[gcc r13-1961] tree-optimization/106521 - unroll-and-jam LC SSA rewrite

[Richard Biener <rguenth@gcc.gnu.org>]

https://gcc.gnu.org/g:d8552eaddc40b72461158e56b5db8709f2eb21ed

commit r13-1961-gd8552eaddc40b72461158e56b5db8709f2eb21ed
Author: Richard Biener <rguenther@suse.de>
Date:   Thu Aug 4 11:55:15 2022 +0200

    tree-optimization/106521 - unroll-and-jam LC SSA rewrite
    
    The LC SSA rewrite performs SSA verification at start but the VN
    run performed on the unrolled-and-jammed body can leave us with
    invalid SSA form until CFG cleanup is run.  So make sure we do that
    before rewriting into LC SSA.
    
            PR tree-optimization/106521
            * gimple-loop-jam.cc (tree_loop_unroll_and_jam): Perform
            CFG cleanup manually before rewriting into LC SSA.
    
            * gcc.dg/torture/pr106521.c: New testcase.

Diff:
---
 gcc/gimple-loop-jam.cc                  | 10 +++++++++-
 gcc/testsuite/gcc.dg/torture/pr106521.c | 17 +++++++++++++++++
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/gcc/gimple-loop-jam.cc b/gcc/gimple-loop-jam.cc
index 8cde6c7c5ce..a8a57d3d384 100644
--- a/gcc/gimple-loop-jam.cc
+++ b/gcc/gimple-loop-jam.cc
@@ -39,6 +39,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "tree-ssa-loop-ivopts.h"
 #include "tree-vectorizer.h"
 #include "tree-ssa-sccvn.h"
+#include "tree-cfgcleanup.h"
 
 /* Unroll and Jam transformation
    
@@ -609,9 +610,16 @@ tree_loop_unroll_and_jam (void)
 
   if (todo)
     {
+      free_dominance_info (CDI_DOMINATORS);
+      /* We need to cleanup the CFG first since otherwise SSA form can
+	 be not up-to-date from the VN run.  */
+      if (todo & TODO_cleanup_cfg)
+	{
+	  cleanup_tree_cfg ();
+	  todo &= ~TODO_cleanup_cfg;
+	}
       rewrite_into_loop_closed_ssa (NULL, 0);
       scev_reset ();
-      free_dominance_info (CDI_DOMINATORS);
     }
   return todo;
 }
diff --git a/gcc/testsuite/gcc.dg/torture/pr106521.c b/gcc/testsuite/gcc.dg/torture/pr106521.c
new file mode 100644
index 00000000000..05c8ce54d0b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr106521.c
@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-floop-unroll-and-jam --param unroll-jam-min-percent=0" } */
+
+short a, b, e;
+volatile long c;
+long d;
+int main() {
+  for (; d; d++) {
+    long g = a = 1;
+    for (; a; a++) {
+      g++;
+      c;
+    }
+    g && (b = e);
+  }
+  return 0;
+}