[gcc r13-1929] tree-optimization/106497 - more forward threader can-copy-bb

[gcc r13-1929] tree-optimization/106497 - more forward threader can-copy-bb

[Richard Biener]

https://gcc.gnu.org/g:0f3514756e0b4d8993ee43dcd958974eb1424061

commit r13-1929-g0f3514756e0b4d8993ee43dcd958974eb1424061
Author: Richard Biener <rguenther@suse.de>
Date:   Tue Aug 2 12:19:25 2022 +0200

    tree-optimization/106497 - more forward threader can-copy-bb
    
    This adds EDGE_COPY_SRC_JOINER_BLOCK sources to the set of blocks
    we need to check we can duplicate.
    
            PR tree-optimization/106497
            * tree-ssa-threadupdate.cc (fwd_jt_path_registry::update_cfg):
            Also verify we can copy EDGE_COPY_SRC_JOINER_BLOCK.
    
            * gcc.dg/torture/pr106497.c: New testcase.

Diff:
---
 gcc/testsuite/gcc.dg/torture/pr106497.c | 20 ++++++++++++++++++++
 gcc/tree-ssa-threadupdate.cc            |  3 ++-
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/gcc/testsuite/gcc.dg/torture/pr106497.c b/gcc/testsuite/gcc.dg/torture/pr106497.c
new file mode 100644
index 00000000000..601200de9e3
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr106497.c
@@ -0,0 +1,20 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-fno-tree-dce" } */
+
+int n;
+
+__attribute__ ((pure,returns_twice)) int
+bar (void);
+
+int
+foo (int x)
+{
+  n = 0;
+
+  bar ();
+
+  if (x && n)
+    return 0;
+
+  foo (x);
+}
diff --git a/gcc/tree-ssa-threadupdate.cc b/gcc/tree-ssa-threadupdate.cc
index 0f2b319d44a..59c268a3567 100644
--- a/gcc/tree-ssa-threadupdate.cc
+++ b/gcc/tree-ssa-threadupdate.cc
@@ -2679,7 +2679,8 @@ fwd_jt_path_registry::update_cfg (bool may_peel_loop_headers)
 	  {
 	    edge e = (*path)[j]->e;
 	    if (m_removed_edges->find_slot (e, NO_INSERT)
-		|| ((*path)[j]->type == EDGE_COPY_SRC_BLOCK
+		|| (((*path)[j]->type == EDGE_COPY_SRC_BLOCK
+		     || (*path)[j]->type == EDGE_COPY_SRC_JOINER_BLOCK)
 		    && !can_duplicate_block_p (e->src)))
 	      break;
 	  }