[PATCH v5 10/15] vla: evaluate operand of sizeof if its type is a vla

[Sanimir Agovic <sanimir.agovic@intel.com>]

The c99 standard in "6.5.3.4 The sizeof operator" states:

 If the type of the operand is a variable length array type, the operand
 is evaluated;[...]

This patch mirrors the following c99 semantic in gdb:

 1| int vla[n][m];
 2| int i = 1;
 3| sizeof(vla[i++][0]); // No sideffect
 4| assert (i == 1);
 5| sizeof(vla[i++]);    // With sideffect
 6| assert (i == 2);

Note: ptype/whatsis still do not allow any sideeffects.

This patch was motivated by:

  https://sourceware.org/ml/gdb-patches/2014-01/msg00732.html

2014-02-05  Sanimir Agovic  <sanimir.agovic@intel.com>
            Keven Boell <keven.boell@intel.com>

	* eval.c (evaluate_subexp_for_sizeof): Add enum noside argument.
	(evaluate_subexp_standard): Pass noside argument.
	(evaluate_subexp_for_sizeof) <BINOP_SUBSCRIPT>: Handle subscript case
	if noside equals EVAL_NORMAL. If the subscript yields a vla type
	re-evaluate subscript operation with EVAL_NORMAL to enable sideffects.
	* gdbtypes.c (resolve_dynamic_bounds): Mark bound as evaluated.
	* gdbtypes.h (enum range_flags): Add RANGE_EVALUATED case.

testsuite/gdb.base/

	* vla-sideeffect.c: New file.
	* vla-sideeffect.exp: New file.


Signed-off-by: Sanimir Agovic <sanimir.agovic@intel.com>
---
 gdb/eval.c                                | 40 ++++++++++++--
 gdb/gdbtypes.c                            |  1 +
 gdb/gdbtypes.h                            |  3 +-
 gdb/testsuite/gdb.base/vla-sideeffect.c   | 42 +++++++++++++++
 gdb/testsuite/gdb.base/vla-sideeffect.exp | 88 +++++++++++++++++++++++++++++++
 5 files changed, 170 insertions(+), 4 deletions(-)
 create mode 100644 gdb/testsuite/gdb.base/vla-sideeffect.c
 create mode 100644 gdb/testsuite/gdb.base/vla-sideeffect.exp

diff --git a/gdb/eval.c b/gdb/eval.c
index b3e45ca..7a34b95 100644
--- a/gdb/eval.c
+++ b/gdb/eval.c
@@ -51,7 +51,8 @@ extern int overload_resolution;
 
 /* Prototypes for local functions.  */
 
-static struct value *evaluate_subexp_for_sizeof (struct expression *, int *);
+static struct value *evaluate_subexp_for_sizeof (struct expression *, int *,
+						 enum noside);
 
 static struct value *evaluate_subexp_for_address (struct expression *,
 						  int *, enum noside);
@@ -2563,7 +2564,7 @@ evaluate_subexp_standard (struct type *expect_type,
 	  evaluate_subexp (NULL_TYPE, exp, pos, EVAL_SKIP);
 	  goto nosideret;
 	}
-      return evaluate_subexp_for_sizeof (exp, pos);
+      return evaluate_subexp_for_sizeof (exp, pos, noside);
 
     case UNOP_CAST:
       (*pos) += 2;
@@ -3000,7 +3001,8 @@ evaluate_subexp_with_coercion (struct expression *exp,
    Advance *POS over the subexpression.  */
 
 static struct value *
-evaluate_subexp_for_sizeof (struct expression *exp, int *pos)
+evaluate_subexp_for_sizeof (struct expression *exp, int *pos,
+			    enum noside noside)
 {
   /* FIXME: This should be size_t.  */
   struct type *size_type = builtin_type (exp->gdbarch)->builtin_int;
@@ -3054,6 +3056,38 @@ evaluate_subexp_for_sizeof (struct expression *exp, int *pos)
       return
 	value_from_longest (size_type, (LONGEST) TYPE_LENGTH (type));
 
