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RFA: fix PR 7286
- From: Tom Tromey <tromey at redhat dot com>
- To: gdb-patches at sourceware dot org
- Date: Mon, 05 Jan 2009 17:52:18 -0700
- Subject: RFA: fix PR 7286
- Reply-to: tromey at redhat dot com
PR 7286 concerns the type of certain decimal integer constants.
According to C99, such a constant is never unsigned, but instead is of
the next wider type (from int, long, and long long) which can
represent its value.
I've included a rather roundabout test case. I think this particular
boundary condition can only be tested where LONGEST is wider than the
target's word size. As LONGEST is a define, and not a typedef, the
test determines the size of LONGEST by using a field whose type is
unlikely to change.
Another oddity here is the interpretation of the most negative 'long
long'. I chose to leave this as unsigned, though it would also make
sense to make this an overflow error. The latter seemed excessively
pedantic, though I don't feel strongly about this.
Please review.
thanks,
Tom
2009-01-05 Tom Tromey <tromey@redhat.com>
PR cli/7286:
* c-exp.y (parse_number): Handle large decimal constants according
to C99.
2009-01-05 Tom Tromey <tromey@redhat.com>
* gdb.gdb/selftest.exp (test_int_parsing): New proc.
(test_with_self): Call it.
diff --git a/gdb/c-exp.y b/gdb/c-exp.y
index d4bbbcc..dbb390e 100644
--- a/gdb/c-exp.y
+++ b/gdb/c-exp.y
@@ -1308,18 +1308,19 @@ parse_number (p, len, parsed_float, putithere)
the case where it is we just always shift the value more than
once, with fewer bits each time. */
- un = (ULONGEST)n >> 2;
+ /* A large decimal (not hex or octal) constant (between INT_MAX and
+ UINT_MAX) uses the smallest type that can hold its value. So,
+ for decimal values, we shift one fewer bit, so that a value that
+ would overflow into the sign bit uses the next higher type. */
+ if (base == 10)
+ un = (ULONGEST)n >> 1;
+ else
+ un = (ULONGEST)n >> 2;
if (long_p == 0
&& (un >> (gdbarch_int_bit (parse_gdbarch) - 2)) == 0)
{
high_bit = ((ULONGEST)1) << (gdbarch_int_bit (parse_gdbarch) - 1);
- /* A large decimal (not hex or octal) constant (between INT_MAX
- and UINT_MAX) is a long or unsigned long, according to ANSI,
- never an unsigned int, but this code treats it as unsigned
- int. This probably should be fixed. GCC gives a warning on
- such constants. */
-
unsigned_type = parse_type->builtin_unsigned_int;
signed_type = parse_type->builtin_int;
}
diff --git a/gdb/testsuite/gdb.gdb/selftest.exp b/gdb/testsuite/gdb.gdb/selftest.exp
index 495ae45..4c9520e 100644
--- a/gdb/testsuite/gdb.gdb/selftest.exp
+++ b/gdb/testsuite/gdb.gdb/selftest.exp
@@ -247,6 +247,54 @@ proc do_steps_and_nexts {} {
}
}
+proc test_int_parsing {} {
+ global gdb_prompt expect_out
+
+ # Try to extract the size of LONGEST. If LONGEST is wider than a
+ # pointer, then we can test a boundary case of C integer constant
+ # parsing without overflow.
+ gdb_test_multiple "print sizeof (((union exp_element *) 0)->longconst)" \
+ "determine size of LONGEST" {
+ -re ".* = \(\[0-9\]+\).*$gdb_prompt $" {
+ set longest_size $expect_out(1,string)
+ }
+ -re ".*$gdb_prompt $" {
+ # Nothing.
+ }
+ }
+ # Always pass. If this fails, we don't want to hear about it.
+ pass "determine size of LONGEST"
+ if {! [info exists longest_size]} {
+ return
+ }
+
+ gdb_test_multiple "print sizeof (void *)" "determine size of void*" {
+ -re ".* = \(\[0-9\]+\).*$gdb_prompt $" {
+ set voidp_size $expect_out(1,string)
+ }
+ -re ".*$gdb_prompt $" {
+ # Nothing.
+ }
+ }
+ # Always pass. If this fails, we don't want to hear about it.
+ pass "determine size of void*"
+ if {! [info exists voidp_size]} {
+ return
+ }
+
+ if {$longest_size <= $voidp_size} {
+ return
+ }
+
+ if {$voidp_size == 4} {
+ # 32-bit machine.
+ gdb_test "print -2147483648" " = -2147483648"
+ } elseif {$voidp_size == 8} {
+ # 64-bit machine.
+ gdb_test "print -9223372036854775808" " = -9223372036854775808"
+ }
+}
+
proc test_with_self { executable } {
global gdb_prompt
global tool
@@ -279,6 +327,8 @@ proc test_with_self { executable } {
return -1
}
+ test_int_parsing
+
if { $gdb_file_cmd_debug_info != "debug" } then {
untested "No debug information, skipping testcase."
return -1