C/C++: Add -Waddress-of-packed-memberhjl/pr51628/master

When address of packed member of struct or union is taken, it may result
in an unaligned pointer value.  This patch adds -Waddress-of-packed-member
to warn it:

$ cat x.i
struct pair_t
{
  char c;
  int i;
} __attribute__ ((packed));

extern struct pair_t p;
int *addr = &p.i;
$ gcc -O2 -S x.i
x.i:8:13: warning: initialization of 'int *' from address of packed member of 'struct pair_t' may result in an unaligned pointer value [-Waddress-of-packed-member]
 int *addr = &p.i;
             ^
$

This warning is enabled by default.

gcc/c/

	PR c/51628
	* doc/invoke.texi: Document -Wno-address-of-packed-member.

gcc/c-family/

	PR c/51628
	* c-common.h (warn_for_address_of_packed_member): New.
	* c-warn.c (warn_for_address_of_packed_member): New function.
	* c.opt: Add -Wno-address-of-packed-member.

gcc/c/

	PR c/51628
	* c-typeck.c (convert_for_assignment): Call
	warn_for_address_of_packed_member.  Issue an warning if address
	of packed member is taken.

gcc/cp/

	PR c/51628
	* call.c (convert_for_arg_passing): Call
	warn_for_address_of_packed_member.  Issue an warning if address
	of packed member is taken.
	* typeck.c (convert_for_assignment): Likewise.

gcc/testsuite/

	PR c/51628
	* c-c++-common/pr51628-1.c: New tests.
	* c-c++-common/pr51628-10.c: Likewise.
	* c-c++-common/pr51628-2.c: Likewise.
	* c-c++-common/pr51628-3.c: Likewise.
	* c-c++-common/pr51628-4.c: Likewise.
	* c-c++-common/pr51628-5.c: Likewise.
	* c-c++-common/pr51628-6.c: Likewise.
	* c-c++-common/pr51628-7.c: Likewise.
	* c-c++-common/pr51628-8.c: Likewise.
	* c-c++-common/pr51628-9.c: Likewise.
	* gcc.dg/pr51628-10.c: Likewise.
	* gcc.dg/pr51628-11.c: Likewise.
	* c-c++-common/ubsan/align-10.c: Add -Wno-address-of-packed-member.
	* c-c++-common/ubsan/align-2.c: Likewise.
	* c-c++-common/ubsan/align-4.c: Likewise.
	* c-c++-common/ubsan/align-6.c: Likewise.
	* c-c++-common/ubsan/align-7.c: Likewise.
	* c-c++-common/ubsan/align-8.c: Likewise.
	* g++.dg/ubsan/align-2.C: Likewise.
	* gcc.target/i386/avx512bw-vmovdqu16-2.c: Likewise.
	* gcc.target/i386/avx512f-vmovdqu32-2.c: Likewise.
	* gcc.target/i386/avx512f-vmovdqu64-2.c: Likewise.
	* gcc.target/i386/avx512vl-vmovdqu16-2.c: Likewise.
	* gcc.target/i386/avx512vl-vmovdqu32-2.c: Likewise.
	* gcc.target/i386/avx512vl-vmovdqu64-2.c: Likewise.

