invoke.texi: Remove the documentation about option -Wunreachable-code.

2010-01-05  Eric Fisher  <joefoxreal@gmail.com>

	* doc/invoke.texi: Remove the documentation about option
	-Wunreachable-code.
	* common.opt (Wunreachable-code):  Preserved for backward
	compatibility.
	* tree-cfg.c: Remove the implementation of -Wunreachable-code.
	* opts.c (common_handle_option): Add OPT_Wunreachable_code to
	the backward compatibility flag section.

	* gcc.dg/pr12603.c: Remove -Wunreachable-code from dg-options.
	* gcc.dg/Wunreachable-1.c: Remove the testcase of
	-Wunreachable-code.
	* gcc.dg/Wunreachable-2.c: Likewise.
	* gcc.dg/Wunreachable-3.c: Likewise.
	* gcc.dg/Wunreachable-4.c: Likewise.
	* gcc.dg/Wunreachable-5.c: Likewise.
	* gcc.dg/Wunreachable-6.c: Likewise.
	* gcc.dg/Wunreachable-7.c: Likewise.
	* gcc.dg/Wunreachable-8.c: Likewise.
	* gcc.dg/20041231-1.c: Likewise.

From-SVN: r155645

gcc/ChangeLog

+2010-01-05  Eric Fisher  <joefoxreal@gmail.com>
+
+	* doc/invoke.texi: Remove the documentation about option
+	-Wunreachable-code.
+	* common.opt (Wunreachable-code):  Preserved for backward
+	compatibility.
+	* tree-cfg.c: Remove the implementation of -Wunreachable-code.
+	* opts.c (common_handle_option): Add OPT_Wunreachable_code to
+	the backward compatibility flag section.
+
 2010-01-05  Richard Guenther  <rguenther@suse.de>
 
 	* tree-ssa-pre.c (bitmap_value_insert_into_set): Optimize.

gcc/common.opt

@@ -201,8 +201,8 @@ Common Var(warn_uninitialized) Init(-1) Warning
 Warn about uninitialized automatic variables
 
 Wunreachable-code
-Common Var(warn_notreached) Warning
-Warn about code that will never be executed
+Common
+Does nothing. Preserved for backward compatibility.
 
 Wunused
 Common Var(warn_unused) Init(0) Warning

gcc/doc/invoke.texi

@@ -259,7 +259,7 @@ Objective-C and Objective-C++ Dialects}.
 -Wstrict-overflow -Wstrict-overflow=@var{n} @gol
 -Wswitch  -Wswitch-default  -Wswitch-enum -Wsync-nand @gol
 -Wsystem-headers  -Wtrigraphs  -Wtype-limits  -Wundef  -Wuninitialized @gol
--Wunknown-pragmas  -Wno-pragmas -Wunreachable-code @gol
+-Wunknown-pragmas  -Wno-pragmas @gol
 -Wunsuffixed-float-constants  -Wunused  -Wunused-function @gol
 -Wunused-label  -Wunused-parameter -Wno-unused-result -Wunused-value  -Wunused-variable @gol
 -Wvariadic-macros -Wvla @gol
@@ -4192,29 +4192,6 @@ cases where multiple declaration is valid and changes nothing.
 @opindex Wno-nested-externs
 Warn if an @code{extern} declaration is encountered within a function.
 
-@item -Wunreachable-code
-@opindex Wunreachable-code
-@opindex Wno-unreachable-code
-Warn if the compiler detects that code will never be executed.
-
-This option is intended to warn when the compiler detects that at
-least a whole line of source code will never be executed, because
-some condition is never satisfied or because it is after a
-procedure that never returns.
-
-It is possible for this option to produce a warning even though there
-are circumstances under which part of the affected line can be executed,
-so care should be taken when removing apparently-unreachable code.
-
-For instance, when a function is inlined, a warning may mean that the
-line is unreachable in only one inlined copy of the function.
-
-This option is not made part of @option{-Wall} because in a debugging
-version of a program there is often substantial code which checks
-correct functioning of the program and is, hopefully, unreachable
-because the program does work.  Another common use of unreachable
-code is to provide behavior which is selectable at compile-time.
-
 @item -Winline
 @opindex Winline
 @opindex Wno-inline