+    case BINOP_SUBSCRIPT:
+      if (noside == EVAL_NORMAL)
+	{
+	  int oldpos = *pos;
+
+	  (*pos) += 1;
+	  val = evaluate_subexp (NULL_TYPE, exp, pos, EVAL_AVOID_SIDE_EFFECTS);
+	  *pos = oldpos;
+	  noside = EVAL_AVOID_SIDE_EFFECTS;
+
+	  type = check_typedef (value_type (val));
+	  if (TYPE_CODE (type) == TYPE_CODE_ARRAY)
+	    {
+	      type = check_typedef (TYPE_TARGET_TYPE (type));
+	      if (TYPE_CODE (type) == TYPE_CODE_ARRAY)
+		{
+		  type = TYPE_INDEX_TYPE (type);
+		  if ((TYPE_RANGE_DATA (type)->flags & RANGE_EVALUATED)
+		      == RANGE_EVALUATED)
+		    {
+		      val = evaluate_subexp (NULL_TYPE, exp, pos, EVAL_NORMAL);
+		      return value_from_longest
+			(size_type, (LONGEST)TYPE_LENGTH (value_type (val)));
+		    }
+		}
+	    }
+	}
+
+      val = evaluate_subexp (NULL_TYPE, exp, pos, EVAL_AVOID_SIDE_EFFECTS);
+      return value_from_longest (size_type,
+				 (LONGEST)TYPE_LENGTH (value_type (val)));
+
     default:
       val = evaluate_subexp (NULL_TYPE, exp, pos, EVAL_AVOID_SIDE_EFFECTS);
       return value_from_longest (size_type,
diff --git a/gdb/gdbtypes.c b/gdb/gdbtypes.c
index 83a2c75..67aa439 100644
--- a/gdb/gdbtypes.c
+++ b/gdb/gdbtypes.c
@@ -1697,6 +1697,7 @@ resolve_dynamic_bounds (struct type *type, CORE_ADDR addr)
     = create_range_type (NULL,
 			 TYPE_TARGET_TYPE (range_type),
 			 &low_bound, &high_bound);
+  TYPE_RANGE_DATA (range_type)->flags |= RANGE_EVALUATED;
   array_type = create_array_type (copy_type (type),
 				  array_type,
 				  range_type);
diff --git a/gdb/gdbtypes.h b/gdb/gdbtypes.h
index 100e3f4..4e92d4a 100644
--- a/gdb/gdbtypes.h
+++ b/gdb/gdbtypes.h
@@ -396,7 +396,8 @@ struct dynamic_prop
 
 enum range_flags
 {
-  RANGE_UPPER_BOUND_IS_COUNT = 1 /* High bound contains number of elements.  */
+  RANGE_UPPER_BOUND_IS_COUNT = 1, /* High bound contains number of elements.  */
+  RANGE_EVALUATED                 /* Bound was dynamic.  */
 };
 
