re PR middle-end/28865 (Structures with a flexible arrray member have wrong .size)

PR middle-end/28865

	* varasm.c (output_constant): Return the number of bytes actually
	emitted.
	(output_constructor_array_range): Update the field size with the
	number of bytes emitted by output_constant.
	(output_constructor_regular_field): Likewise.  Also do not
 	complain if the total number of bytes emitted is now greater
	than the expected fieldpos.
	* output.h (output_constant): Update prototype and descriptive
	comment.

	* gcc.c-torture/compile/pr28865.c: New.
	* gcc.c-torture/execute/pr28865.c: New.

From-SVN: r206661

6 files changed, 77 insertions, 18 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 0580d16..be73e9e 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,16 @@
+2014-01-16  Nick Clifton  <nickc@redhat.com>
+
+	PR middle-end/28865
+	* varasm.c (output_constant): Return the number of bytes actually
+	emitted.
+	(output_constructor_array_range): Update the field size with the
+	number of bytes emitted by output_constant.
+	(output_constructor_regular_field): Likewise.  Also do not
+	complain if the total number of bytes emitted is now greater
+	than the expected fieldpos.
+	* output.h (output_constant): Update prototype and descriptive
+	comment.
+
 2014-01-16  Marek Polacek  <polacek@redhat.com>
 
 	PR middle-end/59827
diff --git a/gcc/output.h b/gcc/output.h
index 15a2b97..fead3d3 100644
--- a/gcc/output.h
+++ b/gcc/output.h
@@ -294,11 +294,13 @@ extern void output_quoted_string (FILE *, const char *);
    This includes the pseudo-op such as ".int" or ".byte", and a newline.
    Assumes output_addressed_constants has been done on EXP already.
 
-   Generate exactly SIZE bytes of assembler data, padding at the end
-   with zeros if necessary.  SIZE must always be specified.
+   Generate at least SIZE bytes of assembler data, padding at the end
+   with zeros if necessary.  SIZE must always be specified.  The returned
+   value is the actual number of bytes of assembler data generated, which
+   may be bigger than SIZE if the object contains a variable length field.
 
    ALIGN is the alignment in bits that may be assumed for the data.  */
-extern void output_constant (tree, unsigned HOST_WIDE_INT, unsigned int);
+extern unsigned HOST_WIDE_INT output_constant (tree, unsigned HOST_WIDE_INT, unsigned int);
 
 /* When outputting delayed branch sequences, this rtx holds the
    sequence being output.  It is null when no delayed branch
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 7db83e6..868593b 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2014-01-16  Nick Clifton  <nickc@redhat.com>
+
+	PR middle-end/28865
+	* gcc.c-torture/compile/pr28865.c: New.
+	* gcc.c-torture/execute/pr28865.c: New.
+
 2014-01-16  Marek Polacek  <polacek@redhat.com>
 
 	PR middle-end/59827
diff --git a/gcc/testsuite/gcc.c-torture/compile/pr28865.c b/gcc/testsuite/gcc.c-torture/compile/pr28865.c
new file mode 100644
index 0000000..aa6ae07
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/pr28865.c
@@ -0,0 +1,16 @@
+struct var_len
+{
+  int field1;
+  const char field2[];
+};
+
+/* Note - strictly speaking this array declaration is illegal
+   since each element has a variable length.  GCC allows it
+   (for the moment) because it is used in existing code, such
+   as glibc.  */
+static const struct var_len var_array[] = 
+{
+  { 1, "Long exposure noise reduction" },
+  { 2, "Shutter/AE lock buttons" },
+  { 3, "Mirror lockup" }
+};
diff --git a/gcc/testsuite/gcc.c-torture/execute/pr28865.c b/gcc/testsuite/gcc.c-torture/execute/pr28865.c
new file mode 100644
index 0000000..627e6b8
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/pr28865.c
@@ -0,0 +1,21 @@
+struct A { int a; char b[]; };
+union B { struct A a; char b[sizeof (struct A) + 31]; };
+union B b = { { 1, "123456789012345678901234567890" } };
+union B c = { { 2, "123456789012345678901234567890" } };
+
+__attribute__((noinline, noclone)) void
+foo (int *x[2])
+{
+  x[0] = &b.a.a;
+  x[1] = &c.a.a;
+}
+
+int
+main ()
+{
+  int *x[2];
+  foo (x);
+  if (*x[0] != 1 || *x[1] != 2)
+    __builtin_abort ();
+  return 0;
+}
diff --git a/gcc/varasm.c b/gcc/varasm.c
index 24b36b6..6a41644 100644
--- a/gcc/varasm.c
+++ b/gcc/varasm.c
@@ -4584,8 +4584,10 @@ static unsigned HOST_WIDE_INT
    This includes the pseudo-op such as ".int" or ".byte", and a newline.
    Assumes output_addressed_constants has been done on EXP already.
 
