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[vta] Some vartrack speedups


This patch saves roughly 5 minutes out of 25 minutes of HTML401F.class
compilation on VTA branch, by avoiding lookups in
changed_variables hashtab, which makes a difference on
a function called 2164813966x during var-tracking of this huge function.
Bootstrapped/regtested on vta branch and tested not to make any debug
info generation differences on > 500 of preprocessed files.
Acked by Richard privately, though I'll still wait for Alex to return and
do whatever testing he wants to do on the VTA branch.

This is just the first part of speeding up HTML401F.class compilation,
I have already bootstrappable port of the r148760 commit (though there are
still a couple of minor debug info generation differences, looking into them
now) and r148852.  Plus I have a callgrind dump I still need to analyze and
try to optimize the most performance critical spots.

2009-06-25  Jakub Jelinek  <>

	* var-tracking.c (VALUE_CHANGED, DECL_CHANGED): Define.
	(set_dv_changed, dv_changed_p): New static inlines.
	(track_expr_p): Clear DECL_CHANGED.
	(variable_was_changed): Call set_dv_changed.
	(emit_note_insn_var_location): Likewise.
	(check_changed_value): Use VALUE_CHANGED instead of hash table lookup.
	(check_changed_var): Use dv_changed_p instead of hash table lookup.

	(dv_is_decl_p): Remove useless decl variable.
	(dv_htab_hash): Add inline keyword, remove useless assert.

--- gcc/var-tracking.c.jj	2009-06-23 00:05:24.000000000 +0200
+++ gcc/var-tracking.c	2009-06-25 11:38:48.000000000 +0200
@@ -684,13 +684,9 @@ adjust_stack_reference (rtx mem, HOST_WI
 static inline bool
 dv_is_decl_p (decl_or_value dv)
-  tree decl;
   if (!dv.ptr)
     return false;
-  decl = (tree)dv.ptr;
   if (GET_CODE ((rtx)dv.ptr) == VALUE)
     return false;
@@ -784,10 +780,9 @@ dv_from_value (rtx value)
   return dv;
-static hashval_t
+static inline hashval_t
 dv_htab_hash (decl_or_value dv)
-  gcc_assert (dv.ptr);
   if (dv_is_value_p (dv))
     return -(hashval_t)(CSELIB_VAL_PTR (dv_as_value (dv))->value);
@@ -1882,6 +1877,33 @@ dataflow_set_union (dataflow_set *dst, d
 /* Whether the value is currently being expanded.  */
+/* Whether the value is in changed_variables hash table.  */
+#define VALUE_CHANGED(x) \
+  (RTL_FLAG_CHECK1 ("VALUE_CHANGED", (x), VALUE)->frame_related)
+/* Whether the decl is in changed_variables hash table.  */
+/* Record that DV has been added into resp. removed from changed_variables
+   hashtable.  */
+static inline void
+set_dv_changed (decl_or_value dv, bool newv)
+  if (dv_is_value_p (dv))
+    VALUE_CHANGED (dv_as_value (dv)) = newv;
+  else
+    DECL_CHANGED (dv_as_decl (dv)) = newv;
+/* Return true if DV is present in changed_variables hash table.  */
+static inline bool
+dv_changed_p (decl_or_value dv)
+  return (dv_is_value_p (dv)
+	  ? VALUE_CHANGED (dv_as_value (dv))
+	  : DECL_CHANGED (dv_as_decl (dv)));
 /* Return a location list node whose loc is rtx_equal to LOC, in the
    location list of a one-part variable or value VAR, or in that of
@@ -3774,6 +3796,8 @@ track_expr_p (tree expr, bool need_rtl)
 	return 0;
+  DECL_CHANGED (expr) = 0;
+  DECL_CHANGED (realdecl) = 0;
   return 1;
@@ -5314,6 +5338,9 @@ variable_was_changed (variable var, htab
       void **slot;
+      /* Remember this decl or VALUE has been added to changed_variables.  */
+      set_dv_changed (var->dv, true);
       slot = htab_find_slot_with_hash (changed_variables,
 				       hash, INSERT);
@@ -5975,6 +6002,7 @@ emit_note_insn_var_location (void **varp
+  set_dv_changed (var->dv, false);
   htab_clear_slot (changed_variables, varp);
   /* When there are no location parts the variable has been already
@@ -5997,14 +6025,11 @@ check_changed_value (rtx *loc, void *dat
   rtx x = *loc;
   bool *changedp = (bool *)data;
-  decl_or_value dv;
   if (GET_CODE (x) != VALUE)
     return 0;
-  dv = dv_from_value (x);
-  if (!htab_find_slot_with_hash (changed_variables, &dv, dv_htab_hash (dv),
-				 NO_INSERT))
+  if (!VALUE_CHANGED (x))
     return 0;
   *changedp = true;
@@ -6025,8 +6050,7 @@ check_changed_var (void **slot, void *da
   if (var->n_var_parts != 1 || !dv_onepart_p (var->dv))
     return 1;
-  if (htab_find_slot_with_hash (changed_variables, &var->dv,
-				dv_htab_hash (var->dv), NO_INSERT))
+  if (dv_changed_p (var->dv))
     return 1;
   if (!dv_is_value_p (var->dv)


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