re PR middle-end/179 (-Wuninitialized missing warning with &var)

2008-08-21  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>

	PR middle-end/179
	* tree-ssa.c (warn_uninit): Do not warn for variables that can be
	initialized outside the current module.
	(warn_uninitialized_var): Ignore left-hand side when walking the
	trees. Ignore address expressions. Examine VUSE operands in gimple
	statements with a variable declaration on the right-hand side.
testsuite/
	* gcc.dg/uninit-6.c (make_something): Remove XFAIL.
	* gcc.dg/uninit-6-O0.c (make_something): Remove XFAIL.
	* gcc.dg/uninit-B.c (baz): Remove XFAIL.
	* gcc.dg/uninit-B-2.c: New.
	* gcc.dg/uninit-B-O0-2.c: New.
	* gcc.dg/uninit-pr19430-O0.c: New.
	* gcc.dg/uninit-pr19430.c: New.
	* gcc.dg/uninit-pr19430-2.c: New.

From-SVN: r139347

gcc/ChangeLog

+2008-08-21  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>
+
+	PR middle-end/179
+	* tree-ssa.c (warn_uninit): Do not warn for variables that can be
+	initialized outside the current module.
+	(warn_uninitialized_var): Ignore left-hand side when walking the
+	trees. Ignore address expressions. Examine VUSE operands in gimple
+	statements with a variable declaration on the right-hand side.
+
 2008-08-20  Richard Sandiford  <rdsandiford@googlemail.com>
 
 	PR bootstrap/37155

gcc/testsuite/ChangeLog

+2008-08-21  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>
+
+	PR middle-end/179
+	* gcc.dg/uninit-6.c (make_something): Remove XFAIL.
+	* gcc.dg/uninit-6-O0.c (make_something): Remove XFAIL.
+	* gcc.dg/uninit-B.c (baz): Remove XFAIL.
+	* gcc.dg/uninit-B-2.c: New.
+	* gcc.dg/uninit-B-O0-2.c: New.
+	* gcc.dg/uninit-pr19430-O0.c: New.
+	* gcc.dg/uninit-pr19430.c: New.
+	* gcc.dg/uninit-pr19430-2.c: New.
+
 2008-08-20  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>
 
 	PR c++/35158

gcc/testsuite/gcc.dg/uninit-6-O0.c

@@ -39,7 +39,7 @@ make_something(int a, int b, int c)
     rv = malloc (sizeof (struct tree));
     rv->car = 0;
 
-    APPEND(rv, field, INTEGER_T, a);  /* { dg-bogus "field" "uninitialized variable warning" { xfail *-*-* } } */
+    APPEND(rv, field, INTEGER_T, a);  /* { dg-bogus "field" "uninitialized variable warning" } */
     APPEND(rv, field, PTR_T, b);
     APPEND(rv, field, INTEGER_T, c);
 

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

@@ -39,7 +39,7 @@ make_something(int a, int b, int c)
     rv = malloc (sizeof (struct tree));
     rv->car = 0;
 
-    APPEND(rv, field, INTEGER_T, a);  /* { dg-bogus "field" "uninitialized variable warning" { xfail *-*-* } } */
+    APPEND(rv, field, INTEGER_T, a);  /* { dg-bogus "field" "uninitialized variable warning" } */
     APPEND(rv, field, PTR_T, b);
     APPEND(rv, field, INTEGER_T, c);
 

gcc/testsuite/gcc.dg/uninit-B-2.c

+/* Origin: PR c/179 inverse of uninit-B-O0.c, we should not warn.  */
+/* { dg-do compile } */
+/* { dg-options "-O2 -Wuninitialized" } */
+extern void foo (int *);
+extern void bar (int);
+
+void
+baz (void)
+{
+  int i;
+  foo (&i); /* { dg-bogus "is used uninitialized" "uninit i warning" } */
+  if (i) 
+    bar (i);
+}
+
+

gcc/testsuite/gcc.dg/uninit-B-O0-2.c

+/* Origin: PR c/179 inverse of uninit-B-O0.c, we should not warn.  */
+/* { dg-do compile } */
+/* { dg-options "-O0 -Wuninitialized" } */
+extern void foo (int *);
+extern void bar (int);
+
+void
+baz (void)
+{
+  int i;
+  foo (&i); /* { dg-bogus "is used uninitialized" "uninit i warning" } */
+  if (i) 
+    bar (i);
+}
+
+

gcc/testsuite/gcc.dg/uninit-B.c

@@ -9,7 +9,7 @@ void
 baz (void)
 {
   int i;
-  if (i) /* { dg-warning "uninit" "uninit i warning" { xfail *-*-* } } */
+  if (i) /* { dg-warning "is used uninitialized" "uninit i warning" } */
     bar (i);
   foo (&i);
 }

