* flow.c (EH_USES): Provide default.

        (calculate_global_regs_live): Use it for EH edges and noreturn calls.
        * doc/tm.texi (EH_USES): New.

        * config/ia64/ia64.c (ia64_eh_uses): New.
        * config/ia64/ia64-protos.h: Update.
        * config/ia64/ia64.h (EH_USES): New.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@51060 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 36 insertions, 14 deletions

diff --git a/gcc/flow.c b/gcc/flow.c
index 04a3dc6b4a5..659815c5043 100644
--- a/gcc/flow.c
+++ b/gcc/flow.c
@@ -167,6 +167,9 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA
 #ifndef EPILOGUE_USES
 #define EPILOGUE_USES(REGNO)  0
 #endif
+#ifndef EH_USES
+#define EH_USES(REGNO)  0
+#endif
 
 #ifdef HAVE_conditional_execution
 #ifndef REVERSE_CONDEXEC_PREDICATES_P
@@ -1144,21 +1147,40 @@ calculate_global_regs_live (blocks_in, blocks_out, flags)
 
       /* Begin by propagating live_at_start from the successor blocks.  */
       CLEAR_REG_SET (new_live_at_end);
-      for (e = bb->succ; e; e = e->succ_next)
-	{
-	  basic_block sb = e->dest;
 
-	  /* Call-clobbered registers die across exception and call edges.  */
-	  /* ??? Abnormal call edges ignored for the moment, as this gets
-	     confused by sibling call edges, which crashes reg-stack.  */
-	  if (e->flags & EDGE_EH)
-	    {
-	      bitmap_operation (tmp, sb->global_live_at_start,
-				call_used, BITMAP_AND_COMPL);
-	      IOR_REG_SET (new_live_at_end, tmp);
-	    }
-	  else
-	    IOR_REG_SET (new_live_at_end, sb->global_live_at_start);
+      if (bb->succ)
+	for (e = bb->succ; e; e = e->succ_next)
+	  {
+	    basic_block sb = e->dest;
+
+	    /* Call-clobbered registers die across exception and
+	       call edges.  */
+	    /* ??? Abnormal call edges ignored for the moment, as this gets
+	       confused by sibling call edges, which crashes reg-stack.  */
+	    if (e->flags & EDGE_EH)
+	      {
+		bitmap_operation (tmp, sb->global_live_at_start,
+				  call_used, BITMAP_AND_COMPL);
+		IOR_REG_SET (new_live_at_end, tmp);
+	      }
+	    else
+	      IOR_REG_SET (new_live_at_end, sb->global_live_at_start);
+
+	    /* If a target saves one register in another (instead of on
+	       the stack) the save register will need to be live for EH.  */
+	    if (e->flags & EDGE_EH)
+	      for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
+		if (EH_USES (i))
+		  SET_REGNO_REG_SET (new_live_at_end, i);
+	  }
+      else
+	{
+	  /* This might be a noreturn function that throws.  And
+	     even if it isn't, getting the unwind info right helps
+	     debugging.  */
+	  for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
+	    if (EH_USES (i))
+	      SET_REGNO_REG_SET (new_live_at_end, i);
 	}
 
       /* The all-important stack pointer must always be live.  */