GCC 4.9.0 Compiler Optimization Tuning
Testing various CFLAGS/CXXFLAGS of different GCC compiler optimizations including the -O optimization levels, Link Time Optimizations, and -march=native targeting. benchmarks by Michael Larabel for a future article on phoronix.com


-O0: 

	Processor: Intel Core i7-4770K @ 3.50GHz (8 Cores), Motherboard: ECS Z87H3-A2X EXTREME v1.0, Chipset: Intel 4th Gen Core DRAM, Memory: 16384MB, Disk: 120GB Samsung SSD 840, Graphics: ECS NVIDIA GeForce GTX 460 768MB (675/1804MHz), Audio: Realtek ALC1150, Monitor: Samsung SyncMaster, Network: Realtek RTL8111/8168/8411

	OS: Ubuntu 14.04, Kernel: 3.13.0-22-generic (x86_64), Desktop: Unity 7.2.0, Display Server: X Server 1.15.0, Display Driver: NVIDIA 337.12, OpenGL: 4.3.0, Compiler: GCC 4.9.0 20140411, File-System: ext4, Screen Resolution: 2560x1600

-O1: 

	Processor: Intel Core i7-4770K @ 3.50GHz (8 Cores), Motherboard: ECS Z87H3-A2X EXTREME v1.0, Chipset: Intel 4th Gen Core DRAM, Memory: 16384MB, Disk: 120GB Samsung SSD 840, Graphics: ECS NVIDIA GeForce GTX 460 768MB (675/1804MHz), Audio: Realtek ALC1150, Monitor: Samsung SyncMaster, Network: Realtek RTL8111/8168/8411

	OS: Ubuntu 14.04, Kernel: 3.13.0-22-generic (x86_64), Desktop: Unity 7.2.0, Display Server: X Server 1.15.0, Display Driver: NVIDIA 337.12, OpenGL: 4.3.0, Compiler: GCC 4.9.0 20140411, File-System: ext4, Screen Resolution: 2560x1600

-O2: 

	Processor: Intel Core i7-4770K @ 3.50GHz (8 Cores), Motherboard: ECS Z87H3-A2X EXTREME v1.0, Chipset: Intel 4th Gen Core DRAM, Memory: 16384MB, Disk: 120GB Samsung SSD 840, Graphics: ECS NVIDIA GeForce GTX 460 768MB (675/1804MHz), Audio: Realtek ALC1150, Monitor: Samsung SyncMaster, Network: Realtek RTL8111/8168/8411

	OS: Ubuntu 14.04, Kernel: 3.13.0-22-generic (x86_64), Desktop: Unity 7.2.0, Display Server: X Server 1.15.0, Display Driver: NVIDIA 337.12, OpenGL: 4.3.0, Compiler: GCC 4.9.0 20140411, File-System: ext4, Screen Resolution: 2560x1600

-Os: 

	Processor: Intel Core i7-4770K @ 3.50GHz (8 Cores), Motherboard: ECS Z87H3-A2X EXTREME v1.0, Chipset: Intel 4th Gen Core DRAM, Memory: 16384MB, Disk: 120GB Samsung SSD 840, Graphics: ECS NVIDIA GeForce GTX 460 768MB (675/1804MHz), Audio: Realtek ALC1150, Monitor: Samsung SyncMaster, Network: Realtek RTL8111/8168/8411

	OS: Ubuntu 14.04, Kernel: 3.13.0-22-generic (x86_64), Desktop: Unity 7.2.0, Display Server: X Server 1.15.0, Display Driver: NVIDIA 337.12, OpenGL: 4.3.0, Compiler: GCC 4.9.0 20140411, File-System: ext4, Screen Resolution: 2560x1600

-Og: 

	Processor: Intel Core i7-4770K @ 3.50GHz (8 Cores), Motherboard: ECS Z87H3-A2X EXTREME v1.0, Chipset: Intel 4th Gen Core DRAM, Memory: 16384MB, Disk: 120GB Samsung SSD 840, Graphics: ECS NVIDIA GeForce GTX 460 768MB (675/1804MHz), Audio: Realtek ALC1150, Monitor: Samsung SyncMaster, Network: Realtek RTL8111/8168/8411

	OS: Ubuntu 14.04, Kernel: 3.13.0-22-generic (x86_64), Desktop: Unity 7.2.0, Display Server: X Server 1.15.0, Display Driver: NVIDIA 337.12, OpenGL: 4.3.0, Compiler: GCC 4.9.0 20140411, File-System: ext4, Screen Resolution: 2560x1600

-O3: 

	Processor: Intel Core i7-4770K @ 3.50GHz (8 Cores), Motherboard: ECS Z87H3-A2X EXTREME v1.0, Chipset: Intel 4th Gen Core DRAM, Memory: 16384MB, Disk: 120GB Samsung SSD 840, Graphics: ECS NVIDIA GeForce GTX 460 768MB (675/1804MHz), Audio: Realtek ALC1150, Monitor: Samsung SyncMaster, Network: Realtek RTL8111/8168/8411