-   Generate exactly SIZE bytes of assembler data, padding at the end
-   with zeros if necessary.  SIZE must always be specified.
+   Generate at least SIZE bytes of assembler data, padding at the end
+   with zeros if necessary.  SIZE must always be specified.  The returned
+   value is the actual number of bytes of assembler data generated, which
+   may be bigger than SIZE if the object contains a variable length field.
 
    SIZE is important for structure constructors,
    since trailing members may have been omitted from the constructor.
@@ -4600,14 +4602,14 @@ static unsigned HOST_WIDE_INT
 
    ALIGN is the alignment of the data in bits.  */
 
-void
+unsigned HOST_WIDE_INT
 output_constant (tree exp, unsigned HOST_WIDE_INT size, unsigned int align)
 {
   enum tree_code code;
   unsigned HOST_WIDE_INT thissize;
 
   if (size == 0 || flag_syntax_only)
-    return;
+    return size;
 
   /* See if we're trying to initialize a pointer in a non-default mode
      to the address of some declaration somewhere.  If the target says
@@ -4672,7 +4674,7 @@ output_constant (tree exp, unsigned HOST_WIDE_INT size, unsigned int align)
       && vec_safe_is_empty (CONSTRUCTOR_ELTS (exp)))
     {
       assemble_zeros (size);
-      return;
+      return size;
     }
 
   if (TREE_CODE (exp) == FDESC_EXPR)
@@ -4684,7 +4686,7 @@ output_constant (tree exp, unsigned HOST_WIDE_INT size, unsigned int align)
 #else
       gcc_unreachable ();
 #endif
-      return;
+      return size;
     }
 
   /* Now output the underlying data.  If we've handling the padding, return.
@@ -4723,8 +4725,7 @@ output_constant (tree exp, unsigned HOST_WIDE_INT size, unsigned int align)
       switch (TREE_CODE (exp))
 	{
 	case CONSTRUCTOR:
-	  output_constructor (exp, size, align, NULL);
-	  return;
+	  return output_constructor (exp, size, align, NULL);
 	case STRING_CST:
 	  thissize
 	    = MIN ((unsigned HOST_WIDE_INT)TREE_STRING_LENGTH (exp), size);
@@ -4752,11 +4753,10 @@ output_constant (tree exp, unsigned HOST_WIDE_INT size, unsigned int align)
     case RECORD_TYPE:
     case UNION_TYPE:
       gcc_assert (TREE_CODE (exp) == CONSTRUCTOR);
-      output_constructor (exp, size, align, NULL);
-      return;
+      return output_constructor (exp, size, align, NULL);
 
     case ERROR_MARK:
-      return;
+      return 0;
 
     default:
       gcc_unreachable ();
@@ -4764,6 +4764,8 @@ output_constant (tree exp, unsigned HOST_WIDE_INT size, unsigned int align)
 
   if (size > thissize)
     assemble_zeros (size - thissize);
+
+  return size;
 }
 
 
@@ -4860,7 +4862,7 @@ output_constructor_array_range (oc_local_state *local)
       if (local->val == NULL_TREE)
 	assemble_zeros (fieldsize);
       else
-	output_constant (local->val, fieldsize, align2);
+	fieldsize = output_constant (local->val, fieldsize, align2);
 
       /* Count its size.  */
       local->total_bytes += fieldsize;
@@ -4909,9 +4911,8 @@ output_constructor_regular_field (oc_local_state *local)
      Note no alignment needed in an array, since that is guaranteed
      if each element has the proper size.  */
   if ((local->field != NULL_TREE || local->index != NULL_TREE)
-      && fieldpos != local->total_bytes)
+      && fieldpos > local->total_bytes)
     {
-      gcc_assert (fieldpos >= local->total_bytes);
       assemble_zeros (fieldpos - local->total_bytes);
       local->total_bytes = fieldpos;
     }
@@ -4948,7 +4949,7 @@ output_constructor_regular_field (oc_local_state *local)
   if (local->val == NULL_TREE)
     assemble_zeros (fieldsize);
   else
-    output_constant (local->val, fieldsize, align2);
+    fieldsize = output_constant (local->val, fieldsize, align2);
 
   /* Count its size.  */
   local->total_bytes += fieldsize;