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c-common.c (decl_with_nonnull_addr_p): New function.

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./:	* c-common.c (decl_with_nonnull_addr_p): New function.
	(c_common_truthvalue_conversion): Call it.
	* c-typeck.c (build_binary_op): Likewise.
	* c-common.h (decl_with_nonnull_addr_p): Declare.
cp/:
	* typeck.c (build_binary_op): Warn about comparing a non-weak
	address to NULL.
testsuite/:
	* gcc.dg/Walways-true-1.c: New test.
	* gcc.dg/Walways-true-2.c: New test.
	* g++.dg/warn/Walways-true-1.C: New test.
	* g++.dg/warn/Walways-true-2.C: New test.

From-SVN: r120493
This commit is contained in:
Ian Lance Taylor 2007-01-05 19:05:46 +00:00 • committed by Ian Lance Taylor
parent 97af925ba7
commit b3c6d2ea00
11 changed files with 293 additions and 22 deletions
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7
gcc/ChangeLog
View file

@ -1,3 +1,10 @@
2007-01-05 Ian Lance Taylor <iant@google.com>
* c-common.c (decl_with_nonnull_addr_p): New function.
(c_common_truthvalue_conversion): Call it.
* c-typeck.c (build_binary_op): Likewise.
* c-common.h (decl_with_nonnull_addr_p): Declare.
2007-01-05 Jakub Jelinek <jakub@redhat.com>
PR c/30360

35
gcc/c-common.c
View file

@ -2591,6 +2591,18 @@ pointer_int_sum (enum tree_code resultcode, tree ptrop, tree intop)
return fold_build2 (resultcode, result_type, ptrop, intop);
}
/* Return whether EXPR is a declaration whose address can never be
NULL. */
bool
decl_with_nonnull_addr_p (tree expr)
{
return (DECL_P (expr)
&& (TREE_CODE (expr) == PARM_DECL
|| TREE_CODE (expr) == LABEL_DECL
|| !DECL_WEAK (expr)));
}
/* Prepare expr to be an argument of a TRUTH_NOT_EXPR,
or for an `if' or `while' statement or ?..: exp. It should already
have been validated to be of suitable type; otherwise, a bad
@ -2656,23 +2668,22 @@ c_common_truthvalue_conversion (tree expr)
case ADDR_EXPR:
{
tree inner = TREE_OPERAND (expr, 0);
if (DECL_P (inner)
&& (TREE_CODE (inner) == PARM_DECL
|| TREE_CODE (inner) == LABEL_DECL
|| !DECL_WEAK (inner)))
if (decl_with_nonnull_addr_p (inner))
{
/* Common Ada/Pascal programmer's mistake. We always warn
about this since it is so bad. */
warning (OPT_Walways_true, "the address of %qD will always evaluate as %<true%>",
/* Common Ada/Pascal programmer's mistake. */
warning (OPT_Walways_true,
"the address of %qD will always evaluate as %<true%>",
inner);
return truthvalue_true_node;
}
/* If we are taking the address of an external decl, it might be
zero if it is weak, so we cannot optimize. */
if (DECL_P (inner)
&& DECL_EXTERNAL (inner))
break;
/* If we still have a decl, it is possible for its address to
be NULL, so we cannot optimize. */
if (DECL_P (inner))
{
gcc_assert (DECL_WEAK (inner));
break;
}
if (TREE_SIDE_EFFECTS (inner))
return build2 (COMPOUND_EXPR, truthvalue_type_node,

1
gcc/c-common.h
View file

@ -652,6 +652,7 @@ extern tree c_common_unsigned_type (tree);
extern tree c_common_signed_type (tree);
extern tree c_common_signed_or_unsigned_type (int, tree);
extern tree c_build_bitfield_integer_type (unsigned HOST_WIDE_INT, int);
extern bool decl_with_nonnull_addr_p (tree);
extern tree c_common_truthvalue_conversion (tree);
extern void c_apply_type_quals_to_decl (int, tree);
extern tree c_sizeof_or_alignof_type (tree, bool, int);

