PR debug/52001

* cselib.c (preserve_only_constants): Rename to...
(preserve_constants_and_equivs): ... this.  Split out...
(invariant_or_equiv_p): ... this.  Preserve plus expressions
of other preserved expressions too.
(cselib_reset_table): Adjust.
* var-tracking.c (reverse_op): Use canonical value to build
reverse operation.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@184571 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 121d74a..4a2c9fb 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,14 @@
+2012-02-25  Alexandre Oliva  <aoliva@redhat.com>
+
+       PR debug/52001
+       * cselib.c (preserve_only_constants): Rename to...
+       (preserve_constants_and_equivs): ... this.  Split out...
+       (invariant_or_equiv_p): ... this.  Preserve plus expressions
+       of other preserved expressions too.
+       (cselib_reset_table): Adjust.
+       * var-tracking.c (reverse_op): Use canonical value to build
+       reverse operation.
+
 2012-02-23  Kai Tietz  <ktietz@redhat.com>
 
        * config/i386/i386.c (ix86_delegitimize_address): Handle

diff --git a/gcc/cselib.c b/gcc/cselib.c
index d7cb355..4985357 100644 (file)
--- a/gcc/cselib.c
+++ b/gcc/cselib.c
@@ -383,22 +383,29 @@ cselib_clear_table (void)
   cselib_reset_table (1);
 }
 
-/* Remove from hash table all VALUEs except constants
-   and function invariants.  */
+/* Return TRUE if V is a constant, a function invariant or a VALUE
+   equivalence; FALSE otherwise.  */
 
-static int
-preserve_only_constants (void **x, void *info ATTRIBUTE_UNUSED)
+static bool
+invariant_or_equiv_p (cselib_val *v)
 {
-  cselib_val *v = (cselib_val *)*x;
   struct elt_loc_list *l;
 
+  if (v == cfa_base_preserved_val)
+    return true;
+
+  /* Keep VALUE equivalences around.  */
+  for (l = v->locs; l; l = l->next)
+    if (GET_CODE (l->loc) == VALUE)
+      return true;
+
   if (v->locs != NULL
       && v->locs->next == NULL)
     {
       if (CONSTANT_P (v->locs->loc)
          && (GET_CODE (v->locs->loc) != CONST
              || !references_value_p (v->locs->loc, 0)))
-       return 1;
+       return true;
       /* Although a debug expr may be bound to different expressions,
         we can preserve it as if it was constant, to get unification
         and proper merging within var-tracking.  */
@@ -406,24 +413,29 @@ preserve_only_constants (void **x, void *info ATTRIBUTE_UNUSED)
          || GET_CODE (v->locs->loc) == DEBUG_IMPLICIT_PTR
          || GET_CODE (v->locs->loc) == ENTRY_VALUE
          || GET_CODE (v->locs->loc) == DEBUG_PARAMETER_REF)
-       return 1;
-      if (cfa_base_preserved_val)
-       {
-         if (v == cfa_base_preserved_val)
-           return 1;
-         if (GET_CODE (v->locs->loc) == PLUS
-             && CONST_INT_P (XEXP (v->locs->loc, 1))
-             && XEXP (v->locs->loc, 0) == cfa_base_preserved_val->val_rtx)
-           return 1;
-       }
+       return true;
+
+      /* (plus (value V) (const_int C)) is invariant iff V is invariant.  */
+      if (GET_CODE (v->locs->loc) == PLUS
+         && CONST_INT_P (XEXP (v->locs->loc, 1))
+         && GET_CODE (XEXP (v->locs->loc, 0)) == VALUE
+         && invariant_or_equiv_p (CSELIB_VAL_PTR (XEXP (v->locs->loc, 0))))
+       return true;
     }
 
-  /* Keep VALUE equivalences around.  */
-  for (l = v->locs; l; l = l->next)
-    if (GET_CODE (l->loc) == VALUE)
-      return 1;
+  return false;
+}
+
+/* Remove from hash table all VALUEs except constants, function
+   invariants and VALUE equivalences.  */
+
+static int
+preserve_constants_and_equivs (void **x, void *info ATTRIBUTE_UNUSED)
+{
+  cselib_val *v = (cselib_val *)*x;
 
-  htab_clear_slot (cselib_hash_table, x);
+  if (!invariant_or_equiv_p (v))
+    htab_clear_slot (cselib_hash_table, x);
   return 1;
 }
 
@@ -463,7 +475,7 @@ cselib_reset_table (unsigned int num)
     }
 
   if (cselib_preserve_constants)
-    htab_traverse (cselib_hash_table, preserve_only_constants, NULL);
+    htab_traverse (cselib_hash_table, preserve_constants_and_equivs, NULL);
   else
     htab_empty (cselib_hash_table);
 

diff --git a/gcc/var-tracking.c b/gcc/var-tracking.c
index e9b5ca8..c6280e2 100644 (file)
--- a/gcc/var-tracking.c
+++ b/gcc/var-tracking.c
@@ -5334,6 +5334,10 @@ reverse_op (rtx val, const_rtx expr, rtx insn)
   if (!v || !cselib_preserved_value_p (v))
     return;
 
+  /* Use canonical V to avoid creating multiple redundant expressions
+     for different VALUES equivalent to V.  */
+  v = canonical_cselib_val (v);
+
   /* Adding a reverse op isn't useful if V already has an always valid
      location.  Ignore ENTRY_VALUE, while it is always constant, we should
      prefer non-ENTRY_VALUE locations whenever possible.  */