Regressions on native/master at commit r15-6797 vs commit r15-6769 on Linux/x86_64

[Haochen Jiang via Gcc-regression]

Regressions on master at commit r15-6797 vs commit r15-6769 on Linux/x86_64
New failures:

New passes:
FAIL: gcc.dg/field-merge-16.c scan-tree-dump-times ifcombine "optimizing" 6
FAIL: gcc.target/i386/pr118017.c (test for excess errors)