10
gcc/c-typeck.c
View file

@ -8013,10 +8013,7 @@ build_binary_op (enum tree_code code, tree orig_op0, tree orig_op1,
else if (code0 == POINTER_TYPE && null_pointer_constant_p (orig_op1))
{
if (TREE_CODE (op0) == ADDR_EXPR
&& DECL_P (TREE_OPERAND (op0, 0))
&& (TREE_CODE (TREE_OPERAND (op0, 0)) == PARM_DECL
|| TREE_CODE (TREE_OPERAND (op0, 0)) == LABEL_DECL
|| !DECL_WEAK (TREE_OPERAND (op0, 0))))
&& decl_with_nonnull_addr_p (TREE_OPERAND (op0, 0)))
warning (OPT_Walways_true, "the address of %qD will never be NULL",
TREE_OPERAND (op0, 0));
result_type = type0;
@ -8024,10 +8021,7 @@ build_binary_op (enum tree_code code, tree orig_op0, tree orig_op1,
else if (code1 == POINTER_TYPE && null_pointer_constant_p (orig_op0))
{
if (TREE_CODE (op1) == ADDR_EXPR
&& DECL_P (TREE_OPERAND (op1, 0))
&& (TREE_CODE (TREE_OPERAND (op1, 0)) == PARM_DECL
|| TREE_CODE (TREE_OPERAND (op1, 0)) == LABEL_DECL
|| !DECL_WEAK (TREE_OPERAND (op1, 0))))
&& decl_with_nonnull_addr_p (TREE_OPERAND (op1, 0)))
warning (OPT_Walways_true, "the address of %qD will never be NULL",
TREE_OPERAND (op1, 0));
result_type = type1;

5
gcc/cp/ChangeLog
View file

@ -1,3 +1,8 @@
2007-01-05 Ian Lance Taylor <iant@google.com>
* typeck.c (build_binary_op): Warn about comparing a non-weak
address to NULL.
2007-01-05 Douglas Gregor <doug.gregor@gmail.com>
* pt.c (tsubst): Propagate the need for structural equality checks

16
gcc/cp/typeck.c
View file

@ -3334,10 +3334,22 @@ build_binary_op (enum tree_code code, tree orig_op0, tree orig_op1,
"comparison");
else if ((code0 == POINTER_TYPE || TYPE_PTRMEM_P (type0))
&& null_ptr_cst_p (op1))
result_type = type0;
{
if (TREE_CODE (op0) == ADDR_EXPR
&& decl_with_nonnull_addr_p (TREE_OPERAND (op0, 0)))
warning (OPT_Walways_true, "the address of %qD will never be NULL",
TREE_OPERAND (op0, 0));
result_type = type0;
}
else if ((code1 == POINTER_TYPE || TYPE_PTRMEM_P (type1))
&& null_ptr_cst_p (op0))
result_type = type1;
{
if (TREE_CODE (op1) == ADDR_EXPR
&& decl_with_nonnull_addr_p (TREE_OPERAND (op1, 0)))
warning (OPT_Walways_true, "the address of %qD will never be NULL",
TREE_OPERAND (op1, 0));
result_type = type1;
}
else if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
{
result_type = type0;

7
gcc/testsuite/ChangeLog
View file

@ -1,3 +1,10 @@
2007-01-05 Ian Lance Taylor <iant@google.com>
* gcc.dg/Walways-true-1.c: New test.
* gcc.dg/Walways-true-2.c: New test.
* g++.dg/warn/Walways-true-1.C: New test.
* g++.dg/warn/Walways-true-2.C: New test.
2007-01-05 Jakub Jelinek <jakub@redhat.com>
PR c/30360

57
gcc/testsuite/g++.dg/warn/Walways-true-1.C Normal file
View file

@ -0,0 +1,57 @@
// Test -Walways-true for testing an address against NULL.
// Origin: Ian Lance Taylor <iant@google.com>
// { dg-do compile}
// { dg-options "-Walways-true" }
extern int foo (int);
int i;
void
bar (int a)
{
lab:
if (foo) // { dg-warning "always evaluate as" "correct warning" }
foo (0);
if (foo (1))
;
if (&i) // { dg-warning "always evaluate as" "correct warning" }
foo (2);
if (i)
foo (3);
if (&a) // { dg-warning "always evaluate as" "correct warning" }
foo (4);
if (a)
foo (5);
if (&&lab) // { dg-warning "always evaluate as" "correct warning" }
foo (6);
if (foo == 0) // { dg-warning "never be NULL" "correct warning" }
foo (7);
if (foo (1) == 0)
foo (8);
if (&i == 0) // { dg-warning "never be NULL" "correct warning" }
foo (9);
if (i == 0)
foo (10);
if (&a == 0) // { dg-warning "never be NULL" "correct warning" }
foo (11);
if (a == 0)
foo (12);
if (&&lab == 0) // { dg-warning "never be NULL" "correct warning" }
foo (13);
if (0 == foo) // { dg-warning "never be NULL" "correct warning" }
foo (14);
if (0 == foo (1))
foo (15);
if (0 == &i) // { dg-warning "never be NULL" "correct warning" }
foo (16);
if (0 == i)
foo (17);
if (0 == &a) // { dg-warning "never be NULL" "correct warning" }
foo (18);
if (0 == a)
foo (19);
if (0 == &&lab) // { dg-warning "never be NULL" "correct warning" }
foo (20);
}