	OS: Ubuntu 14.04, Kernel: 3.13.0-22-generic (x86_64), Desktop: Unity 7.2.0, Display Server: X Server 1.15.0, Display Driver: NVIDIA 337.12, OpenGL: 4.3.0, Compiler: GCC 4.9.0 20140411, File-System: ext4, Screen Resolution: 2560x1600

-Ofast: 

	Processor: Intel Core i7-4770K @ 3.50GHz (8 Cores), Motherboard: ECS Z87H3-A2X EXTREME v1.0, Chipset: Intel 4th Gen Core DRAM, Memory: 16384MB, Disk: 120GB Samsung SSD 840, Graphics: ECS NVIDIA GeForce GTX 460 768MB (675/1804MHz), Audio: Realtek ALC1150, Monitor: Samsung SyncMaster, Network: Realtek RTL8111/8168/8411

	OS: Ubuntu 14.04, Kernel: 3.13.0-22-generic (x86_64), Desktop: Unity 7.2.0, Display Server: X Server 1.15.0, Display Driver: NVIDIA 337.12, OpenGL: 4.3.0, Compiler: GCC 4.9.0 20140411, File-System: ext4, Screen Resolution: 2560x1600

-O3 -march=native: 

	Processor: Intel Core i7-4770K @ 3.50GHz (8 Cores), Motherboard: ECS Z87H3-A2X EXTREME v1.0, Chipset: Intel 4th Gen Core DRAM, Memory: 16384MB, Disk: 120GB Samsung SSD 840, Graphics: ECS NVIDIA GeForce GTX 460 768MB (675/1804MHz), Audio: Realtek ALC1150, Monitor: Samsung SyncMaster, Network: Realtek RTL8111/8168/8411

	OS: Ubuntu 14.04, Kernel: 3.13.0-22-generic (x86_64), Desktop: Unity 7.2.0, Display Server: X Server 1.15.0, Display Driver: NVIDIA 337.12, OpenGL: 4.3.0, Compiler: GCC 4.9.0 20140411, File-System: ext4, Screen Resolution: 2560x1600

-O3 -march=native -flto: 

	Processor: Intel Core i7-4770K @ 3.50GHz (8 Cores), Motherboard: ECS Z87H3-A2X EXTREME v1.0, Chipset: Intel 4th Gen Core DRAM, Memory: 16384MB, Disk: 120GB Samsung SSD 840, Graphics: ECS NVIDIA GeForce GTX 460 768MB (675/1804MHz), Audio: Realtek ALC1150, Monitor: Samsung SyncMaster, Network: Realtek RTL8111/8168/8411

	OS: Ubuntu 14.04, Kernel: 3.13.0-22-generic (x86_64), Desktop: Unity 7.2.0, Display Server: X Server 1.15.0, Display Driver: NVIDIA 337.12, OpenGL: 4.3.0, Compiler: GCC 4.9.0 20140411, File-System: ext4, Screen Resolution: 2560x1600


GraphicsMagick 1.3.19
Operation: Blur
Iterations Per Minute > Higher Is Better
-O0 ..................... 99  |=============================
-O1 ..................... 164 |================================================
-O2 ..................... 161 |===============================================
-Os ..................... 141 |=========================================
-Og ..................... 152 |============================================
-O3 ..................... 164 |================================================
-Ofast .................. 163 |===============================================
-O3 -march=native ....... 165 |================================================
-O3 -march=native -flto . 165 |================================================


GraphicsMagick 1.3.19
Operation: Sharpen
Iterations Per Minute > Higher Is Better
-O0 ..................... 54  |===================
-O1 ..................... 125 |===========================================
-O2 ..................... 128 |============================================
-Os ..................... 109 |=====================================
-Og ..................... 83  |============================
-O3 ..................... 127 |============================================
-Ofast .................. 126 |===========================================
-O3 -march=native ....... 140 |================================================
-O3 -march=native -flto . 140 |================================================


GraphicsMagick 1.3.19
Operation: Resizing
Iterations Per Minute > Higher Is Better
-O0 ..................... 100 |========================
-O1 ..................... 192 |===============================================
-O2 ..................... 192 |===============================================
-Os ..................... 187 |=============================================
-Og ..................... 174 |==========================================
-O3 ..................... 191 |==============================================
-Ofast .................. 192 |===============================================
-O3 -march=native ....... 198 |================================================
-O3 -march=native -flto . 198 |================================================


