User:Zucca/trash/Safe CFLAGS - in table format/draft

Note
This acticle has gone trough complete overhaul in terms of layout. It has the content snapped at 2017-05-10T01:10:06‎. There are still errors in layout.

This article attempts to summarize 'safe' settings for CPU flags on Gentoo Linux.

Automatic CPU detection

A recommended default choice for CFLAGS or CXXFLAGS is to use -march=native. This enables auto-detection of the CPU's architecture. A possible entry might look like:

FILE /etc/portage/make.conf

CFLAGS="-O2 -pipe -march=native"
CXXFLAGS="${CFLAGS}"

Warning
Do not use -march=native or -mtune=native in the CFLAGS or CXXFLAGS variables of make.conf when compiling with distcc. Consult the distcc page about how to set up CFLAGS/CXXFLAGS correctly.

Note
Additional information can be found at the GCC optimization page.

Manual

Finding the CPU

To identify the model of the CPU, take a look inside /proc/cpuinfo for the "cpu family" and "model" numbers like so:

user $grep -m1 -A3 "vendor_id" /proc/cpuinfo

Once this information is found match the CPU to one listed on this page in order to find out the suggested "safe" CFLAGS.

Below is a list of CFLAGS which are to be considered "safe" for the given processors. These are the settings that should be used, especially when unsure which CFLAGS the processor needs.

x86/amd64

Intel

Skylake

Core i3/i5/i7 and Xeon E3/E5 *V5

vendor_id       : GenuineIntel
cpu family      : 6
model           : 94
model name      : Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz

FILE /etc/portage/make.conf

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-march=broadwell -O2 -pipe"
CXXFLAGS="${CFLAGS}"

Note
Skylake march support has been introduced with GCC 6. As Gentoo is still using an earlier version of GCC, we use -march=broadwell.

Note
Even though they fit the family and model, this set of CFLAGS does NOT work for Skylake Pentium CPUs (e. g. G4400) producing invalid code. -march=native works.

Haswell

Core i3/i5/i7 and Xeon E3/E5/E7 *V3

vendor_id	: GenuineIntel
cpu family	: 6
model		: 60
model name	: Intel(R) Xeon(R) CPU E3-1271 v3 @ 3.60GHz
…
model           : 60
model name      : Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz

FILE /etc/portage/make.conf

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-march=haswell -O2 -pipe"
CXXFLAGS="${CFLAGS}"

Ivy Bridge

Core i3/i5/i7 and Xeon E3/E5/E7 *V2

vendor_id       : GenuineIntel
cpu family      : 6
model           : 58
model name      : Intel(R) Core(TM) i7-3610QM CPU @ 2.30GHz

FILE /etc/portage/make.conf

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-march=ivybridge -O2 -pipe"
CXXFLAGS="${CFLAGS}"

Pentium

vendor_id	: GenuineIntel
cpu family	: 6
model		: 58
model name	: Intel(R) Pentium(R) CPU G2020 @ 2.90GHz

FILE /etc/portage/make.conf

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-march=ivybridge -mno-avx -mno-aes -mno-rdrnd -O2 -pipe"
CXXFLAGS="${CFLAGS}"

Sandy Bridge

Core i3/i5/i7 and Xeon E3/E5/E7

vendor_id	: GenuineIntel
cpu family	: 6
…
model		: 42
model name	: Intel(R) Core(TM) i5-2400 CPU @ 3.10GHz
…
model		: 45
model name	: Intel(R) Core(TM) i7-3930K CPU @ 3.20GHz
… 
model		: 42
model name	: Intel(R) Xeon(R) CPU E31245 @ 3.30GHz
… 
model           : 45
model name      : Intel(R) Xeon(R) CPU E5-2407 0 @ 2.20GHz

FILE /etc/portage/make.conf

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-march=sandybridge -O2 -pipe"
CXXFLAGS="${CFLAGS}"

Pentium

vendor_id	: GenuineIntel
cpu family	: 6
model		: 42
model name	: Intel(R) Pentium(R) CPU B960 @ 2.20GHz

FILE /etc/portage/make.conf

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-march=sandybridge -mno-avx -mno-aes -mno-rdrnd -O2 -pipe"
CXXFLAGS="${CFLAGS}"

Nehalem

Core i3/i5/i7

vendor_id	: GenuineIntel
cpu family	: 6
model		: 30
model name	: Intel(R) Core(TM) i5-750 CPU @ 2.66GHz

