ia64 patch to handle predicated insns in prologue

["J. Johnston" <jjohnstn@redhat.com>]

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The accompanying patch handles a bug in backtracing through glibc's sleep.
The compiler generates some predicated insns prior to saving the return register
b0 into a register stack register.  The current code stops when it sees a
predicated insn.  The change makes the prologue examination stop only if the
function is frameless or we have already seen the return register.

This removes a number of failures in gdb.threads caused when we catch another
thread in sleep and we try and backtrace.

Ok to commit?

-- Jeff J.

2003-08-26  Jeff Johnston  <jjohnstn@redhat.com>

	* ia64-tdep.c (examine_prologue): Only stop at predicated insns if
	we are frameless or the return address register is already known.

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Index: ia64-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/ia64-tdep.c,v
retrieving revision 1.94
diff -u -r1.94 ia64-tdep.c
--- ia64-tdep.c	26 Aug 2003 17:33:22 -0000	1.94
+++ ia64-tdep.c	26 Aug 2003 17:46:44 -0000
@@ -1143,11 +1143,18 @@
       if (next_pc == 0)
 	break;
 
-      if ((it == B && ((instr & 0x1e1f800003f) != 0x04000000000))
-          || ((instr & 0x3fLL) != 0LL))
+      if (it == B && ((instr & 0x1e1f800003f) != 0x04000000000))
 	{
-	  /* Exit loop upon hitting a non-nop branch instruction 
-	     or a predicated instruction. */
+	  /* Exit loop upon hitting a non-nop branch instruction. */ 
+	  if (trust_limit)
+	    lim_pc = pc;
+	  break;
+	}
+      else if (((instr & 0x3fLL) != 0LL) && 
+	       (frameless || ret_reg != 0))
+	{
+	  /* Exit loop upon hitting a predicated instruction if
+	     we already have the return register or if we are frameless.  */ 
 	  if (trust_limit)
 	    lim_pc = pc;
 	  break;