Regressions on native/master at commit r17-2745 vs commit r17-2738 on Linux/x86_64

[Haochen Jiang via Gcc-regression]

Regressions on master at commit r17-2745 vs commit r17-2738 on Linux/x86_64
New failures:

New passes:
FAIL: gcc.target/i386/xchg-2.c scan-assembler xchgb