gcc/opts.c

@@ -2131,6 +2131,7 @@ common_handle_option (size_t scode, const char *arg, int value,
     case OPT_fforce_addr:
     case OPT_ftree_salias:
     case OPT_ftree_store_ccp:
+    case OPT_Wunreachable_code:
       /* These are no-ops, preserved for backward compatibility.  */
       break;
 

gcc/testsuite/ChangeLog

+2010-01-05  Eric Fisher  <joefoxreal@gmail.com>
+
+	* gcc.dg/pr12603.c: Remove -Wunreachable-code from dg-options.
+	* gcc.dg/Wunreachable-1.c: Remove the testcase of
+	-Wunreachable-code.
+	* gcc.dg/Wunreachable-2.c: Likewise.
+	* gcc.dg/Wunreachable-3.c: Likewise.
+	* gcc.dg/Wunreachable-4.c: Likewise.
+	* gcc.dg/Wunreachable-5.c: Likewise.
+	* gcc.dg/Wunreachable-6.c: Likewise.
+	* gcc.dg/Wunreachable-7.c: Likewise.
+	* gcc.dg/Wunreachable-8.c: Likewise.
+	* gcc.dg/20041231-1.c: Likewise.
+
 2010-01-05  Jakub Jelinek  <jakub@redhat.com>
 
 	PR other/42611

gcc/testsuite/gcc.dg/20041231-1.c

-/* PR17544 Incorrect -Wunreachable-code warning
-   Origin: Giovanni Bajo
-
-   In C99 we append a "return 0;" when finishing a function, but it was
-   not given a source location.  The gimplifier thinks a return statement
-   needs a locus so it would add one, making the compiler generated code
-   visible to the unreachable code warning.  */
-
-/* { dg-do compile } */
-/* { dg-options "-std=c99 -O -Wunreachable-code" } */
-
-int main (void)    // 1
-{                  // 2
-  return 0;        // 3
-}                  // 4

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

-/* { dg-do compile } */
-/* { dg-options "-O2 -Wunreachable-code" } */
-
-extern void foo (void);
-extern void baz (void);
-
-void bar (int i)
-{
-  if (i < 2)
-    {
-      baz ();
-      return;
-    }
-  else
-    {
-      if (i >= 4 && i <= 5)
-        foo ();
-      return;
-    }
-
-  baz ();	/* { dg-warning "will never be executed" "" } */
-  baz ();
-  baz ();
-}

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

-/* { dg-do compile } */
-/* { dg-options "-O2 -Wunreachable-code" } */
-
-extern int foo (const char *);
-extern void baz (void);
-const char *a[] = { "one", "two" };
-
-void bar (void)
-{
-  int i;
-
-  for (i = 0; i < 2; i++)  /* { dg-bogus "will never be executed" "" { xfail *-*-* } } */
-    if (! foo (a[i]))  /* { dg-bogus "will never be executed" "" { xfail *-*-* } } */
-      return;
-
-  baz ();	/* { dg-bogus "will never be executed" } */
-  baz ();
-  baz ();
-}

gcc/testsuite/gcc.dg/Wunreachable-3.c

-/* PR c/10175 */
-/* { dg-do compile } */
-/* { dg-options "-Wunreachable-code" } */
-
-int i,j;
-int main(void)
-{
-  if (0) {
-    i = 0;		   /* { dg-warning "will never be executed" "" } */
-    j = 0;
-  } else {
-    i = 1;
-    j = 1;
-  }
-
-  return 0;
-}

gcc/testsuite/gcc.dg/Wunreachable-4.c

-/* PR middle-end/10336 */
-/* { dg-options "-Wunreachable-code" } */
-
-void foo(int i)
-{
-  switch(i) {
-    case 0:
-      break;
-    case 1:
-      break;
-  }
-}