FILE /etc/portage/make.conf

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-march=nehalem -O2 -pipe"
CXXFLAGS="${CFLAGS}"

Westmere

Core i3/i5/i7

vendor_id	: GenuineIntel
cpu family	: 6
model		: 37
model name	: Intel(R) Core(TM) i5-650 CPU @ 3.20GHz

FILE /etc/portage/make.conf

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-march=westmere -O2 -pipe"
CXXFLAGS="${CFLAGS}"

Intel Core

vendor_id       : GenuineIntel
cpu family      : 6
…
model		: 15
model name	: Intel(R) Core(TM)2 Duo CPU     T7500  @ 2.20GHz
…
model           : 15
model name      : Intel(R) Xeon(R) CPU            3040  @ 1.86GHz

FILE /etc/portage/make.conf

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-march=core2 -O2 -pipe"
CXXFLAGS="${CFLAGS}"

Older microarchitecture

Pentium M (Dothan)

vendor_id	: GenuineIntel
cpu family	: 6
model		: 13
model name	: Intel(R) Pentium(R) M processor 2.13GHz

FILE /etc/portage/make.conf

CHOST="i686-pc-linux-gnu"
CFLAGS="-O2 -march=pentium-m -pipe -fomit-frame-pointer"
CXXFLAGS="${CFLAGS}"

Pentium 4 (Prescott)

64-bit capable models: 505, 505J, 506, 511, 516, 517, 519K, 521, 524, 531, 541, 551, 561, 571, 6xx and the 3.73(3)GHz Pentium 4 Extreme Edition.

Note
Check the /proc/cpuinfo for the lm flag to detect 64-bit CPUs:

user $grep lm /proc/cpuinfo

The cpuid model (4 vs 3) is not an indicator of 64-bit compatibility; there are 32-bit family15/model4 CPUs!

vendor_id	: GenuineIntel
cpu family	: 15
model		: 4
model name	: Intel(R) Pentium(R) 4 CPU XXXGHz

FILE /etc/portage/make.conf

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-O2 -march=nocona -pipe"
CXXFLAGS="${CFLAGS}"

All other Prescotts

vendor_id	: GenuineIntel
cpu family	: 15
model		: 3
model name	: Intel(R) Pentium(R) 4 CPU XXXGHz

FILE /etc/portage/make.conf

CHOST="i686-pc-linux-gnu"
CFLAGS="-O2 -march=prescott -pipe"
CXXFLAGS="${CFLAGS}"

AMD

Ryzen (Zen)

1700, 1700X, 1800X

vendor_id	: AuthenticAMD
cpu family	: 23
model		: 1
model name	: AMD Ryzen 7 1800X Eight-Core Processor

FILE /etc/portage/make.conf

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-O2 -march=bdver4 -pipe"
CXXFLAGS="${CFLAGS}"

Note
Although -march=znver1 support was introduced with GCC 6, as of May 9th, 2017, Gentoo (stable) is still on GCC 5.4.0. For now -march=bdver4 is the recommended value for stable Gentoo systems.

A6/A8/A9/A10/A12-8XXX/9XXX (Excavator)

Carrizo, Bristol Ridge, and Stoney Ridge

vendor_id	: AuthenticAMD
cpu family	: 21
model		: 96 or 101 or 112
model name	: AMD A12-9800 RADEON R7, 12 COMPUTE CORES 4C+8G

FILE /etc/portage/make.conf

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-O2 -march=bdver4 -pipe"
CXXFLAGS="${CFLAGS}"

A4/A6/A8/A10-7XXX/8XXX (Steamroller)

Kaveri and Godavari

vendor_id	: AuthenticAMD
cpu family	: 21
model		: 48 or 56
model name	: AMD A10-7850K Radeon R7, 12 Compute Cores 4C+8G

FILE /etc/portage/make.conf

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-O2 -march=bdver3 -pipe"
CXXFLAGS="${CFLAGS}"

Note
Various lowpower AMD APUs branded as AX-7XXX (eg. A4-7210) don't belong to cpu family 21!

