2005-06-14 Ed Schonberg <schonberg@adacore.com>

[pf3gnuchains/gcc-fork.git] / gcc / params.def

diff --git a/gcc/params.def b/gcc/params.def
index f2b25c0..d9871a5 100644 (file)
--- a/gcc/params.def
+++ b/gcc/params.def
@@ -443,6 +443,30 @@ DEFPARAM (PARAM_INTEGER_SHARE_LIMIT,
          "The upper bound for sharing integer constants",
          256, 2, 2)
 
+/* Incremental SSA updates for virtual operands may be very slow if
+   there is a large number of mappings to process.  In those cases, it
+   is faster to rewrite the virtual symbols from scratch as if they
+   had been recently introduced.  This heuristic cannot be applied to
+   SSA mappings for real SSA names, only symbols kept in FUD chains.
+
+   PARAM_MIN_VIRTUAL_MAPPINGS specifies the minimum number of virtual
+   mappings that should be registered to trigger the heuristic.
+   
+   PARAM_VIRTUAL_MAPPINGS_TO_SYMS_RATIO specifies the ratio between
+   mappings and symbols.  If the number of virtual mappings is
+   PARAM_VIRTUAL_MAPPINGS_TO_SYMS_RATIO bigger than the number of
+   virtual symbols to be updated, then the updater switches to a full
+   update for those symbols.  */
+DEFPARAM (PARAM_MIN_VIRTUAL_MAPPINGS,
+         "min-virtual-mappings",
+         "Minimum number of virtual mappings to consider switching to full virtual renames",
+         100, 0, 0)
+
+DEFPARAM (PARAM_VIRTUAL_MAPPINGS_TO_SYMS_RATIO,
+         "virtual-mappings-ratio",
+         "Ratio between virtual mappings and virtual symbols to do full virtual renames",
+         3, 0, 0)
+
 /*
 Local variables:
 mode:c