gcc/testsuite/gcc.dg/Wunreachable-5.c

-/* PR c/10175 */
-
-/* { dg-do compile } */
-/* { dg-options "-Wunreachable-code" } */
-
-int value;
-
-int main(void)
-{
-    if (0)
-        value = 0;  /* { dg-warning "will never be executed" "" } */
-    else
-        value = 1;
-
-    return 0;
-}
-

gcc/testsuite/gcc.dg/Wunreachable-6.c

-/* PR c/11370  */
-/* { dg-do compile } */
-/* { dg-options "-Wunreachable-code" } */
-
-extern int printf (const char *, ...);
-extern void exit (int);
-
-int main(int argc, char *argv[])
-{
-  if (argc != 1)
-    exit(1);
-
-  {
-    int ix;  /* { dg-bogus "will never be executed" } */
-    ix = printf("hello\n");
-    printf("%d\n", ix);
-  }
-
-  return 0;
-}
-

gcc/testsuite/gcc.dg/Wunreachable-7.c

-/* PR c/11370  */
-/* { dg-do compile } */
-/* { dg-options "-O2 -Wunreachable-code" } */
-
-extern int printf (const char *, ...);
-extern void exit (int);
-
-int main(int argc, char *argv[])
-{
-  if (argc != 1)
-    exit(1);
-
-  {
-    int ix;  /* { dg-bogus "will never be executed" } */
-    ix = printf("hello\n");
-    printf("%d\n", ix);
-  }
-
-  return 0;
-}
-

gcc/testsuite/gcc.dg/Wunreachable-8.c

-/* { dg-do compile } */
-/* { dg-options "-O2 -Wunreachable-code" } */
-float Factorial(float X)
-{
-  float val = 1.0;
-  int k,j;
-  for (k=1; k < 5; k++) /* { dg-bogus "will never be executed" "" { xfail *-*-* } } */
-    {
-      val += 1.0; /* { dg-bogus "will never be executed" "" { xfail *-*-* } } */
-    }
-  return (val); /* { dg-bogus "will never be executed" } */
-}
-
-int main (void)
-{
-  float result;
-  result=Factorial(2.1);
-  return (0);
-}
-

gcc/testsuite/gcc.dg/pr12603.c

 /* PR 12603: No return statement warning on function that never returns with -O3. */
 /* { dg-do compile } */
-/* { dg-options "-O3 -Wall -Wextra -Wreturn-type -Wunreachable-code" } */
+/* { dg-options "-O3 -Wall -Wextra -Wreturn-type" } */
 int
 this_function_never_returns ()
 {

gcc/tree-cfg.c

@@ -1760,7 +1760,6 @@ static void
 remove_bb (basic_block bb)
 {
   gimple_stmt_iterator i;
-  source_location loc = UNKNOWN_LOCATION;
 
   if (dump_file)
     {
@@ -1830,24 +1829,9 @@ remove_bb (basic_block bb)
 	    i = gsi_last_bb (bb);
 	  else
 	    gsi_prev (&i);
-
-	  /* Don't warn for removed gotos.  Gotos are often removed due to
-	     jump threading, thus resulting in bogus warnings.  Not great,
-	     since this way we lose warnings for gotos in the original
-	     program that are indeed unreachable.  */
-	  if (gimple_code (stmt) != GIMPLE_GOTO
-	      && gimple_has_location (stmt))
-	    loc = gimple_location (stmt);
 	}
     }
 
-  /* If requested, give a warning that the first statement in the
-     block is unreachable.  We walk statements backwards in the
-     loop above, so the last statement we process is the first statement
-     in the block.  */
-  if (loc > BUILTINS_LOCATION && LOCATION_LINE (loc) > 0)
-    warning_at (loc, OPT_Wunreachable_code, "will never be executed");
-
   remove_phi_nodes_and_edges_for_unreachable_block (bb);
   bb->il.gimple = NULL;
 }