.org>
 
 	PR libfortran/44934

gcc/testsuite/gcc.dg/Wtrampolines.c

@@ -0,0 +1,57 @@
+/* Origin: trampoline-1.c Waldek Hebisch <hebisch@math.uni.wroc.pl> */
+/* Ported to test -Wtrampolines Magnus Granberg <zorry@gentoo.org> */
+
+/* { dg-do compile } */
+/* { dg-require-effective-target trampolines } */
+/* { dg-options "-O2 -Wtrampolines" } */
+
+#ifndef NO_TRAMPOLINES
+
+/* This used to fail on various versions of Solaris 2 because the
+   trampoline couldn't be made executable.  */
+
+extern void abort(void);
+extern double fabs(double);
+
+void foo (void)
+{
+  const int correct[1100] = {1, 0, -2, 0, 1, 0, 1, -1, -10, -30, -67};
+  int i;
+
+  double x1 (void) {return 1; }
+  double x2 (void) {return -1;}
+  double x3 (void) {return -1;}
+  double x4 (void) {return 1; }
+  double x5 (void) {return 0; }
+
+  typedef double pfun(void);
+
+  double a (int k, pfun x1, pfun x2, pfun x3, pfun x4, pfun x5)
+  {
+    double b (void)  /* { dg-warning "trampoline generated for nested function 'b'" } */
+    { 
+      k = k - 1;
+      return a (k, b, x1, x2, x3, x4 );
+    }
+
+    if (k <= 0)
+      return x4 () + x5 ();
+    else
+      return b ();
+  }
+
+  for (i=0; i<=10; i++)
+  {
+    if (fabs(a( i, x1, x2, x3, x4, x5 ) - correct [i]) > 0.1)
+      abort();
+  }
+}
+#endif
+
+int main (void)
+{
+#ifndef NO_TRAMPOLINES
+  foo ();
+#endif
+  return 0;
+}