16 files changed, 329 insertions, 6 deletions

diff --git a/gcc/testsuite/c-c++-common/pr51628-1.c b/gcc/testsuite/c-c++-common/pr51628-1.c
new file mode 100644
index 00000000000..5324f9cc964
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/pr51628-1.c
@@ -0,0 +1,29 @@
+/* PR c/51628.  */
+/* { dg-do compile } */
+/* { dg-options "-O" } */
+
+struct pair_t
+{
+  int x;
+  int i;
+} __attribute__((packed, aligned (4)));
+
+extern struct pair_t p;
+extern int *x;
+extern void bar (int *);
+
+int *addr = &p.i;
+
+int *
+foo (void)
+{
+  struct pair_t arr[2] = { { 1, 10 }, { 2, 20 } };
+  int *p0, *p1;
+  p0 = &arr[0].i;
+  bar (p0);
+  p1 = &arr[1].i;
+  bar (p1);
+  bar (&p.i);
+  x = &p.i;
+  return &p.i;
+}
diff --git a/gcc/testsuite/c-c++-common/pr51628-10.c b/gcc/testsuite/c-c++-common/pr51628-10.c
new file mode 100644
index 00000000000..085fe1608c4
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/pr51628-10.c
@@ -0,0 +1,24 @@
+/* PR c/51628.  */
+/* { dg-do run { target int128 } } */
+/* { dg-options "-O2" } */
+
+struct pair_t
+{
+  char c;
+  __int128_t i;
+} __attribute__ ((packed));
+
+typedef struct unaligned_int128_t_
+{
+  __int128_t value;
+} __attribute__((packed)) unaligned_int128_t;
+
+struct pair_t p = {0, 1};
+unaligned_int128_t *addr = (unaligned_int128_t *) &p.i;
+
+int 
+main() 
+{
+  addr->value = ~(__int128_t)0;
+  return (p.i != 1) ? 0 : 1;
+}
diff --git a/gcc/testsuite/c-c++-common/pr51628-2.c b/gcc/testsuite/c-c++-common/pr51628-2.c
new file mode 100644
index 00000000000..abfb84ddd05
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/pr51628-2.c
@@ -0,0 +1,29 @@
+/* PR c/51628.  */
+/* { dg-do compile } */
+/* { dg-options "-O" } */
+
+struct pair_t
+{
+  int x;
+  int i;
+} __attribute__((packed, aligned (8)));
+
+extern struct pair_t p;
+extern int *x;
+extern void bar (int *);
+
+int *addr = &p.i;
+
+int *
+foo (void)
+{
+  struct pair_t arr[2] = { { 1, 10 }, { 2, 20 } };
+  int *p0, *p1;
+  p0 = &arr[0].i;
+  bar (p0);
+  p1 = &arr[1].i;
+  bar (p1);
+  bar (&p.i);
+  x = &p.i;
+  return &p.i;
+}
diff --git a/gcc/testsuite/c-c++-common/pr51628-3.c b/gcc/testsuite/c-c++-common/pr51628-3.c
new file mode 100644
index 00000000000..0ea94c845a0
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/pr51628-3.c
@@ -0,0 +1,35 @@
+/* PR c/51628.  */
+/* { dg-do compile } */
+/* { dg-options "-O" } */
+
+struct pair_t
+{
+  int x;
+  int i;
+} __attribute__((packed, aligned (2)));
+
+extern struct pair_t p;
+extern int *x;
+extern void bar (int *);
+
+int *addr = &p.i;
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+
+int *
+foo (void)
+{
+  struct pair_t arr[2] = { { 1, 10 }, { 2, 20 } };
+  int *p0, *p1;
+  p0 = &arr[0].i;
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+  bar (p0);
+  p1 = &arr[1].i;
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+  bar (p1);
+  bar (&p.i);
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+  x = &p.i;
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+  return &p.i;
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+}
diff --git a/gcc/testsuite/c-c++-common/pr51628-4.c b/gcc/testsuite/c-c++-common/pr51628-4.c
new file mode 100644
index 00000000000..c4c1fb72d6d
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/pr51628-4.c
@@ -0,0 +1,35 @@
+/* PR c/51628.  */
+/* { dg-do compile } */
+/* { dg-options "-O" } */
+
+struct pair_t
+{
+  int x;
+  int i;
+} __attribute__((packed));
+
+extern struct pair_t p;
+extern int *x;
+extern void bar (int *);
+
+int *addr = &p.i;
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+
+int *
+foo (void)
+{
+  struct pair_t arr[2] = { { 1, 10 }, { 2, 20 } };
+  int *p0, *p1;
+  p0 = &arr[0].i;
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+  bar (p0);
+  p1 = &arr[1].i;
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+  bar (p1);
+  bar (&p.i);
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+  x = &p.i;
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+  return &p.i;
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+}
diff --git a/gcc/testsuite/c-c++-common/pr51628-5.c b/gcc/testsuite/c-c++-common/pr51628-5.c
new file mode 100644
index 00000000000..9d7c309a0ef
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/pr51628-5.c
@@ -0,0 +1,35 @@
+/* PR c/51628.  */
+/* { dg-do compile } */
+/* { dg-options "-O" } */
+
+struct pair_t
+{
+  char x;
+  int i;
+} __attribute__((packed));
+
+extern struct pair_t p;
+extern int *x;
+extern void bar (int *);
+
+int *addr = &p.i;
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+
+int *
+foo (void)
+{
+  struct pair_t arr[2] = { { 1, 10 }, { 2, 20 } };
+  int *p0, *p1;
