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common.opt (Wcast-align=strict): New warning option.

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2017-09-15  Bernd Edlinger  <bernd.edlinger@hotmail.de>

        * common.opt (Wcast-align=strict): New warning option.
        * doc/invoke.texi: Document -Wcast-align=strict.

c:
2017-09-15  Bernd Edlinger  <bernd.edlinger@hotmail.de>

        * c-typeck.c (build_c_cast): Implement -Wcast-align=strict.

cp:
2017-09-15  Bernd Edlinger  <bernd.edlinger@hotmail.de>

        * typeck.c (build_reinterpret_cast_1,
        build_const_cast_1): Implement -Wcast-align=strict.

testsuite:
2017-09-15  Bernd Edlinger  <bernd.edlinger@hotmail.de>

        * c-c++-common/Wcast-align.c: New test.

From-SVN: r252832
This commit is contained in:
Bernd Edlinger 2017-09-15 17:21:50 +00:00 • committed by Bernd Edlinger
parent 4a8ca690b0
commit 1d9335766d
9 changed files with 69 additions and 7 deletions
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5
gcc/ChangeLog
View file

@ -1,3 +1,8 @@
2017-09-15 Bernd Edlinger <bernd.edlinger@hotmail.de>
* common.opt (Wcast-align=strict): New warning option.
* doc/invoke.texi: Document -Wcast-align=strict.
2017-09-15 Pierre-Marie de Rodat <derodat@adacore.com>
* cgraph.h (cgraph_thunk_info): Add comments.

4
gcc/c/ChangeLog
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@ -1,3 +1,7 @@
2017-09-15 Bernd Edlinger <bernd.edlinger@hotmail.de>
* c-typeck.c (build_c_cast): Implement -Wcast-align=strict.
2017-09-13 Marek Polacek <polacek@redhat.com>
PR c/82167

5
gcc/c/c-typeck.c
View file

@ -5578,7 +5578,7 @@ build_c_cast (location_t loc, tree type, tree expr)
}
/* Warn about possible alignment problems. */
if (STRICT_ALIGNMENT
if ((STRICT_ALIGNMENT || warn_cast_align == 2)
&& TREE_CODE (type) == POINTER_TYPE
&& TREE_CODE (otype) == POINTER_TYPE
&& TREE_CODE (TREE_TYPE (otype)) != VOID_TYPE
@ -5587,7 +5587,8 @@ build_c_cast (location_t loc, tree type, tree expr)
restriction is unknown. */
&& !(RECORD_OR_UNION_TYPE_P (TREE_TYPE (otype))
&& TYPE_MODE (TREE_TYPE (otype)) == VOIDmode)
&& TYPE_ALIGN (TREE_TYPE (type)) > TYPE_ALIGN (TREE_TYPE (otype)))
&& min_align_of_type (TREE_TYPE (type))
> min_align_of_type (TREE_TYPE (otype)))
warning_at (loc, OPT_Wcast_align,
"cast increases required alignment of target type");

4
gcc/common.opt
View file

@ -566,6 +566,10 @@ Wcast-align
Common Var(warn_cast_align) Warning
Warn about pointer casts which increase alignment.
Wcast-align=strict
Common Var(warn_cast_align,2) Warning
Warn about pointer casts which increase alignment.
Wcpp
Common Var(warn_cpp) Init(1) Warning
Warn when a #warning directive is encountered.

5
gcc/cp/ChangeLog
View file

@ -1,3 +1,8 @@
2017-09-15 Bernd Edlinger <bernd.edlinger@hotmail.de>
* typeck.c (build_reinterpret_cast_1,
build_const_cast_1): Implement -Wcast-align=strict.
2017-09-15 Jakub Jelinek <jakub@redhat.com>
* decl.c (redeclaration_error_message): Use cxx17 instead of cxx1z,

