Re: [PATCH] Do not record dependences from debug stmts in tail merging

Re: [PATCH] Do not record dependences from debug stmts in tail merging

[Jakub Jelinek]

On Thu, Feb 15, 2024 at 11:00:29AM +0100, Richard Biener wrote:
> The following avoids recording BB dependences for debug stmt uses.
> 
> Bootstrap and regtest running on x86_64-unknown-linux-gnu.
> 
> It's unlikely a dependence is just because of debug stmts so
> actual compare-debug issues are very unlikely.  Still spotted
> while investigating a CI regression mail (for an obsolete broken
> patch ...)
> 
> 	* tree-ssa-tail-merge.cc (same_succ_hash): Skip debug
> 	stmts.

LGTM.

	Jakub

[PATCH] Do not record dependences from debug stmts in tail merging

[Richard Biener]

The following avoids recording BB dependences for debug stmt uses.

Bootstrap and regtest running on x86_64-unknown-linux-gnu.

It's unlikely a dependence is just because of debug stmts so
actual compare-debug issues are very unlikely.  Still spotted
while investigating a CI regression mail (for an obsolete broken
patch ...)

	* tree-ssa-tail-merge.cc (same_succ_hash): Skip debug
	stmts.
---
 gcc/tree-ssa-tail-merge.cc | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/gcc/tree-ssa-tail-merge.cc b/gcc/tree-ssa-tail-merge.cc
index f4e6ae6e8a2..c8b4a79294d 100644
--- a/gcc/tree-ssa-tail-merge.cc
+++ b/gcc/tree-ssa-tail-merge.cc
@@ -474,6 +474,9 @@ same_succ_hash (const same_succ *e)
        !gsi_end_p (gsi); gsi_next_nondebug (&gsi))
     {
       stmt = gsi_stmt (gsi);
+      if (is_gimple_debug (stmt))
+	continue;
+
       stmt_update_dep_bb (stmt);
       if (stmt_local_def (stmt))
 	continue;
-- 
2.35.3