re PR middle-end/90726 (exponential behavior on SCEV results everywhere)

2019-06-05  Richard Biener  <rguenther@suse.de>

	PR middle-end/90726
	* tree-ssa-loop-niter.c (expand_simple_operations): Do not
	turn an expression graph into a tree.

	* gcc.dg/pr90726.c: Enable IVOPTs.

From-SVN: r271950

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 6dc657f..f5208e1 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2019-06-05  Richard Biener  <rguenther@suse.de>
+
+       PR middle-end/90726
+       * tree-ssa-loop-niter.c (expand_simple_operations): Do not
+       turn an expression graph into a tree.
+
 2019-06-05  Jakub Jelinek  <jakub@redhat.com>
 
        * omp-expand.c (struct omp_region): Add has_lastprivate_conditional

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index c4293bb..35a2d54 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2019-06-05  Richard Biener  <rguenther@suse.de>
+
+       PR middle-end/90726
+       * gcc.dg/pr90726.c: Enable IVOPTs.
+
 2019-06-05  Jakub Jelinek  <jakub@redhat.com>
 
        * g++.dg/vect/simd-1.cc: New test.

diff --git a/gcc/testsuite/gcc.dg/pr90726.c b/gcc/testsuite/gcc.dg/pr90726.c
index acdb0fe..92987de 100644 (file)
--- a/gcc/testsuite/gcc.dg/pr90726.c
+++ b/gcc/testsuite/gcc.dg/pr90726.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-fgimple -O2 -fno-ivopts" } */
+/* { dg-options "-fgimple -O2" } */
 
 int __GIMPLE (ssa,guessed_local(12348030),startwith("fix_loops"))
 un (int dd)

diff --git a/gcc/tree-ssa-loop-niter.c b/gcc/tree-ssa-loop-niter.c
index 8cf8ef9..84e6e31 100644 (file)
--- a/gcc/tree-ssa-loop-niter.c
+++ b/gcc/tree-ssa-loop-niter.c
@@ -1984,8 +1984,8 @@ simplify_replace_tree (tree expr, tree old, tree new_tree,
    enough, and return the new expression.  If STOP is specified, stop
    expanding if EXPR equals to it.  */
 
-tree
-expand_simple_operations (tree expr, tree stop)
+static tree
+expand_simple_operations (tree expr, tree stop, hash_map<tree, tree> &cache)
 {
   unsigned i, n;
   tree ret = NULL_TREE, e, ee, e1;
@@ -2005,7 +2005,24 @@ expand_simple_operations (tree expr, tree stop)
       for (i = 0; i < n; i++)
        {
          e = TREE_OPERAND (expr, i);
-         ee = expand_simple_operations (e, stop);
+         /* SCEV analysis feeds us with a proper expression
+            graph matching the SSA graph.  Avoid turning it
+            into a tree here, thus handle tree sharing
+            properly.
+            ???  The SSA walk below still turns the SSA graph
+            into a tree but until we find a testcase do not
+            introduce additional tree sharing here.  */
+         bool existed_p;
+         tree &cee = cache.get_or_insert (e, &existed_p);
+         if (existed_p)
+           ee = cee;
+         else
+           {
+             cee = e;
+             ee = expand_simple_operations (e, stop, cache);
+             if (ee != e)
+               *cache.get (e) = ee;
+           }
          if (e == ee)
            continue;
 
@@ -2045,7 +2062,7 @@ expand_simple_operations (tree expr, tree stop)
          && src->loop_father != dest->loop_father)
        return expr;
 
-      return expand_simple_operations (e, stop);
+      return expand_simple_operations (e, stop, cache);
     }
   if (gimple_code (stmt) != GIMPLE_ASSIGN)
     return expr;
@@ -2065,7 +2082,7 @@ expand_simple_operations (tree expr, tree stop)
        return e;
 
       if (code == SSA_NAME)
-       return expand_simple_operations (e, stop);
+       return expand_simple_operations (e, stop, cache);
       else if (code == ADDR_EXPR)
        {
          poly_int64 offset;
@@ -2074,7 +2091,8 @@ expand_simple_operations (tree expr, tree stop)
          if (base
              && TREE_CODE (base) == MEM_REF)
            {
-             ee = expand_simple_operations (TREE_OPERAND (base, 0), stop);
+             ee = expand_simple_operations (TREE_OPERAND (base, 0), stop,
+                                            cache);
              return fold_build2 (POINTER_PLUS_EXPR, TREE_TYPE (expr), ee,
                                  wide_int_to_tree (sizetype,
                                                    mem_ref_offset (base)
@@ -2089,7 +2107,7 @@ expand_simple_operations (tree expr, tree stop)
     {
     CASE_CONVERT:
       /* Casts are simple.  */
-      ee = expand_simple_operations (e, stop);
+      ee = expand_simple_operations (e, stop, cache);
       return fold_build1 (code, TREE_TYPE (expr), ee);
 
     case PLUS_EXPR:
@@ -2104,7 +2122,7 @@ expand_simple_operations (tree expr, tree stop)
       if (!is_gimple_min_invariant (e1))
        return expr;
 
-      ee = expand_simple_operations (e, stop);
+      ee = expand_simple_operations (e, stop, cache);
       return fold_build2 (code, TREE_TYPE (expr), ee, e1);
 
     default:
@@ -2112,6 +2130,13 @@ expand_simple_operations (tree expr, tree stop)
     }
 }
 
+tree
+expand_simple_operations (tree expr, tree stop)
+{
+  hash_map<tree, tree> cache;
+  return expand_simple_operations (expr, stop, cache);
+}
+
 /* Tries to simplify EXPR using the condition COND.  Returns the simplified
    expression (or EXPR unchanged, if no simplification was possible).  */