[COMMITTED] path solver: Compute ranges in path in gimple order.

Aldy Hernandez aldyh@redhat.com
Thu Nov 25 10:54:58 GMT 2021


Andrew's patch for this PR103254 papered over some underlying
performance issues in the path solver that I'd like to address.

We are currently solving the SSA's defined in the current block in
bitmap order, which amounts to random order for all purposes.  This is
causing unnecessary recursion in gori.  This patch changes the order
to gimple order, thus solving dependencies before uses.

There is no change in threadable paths with this change.

Tested on x86-64 & ppc64le Linux.

gcc/ChangeLog:

	PR tree-optimization/103254
	* gimple-range-path.cc (path_range_query::compute_ranges_defined): New
	(path_range_query::compute_ranges_in_block): Move to
	compute_ranges_defined.
	* gimple-range-path.h (compute_ranges_defined): New.
---
 gcc/gimple-range-path.cc | 33 ++++++++++++++++++++++-----------
 gcc/gimple-range-path.h  |  1 +
 2 files changed, 23 insertions(+), 11 deletions(-)

diff --git a/gcc/gimple-range-path.cc b/gcc/gimple-range-path.cc
index 4aa666d2c8b..e24086691c4 100644
--- a/gcc/gimple-range-path.cc
+++ b/gcc/gimple-range-path.cc
@@ -401,6 +401,27 @@ path_range_query::compute_ranges_in_phis (basic_block bb)
     }
 }
 
+// Compute ranges defined in block.
+
+void
+path_range_query::compute_ranges_defined (basic_block bb)
+{
+  int_range_max r;
+
+  compute_ranges_in_phis (bb);
+
+  // Iterate in gimple order to minimize recursion.
+  for (auto gsi = gsi_start_nondebug_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+    if (gimple_has_lhs (gsi_stmt (gsi)))
+      {
+	tree name = gimple_get_lhs (gsi_stmt (gsi));
+	if (TREE_CODE (name) == SSA_NAME
+	    && bitmap_bit_p (m_imports, SSA_NAME_VERSION (name))
+	    && range_defined_in_block (r, name, bb))
+	  set_cache (r, name);
+      }
+}
+
 // Compute ranges defined in the current block, or exported to the
 // next block.
 
@@ -423,17 +444,7 @@ path_range_query::compute_ranges_in_block (basic_block bb)
 	clear_cache (name);
     }
 
-  // Solve imports defined in this block, starting with the PHIs...
-  compute_ranges_in_phis (bb);
-  // ...and then the rest of the imports.
-  EXECUTE_IF_SET_IN_BITMAP (m_imports, 0, i, bi)
-    {
-      tree name = ssa_name (i);
-
-      if (gimple_code (SSA_NAME_DEF_STMT (name)) != GIMPLE_PHI
-	  && range_defined_in_block (r, name, bb))
-	set_cache (r, name);
-    }
+  compute_ranges_defined (bb);
 
   if (at_exit ())
     return;
diff --git a/gcc/gimple-range-path.h b/gcc/gimple-range-path.h
index 57a9ae9bdcd..81c87d475dd 100644
--- a/gcc/gimple-range-path.h
+++ b/gcc/gimple-range-path.h
@@ -58,6 +58,7 @@ private:
   // Methods to compute ranges for the given path.
   bool range_defined_in_block (irange &, tree name, basic_block bb);
   void compute_ranges_in_block (basic_block bb);
+  void compute_ranges_defined (basic_block bb);
   void compute_ranges_in_phis (basic_block bb);
   void adjust_for_non_null_uses (basic_block bb);
   void ssa_range_in_phi (irange &r, gphi *phi);
-- 
2.31.1



More information about the Gcc-patches mailing list