E1/E2-XXXX, A4/A6/A8/A10-XXXX (Jaguar, Puma)

Kabini, Temash, Beema, Mullins, and Carrizo-L

vendor_id	: AuthenticAMD
cpu family	: 22
model		: 0 or 48
model name	: AMD A4-5000 APU with Radeon(TM) HD Graphics

FILE /etc/portage/make.conf

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-O2 -march=btver2 -pipe"
CXXFLAGS="${CFLAGS}"

Note
Majority of AMD APUs branded as A4/A6/A8-XXXX (eg. A4-5300, A4-4000 or A6-5345M) don't belong to cpu family 22! They should use settings listed for AMD APU model given by the cpu family and model.

A4/A6/A8/A10-4XXX/5XXX/6XXX (Piledriver)

Trinity and Richland

vendor_id	: AuthenticAMD
cpu family	: 21
model		: 16 or 19
model name	: AMD A8-4500M APU with Radeon(tm) HD Graphics

FILE /etc/portage/make.conf

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-O2 -march=bdver2 -pipe"
CXXFLAGS="${CFLAGS}"

Note
Various low power AMD APUs branded as AX-5XXX/6XXX (eg. A4-5000, A4-5100 or A6-6310) don't belong to CPU family 21!

FX-XXXX

Bulldozer and Piledriver

vendor_id	: AuthenticAMD
cpu family	: 21
model		: 1 or 2
model name	: AMD FX(tm)-8150 Eight-Core Processor

Note
Make sure and check the number listed by model on the system, the -march flag should be bdverX where X is the model number.

Note
Various AMD APUs branded as FX don't match model 1 or 2! They should use settings listed for AMD APU model given by the cpu family and model.

FILE /etc/portage/make.conf

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-O2 -march=bdver1 -pipe"
CXXFLAGS="${CFLAGS}"

Z-XX, C-X0, E-XX0, E1/E2-1X00, E2-2000 (Bobcat)

Ontario, Hondo, Desna, and Zacate

vendor_id	: AuthenticAMD
cpu family	: 20
model		: 1 or 2
model name	: AMD E-350 Processor

FILE /etc/portage/make.conf

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-O2 -march=btver1 -pipe"
CXXFLAGS="${CFLAGS}"

A4/A6/A8-3XXX/3XXXM (12h)

Llano

vendor_id	: AuthenticAMD
cpu family	: 18
model		: 1
model name	: AMD A8-3500M APU with Radeon(tm) HD Graphics

FILE /etc/portage/make.conf

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-O2 -march=amdfam10 -mcx16 -mpopcnt -pipe"
CXXFLAGS="${CFLAGS}"

Phenom/Phenom II, Athlon II, Sempron (10h)

Agena, Deneb, Thuban, and derivatives

vendor_id	: AuthenticAMD
cpu family	: 16
model		: X
model name	: AMD Phenom(tm) II X6 1090T Processor

FILE /etc/portage/make.conf

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-O2 -march=amdfam10 -pipe"
CXXFLAGS="${CFLAGS}"

Older microarchitectures

E+ revisions - Athlon 64, Athlon 64 X2/FX, Sempron (0Fh)

vendor_id	: AuthenticAMD
cpu family	: 15
model		: >= 39
model name	: AMD Athlon(tm) 64 X2 Dual Core Processor 4200+

FILE /etc/portage/make.conf

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-O2 -march=opteron-sse3 -pipe"
CXXFLAGS="${CFLAGS}"

Note
Various AMD CPUs branded as Sempron (eg. Sempron 2200+ or Sempron 3000+) don't belong to cpu family 15!

Geode LX

vendor_id	: AuthenticAMD
cpu family	: 5
model		: 10
model name	: Geode(TM) Integrated Processor by AMD PCS

FILE /etc/portage/make.conf

CHOST="i486-pc-linux-gnu"
CFLAGS="-Os -pipe -march=geode -mmmx -m3dnow -fomit-frame-pointer"
CXXFLAGS="${CFLAGS}"

Pre-E revisions - Athlon 64, Athlon 64 FX, Sempron (0Fh)

vendor_id	: AuthenticAMD
cpu family	: 15
model		: < 39
model name	: AMD Athlon(tm) 64 Processor 3200+

FILE /etc/portage/make.conf

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-O2 -march=opteron -pipe"
CXXFLAGS="${CFLAGS}"

Note
Various AMD CPUs branded as Sempron (eg. Sempron 2200+ or Sempron 3000+) don't belong to cpu family 15!

ARM

Note
To identify the respective ARM core of the SoC on your board, List of ARM microarchitectures and List of applications of ARM cores on Wikipedia may help.

