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

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

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index b3d3407f17182fbbb0091b1784594315867fedf3..050aef814452be39bfae5d5dad2f381a7a450b43 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -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.

diff --git a/gcc/c/ChangeLog b/gcc/c/ChangeLog
index 957daeb4fe9979e7587c69fbf8daa2813e6a2636..e8e0fb087d349d1db598c3f8143c9c4f281c7094 100644 (file)
--- a/gcc/c/ChangeLog
+++ b/gcc/c/ChangeLog
@@ -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

diff --git a/gcc/c/c-typeck.c b/gcc/c/c-typeck.c
index f45fd3cfbbf0942aa6f048f0cef0f8dbd9197ff7..1956d45e2517a54945267b7716d0a62e9c4f9d24 100644 (file)
--- a/gcc/c/c-typeck.c
+++ b/gcc/c/c-typeck.c
@@ -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");
 

diff --git a/gcc/common.opt b/gcc/common.opt
index 1581ca885e51b5d520ef860905af9fd519ddb2c6..fa6dd845d54f5fa2563202c62db6d06b0ad05dff 100644 (file)
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -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.

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 0a3b80f451805d1a035610dbc0ee0ebb6dc6ec68..c0132251edc6c7613011593570a74f3ddabfd91f 100644 (file)
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -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,

diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c
index aa5d1288a5a0fb3693c11948b0a307beb5cfbc14..028d56ff18cde8686f72d82085ee29c8c4d929f0 100644 (file)
--- a/gcc/cp/typeck.c
+++ b/gcc/cp/typeck.c
@@ -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)
            {

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index a727d952fd2d3ce97b01a6cbc088b0d035edec3a..60650c8391762b09e7a71f11cb7b1062ecd2d35d 100644 (file)
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -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

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 303f700c451dbe9c7264ef491b53ca08bd678857..0091855e2c9607f6bce1d18938bd1168fd5cd282 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -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.

diff --git a/gcc/testsuite/c-c++-common/Wcast-align.c b/gcc/testsuite/c-c++-common/Wcast-align.c
new file mode 100644 (file)
index 0000000..fac1795
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/Wcast-align.c
@@ -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" } */
+}