+  p0 = &arr[0].i;
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+  bar (p0);
+  p1 = &arr[1].i;
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+  bar (p1);
+  bar (&p.i);
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+  x = &p.i;
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+  return &p.i;
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+}
diff --git a/gcc/testsuite/c-c++-common/pr51628-6.c b/gcc/testsuite/c-c++-common/pr51628-6.c
new file mode 100644
index 00000000000..52aa07a4cf3
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/pr51628-6.c
@@ -0,0 +1,35 @@
+/* PR c/51628.  */
+/* { dg-do compile } */
+/* { dg-options "-O" } */
+
+struct pair_t
+{
+  char x;
+  int i;
+} __attribute__((packed, aligned (4)));
+
+extern struct pair_t p;
+extern int *x;
+extern void bar (int *);
+
+int *addr = &p.i;
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+
+int *
+foo (void)
+{
+  struct pair_t arr[2] = { { 1, 10 }, { 2, 20 } };
+  int *p0, *p1;
+  p0 = &arr[0].i;
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+  bar (p0);
+  p1 = &arr[1].i;
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+  bar (p1);
+  bar (&p.i);
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+  x = &p.i;
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+  return &p.i;
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+}
diff --git a/gcc/testsuite/c-c++-common/pr51628-7.c b/gcc/testsuite/c-c++-common/pr51628-7.c
new file mode 100644
index 00000000000..ae4a681f966
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/pr51628-7.c
@@ -0,0 +1,29 @@
+/* PR c/51628.  */
+/* { dg-do compile } */
+/* { dg-options "-O" } */
+
+struct pair_t
+{
+  int x;
+  int i[4];
+} __attribute__((packed, aligned (4)));
+
+extern struct pair_t p;
+extern int *x;
+extern void bar (int *);
+
+int *addr = p.i;
+
+int *
+foo (struct pair_t *p)
+{
+  int *p0, *p1;
+  p0 = p->i;
+  bar (p0);
+  p1 = &p->i[1];
+  bar (p1);
+  bar (p->i);
+  bar (&p->i[2]);
+  x = p->i;
+  return &p->i[3];
+}
diff --git a/gcc/testsuite/c-c++-common/pr51628-8.c b/gcc/testsuite/c-c++-common/pr51628-8.c
new file mode 100644
index 00000000000..cc2dae096ae
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/pr51628-8.c
@@ -0,0 +1,36 @@
+/* PR c/51628.  */
+/* { dg-do compile } */
+/* { dg-options "-O" } */
+
+struct pair_t
+{
+  char x;
+  int i[4];
+} __attribute__ ((packed, aligned (4)));
+
+extern struct pair_t p;
+extern int *x;
+extern void bar (int *);
+
+int *addr = p.i;
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+
+int *
+foo (struct pair_t *p)
+{
+  int *p0, *p1;
+  p0 = p->i;
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+  bar (p0);
+  p1 = &p->i[1];
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+  bar (p1);
+  bar (p->i);
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+  bar (&p->i[2]);
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+  x = p->i;
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+  return &p->i[3];
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+}
diff --git a/gcc/testsuite/c-c++-common/pr51628-9.c b/gcc/testsuite/c-c++-common/pr51628-9.c
new file mode 100644
index 00000000000..0470aa3b93d
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/pr51628-9.c
@@ -0,0 +1,36 @@
+/* PR c/51628.  */
+/* { dg-do compile } */
+/* { dg-options "-O" } */
+
+struct pair_t
+{
+  int x;
+  int i[4];
+} __attribute__ ((packed));
+
+extern struct pair_t p;
+extern int *x;
+extern void bar (int *);
+
+int *addr = p.i;
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+
+int *
+foo (struct pair_t *p)
+{
+  int *p0, *p1;
+  p0 = p->i;
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+  bar (p0);
+  p1 = &p->i[1];
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+  bar (p1);
+  bar (p->i);
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+  bar (&p->i[2]);
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+  x = p->i;
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+  return &p->i[3];
+/* { dg-warning "may result in an unaligned pointer value" "" { target *-*-* } .-1 } */
+}
diff --git a/gcc/testsuite/c-c++-common/ubsan/align-10.c b/gcc/testsuite/c-c++-common/ubsan/align-10.c
index 56ae9ebfe30..6210533173c 100644
--- a/gcc/testsuite/c-c++-common/ubsan/align-10.c
+++ b/gcc/testsuite/c-c++-common/ubsan/align-10.c
@@ -1,6 +1,6 @@
 /* Limit this to known non-strict alignment targets.  */
 /* { dg-do run { target { i?86-*-linux* x86_64-*-linux* } } } */
-/* { dg-options "-O -fsanitize=alignment -fsanitize-recover=alignment" } */
+/* { dg-options "-O -fsanitize=alignment -fsanitize-recover=alignment -Wno-address-of-packed-member" } */
 
