[PATCH] ia64-tdep.c: Only warn about slot numbers > 2

Kevin Buettner kevinb@cygnus.com
Wed Mar 21 18:34:00 GMT 2001

I've just committed the changes below.

This patch addresses the concerns raised in the following bug report:


In particular, GDB doesn't segfault anymore.  A warning message
regarding slot numbers that are greater than zero is still printed,
but IMO, it is better to print these to alert the user that something
may wrong...

	* ia64-tdep.c (fetch_instruction): Warn about slot numbers greater
	than two instead of generating an error.

Index: ia64-tdep.c
RCS file: /cvs/src/src/gdb/ia64-tdep.c,v
retrieving revision 1.15
diff -u -p -r1.15 ia64-tdep.c
--- ia64-tdep.c	2001/03/01 01:39:21	1.15
+++ ia64-tdep.c	2001/03/22 01:55:48
@@ -492,8 +492,25 @@ fetch_instruction (CORE_ADDR addr, instr
   long long template;
   int val;
+  /* Warn about slot numbers greater than 2.  We used to generate
+     an error here on the assumption that the user entered an invalid
+     address.  But, sometimes GDB itself requests an invalid address.
+     This can (easily) happen when execution stops in a function for
+     which there are no symbols.  The prologue scanner will attempt to
+     find the beginning of the function - if the nearest symbol
+     happens to not be aligned on a bundle boundary (16 bytes), the
+     resulting starting address will cause GDB to think that the slot
+     number is too large.
+     So we warn about it and set the slot number to zero.  It is
+     not necessarily a fatal condition, particularly if debugging
+     at the assembly language level.  */
   if (slotnum > 2)
-    error("Can't fetch instructions for slot numbers greater than 2.");
+    {
+      warning ("Can't fetch instructions for slot numbers greater than 2.\n"
+	       "Using slot 0 instead");
+      slotnum = 0;
+    }
   addr &= ~0x0f;

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