GraphicsMagick 1.3.19
Operation: HWB Color Space
Iterations Per Minute > Higher Is Better
-O0 ..................... 127 |===========================
-O1 ..................... 215 |==============================================
-O2 ..................... 213 |==============================================
-Os ..................... 215 |==============================================
-Og ..................... 209 |=============================================
-O3 ..................... 212 |=============================================
-Ofast .................. 224 |================================================
-O3 -march=native ....... 213 |==============================================
-O3 -march=native -flto . 213 |==============================================


GraphicsMagick 1.3.19
Operation: Local Adaptive Thresholding
Iterations Per Minute > Higher Is Better
-O0 ..................... 20  |=========
-O1 ..................... 96  |=============================================
-O2 ..................... 97  |==============================================
-Os ..................... 78  |=====================================
-Og ..................... 63  |==============================
-O3 ..................... 97  |==============================================
-Ofast .................. 97  |==============================================
-O3 -march=native ....... 102 |================================================
-O3 -march=native -flto . 102 |================================================


Himeno Benchmark 3.0
Poisson Pressure Solver
MFLOPS > Higher Is Better
-O0 ..................... 479.71  |===========
-O1 ..................... 1158.41 |==========================
-O2 ..................... 1919.66 |===========================================
-Os ..................... 1250.49 |============================
-Og ..................... 1240.97 |============================
-O3 ..................... 1958.10 |============================================
-Ofast .................. 1960.56 |============================================
-O3 -march=native ....... 1827.55 |=========================================
-O3 -march=native -flto . 1825.39 |=========================================


Timed Apache Compilation 2.4.7
Time To Compile
Seconds < Lower Is Better
-O0 ..................... 13.63 |==============
-O1 ..................... 19.42 |====================
-O2 ..................... 24.66 |=========================
-Os ..................... 23.08 |=======================
-Og ..................... 17.70 |==================
-O3 ..................... 27.32 |============================
-Ofast .................. 27.39 |============================
-O3 -march=native ....... 27.83 |============================
-O3 -march=native -flto . 45.49 |==============================================


Timed ImageMagick Compilation 6.8.1-10
Time To Compile
Seconds < Lower Is Better
-O0 ..................... 16.70  |======
-O1 ..................... 32.31  |===========
-O2 ..................... 47.38  |================
-Os ..................... 40.82  |==============
-Og ..................... 26.08  |=========
-O3 ..................... 59.07  |====================
-O3 -march=native ....... 60.90  |=====================
-O3 -march=native -flto . 130.29 |=============================================


Timed PHP Compilation 5.2.9
Time To Compile
Seconds < Lower Is Better
-O0 ..................... 10.21 |=====
-O1 ..................... 17.16 |========
-O2 ..................... 22.96 |===========
-Os ..................... 20.24 |==========
-Og ..................... 14.95 |=======
-O3 ..................... 26.22 |=============
-Ofast .................. 26.30 |=============
-O3 -march=native ....... 27.01 |=============
-O3 -march=native -flto . 95.96 |==============================================


C-Ray 1.1
Total Time
Seconds < Lower Is Better
-O0 ..................... 63.93 |=============================================
-O1 ..................... 44.23 |===============================
-O2 ..................... 40.42 |============================
-Os ..................... 65.76 |==============================================
-Og ..................... 43.35 |==============================
-O3 ..................... 22.82 |================
-Ofast .................. 22.65 |================
-O3 -march=native ....... 17.09 |============
-O3 -march=native -flto . 17.09 |============


FLAC Audio Encoding 1.3.0
WAV To FLAC
Seconds < Lower Is Better
-O0 ..................... 19.85 |==============================================
-O1 ..................... 5.56  |=============
-O2 ..................... 5.37  |============
-Os ..................... 5.96  |==============
-Og ..................... 6.14  |==============
-O3 ..................... 4.63  |===========
-Ofast .................. 4.52  |==========
-O3 -march=native ....... 3.61  |========
-O3 -march=native -flto . 3.62  |========


LAME MP3 Encoding 3.99.3
WAV To MP3
Seconds < Lower Is Better
-O0 ..................... 33.12 |==============================================
-O1 ..................... 15.01 |=====================
-O2 ..................... 12.54 |=================
-Os ..................... 14.20 |====================
-Og ..................... 15.55 |======================
-O3 ..................... 11.83 |================
-Ofast .................. 11.49 |================
-O3 -march=native ....... 10.87 |===============
-O3 -march=native -flto . 10.87 |===============


Hierarchical INTegration 1.0
Test: FLOAT
QUIPs > Higher Is Better
-O0 ..................... 113640165.43 |============
-O1 ..................... 272724038.56 |============================
-O2 ..................... 357045741.73 |=====================================
-Os ..................... 338799356.97 |===================================
-Og ..................... 276760433.28 |=============================
-O3 ..................... 353630824.75 |=====================================
-Ofast .................. 372135723.16 |=======================================
-O3 -march=native ....... 373780357.46 |=======================================
-O3 -march=native -flto . 372669017.17 |=======================================