regmove.c (combine_stack_adjustments_for_block): Avoid emitting a stack adjustment...

        * regmove.c (combine_stack_adjustments_for_block): Avoid
        emitting a stack adjustment of zero bytes.  Let delete_insn
        update bb->head.

Co-Authored-By: Richard Henderson <rth@redhat.com>
From-SVN: r51628

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index f11319c..07eb3c4 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2002-03-30  Roger Sayle <roger@eyesopen.com>
+            Richard Henderson  <rth@redhat.com>
+
+        * regmove.c (combine_stack_adjustments_for_block): Avoid
+        emitting a stack adjustment of zero bytes.  Let delete_insn
+        update bb->head.
+
 2002-03-30  Richard Henderson  <rth@redhat.com>
 
        * config/sparc/sparc.c: Remove all references to TARGET_EPILOGUE.

diff --git a/gcc/regmove.c b/gcc/regmove.c
index aa1c17b..59b1005 100644 (file)
--- a/gcc/regmove.c
+++ b/gcc/regmove.c
@@ -2331,19 +2331,17 @@ combine_stack_adjustments_for_block (bb)
   HOST_WIDE_INT last_sp_adjust = 0;
   rtx last_sp_set = NULL_RTX;
   struct csa_memlist *memlist = NULL;
-  rtx pending_delete;
-  rtx insn, next;
+  rtx insn, next, set;
   struct record_stack_memrefs_data data;
+  bool end_of_block = false;
 
-  for (insn = bb->head; ; insn = next)
+  for (insn = bb->head; !end_of_block ; insn = next)
     {
-      rtx set;
-
-      pending_delete = NULL_RTX;
+      end_of_block = insn == bb->end;
       next = NEXT_INSN (insn);
 
       if (! INSN_P (insn))
-       goto processed;
+       continue;
 
       set = single_set_for_csa (insn);
       if (set)
@@ -2365,7 +2363,7 @@ combine_stack_adjustments_for_block (bb)
                {
                  last_sp_set = insn;
                  last_sp_adjust = this_adjust;
-                 goto processed;
+                 continue;
                }
 
              /* If not all recorded memrefs can be adjusted, or the
@@ -2397,9 +2395,9 @@ combine_stack_adjustments_for_block (bb)
                                                  this_adjust))
                    {
                      /* It worked!  */
-                     pending_delete = insn;
+                     delete_insn (insn);
                      last_sp_adjust += this_adjust;
-                     goto processed;
+                     continue;
                    }
                }
 
@@ -2418,16 +2416,20 @@ combine_stack_adjustments_for_block (bb)
                      last_sp_adjust += this_adjust;
                      free_csa_memlist (memlist);
                      memlist = NULL;
-                     goto processed;
+                     continue;
                    }
                }
 
-             /* Combination failed.  Restart processing from here.  */
+             /* Combination failed.  Restart processing from here.  If
+                deallocation+allocation conspired to cancel, we can
+                delete the old deallocation insn.  */
+             if (last_sp_set && last_sp_adjust == 0)
+               delete_insn (insn);
              free_csa_memlist (memlist);
              memlist = NULL;
              last_sp_set = insn;
              last_sp_adjust = this_adjust;
-             goto processed;
+             continue;
            }
 
          /* Find a predecrement of exactly the previous adjustment and
@@ -2453,15 +2455,12 @@ combine_stack_adjustments_for_block (bb)
                                                         stack_pointer_rtx),
                                  0))
            {
-             if (last_sp_set == bb->head)
-               bb->head = NEXT_INSN (last_sp_set);
              delete_insn (last_sp_set);
-
              free_csa_memlist (memlist);
              memlist = NULL;
              last_sp_set = NULL_RTX;
              last_sp_adjust = 0;
-             goto processed;
+             continue;
            }
        }
 
@@ -2471,7 +2470,7 @@ combine_stack_adjustments_for_block (bb)
          && !for_each_rtx (&PATTERN (insn), record_stack_memrefs, &data))
        {
           memlist = data.memlist;
-          goto processed;
+          continue;
        }
       memlist = data.memlist;
 
@@ -2481,20 +2480,15 @@ combine_stack_adjustments_for_block (bb)
          && (GET_CODE (insn) == CALL_INSN
              || reg_mentioned_p (stack_pointer_rtx, PATTERN (insn))))
        {
+         if (last_sp_set && last_sp_adjust == 0)
+           delete_insn (last_sp_set);
          free_csa_memlist (memlist);
          memlist = NULL;
          last_sp_set = NULL_RTX;
          last_sp_adjust = 0;
        }
-
-    processed:
-      if (insn == bb->end)
-       break;
-
-      if (pending_delete)
-       delete_insn (pending_delete);
     }
 
-  if (pending_delete)
-    delete_insn (pending_delete);
+  if (last_sp_set && last_sp_adjust == 0)
+    delete_insn (last_sp_set);
 }