[Bug tree-optimization/59644] [4.9 Regression] r206243 miscompiles Linux kernel

[trippels at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59644

--- Comment #2 from Markus Trippelsdorf <trippels at gcc dot gnu.org> ---
kernel/printk/printk.o gets miscompiled.

 % gcc -Wp,-MD,kernel/printk/.printk.o.d  -nostdinc -isystem
/var/tmp/gcc_test_/usr/local/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.9.0/include
-I/var/tmp/linux/arch/x86/include -Iarch/x86/include/generated  -Iinclude
-I/var/tmp/linux/arch/x86/include/uapi -Iarch/x86/include/generated/uapi
-I/var/tmp/linux/include/uapi -Iinclude/generated/uapi -include
/var/tmp/linux/include/linux/kconfig.h -D__KERNEL__ -Wall -Wundef
-Wstrict-prototypes -Wno-trigraphs -fno-strict-aliasing -fno-common
-Werror-implicit-function-declaration -Wno-format-security
-fno-delete-null-pointer-checks -O2 -m64 -mno-mmx -mno-sse
-mpreferred-stack-boundary=3 -march=native -mno-red-zone -mcmodel=kernel
-funit-at-a-time -maccumulate-outgoing-args -DCONFIG_AS_CFI=1
-DCONFIG_AS_CFI_SIGNAL_FRAME=1 -DCONFIG_AS_CFI_SECTIONS=1 -DCONFIG_AS_FXSAVEQ=1
-DCONFIG_AS_AVX=1 -DCONFIG_AS_AVX2=1 -pipe -Wno-sign-compare
-fno-asynchronous-unwind-tables -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx
-Wframe-larger-than=1024 -fno-stack-protector -Wno-unused-but-set-variable
-fomit-frame-pointer -Wdeclaration-after-statement -Wno-pointer-sign
-fno-strict-overflow -fconserve-stack -Werror=implicit-int
-Werror=strict-prototypes -DCC_HAVE_ASM_GOTO    -D"KBUILD_STR(s)=#s"
-D"KBUILD_BASENAME=KBUILD_STR(printk)"  -D"KBUILD_MODNAME=KBUILD_STR(printk)"
-c -o kernel/printk/printk.o kernel/printk/printk.c --save-temps