 struct R { int a; } r;
 struct S { struct R a; char b; long long c; short d[10]; };
diff --git a/gcc/testsuite/c-c++-common/ubsan/align-2.c b/gcc/testsuite/c-c++-common/ubsan/align-2.c
index 071de8c202a..336b1c3c907 100644
--- a/gcc/testsuite/c-c++-common/ubsan/align-2.c
+++ b/gcc/testsuite/c-c++-common/ubsan/align-2.c
@@ -1,6 +1,6 @@
 /* Limit this to known non-strict alignment targets.  */
 /* { dg-do run { target { i?86-*-linux* x86_64-*-linux* } } } */
-/* { dg-options "-fsanitize=alignment" } */
+/* { dg-options "-fsanitize=alignment -Wno-address-of-packed-member" } */
 
 struct S { int a; char b; long long c; short d[10]; };
 struct T { char a; long long b; };
diff --git a/gcc/testsuite/c-c++-common/ubsan/align-4.c b/gcc/testsuite/c-c++-common/ubsan/align-4.c
index 3252595d330..d5feeee29c6 100644
--- a/gcc/testsuite/c-c++-common/ubsan/align-4.c
+++ b/gcc/testsuite/c-c++-common/ubsan/align-4.c
@@ -1,6 +1,6 @@
 /* Limit this to known non-strict alignment targets.  */
 /* { dg-do run { target { i?86-*-linux* x86_64-*-linux* } } } */
-/* { dg-options "-fsanitize=null,alignment" } */
+/* { dg-options "-fsanitize=null,alignment -Wno-address-of-packed-member" } */
 
 #include "align-2.c"
 
diff --git a/gcc/testsuite/c-c++-common/ubsan/align-6.c b/gcc/testsuite/c-c++-common/ubsan/align-6.c
index 3364746fb27..0302b7b8894 100644
--- a/gcc/testsuite/c-c++-common/ubsan/align-6.c
+++ b/gcc/testsuite/c-c++-common/ubsan/align-6.c
@@ -1,6 +1,6 @@
 /* Limit this to known non-strict alignment targets.  */
 /* { dg-do run { target { i?86-*-linux* x86_64-*-linux* } } } */
-/* { dg-options "-O -fsanitize=alignment -fsanitize-recover=alignment" } */
+/* { dg-options "-O -fsanitize=alignment -fsanitize-recover=alignment -Wno-address-of-packed-member" } */
 
 struct S { int a; char b; long long c; short d[10]; };
 struct T { char a; long long b; };
diff --git a/gcc/testsuite/c-c++-common/ubsan/align-7.c b/gcc/testsuite/c-c++-common/ubsan/align-7.c
index ec4e87f56d5..dd1e8c91cef 100644
--- a/gcc/testsuite/c-c++-common/ubsan/align-7.c
+++ b/gcc/testsuite/c-c++-common/ubsan/align-7.c
@@ -1,6 +1,6 @@
 /* Limit this to known non-strict alignment targets.  */
 /* { dg-do run { target { i?86-*-linux* x86_64-*-linux* } } } */
-/* { dg-options "-O -fsanitize=alignment -fno-sanitize-recover=alignment -fdump-tree-sanopt-details" } */
+/* { dg-options "-O -fsanitize=alignment -fno-sanitize-recover=alignment -Wno-address-of-packed-member -fdump-tree-sanopt-details" } */
 /* { dg-skip-if "" { *-*-* } { "-flto -fno-fat-lto-objects" } } */
 /* { dg-shouldfail "ubsan" } */
 
diff --git a/gcc/testsuite/c-c++-common/ubsan/align-8.c b/gcc/testsuite/c-c++-common/ubsan/align-8.c
index 61c1ceb6682..5fe0e0fe931 100644
--- a/gcc/testsuite/c-c++-common/ubsan/align-8.c
+++ b/gcc/testsuite/c-c++-common/ubsan/align-8.c
@@ -1,6 +1,6 @@
 /* Limit this to known non-strict alignment targets.  */
 /* { dg-do run { target { i?86-*-linux* x86_64-*-linux* } } } */
-/* { dg-options "-O -fsanitize=alignment -fsanitize-undefined-trap-on-error -fdump-tree-sanopt-details" } */
+/* { dg-options "-O -fsanitize=alignment -fsanitize-undefined-trap-on-error -Wno-address-of-packed-member -fdump-tree-sanopt-details" } */
 /* { dg-skip-if "" { *-*-* } { "-flto -fno-fat-lto-objects" } } */
 /* { dg-shouldfail "ubsan" } */