17
gcc/cp/typeck.c
View file

@ -7265,15 +7265,16 @@ build_reinterpret_cast_1 (tree type, tree expr, bool c_cast_p,
complain))
return error_mark_node;
/* Warn about possible alignment problems. */
if (STRICT_ALIGNMENT && warn_cast_align
&& (complain & tf_warning)
if ((STRICT_ALIGNMENT || warn_cast_align == 2)
&& (complain & tf_warning)
&& !VOID_TYPE_P (type)
&& TREE_CODE (TREE_TYPE (intype)) != FUNCTION_TYPE
&& COMPLETE_TYPE_P (TREE_TYPE (type))
&& COMPLETE_TYPE_P (TREE_TYPE (intype))
&& TYPE_ALIGN (TREE_TYPE (type)) > TYPE_ALIGN (TREE_TYPE (intype)))
&& min_align_of_type (TREE_TYPE (type))
> min_align_of_type (TREE_TYPE (intype)))
warning (OPT_Wcast_align, "cast from %qH to %qI "
"increases required alignment of target type", intype, type);
"increases required alignment of target type", intype, type);
/* We need to strip nops here, because the front end likes to
create (int *)&a for array-to-pointer decay, instead of &a[0]. */
@ -7447,6 +7448,14 @@ build_const_cast_1 (tree dst_type, tree expr, tsubst_flags_t complain,
the user is making a potentially unsafe cast. */
check_for_casting_away_constness (src_type, dst_type,
CAST_EXPR, complain);
/* ??? comp_ptr_ttypes_const ignores TYPE_ALIGN. */
if ((STRICT_ALIGNMENT || warn_cast_align == 2)
&& (complain & tf_warning)
&& min_align_of_type (TREE_TYPE (dst_type))
> min_align_of_type (TREE_TYPE (src_type)))
warning (OPT_Wcast_align, "cast from %qH to %qI "
"increases required alignment of target type",
src_type, dst_type);
}
if (reference_type)
{

9
gcc/doc/invoke.texi
View file

@ -266,7 +266,8 @@ Objective-C and Objective-C++ Dialects}.
-Wno-attributes -Wbool-compare -Wbool-operation @gol
-Wno-builtin-declaration-mismatch @gol
-Wno-builtin-macro-redefined -Wc90-c99-compat -Wc99-c11-compat @gol
-Wc++-compat -Wc++11-compat -Wc++14-compat -Wcast-align -Wcast-qual @gol
-Wc++-compat -Wc++11-compat -Wc++14-compat @gol
-Wcast-align -Wcast-align=strict -Wcast-qual @gol
-Wchar-subscripts -Wchkp -Wcatch-value -Wcatch-value=@var{n} @gol
-Wclobbered -Wcomment -Wconditionally-supported @gol
-Wconversion -Wcoverage-mismatch -Wno-cpp -Wdangling-else -Wdate-time @gol
@ -5931,6 +5932,12 @@ target is increased. For example, warn if a @code{char *} is cast to
an @code{int *} on machines where integers can only be accessed at
two- or four-byte boundaries.
@item -Wcast-align=strict
@opindex Wcast-align=strict
Warn whenever a pointer is cast such that the required alignment of the
target is increased. For example, warn if a @code{char *} is cast to
an @code{int *} regardless of the target machine.
@item -Wwrite-strings
@opindex Wwrite-strings
@opindex Wno-write-strings

4
gcc/testsuite/ChangeLog
View file

@ -1,3 +1,7 @@
2017-09-15 Bernd Edlinger <bernd.edlinger@hotmail.de>
* c-c++-common/Wcast-align.c: New test.
2017-09-15 Eric Botcazou <ebotcazou@adacore.com>
* g++.dg/sso-1.C: New test.

23
gcc/testsuite/c-c++-common/Wcast-align.c Normal file
View file

@ -0,0 +1,23 @@
/* { dg-do compile } */
/* { dg-options "-Wcast-align=strict" } */
typedef char __attribute__ ((__aligned__(__BIGGEST_ALIGNMENT__))) c;
typedef struct __attribute__ ((__aligned__(__BIGGEST_ALIGNMENT__)))
{
char x;
} d;
char *x;
c *y;
d *z;
struct s { long long x; } *p;
struct t { double x; } *q;
void
foo (void)
{
y = (c *) x; /* { dg-warning "alignment" } */
z = (d *) x; /* { dg-warning "alignment" } */
(long long *) p; /* { dg-bogus "alignment" } */
(double *) q; /* { dg-bogus "alignment" } */
}