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other/4932: the i386 backend crashes on incorrect asm("... %c0 ...")
- From: espenlaub at informatik dot uni-ulm dot de
- To: gcc-gnats at gcc dot gnu dot org
- Date: 23 Nov 2001 09:41:42 -0000
- Subject: other/4932: the i386 backend crashes on incorrect asm("... %c0 ...")
- Reply-to: espenlaub at informatik dot uni-ulm dot de
[Get raw message]
>Number: 4932
>Category: other
>Synopsis: the i386 backend crashes on incorrect asm("... %c0 ...")
>Confidential: no
>Severity: non-critical
>Priority: medium
>Responsible: unassigned
>State: open
>Class: ice-on-illegal-code
>Submitter-Id: net
>Arrival-Date: Fri Nov 23 01:46:01 PST 2001
>Closed-Date:
>Last-Modified:
>Originator: Klaus Espenlaub
>Release: gcc-3.0
>Organization:
>Environment:
System: Linux deadbeef 2.4.4-4GB #2 Fri Jul 20 08:48:42 CEST 2001 i686 unknown
Architecture: i686
host: i686-pc-linux-gnu
build: i686-pc-linux-gnu
target: i686-pc-linux-gnu
configured with: ./configure --enable-languages=c
>Description:
If an asm(...) output pattern contains the `%c' code, but
the actual operand isn't a constant, then the code in
i386.c tries to treat it as a condition code that should
be reversed - and that fails with a SIGSEGV.
>How-To-Repeat:
gcc testcase.c -S testcase.s
>Fix:
--- i386.c-orig Fri Nov 23 10:29:42 2001
+++ i386.c Fri Nov 23 10:35:19 2001
@@ -3522,6 +3522,15 @@ print_operand (file, x, code)
/* Like above, but reverse condition */
case 'c':
+ /* Buggy user-written assembler instructions may contain this code
+ * (the user expects the meaning "output constant value without the
+ * syntax that normally indicates an immediate operand"), but the
+ * actual operand the compiler uses isn't a constant after all. */
+ if (GET_RTX_CLASS (GET_CODE (x)) != '<')
+ {
+ output_operand_lossage ("operand is neither a constant nor a condition code, invalid operand code `c'");
+ return;
+ }
put_condition_code (GET_CODE (x), GET_MODE (XEXP (x, 0)), 1, 0, file);
return;
case 'f':
>Release-Note:
>Audit-Trail:
>Unformatted:
----gnatsweb-attachment----
Content-Type: text/plain; name="testcase.c"
Content-Disposition: inline; filename="testcase.c"
void *abc;
int main(void)
{
__asm__ __volatile__("some assembly code containing %c0"
: /* no output */ : "ir" (abc));
}