From: Richard Biener <rguenther@suse.de>
Date: Thu, 13 Nov 2025 10:20:31 +0000 (+0100)
Subject: Make simple_dce_from_worklist remove unused call LHSs
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c9108d4dccb4b91e2ee4b8968891abe8ad7958a1;p=thirdparty%2Fgcc.git

Make simple_dce_from_worklist remove unused call LHSs

The following teaches simple_dce_from_worklist to remove the LHS
from calls like DCE does.

	* tree-ssa-dce.cc (simple_dce_from_worklist): For calls
	with side-effects remove their LHS.
---

diff --git a/gcc/tree-ssa-dce.cc b/gcc/tree-ssa-dce.cc
index 160c28cb807..53bbd7584fd 100644
--- a/gcc/tree-ssa-dce.cc
+++ b/gcc/tree-ssa-dce.cc
@@ -2399,7 +2399,15 @@ simple_dce_from_worklist (bitmap worklist, bitmap need_eh_cleanup)
 
       gimple *t = SSA_NAME_DEF_STMT (def);
       if (gimple_has_side_effects (t))
-	continue;
+	{
+	  if (gcall *call = dyn_cast <gcall *> (t))
+	    {
+	      gimple_call_set_lhs (call, NULL_TREE);
+	      update_stmt (call);
+	      release_ssa_name (def);
+	    }
+	  continue;
+	}
 
       /* The defining statement needs to be defining only this name.
 	 ASM is the only statement that can define more than one