[RFA] Fix UNOP_CAST_TYPE, UNOP_MEMVAL_TYPE, et. al.

dje@google.com dje@google.com
Mon Aug 6 23:08:00 GMT 2012


Hi.

While working on another patch I found gdb crashing on "p {char[4]} foo".
Using "set debug expression 1" I then found gdb rejecting valid expressions.

This patch fixes the issues I found.
I'm entirely sure it's complete, for example dump_prefix_expression
says type printing is not supported: It may just be that there was
no need for it (and not wanting to support something that "can't happen" -
or at least "couldn't happen until now" :-)), but I kinda wonder if adding
the support is as easy as this patch.

I also wonder about adding tests for "set debug expression 1",
but they make it easy to repro the problem so I've included them here.

Ok to check in?

2012-08-06  Doug Evans  <dje@google.com>

	* eval.c (evaluate_subexp_standard): Fix thinko in handling
	UNOP_MEMVAL_TYPE.
	* expprint.c (print_subexp_standard, case OP_TYPE): New
	(print_subexp_standard, case UNOP_CAST_TYPE): Don't increment pos.
	(print_subexp_standard, case UNOP_DYNAMIC_CAST): Ditto.
	(print_subexp_standard, case UNOP_REINTERPRET_CAST): Ditto.
	(print_subexp_standard, case UNOP_MEMVAL_TYPE): Ditto.
	(dump_subexp_body_standard, case UNOP_DYNAMIC_CAST): Don't increment
	elt.
	(dump_subexp_body_standard, case UNOP_REINTERPRET_CAST): Ditto.
	(dump_subexp_body_standard, case UNOP_CAST_TYPE): Ditto.
	(dump_subexp_body_standard, case UNOP_MEMVAL_TYPE): Ditto.
	(dump_prefix_expression): Handle OP_TYPE.

	testsuite/
	* gdb.base/debug-expr.c: New file.
	* gdb.base/debug-expr.exp: New file.
	* gdb.base/exprs.exp: Test {type} casts.
	* gdb.cp/debug-expr.exp: New file.

Index: eval.c
===================================================================
RCS file: /cvs/src/src/gdb/eval.c,v
retrieving revision 1.167
diff -u -p -r1.167 eval.c
--- eval.c	19 Jul 2012 15:38:16 -0000	1.167
+++ eval.c	6 Aug 2012 22:53:24 -0000
@@ -2751,10 +2751,9 @@ evaluate_subexp_standard (struct type *e
       if (noside == EVAL_SKIP)
 	goto nosideret;
       if (noside == EVAL_AVOID_SIDE_EFFECTS)
-	return value_zero (exp->elts[pc + 1].type, lval_memory);
+	return value_zero (type, lval_memory);
       else
-	return value_at_lazy (exp->elts[pc + 1].type,
-			      value_as_address (arg1));
+	return value_at_lazy (type, value_as_address (arg1));
 
     case UNOP_MEMVAL_TLS:
       (*pos) += 3;
Index: expprint.c
===================================================================
RCS file: /cvs/src/src/gdb/expprint.c,v
retrieving revision 1.58
diff -u -p -r1.58 expprint.c
--- expprint.c	19 Jul 2012 15:38:16 -0000	1.58
+++ expprint.c	6 Aug 2012 22:53:25 -0000
@@ -83,6 +83,11 @@ print_subexp_standard (struct expression
     {
       /* Common ops */
 
+    case OP_TYPE:
+      (*pos) += 2;
+      type_print (exp->elts[pc + 1].type, "", stream, 0);
+      return;
+
     case OP_SCOPE:
       myprec = PREC_PREFIX;
       assoc = 0;
@@ -430,7 +435,6 @@ print_subexp_standard (struct expression
       return;
 
     case UNOP_CAST_TYPE:
-      (*pos) += 1;
       if ((int) prec > (int) PREC_PREFIX)
 	fputs_filtered ("(", stream);
       fputs_filtered ("(", stream);
@@ -446,7 +450,6 @@ print_subexp_standard (struct expression
       fputs_filtered (opcode == UNOP_DYNAMIC_CAST ? "dynamic_cast"
 		      : "reinterpret_cast", stream);
       fputs_filtered ("<", stream);
-      (*pos) += 1;
       print_subexp (exp, pos, stream, PREC_PREFIX);
       fputs_filtered ("> (", stream);
       print_subexp (exp, pos, stream, PREC_PREFIX);
@@ -484,7 +487,6 @@ print_subexp_standard (struct expression
       return;
 
