From: Jeff Law <jeffreyalaw@gmail.com>
Date: Tue, 11 Oct 2022 04:44:26 +0000 (-0400)
Subject: [PR rtl-optimization/107182] Clear EDGE_CROSSING for jump->ret optimization
X-Git-Tag: basepoints/gcc-14~3996
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=db24bdc743cf23ea12d2dcf8254d86ab366bb46d;p=thirdparty%2Fgcc.git

[PR rtl-optimization/107182] Clear EDGE_CROSSING for jump->ret optimization

When turning a jump to a return into a return, we need to clear EDGE_CROSSING
of the fallthru edge to prevent a checking failure.

I considered not applying the transformation when the edge has EDGE_CROSSING
set, but it still seems like we ought to eliminate the unnecessary jump in
that case.

gcc/
	PR rtl-optimization/107182
	* cfgrtl.cc (fixup_reorder_chain): When optimizing a jump to a
	return, clear EDGE_CROSSING on the appropriate edge.
---

diff --git a/gcc/cfgrtl.cc b/gcc/cfgrtl.cc
index 281a432f6a6c..f31941a61f97 100644
--- a/gcc/cfgrtl.cc
+++ b/gcc/cfgrtl.cc
@@ -4055,6 +4055,7 @@ fixup_reorder_chain (void)
 	  ret_label = PATTERN (ret);
 	  dest = EXIT_BLOCK_PTR_FOR_FN (cfun);
 
+	  e_fall->flags &= ~EDGE_CROSSING;
 	  /* E_FALL->dest might become unreachable as a result of
 	     replacing the jump with a return.  So arrange to remove
 	     unreachable blocks.  */