Cortex-A

ARMv7-A/Cortex-A9 MPCore

with optional VFPv3 FPU

processor       : 0
model name      : ARMv7 Processor rev 0 (v7l)
BogoMIPS        : 2.00
Features        : half thumb fastmult vfp edsp vfpv3 vfpv3d16 tls 
CPU implementer : 0x41
CPU architecture: 7
CPU variant     : 0x1
CPU part        : 0xc09
CPU revision    : 0

processor       : 1
model name      : ARMv7 Processor rev 0 (v7l)
BogoMIPS        : 2.00
Features        : half thumb fastmult vfp edsp vfpv3 vfpv3d16 tls 
CPU implementer : 0x41
CPU architecture: 7
CPU variant     : 0x1
CPU part        : 0xc09
CPU revision    : 0

Hardware        : NVIDIA Tegra SoC (Flattened Device Tree)
Revision        : 0000
Serial          : 0000000000000000

FILE /etc/portage/make.conf

CHOST="armv7a-hardfloat-linux-gnueabi"
CFLAGS="-O2 -march=cortex-a9 -mfpu=vfpv3-d16 -mfloat-abi=hard -pipe -fomit-frame-pointer"
CXXFLAGS="${CFLAGS}"

Note
This ARM core (equipped with the optional vfpv3d16 FPU but missing the NEON extension) is used in the Toshiba AC100/Dynabook AZ/Compal Paz00 Board.

ARMv8-A/BCM2837

Note
This is the Broadcom chip used in the Raspberry Pi 3 Model B.

AArch32 with neon FPU

processor	: 0-3
model name	: ARMv7 Processor rev 4 (v7l)
BogoMIPS	: 38.40
Features	: half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm crc32 
CPU implementer	: 0x41
CPU architecture: 7
CPU variant	: 0x0
CPU part	: 0xd03
CPU revision	: 4

Hardware	: BCM2709
Revision        : 0000
Serial          : 0000000000000000

FILE /etc/portage/make.conf

CHOST="armv7a-hardfloat-linux-gnueabi"
CFLAGS="-O2 -pipe -march=armv7-a -mfpu=neon-vfpv4 -mfloat-abi=hard"
CXXFLAGS="${CFLAGS}"

AArch64

processor	: 0-3
BogoMIPS	: 38.40
Features	: fp asimd evtstrm crc32
CPU implementer	: 0x41
CPU architecture: 8
CPU variant	: 0x0
CPU part	: 0xd03
CPU revision	: 4

FILE /etc/portage/make.conf

CHOST="aarch64-unknown-linux-gnu"
CFLAGS="-march=armv8-a+crc -mtune=cortex-a53 -O2 -pipe"
CXXFLAGS="${CFLAGS}"

ARM11

ARMv6/ARM1176JZF-S

Note
This ARM core is used in the first generation of the Raspberry Pi.

processor	: 0
model name	: ARMv6-compatible processor rev 7 (v6l)
BogoMIPS	: 697.95
Features	: half thumb fastmult vfp edsp java tls 
CPU implementer	: 0x41
CPU architecture: 7
CPU variant	: 0x0
CPU part	: 0xb76
CPU revision	: 7

Hardware	: BCM2835
Revision	: 0000
Serial		: 000000000XXXXXXX

FILE /etc/portage/make.conf

CHOST="armv6j-hardfloat-linux-gnueabi"
CFLAGS="-O2 -pipe -march=arm1176jzf-s -mfpu=vfp -mfloat-abi=hard"
CXXFLAGS="${CFLAGS}"

ARMv6/ARM1136JF-S

Processor       : ARMv6-compatible processor rev 5 (v6l)
BogoMIPS        : 791.34
Features        : swp half thumb fastmult vfp edsp java 
CPU implementer : 0x41
CPU architecture: 6TEJ
CPU variant     : 0x1
CPU part        : 0xb36
CPU revision    : 5

Hardware        : IMAPX200
Revision        : 0000
Serial          : 0000000000000000

FILE /etc/portage/make.conf

CHOST="armv6j-hardfloat-linux-gnueabi"
CFLAGS="-Os -march=arm1136jf-s -mfpu=vfp -mfloat-abi=hard -pipe -fomit-frame-pointer"
CXXFLAGS="${CFLAGS}"

ppc/ppc64

Note
-march=native almost never works on PowerPC.