gcc/testsuite/gcc.dg/uninit-pr19430-2.c

+/* { dg-do compile } */
+/* { dg-options "-O -Wuninitialized" } */
+
+int  *p, *q;
+
+int foo (int b)
+{
+  int i, j = 0;
+  int *x;
+  p = &i;
+  q = &j;
+  if (b)
+    x = p;
+  else
+    x = q;
+  return *x;
+}
+

gcc/testsuite/gcc.dg/uninit-pr19430-O0.c

+/* { dg-do compile } */
+/* { dg-options "-O0 -Wuninitialized" } */
+extern int bar (int);
+extern void baz (int *);
+
+int
+foo (int i)
+{
+  int j; /* { dg-warning "'j' may be used uninitialized in this function" "uninitialized" { xfail *-*-* } 9 } */
+
+  if (bar (i)) {
+    baz (&j);
+  } else {
+  }
+
+  return j;
+}
+
+
+int foo2( void ) {
+  int rc;  /* { dg-warning "'rc' is used uninitialized in this function" "uninitialized" { xfail *-*-* } 21 } */
+  return rc;
+  *&rc = 0;
+}
+
+extern int printf(const char *, ...);
+void frob(int *pi);
+
+int main(void)
+{
+  int i; 
+  printf("i = %d\n", i); /* { dg-warning "'i' is used uninitialized in this function" "uninitialized" { xfail *-*-* } 32 } */
+  frob(&i);
+
+  return 0;
+}
+
+void foo3(int*);
+void bar3(void) { 
+  int x; 
+  if(x) /* { dg-warning "'x' is used uninitialized in this function" "uninitialized" { xfail *-*-* } 41 } */
+    foo3(&x); 
+}

gcc/testsuite/gcc.dg/uninit-pr19430.c

+/* { dg-do compile } */
+/* { dg-options "-O -Wuninitialized" } */
+extern int bar (int);
+extern void baz (int *);
+int
+foo (int i)
+{
+  int j; /* { dg-warning "'j' may be used uninitialized in this function" "uninitialized" { xfail *-*-* } 8 } */
+
+  if (bar (i)) { 
+    baz (&j);
+  } else {
+  }
+
+  return j;
+}
+
+
+
+int foo2( void ) {
+  int rc;  /* { dg-warning "'rc' is used uninitialized in this function" } */
+  return rc;
+  *&rc = 0;
+}
+
+extern int printf(const char *, ...);
+void frob(int *pi);
+
+int main(void)
+{
+  int i; 
+  printf("i = %d\n", i); /* { dg-warning "'i' is used uninitialized in this function" } */
+  frob(&i);
+
+  return 0;
+}
+
+void foo3(int*);
+void bar3(void) { 
+  int x; 
+  if(x) /* { dg-warning "'x' is used uninitialized in this function" "uninitialized" } */
+    foo3(&x); 
+}

gcc/tree-ssa.c

@@ -1411,6 +1411,10 @@ warn_uninit (tree t, const char *gmsgid, void *data)
   if (TREE_NO_WARNING (var))
     return;
 
+  /* Do not warn if it can be initialized outside this module.  */
+  if (is_global_var (var))
+    return;
+  
   location = (context != NULL && gimple_has_location (context))
 	     ? gimple_location (context)
 	     : DECL_SOURCE_LOCATION (var);
@@ -1443,8 +1447,46 @@ warn_uninitialized_var (tree *tp, int *walk_subtrees, void *data_)
   struct walk_data *data = (struct walk_data *) wi->info;
   tree t = *tp;
 
+  /* We do not care about LHS.  */
+  if (wi->is_lhs)
+    return NULL_TREE;
+
   switch (TREE_CODE (t))
     {
+    case ADDR_EXPR:
+      /* Taking the address of an uninitialized variable does not
+	 count as using it.  */
+      *walk_subtrees = 0;
+      break;
+
+    case VAR_DECL:
+      {
+	/* A VAR_DECL in the RHS of a gimple statement may mean that
+	   this variable is loaded from memory.  */
+	use_operand_p vuse;
+	tree op;
+
+	/* If there is not gimple stmt, 
+	   or alias information has not been computed,
+	   then we cannot check VUSE ops.  */
+	if (data->stmt == NULL
+            || !gimple_aliases_computed_p (cfun))
+	  return NULL_TREE;
+
+	vuse = SINGLE_SSA_USE_OPERAND (data->stmt, SSA_OP_VUSE);
+	if (vuse == NULL_USE_OPERAND_P)
+	    return NULL_TREE;
+
+	op = USE_FROM_PTR (vuse);
+	if (t != SSA_NAME_VAR (op) 
+	    || !SSA_NAME_IS_DEFAULT_DEF (op))
+	  return NULL_TREE;
+	/* If this is a VUSE of t and it is the default definition,
+	   then warn about op.  */
+	t = op;
+	/* Fall through into SSA_NAME.  */
+      }
+
     case SSA_NAME:
       /* We only do data flow with SSA_NAMEs, so that's all we
 	 can warn about.  */