[gcc r11-6746] libstdc++-v3: Add -fcf-protection=none to -march=i486

[gcc r11-6746] libstdc++-v3: Add -fcf-protection=none to -march=i486

[H.J. Lu]

https://gcc.gnu.org/g:2c356f221bbab29bf4d1626d161e0f584dddd600

commit r11-6746-g2c356f221bbab29bf4d1626d161e0f584dddd600
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Fri Jan 15 17:27:53 2021 -0800

    libstdc++-v3: Add -fcf-protection=none to -march=i486
    
    -fcf-protection is automatically enabled in libstdc++ on Linux/x86.
    Starting from
    
    commit 77d372abec0fbf2cfe922e3140ee3410248f979e
    Author: H.J. Lu <hjl.tools@gmail.com>
    Date:   Thu Jan 14 05:56:46 2021 -0800
    
        x86: Error on -fcf-protection with incompatible target
    
    GCC issues an error on -fcf-protection with incompatible target:
    
    ... -fcf-protection ... libstdc++-v3/testsuite/29_atomics/atomic_flag/test_and_set/explicit-hle.cc  -m32   -O2 -g0 -fno-exceptions -fno-asynchronous-unwind-tables -march=i486 ...
    cc1plus: error: '-fcf-protection' is not compatible with this target
    FAIL: 29_atomics/atomic_flag/test_and_set/explicit-hle.cc (test for excess errors)
    
    Add -fcf-protection=none to -march=i486 to compile explicit-hle.cc.
    
            * testsuite/29_atomics/atomic_flag/test_and_set/explicit-hle.cc:
            Add -fcf-protection=none to -march=i486.

Diff:
---
 .../testsuite/29_atomics/atomic_flag/test_and_set/explicit-hle.cc       | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libstdc++-v3/testsuite/29_atomics/atomic_flag/test_and_set/explicit-hle.cc b/libstdc++-v3/testsuite/29_atomics/atomic_flag/test_and_set/explicit-hle.cc
index 0fd81709688..8ec46283208 100644
--- a/libstdc++-v3/testsuite/29_atomics/atomic_flag/test_and_set/explicit-hle.cc
+++ b/libstdc++-v3/testsuite/29_atomics/atomic_flag/test_and_set/explicit-hle.cc
@@ -1,6 +1,6 @@
 // { dg-do compile { target i?86-*-* x86_64-*-* } }
 // { dg-options "-O2 -g0 -fno-exceptions -fno-asynchronous-unwind-tables" }
-// { dg-additional-options "-march=i486" { target ia32 } }
+// { dg-additional-options "-march=i486 -fcf-protection=none" { target ia32 } }
 // { dg-require-effective-target c++11 }
 // { dg-skip-if "scans fail with LTO" { lto } { "-flto" } }
 // { dg-final { scan-assembler-times "xacquire\|\.byte\[^\n\r]*0xf2" 14 } }