     case UNOP_MEMVAL_TYPE:
-      (*pos) += 1;
       if ((int) prec > (int) PREC_PREFIX)
 	fputs_filtered ("(", stream);
       fputs_filtered ("{", stream);
@@ -938,7 +940,6 @@ dump_subexp_body_standard (struct expres
     case UNOP_REINTERPRET_CAST:
     case UNOP_CAST_TYPE:
     case UNOP_MEMVAL_TYPE:
-      ++elt;
       fprintf_filtered (stream, " (");
       elt = dump_subexp (exp, stream, elt);
       fprintf_filtered (stream, ")");
@@ -1056,10 +1057,7 @@ dump_prefix_expression (struct expressio
   fprintf_filtered (stream, "Dump of expression @ ");
   gdb_print_host_address (exp, stream);
   fputs_filtered (", after conversion to prefix form:\nExpression: `", stream);
-  if (exp->elts[0].opcode != OP_TYPE)
-    print_expression (exp, stream);
-  else
-    fputs_filtered ("Type printing not yet supported....", stream);
+  print_expression (exp, stream);
   fprintf_filtered (stream, "'\n\tLanguage %s, %d elements, %ld bytes each.\n",
 		    exp->language_defn->la_name, exp->nelts,
 		    (long) sizeof (union exp_element));
Index: testsuite/gdb.base/debug-expr.c
===================================================================
RCS file: testsuite/gdb.base/debug-expr.c
diff -N testsuite/gdb.base/debug-expr.c
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ testsuite/gdb.base/debug-expr.c	6 Aug 2012 22:53:26 -0000
@@ -0,0 +1,7 @@
+char array[4];
+
+int
+main ()
+{
+  return 0;
+}
Index: testsuite/gdb.base/debug-expr.exp
===================================================================
RCS file: testsuite/gdb.base/debug-expr.exp
diff -N testsuite/gdb.base/debug-expr.exp
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ testsuite/gdb.base/debug-expr.exp	6 Aug 2012 22:53:26 -0000
@@ -0,0 +1,52 @@
+# Copyright 2012 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/>.
+
+# Test "set debug expr 1" on c expressions.
+
+standard_testfile .c
+
+if {[prepare_for_testing $testfile.exp $testfile $srcfile {debug}]} {
+    return -1
+}
+
+if ![runto_main] {
+    fail "run to main"
+    return -1
+}
+
+# Test whether the expression debug machinery accepts the expression.
+
+proc test_debug_expr { cmd output } {
+    global gdb_prompt
+
+    gdb_test_multiple $cmd "" {
+	-re ".*Invalid expression.*\r\n$gdb_prompt $" {
+	    fail $cmd
+	}
+	-re ".*\[\r\n\]$output\r\n$gdb_prompt $" {
+	    pass $cmd
+	}
+    }
+}
+
+for { set i 0 } { $i < 4 } { incr i } {
+    gdb_test_no_output "set variable array\[$i\] = $i"
+}
+
+gdb_test_no_output "set debug expression 1"
+
+# This caused gdb to segfault.
+test_debug_expr "print /x {char\[4\]} array" \
+    "\[$\]$decimal = \\{0x0, 0x1, 0x2, 0x3\\}"
Index: testsuite/gdb.base/exprs.exp
===================================================================
RCS file: /cvs/src/src/gdb/testsuite/gdb.base/exprs.exp,v
retrieving revision 1.25
diff -u -p -r1.25 exprs.exp
--- testsuite/gdb.base/exprs.exp	21 Jun 2012 20:46:21 -0000	1.25
+++ testsuite/gdb.base/exprs.exp	6 Aug 2012 22:53:26 -0000
@@ -266,3 +266,7 @@ gdb_test {print *v_int_array_init@2} { =
 gdb_test {print v_int_array_init[0]@1} { = \{10\}}
 gdb_test {print v_int_array_init[0]@2} { = \{10, 20\}}
 gdb_test {print v_int_array_init[1]@1} { = \{20\}}
+
+# gdb's {} extension
+gdb_test_no_output "set variable v_short_array\[0\] = 42"
+gdb_test "print {short} v_short_array" "$decimal = 42"
Index: testsuite/gdb.cp/debug-expr.exp
===================================================================
RCS file: testsuite/gdb.cp/debug-expr.exp
diff -N testsuite/gdb.cp/debug-expr.exp
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ testsuite/gdb.cp/debug-expr.exp	6 Aug 2012 22:53:26 -0000
@@ -0,0 +1,43 @@
+# Copyright 2012 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/>.
+
+# Test "set debug expr 1" on c++ expressions.
+
+if { [skip_cplus_tests] } { continue }
+
+gdb_start
+gdb_test_no_output "set language c++"
+gdb_test_no_output "set debug expression 1"
+
+# Test whether the expression debug machinery accepts the expression.
+
+proc test_debug_expr { cmd output } {
+    global gdb_prompt
+
+    gdb_test_multiple $cmd "" {
+	-re ".*Invalid expression.*\r\n$gdb_prompt $" {
+	    fail $cmd
+	}
+	-re ".*\[\r\n\]$output\r\n$gdb_prompt $" {
+	    pass $cmd
+	}
+    }
+}
+
+set void_star_zero_regex "\[$\]$decimal = \\(void \[*\]\\) 0x0"
+
+test_debug_expr "print static_cast<void*>(0)" "$void_star_zero_regex"
+test_debug_expr "print reinterpret_cast<void*>(0)" "$void_star_zero_regex"
+test_debug_expr "print dynamic_cast<void*>(0)" "$void_star_zero_regex"



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