tree-optimization/122079 - PRE antic_compute doesn't converge

The following fixes another case of us pruning from the value set
based on the expression set after expression removal when the
maximum expression set is involved.

	PR tree-optimization/122079
	* tree-ssa-pre.cc (prune_clobbered_mems): Do not prune
	values when the maximum expression set is involved.

	* gcc.dg/torture/pr122079-1.c: New testcase.

diff --git a/gcc/testsuite/gcc.dg/torture/pr122079-1.c b/gcc/testsuite/gcc.dg/torture/pr122079-1.c
new file mode 100644 (file)
index 0000000..0af01a5
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr122079-1.c
@@ -0,0 +1,27 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-fcode-hoisting" } */
+
+int a, b, c;
+void e(int *f) {
+  int d = 0;
+  if (f)
+    goto g;
+  goto h;
+i:
+  d = 1 + f[0];
+j:
+  if (c)
+    goto h;
+k:
+  if (b)
+    goto i;
+  if (a)
+    goto j;
+g:
+  if (d + f[0])
+    goto k;
+h:
+  int l[] = {f[0]};
+  if (a)
+    e(l);
+}

diff --git a/gcc/tree-ssa-pre.cc b/gcc/tree-ssa-pre.cc
index 64ffaca21aba1b869d4c079c4766a4bd860086fb..d08caab952a1b91517486e04002101fbfb9bd1fb 100644 (file)
--- a/gcc/tree-ssa-pre.cc
+++ b/gcc/tree-ssa-pre.cc
@@ -2049,8 +2049,12 @@ prune_clobbered_mems (bitmap_set_t set, basic_block block, bool clean_traps)
      the bitmap_find_leader way to see if there's still an expression
      for it.  For some ratio of to be removed values and number of
      values/expressions in the set this might be faster than rebuilding
-     the value-set.  */
-  if (any_removed)
+     the value-set.
+     Note when there's a MAX solution on one edge (clean_traps) do not
+     prune values as we need to consider the resulting expression set MAX
+     as well.  This avoids a later growing ANTIC_IN value-set during
+     iteration, when the explicitly represented expression set grows. */
+  if (any_removed && !clean_traps)
     {
       bitmap_clear (&set->values);
       FOR_EACH_EXPR_ID_IN_SET (set, i, bi)