https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80180
Bug ID: 80180
Summary: Incorrect codegen from rdseed intrinsic use
Product: gcc
Version: 6.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: teisenbe at google dot com
Target Milestone: ---
Created attachment 41051
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=41051&action=edit
Preprocessed source file
When the attached source is compiled, the resulting assembly improperly handles
the success bit (CF) for rdseed. The instruction immediately following "rdseed
%rax" is "testl %r8d, r8d" which clears CF. The debug information does
identify the "setc" that should follow rdseed, but it is no where near the
rdseed instruction.
gcc -v output:
Using built-in specs.
COLLECT_GCC=./prebuilt/downloads/x86_64-elf-6.2.0-Linux-x86_64/bin/x86_64-elf-gcc
COLLECT_LTO_WRAPPER=/home/teisenbe/src/magenta/magenta/prebuilt/downloads/x86_64-elf-6.2.0-Linux-x86_64/bin/../libexec/gcc/x86_64-elf/6.2.0/lto-wrapper
Target: x86_64-elf
Configured with: ../gcc-6.2.0/configure --with-included-gettext
--target=x86_64-elf
--prefix=/home/phosek/fuchsia/third_party/gcc_none_toolchains/x86_64-elf-6.2.0-Linux-x86_64
--enable-languages=c,c++ --disable-werror --enable-initfini-array
Thread model: single
gcc version 6.2.0 (GCC)
Command used to generate:
./prebuilt/downloads/x86_64-elf-6.2.0-Linux-x86_64/bin/x86_64-elf-gcc -O2 -g
-finline -include ./build-magenta-pc-x86-64/config-global.h -Wall -Wextra
-Wno-multichar -Werror -Wno-error=deprecated-declarations -Wno-unused-parameter
-Wno-unused-function -Wno-unused-label -Werror=return-type -fno-common
-Wno-nonnull-compare -fasynchronous-unwind-tables -ffunction-sections
-fdata-sections -fno-pic -ffreestanding -include
./build-magenta-pc-x86-64/config-kernel.h -Wformat=2 -Wformat-signedness
-fno-omit-frame-pointer -falign-jumps=1 -falign-loops=1 -falign-functions=4
-msoft-float -mno-mmx -mno-sse -mno-sse2 -mno-3dnow -mno-avx -mno-avx2
-mno-80387 -mno-fp-ret-in-387 -mcmodel=kernel -mno-red-zone -mskip-rax-setup
-mrdseed --include ./build-magenta-pc-x86-64/dev/intel_rng/config-module.h
--std=c11 -Werror-implicit-function-declaration -Wstrict-prototypes
-Wwrite-strings -Wmissing-prototypes -Isystem/public -Isystem/private
-I./build-magenta-pc-x86-64/gen/include -I./build-magenta-pc-x86-64
-Ikernel/include -Isystem/include -Ithird_party/include
-Ikernel/target/pc-x86/include -Ikernel/platform/pc/include
-Ikernel/arch/x86/include -Ikernel/top/include -Ikernel/kernel/include
-Ikernel/app/include -Ikernel/app/stringtests/include
-Ikernel/app/tests/include -Ikernel/dev/include -Ikernel/dev/intel_rng/include
-Ikernel/dev/interrupt/include -Ikernel/dev/pcie/include
-Isystem/ulib/bitmap/include -Ikernel/lib/bitmap/include
-Ikernel/lib/cbuf/include -Ikernel/lib/debugcommands/include
-Ikernel/lib/debuglog/include -Ikernel/lib/fixed_point/include
-Ikernel/lib/gfxconsole/include -Ikernel/lib/ktrace/include
-Ikernel/lib/mtrace/include -Ikernel/lib/pow2_range_allocator/include
-Ikernel/lib/syscalls/include -Ikernel/lib/userboot/include
-Ikernel/lib/version/include -Ikernel/platform/include -Ikernel/target/include
-Ithird_party/lib/acpica/source/include -Ithird_party/lib/acpica/include
-Ikernel/dev/hw_rng/include -Ikernel/kernel/vm/include
-Ikernel/lib/console/include -Ikernel/lib/crypto/include
-Ikernel/lib/debug/include -Ikernel/lib/font/include -Ikernel/lib/gfx/include
-Ikernel/lib/header_tests/include -Ikernel/lib/heap/include
-Ikernel/lib/heap/include -Ikernel/lib/libc/include
-Ikernel/lib/magenta/include -Ikernel/lib/mxtl/include
-Isystem/ulib/mxtl/include -Ikernel/lib/mxtl/include
-Isystem/ulib/region-alloc/include -Ikernel/lib/region-alloc/include
-Ikernel/lib/unittest/include -Ikernel/lib/user_copy/include
-Ikernel/lib/vdso/include -Ithird_party/lib/safeint/source/include
-Ithird_party/lib/safeint/include -Ikernel/dev/udisplay/include
-Ikernel/lib/dpc/include -Ikernel/lib/heap/cmpctmalloc/include
-Ikernel/lib/io/include -Ithird_party/ulib/cryptolib/include
-Ithird_party/lib/cryptolib/include -Ithird_party/ulib/qrcodegen/include
-Ithird_party/lib/qrcodegen/include -c kernel/dev/intel_rng/intel-rng.c -MD -MP
-MT build-magenta-pc-x86-64/dev/intel_rng/kernel/dev/intel_rng/intel-rng.c.o
-MF build-magenta-pc-x86-64/dev/intel_rng/kernel/dev/intel_rng/intel-rng.c.d -o
build-magenta-pc-x86-64/dev/intel_rng/kernel/dev/intel_rng/intel-rng.c.o
--save-temps
Compiler console output: None
