[PATCH 1/2] SH epilogue unwind, dwarf2 pass changes

[Chung-Lin Tang <cltang@codesourcery.com>]

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Hi,

I found a few changes were needed to the dwarf2 pass when trying to
implement epilogue unwind for SH, mainly that the current handling of
annulled-taken branches does not seem correct; the delay slot insn
should be handled in a manner similar to an insn in the fallthru block.

Cross-tested on SH and MIPS, and bootstrapped/tested on x86_64.

Thanks,
Chung-Lin

2012-05-18  Chung-Lin Tang  <cltang@codesourcery.com>

	* dwarf2cfi.c (scan_trace): Update CFA before exiting scan.
	Handle annulled-taken branch (!INSN_FROM_TARGET_P) case.


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Index: dwarf2cfi.c
===================================================================
--- dwarf2cfi.c	(revision 187548)
+++ dwarf2cfi.c	(working copy)
@@ -2401,6 +2401,7 @@ scan_trace (dw_trace_info *trace)
 	{
 	  /* Propagate across fallthru edges.  */
 	  dwarf2out_flush_queued_reg_saves ();
+	  def_cfa_1 (&this_cfa);
 	  maybe_record_trace_start (insn, NULL);
 	  break;
 	}
@@ -2455,6 +2456,18 @@ scan_trace (dw_trace_info *trace)
 		  cur_cfa = &this_cfa;
 		  continue;
 		}
+	      else
+		{
+		  /* If ELT is a annulled branch-taken instruction (i.e. executed
+		     only when branch is not taken), the args_size and CFA should
+		     not change through the jump.  */
+		  create_trace_edges (control);
+
+		  /* Update and continue with the trace.  */
+		  add_cfi_insn = insn;
+		  scan_insn_after (elt);
+		  continue;
+		}
 	    }
 
 	  /* The insns in the delay slot should all be considered to happen