[patch] 0001-Disable-fdelayed-branch-by-default.patch

0001-Disable-fdelayed-branch-by-default.patch (text/plain), 1.57 KB, created by Sergei Trofimovich (RETIRED) on 2020-07-03 21:55:44 UTC

From 6d0d3ae914bf19706550a539ef304c5875535ffc Mon Sep 17 00:00:00 2001
From: Sergei Trofimovich <[e-mail]>
Date: Fri, 3 Jul 2020 22:50:33 +0100
Subject: [PATCH] Disable -fdelayed-branch by default.

From https://gcc.gnu.org/PR96015 / https://bugs.gentoo.org/729570.
delayed branches are known to generate invalid code around
__builtin_unreachable(); and mis-compiles python.

Use blunt hammer and disable delayed slots until we have better fix.

Reported-by: Jeroen Roovers
Bug: From https://gcc.gnu.org/PR96015
Bug: https://bugs.gentoo.org/729570.
Signed-off-by: Sergei Trofimovich <[e-mail]>
---
 gcc/opts.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/gcc/opts.c b/gcc/opts.c
index 340d99434b3..f9aad8418bf 100644
--- a/gcc/opts.c
+++ b/gcc/opts.c
@@ -458,7 +458,14 @@ static const struct default_options default_options_table[] =
     /* -O1 (and not -Og) optimizations.  */
     { OPT_LEVELS_1_PLUS_NOT_DEBUG, OPT_fbranch_count_reg, NULL, 1 },
 #if DELAY_SLOTS
-    { OPT_LEVELS_1_PLUS_NOT_DEBUG, OPT_fdelayed_branch, NULL, 1 },
+    /*
+     * From https://gcc.gnu.org/PR96015 / https://bugs.gentoo.org/729570.
+     * delayed branches are known to generate invalid code around
+     * __builtin_unreachable(); and mis-compiles python.
+     *
+     * Use blunt hammer and disable delayed slots until we have better fix.
+     */
+    /* { OPT_LEVELS_1_PLUS_NOT_DEBUG, OPT_fdelayed_branch, NULL, 1 }, */
 #endif
     { OPT_LEVELS_1_PLUS_NOT_DEBUG, OPT_fdse, NULL, 1 },
     { OPT_LEVELS_1_PLUS_NOT_DEBUG, OPT_fif_conversion, NULL, 1 },
-- 
2.27.0