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

[Chung-Lin Tang]

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  <clt...@codesourcery.com>

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


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