[PATCH] tree-optimization/100414 - compute dominance info in phiopt

[Richard Biener <rguenther@suse.de>]

phiopt now has dominator queries but fails to compute dominance
info.

Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.

2021-05-04  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/100414
	* tree-ssa-phiopt.c (get_non_trapping): Do not compute dominance
	info here.
	(tree_ssa_phiopt_worker): But unconditionally here.

	* gcc.dg/pr100414.c: New testcase.
---
 gcc/testsuite/gcc.dg/pr100414.c | 9 +++++++++
 gcc/tree-ssa-phiopt.c           | 5 ++---
 2 files changed, 11 insertions(+), 3 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/pr100414.c

diff --git a/gcc/testsuite/gcc.dg/pr100414.c b/gcc/testsuite/gcc.dg/pr100414.c
new file mode 100644
index 00000000000..7876f6b56e9
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr100414.c
@@ -0,0 +1,9 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fno-tree-dce -fno-tree-dse -fchecking" } */
+
+int i;
+void
+foo (void)
+{
+  i &= i && __builtin_bswap16 (i);
+}
diff --git a/gcc/tree-ssa-phiopt.c b/gcc/tree-ssa-phiopt.c
index 35ce51e5977..5c18ea16600 100644
--- a/gcc/tree-ssa-phiopt.c
+++ b/gcc/tree-ssa-phiopt.c
@@ -174,6 +174,8 @@ tree_ssa_phiopt_worker (bool do_store_elim, bool do_hoist_loads, bool early_p)
   bool cfgchanged = false;
   hash_set<tree> *nontrap = 0;
 
+  calculate_dominance_info (CDI_DOMINATORS);
+
   if (do_store_elim)
     /* Calculate the set of non-trapping memory accesses.  */
     nontrap = get_non_trapping ();
@@ -2438,9 +2440,6 @@ get_non_trapping (void)
 {
   nt_call_phase = 0;
   hash_set<tree> *nontrap = new hash_set<tree>;
-  /* We're going to do a dominator walk, so ensure that we have
-     dominance information.  */
-  calculate_dominance_info (CDI_DOMINATORS);
 
   nontrapping_dom_walker (CDI_DOMINATORS, nontrap)
     .walk (cfun->cfg->x_entry_block_ptr);
-- 
2.26.2