diff mbox series

Avoid left around copies when value-numbering BBs

Message ID 20231005082559.8C3A83857C66@sourceware.org
State Accepted
Headers
Series Avoid left around copies when value-numbering BBs |

Checks

Context Check Description
snail/gcc-patch-check success Github commit url

Commit Message

Richard Biener Oct. 5, 2023, 8:25 a.m. UTC 
  The following makes sure to treat values whose definition we didn't
visit as available since those by definition must dominate the entry
of the region.  That avoids unpropagated copies after if-conversion
and resulting SLP discovery fails (which doesn't handle plain copies).

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

	* tree-ssa-sccvn.cc (rpo_elim::eliminate_avail): Not
	visited value numbers are available itself.
---
 gcc/tree-ssa-sccvn.cc | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/gcc/tree-ssa-sccvn.cc b/gcc/tree-ssa-sccvn.cc
index e46498568cb..d2aab38c2d2 100644
--- a/gcc/tree-ssa-sccvn.cc
+++ b/gcc/tree-ssa-sccvn.cc
@@ -7688,7 +7688,11 @@  rpo_elim::eliminate_avail (basic_block bb, tree op)
     {
       if (SSA_NAME_IS_DEFAULT_DEF (valnum))
 	return valnum;
-      vn_avail *av = VN_INFO (valnum)->avail;
+      vn_ssa_aux_t valnum_info = VN_INFO (valnum);
+      /* See above.  */
+      if (!valnum_info->visited)
+	return valnum;
+      vn_avail *av = valnum_info->avail;
       if (!av)
 	return NULL_TREE;
       if (av->location == bb->index)