Patch: Add a stop bit in alignment for alloc.

[H. J. Lu]

On Wed, Feb 18, 2004 at 02:05:35PM -0800, David Mosberger wrote:
> 
>   >> >> It crashes with IP=0xa000000100320ec0 due to the fact that the "alloc"
>   >> >> is not the first instruction in the instruction-group.  The
>   >> >> corresponding source code looks like this:
> 
>   Jim> It might be worthwhile to submit a gcc bugzilla bug report for this, as
>   Jim> I am unlikely to look into this anytime soon.
> 
> I'll wait to see what HJ has to say.  It's clearly an important bug
> because it will silently lead to bad code.

This is the patch for the assembler bug. At least, kernel won't crash.
Ok to instal?


H.J.
-------------- next part --------------
2004-03-01  H.J. Lu  <hongjiu.lu@intel.com>

	* config/tc-ia64.c (ia64_handle_align): Add a stop bit for
	alloc.

--- gas/config/tc-ia64.c.alloc	2004-02-24 09:32:19.000000000 -0800
+++ gas/config/tc-ia64.c	2004-03-01 12:33:31.000000000 -0800
@@ -10823,9 +10823,14 @@ ia64_handle_align (fragp)
   static const unsigned char le_nop[]
     = { 0x0c, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00,
 	0x00, 0x02, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00};
+  static const unsigned char le_nop_stop[]
+    = { 0x0d, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00,
+	0x00, 0x02, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00};
 
   int bytes;
   char *p;
+  const unsigned char *nop = le_nop;
+  bfd_vma i0;
 
   if (fragp->fr_type != rs_align_code)
     return;
@@ -10833,6 +10838,20 @@ ia64_handle_align (fragp)
   bytes = fragp->fr_next->fr_address - fragp->fr_address - fragp->fr_fix;
   p = fragp->fr_literal + fragp->fr_fix;
 
+  if (fragp->fr_next->fr_fix >= 8)
+    {
+      /* Get the first instruction of the next bundle.  */
+      i0 = bfd_get_64 (stdoutput,
+		       (bfd_byte *) fragp->fr_next->fr_literal);
+      i0 = (i0 >> 5) & 0x1ffffffffffLL;
+
+      /* If the next instruction is alloc, we have to make sure
+	 there is a stop bit before it so that alloc is the first
+	 instruction of the instruction group.  */
+      if ((i0 & 0x1ff80000000LL) == 0x2c00000000)
+	nop = le_nop_stop;
+    }
+
   /* Make sure we are on a 16-byte boundary, in case someone has been
      putting data into a text section.  */
   if (bytes & 15)
@@ -10845,7 +10864,7 @@ ia64_handle_align (fragp)
     }
 
   /* Instruction bundles are always little-endian.  */
-  memcpy (p, le_nop, 16);
+  memcpy (p, nop, 16);
   fragp->fr_var = 16;
 }