PR target/56742

        * config/i386/i386.c (ix86_seh_fixup_eh_fallthru): New.
        (ix86_reorg): Call it.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@199264 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 0288258..51e7b9e 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2013-05-23  Richard Henderson  <rth@redhat.com>
+
+       PR target/56742
+       * config/i386/i386.c (ix86_seh_fixup_eh_fallthru): New.
+       (ix86_reorg): Call it.
+
 2013-05-23  Uros Bizjak  <ubizjak@gmail.com>
 
        PR target/57379

diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 3470fef..20163b1 100644 (file)
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -35564,6 +35564,46 @@ ix86_pad_short_function (void)
     }
 }
 
+/* Fix up a Windows system unwinder issue.  If an EH region falls thru into
+   the epilogue, the Windows system unwinder will apply epilogue logic and
+   produce incorrect offsets.  This can be avoided by adding a nop between
+   the last insn that can throw and the first insn of the epilogue.  */
+
+static void
+ix86_seh_fixup_eh_fallthru (void)
+{
+  edge e;
+  edge_iterator ei;
+
+  FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
+    {
+      rtx insn, next;
+
+      /* Find the beginning of the epilogue.  */
+      for (insn = BB_END (e->src); insn != NULL; insn = PREV_INSN (insn))
+       if (NOTE_P (insn) && NOTE_KIND (insn) == NOTE_INSN_EPILOGUE_BEG)
+         break;
+      if (insn == NULL)
+       continue;
+
+      /* We only care about preceeding insns that can throw.  */
+      insn = prev_active_insn (insn);
+      if (insn == NULL || !can_throw_internal (insn))
+       continue;
+
+      /* Do not separate calls from their debug information.  */
+      for (next = NEXT_INSN (insn); next != NULL; next = NEXT_INSN (next))
+       if (NOTE_P (next)
+            && (NOTE_KIND (next) == NOTE_INSN_VAR_LOCATION
+                || NOTE_KIND (next) == NOTE_INSN_CALL_ARG_LOCATION))
+         insn = next;
+       else
+         break;
+
+      emit_insn_after (gen_nops (const1_rtx), insn);
+    }
+}
+
 /* Implement machine specific optimizations.  We implement padding of returns
    for K8 CPUs and pass to avoid 4 jumps in the single 16 byte window.  */
 static void
@@ -35573,6 +35613,9 @@ ix86_reorg (void)
      with old MDEP_REORGS that are not CFG based.  Recompute it now.  */
   compute_bb_for_insn ();
 
+  if (TARGET_SEH && current_function_has_exception_handlers ())
+    ix86_seh_fixup_eh_fallthru ();
+
   if (optimize && optimize_function_for_speed_p (cfun))
     {
       if (TARGET_PAD_SHORT_FUNCTION)