 /* Determine which field of the union main_type.fields[x].loc is used.  */
diff --git a/gdb/testsuite/gdb.base/vla-sideeffect.c b/gdb/testsuite/gdb.base/vla-sideeffect.c
new file mode 100644
index 0000000..29ee99b
--- /dev/null
+++ b/gdb/testsuite/gdb.base/vla-sideeffect.c
@@ -0,0 +1,42 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2014 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include <stddef.h>
+#define SIZE 10
+
+int
+main ()
+{
+  int n = SIZE;
+  int i = 0;
+  int j = 0;
+  int vla2[SIZE][n];
+  int vla1[n];
+
+  for (i = 0; i < n; i++)
+    vla1[i] = (i * 2) + n;
+
+  for (i = 0; i < SIZE; i++)
+    for (j = 0; j < n; j++)
+      vla2[i][j] = (i + j) + n;
+
+
+  i = 0;
+  j = 0;
+
+  return 0;           /* vla-filled */
+}
diff --git a/gdb/testsuite/gdb.base/vla-sideeffect.exp b/gdb/testsuite/gdb.base/vla-sideeffect.exp
new file mode 100644
index 0000000..0ea9bc2
--- /dev/null
+++ b/gdb/testsuite/gdb.base/vla-sideeffect.exp
@@ -0,0 +1,88 @@
+# Copyright 2014 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# Tests sideffect of sizeof evaluation.
+# Based on gcc/testsuite/gcc.dg/vla-4.c; vla-15.c
+
+standard_testfile ".c"
+if { [prepare_for_testing ${testfile}.exp ${testfile} ${srcfile}] } {
+    return -1
+}
+
+if ![runto_main] {
+    return -1
+}
+
+gdb_breakpoint [gdb_get_line_number "vla-filled"]
+gdb_continue_to_breakpoint "vla-filled"
+
+# Check side effects for sizeof argument.
+set sizeof_int [get_sizeof "int" 4]
+set sizeof_vla [ expr "10" * "$sizeof_int" ]
+
+gdb_test "print sizeof (vla1\[i++\])" "\\$\\d+ = ${sizeof_int}" \
+         "print sizeof (vla1\[i++\])"
+gdb_test "print i" "\\$\\d+ = 0" \
+         "print i - sizeof no side effects"
+
+gdb_test "print sizeof (++vla1\[0\])" "\\$\\d+ = ${sizeof_int}" \
+         "print sizeof (++vla1\[0\])"
+gdb_test "print vla1\[0\]" "\\$\\d+ = 10" \
+         "print vla1\[0\] - sizeof no side effects"
+
+gdb_test "ptype ++vla1\[0\]" "type = int" "ptype ++vla1\[0\]"
+gdb_test "print vla1\[0\]" "\\$\\d+ = 10" \
+         "print vla1\[0\] - ptype no side effects"
+
+gdb_test "whatis ++vla1\[0\]" "type = int" "whatis ++vla1\[0\]"
+gdb_test "print vla1\[0\]" "\\$\\d+ = 10" \
+         "print vla1\[0\] - whatis no side effects"
+
+
+gdb_test "print sizeof (vla2\[i++\])" "\\$\\d+ = ${sizeof_vla}" \
+         "print sizeof (vla2\[i++\])"
+gdb_test "print i" "\\$\\d+ = 1" \
+         "print i - sizeof with side effects (1)"
+
+gdb_test "print sizeof (vla2\[i++ + sizeof(j++)\])" "\\$\\d+ = ${sizeof_vla}" \
+         "print sizeof (vla2\[i++ + sizeof(j++)\])"
+gdb_test "print i" "\\$\\d+ = 2" \
+         "print i - sizeof with side effects (2)"
+gdb_test "print j" "\\$\\d+ = 0" \
+         "print j - sizeof with no side effects"
+
+gdb_test "ptype vla2\[i++\]" "type = int \\\[10\\\]" \
+         "ptype vla2\[i++\]"
+gdb_test "print i" "\\$\\d+ = 2" \
+         "print i - ptype with side effects (1)"
+
+gdb_test "ptype vla2\[i++ + sizeof(j++)\]" "type = int \\\[10\\\]" \
+         "ptype vla2\[i++ + sizeof(j++)\]"
+gdb_test "print i" "\\$\\d+ = 2" \
+         "print i - ptype with side effects (2)"
+gdb_test "print j" "\\$\\d+ = 0" \
+         "print j - ptype with no side effects"
+
+gdb_test "whatis vla2\[i++\]" "type = int \\\[10\\\]" \
+         "whatis vla2\[i++\]"
+gdb_test "print i" "\\$\\d+ = 2" \
+         "print i - whatis with side effects (1)"
+
+gdb_test "whatis vla2\[i++ + sizeof(j++)\]" "type = int \\\[10\\\]" \
+         "whatis vla2\[i++ + sizeof(j++)\]"
+gdb_test "print i" "\\$\\d+ = 2" \
+         "print i - whatis with side effects (2)"
+gdb_test "print j" "\\$\\d+ = 0" \
+         "print j - whatis with no side effects"
-- 
1.8.4.2