From: Richard Biener <rguenther@suse.de>
Date: Wed, 22 Mar 2023 13:13:02 +0000 (+0100)
Subject: Remove odd code from gimple_can_merge_blocks_p
X-Git-Tag: basepoints/gcc-15~10058
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1da16c1141ebf3948de69eaeb1148778bf0790a9;p=thirdparty%2Fgcc.git

Remove odd code from gimple_can_merge_blocks_p

The following removes a special case to not merge a block with
only a non-local label.  We have a restriction of non-local labels
to be the first statement (and label) in a block, but otherwise nothing,
if the last stmt of A is a non-local label then it will be still
the first statement of the combined A + B.  In particular we'd
happily merge when there's a stmt after that label.

The check originates from the tree-ssa merge.

Bootstrapped and tested on x86_64-unknown-linux-gnu with all
languages.

	* tree-cfg.cc (gimple_can_merge_blocks_p): Remove condition
	rejecting the merge when A contains only a non-local label.
---

diff --git a/gcc/tree-cfg.cc b/gcc/tree-cfg.cc
index a9fcc7fd050f..ae53e15158a7 100644
--- a/gcc/tree-cfg.cc
+++ b/gcc/tree-cfg.cc
@@ -1960,12 +1960,6 @@ gimple_can_merge_blocks_p (basic_block a, basic_block b)
   if (stmt && stmt_ends_bb_p (stmt))
     return false;
 
-  /* Do not allow a block with only a non-local label to be merged.  */
-  if (stmt)
-    if (glabel *label_stmt = dyn_cast <glabel *> (stmt))
-      if (DECL_NONLOCAL (gimple_label_label (label_stmt)))
-	return false;
-
   /* Examine the labels at the beginning of B.  */
   for (gimple_stmt_iterator gsi = gsi_start_bb (b); !gsi_end_p (gsi);
        gsi_next (&gsi))