60
gcc/testsuite/g++.dg/warn/Walways-true-2.C Normal file
View file

@ -0,0 +1,60 @@
// Make sure we don't assume that a weak symbol is always non-NULL.
// This is just like Walways-true-1.C, except that it uses a weak
// symbol.
// Origin: Ian Lance Taylor <iant@google.com>
// { dg-do compile}
// { dg-options "-Walways-true" }
// { dg-require-weak "" }
extern int foo (int) __attribute__ ((weak));
int i __attribute__ ((weak));
void
bar (int a)
{
lab:
if (foo)
foo (0);
if (foo (1))
;
if (&i)
foo (2);
if (i)
foo (3);
if (&a) // { dg-warning "always evaluate as" "correct warning" }
foo (4);
if (a)
foo (5);
if (&&lab) // { dg-warning "always evaluate as" "correct warning" }
foo (6);
if (foo == 0)
foo (7);
if (foo (1) == 0)
foo (8);
if (&i == 0)
foo (9);
if (i == 0)
foo (10);
if (&a == 0) // { dg-warning "never be NULL" "correct warning" }
foo (11);
if (a == 0)
foo (12);
if (&&lab == 0) // { dg-warning "never be NULL" "correct warning" }
foo (13);
if (0 == foo)
foo (14);
if (0 == foo (1))
foo (15);
if (0 == &i)
foo (16);
if (0 == i)
foo (17);
if (0 == &a) // { dg-warning "never be NULL" "correct warning" }
foo (18);
if (0 == a)
foo (19);
if (0 == &&lab) // { dg-warning "never be NULL" "correct warning" }
foo (20);
}

57
gcc/testsuite/gcc.dg/Walways-true-1.c Normal file
View file

@ -0,0 +1,57 @@
/* Test -Walways-true for testing an address against NULL.
Origin: Ian Lance Taylor <iant@google.com>. */
/* { dg-do compile} */
/* { dg-options "-Walways-true" } */
extern int foo (int);
int i;
void
bar (int a)
{
lab:
if (foo) /* { dg-warning "always evaluate as" "correct warning" } */
foo (0);
if (foo (1))
;
if (&i) /* { dg-warning "always evaluate as" "correct warning" } */
foo (2);
if (i)
foo (3);
if (&a) /* { dg-warning "always evaluate as" "correct warning" } */
foo (4);
if (a)
foo (5);
if (&&lab) /* { dg-warning "always evaluate as" "correct warning" } */
foo (6);
if (foo == 0) /* { dg-warning "never be NULL" "correct warning" } */
foo (7);
if (foo (1) == 0)
foo (8);
if (&i == 0) /* { dg-warning "never be NULL" "correct warning" } */
foo (9);
if (i == 0)
foo (10);
if (&a == 0) /* { dg-warning "never be NULL" "correct warning" } */
foo (11);
if (a == 0)
foo (12);
if (&&lab == 0) /* { dg-warning "never be NULL" "correct warning" } */
foo (13);
if (0 == foo) /* { dg-warning "never be NULL" "correct warning" } */
foo (14);
if (0 == foo (1))
foo (15);
if (0 == &i) /* { dg-warning "never be NULL" "correct warning" } */
foo (16);
if (0 == i)
foo (17);
if (0 == &a) /* { dg-warning "never be NULL" "correct warning" } */
foo (18);
if (0 == a)
foo (19);
if (0 == &&lab) /* { dg-warning "never be NULL" "correct warning" } */
foo (20);
}

60
gcc/testsuite/gcc.dg/Walways-true-2.c Normal file
View file

@ -0,0 +1,60 @@
/* Make sure we don't assume that a weak symbol is always non-NULL.
This is just like Walways-true-1.C, except that it uses a weak
symbol.
Origin: Ian Lance Taylor <iant@google.com>. */
/* { dg-do compile} */
/* { dg-options "-Walways-true" } */
/* { dg-require-weak "" } */
extern int foo (int) __attribute__ ((weak));
int i __attribute__ ((weak));
void
bar (int a)
{
lab:
if (foo)
foo (0);
if (foo (1))
;
if (&i)
foo (2);
if (i)
foo (3);
if (&a) /* { dg-warning "always evaluate as" "correct warning" } */
foo (4);
if (a)
foo (5);
if (&&lab) /* { dg-warning "always evaluate as" "correct warning" } */
foo (6);
if (foo == 0)
foo (7);
if (foo (1) == 0)
foo (8);
if (&i == 0)
foo (9);
if (i == 0)
foo (10);
if (&a == 0) /* { dg-warning "never be NULL" "correct warning" } */
foo (11);
if (a == 0)
foo (12);
if (&&lab == 0) /* { dg-warning "never be NULL" "correct warning" } */
foo (13);
if (0 == foo)
foo (14);
if (0 == foo (1))
foo (15);
if (0 == &i)
foo (16);
if (0 == i)
foo (17);
if (0 == &a) /* { dg-warning "never be NULL" "correct warning" } */
foo (18);
if (0 == a)
foo (19);
if (0 == &&lab) /* { dg-warning "never be NULL" "correct warning" } */
foo (20);
}