POWER8

processor       : 0
cpu             : POWER8E (raw), altivec supported
clock           : 3026.000000MHz
revision        : 2.1 (pvr 004b 0201)

timebase        : 512000000
platform        : pSeries
model           : IBM pSeries (emulated by qemu)
machine         : CHRP IBM pSeries (emulated by qemu)

Note
Currently Gentoo does not support POWER8, but safe CFLAGS for it would look like the following.

FILE /etc/portage/make.conf

CHOST="powerpc64le-linux-gnu"
CFLAGS="-mcpu=power8 -O2 -pipe -mabi=altivec -maltivec"
CXXFLAGS="${CFLAGS}"

Cell

processor	: 0
cpu		: Cell Broadband Engine, altivec supported
clock		: 3192.000000MHz
revision	: 5.1 (pvr 0070 0501)

processor	: 1
cpu		: Cell Broadband Engine, altivec supported
clock		: 3192.000000MHz
revision	: 5.1 (pvr 0070 0501)

timebase	: 79800000
platform	: PS3
model		: SonyPS3

FILE /etc/portage/make.conf

CHOST="powerpc-unknown-linux-gnu"
CFLAGS="-mcpu=cell -O2 -pipe -mabi=altivec -maltivec"
CXXFLAGS="${CFLAGS}"

Note
GCC's -mspe and -mabi=spe options are not targetting PS3 systems and IBM Cell. Instead, those options are dedicated to IBM e500. More info:

G4

PPC 7447A

processor	: 0
cpu		: 7447A, altivec supported
clock		: 1666.666000MHz
revision	: 1.5 (pvr 8003 0105)
bogomips	: 33.28
timebase	: 8320000
platform	: PowerMac
model		: PowerBook5,9
machine		: PowerBook5,9
motherboard	: PowerBook5,9 MacRISC3 Power Macintosh 
detected as	: 287 (PowerBook G4 17")
pmac flags	: 00000018
L2 cache	: 512K unified
pmac-generation	: NewWorld

FILE /etc/portage/make.conf

CHOST="powerpc-unknown-linux-gnu"
CFLAGS="-mcpu=7450 -O2 -maltivec -mabi=altivec -fno-strict-aliasing -pipe"
CXXFLAGS="${CFLAGS}"

G3 (PPC 7XX)

processor       : 0
cpu             : 740/750
clock           : 400.000000MHz
revision        : 131.0 (pvr 0008 8300)
bogomips        : 49.93
timebase        : 24966218
platform        : PowerMac
model           : PowerBook3,1
machine         : PowerBook3,1
motherboard     : PowerBook3,1 MacRISC2 MacRISC Power Macintosh
detected as     : 70 (PowerBook Pismo)
pmac flags      : 0000001f
L2 cache        : 1024K unified
pmac-generation : NewWorld

FILE /etc/portage/make.conf

CHOST="powerpc-unknown-linux-gnu"
CFLAGS="-mcpu=750 -Os -pipe -fno-strict-aliasing"
CXXFLAGS="${CFLAGS}"

m68k

External resources

GCC Online Documentation on GNU.org
GCC x86 performance hints

User:Zucca/trash/Safe CFLAGS - in table format/draft

Automatic CPU detection

Manual

Finding the CPU

x86/amd64

Intel

Skylake

Haswell

Ivy Bridge

Sandy Bridge

Nehalem

Westmere

Intel Core

Older microarchitecture

AMD

Ryzen (Zen)

A6/A8/A9/A10/A12-8XXX/9XXX (Excavator)

A4/A6/A8/A10-7XXX/8XXX (Steamroller)

E1/E2-XXXX, A4/A6/A8/A10-XXXX (Jaguar, Puma)

A4/A6/A8/A10-4XXX/5XXX/6XXX (Piledriver)

FX-XXXX

Z-XX, C-X0, E-XX0, E1/E2-1X00, E2-2000 (Bobcat)

A4/A6/A8-3XXX/3XXXM (12h)

Phenom/Phenom II, Athlon II, Sempron (10h)

Older microarchitectures

ARM

Cortex-A

ARMv7-A/Cortex-A9 MPCore

ARMv8-A/BCM2837

ARM11

ARMv6/ARM1176JZF-S

ARMv6/ARM1136JF-S

ppc/ppc64

POWER8

Cell

G4

PPC 7447A

G3 (PPC 7XX)

m68k

See also

External resources