Laszlo: Thanks for your suggestion. I will try O2 option and see the performance and warning.
Thanks Liming From: Laszlo Ersek [mailto:[email protected]] Sent: Friday, September 30, 2016 2:30 AM To: Gao, Liming <[email protected]> Cc: [email protected]; Ard Biesheuvel <[email protected]>; Justen, Jordan L <[email protected]> Subject: Re: [edk2] [Patch 4/4] BaseTools Makefile: Enable Ofast option for GCC tool chain Hi Liming, On 09/29/16 16:12, Liming Gao wrote: > Enable Ofast option to generate fast code for performance improvement. > > Contributed-under: TianoCore Contribution Agreement 1.0 > Signed-off-by: Liming Gao > --- > BaseTools/Source/C/Makefiles/header.makefile | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/BaseTools/Source/C/Makefiles/header.makefile > b/BaseTools/Source/C/Makefiles/header.makefile > index f2041f8..ca2dc2e 100644 > --- a/BaseTools/Source/C/Makefiles/header.makefile > +++ b/BaseTools/Source/C/Makefiles/header.makefile > @@ -44,12 +44,12 @@ ARCH_INCLUDE = -I $(MAKEROOT)/Include/AArch64/ > endif > > INCLUDE = $(TOOL_INCLUDE) -I $(MAKEROOT) -I $(MAKEROOT)/Include/Common -I > $(MAKEROOT)/Include/ -I $(MAKEROOT)/Include/IndustryStandard -I > $(MAKEROOT)/Common/ -I .. -I . $(ARCH_INCLUDE) > -BUILD_CPPFLAGS = $(INCLUDE) > +BUILD_CPPFLAGS = $(INCLUDE) -Ofast > ifeq ($(DARWIN),Darwin) > # assume clang or clang compatible flags on OS X > -BUILD_CFLAGS = -MD -fshort-wchar -fno-strict-aliasing -Wall -Werror > -Wno-deprecated-declarations -Wno-self-assign -nostdlib -c -g > +BUILD_CFLAGS = -MD -fshort-wchar -fno-strict-aliasing -Wall -Werror > -Wno-deprecated-declarations -Wno-self-assign -Wno-unused-result -nostdlib -c > -g > else > -BUILD_CFLAGS = -MD -fshort-wchar -fno-strict-aliasing -Wall -Werror > -Wno-deprecated-declarations -nostdlib -c -g > +BUILD_CFLAGS = -MD -fshort-wchar -fno-strict-aliasing -Wall -Werror > -Wno-deprecated-declarations -Wno-unused-result -nostdlib -c -g > endif > BUILD_LFLAGS = > BUILD_CXXFLAGS = > are you sure -Ofast is a good idea? The gcc manual says, -Ofast Disregard strict standards compliance. -Ofast enables all -O3 optimizations. It also enables optimizations that are not valid for all standard-compliant programs. It turns on -ffast-math and the Fortran-specific -fno-protect-parens and -fstack-arrays. To me this sounds quite scary -- I'm worried it might break the base utilities in various obscure ways, which in turn could break the firmware built with these tools in obscure ways. Most upstream projects and GNU/Linux distributions use -O2 for performance-optimized builds. Can you try that please and see if the performance improvements (relative to the current status) are still acceptable? If so, I would strongly prefer -O2 over -Ofast. Also, while building BaseTools with your series applied (using gcc-4.8), I saw one warning issued: > g++ -c -I Pccts/h -I .. -I ../Include/Common -I ../Include/ -I > ../Include/IndustryStandard -I ../Common/ -I .. -I . -I ../Include/X64/ > -Ofast VfrFormPkg.cpp -o VfrFormPkg.o > VfrFormPkg.cpp: In member function 'void > CIfrRecordInfoDB::IfrUpdateRecordInfoForDynamicOpcode(BOOLEAN)': > VfrFormPkg.cpp:1360:91: warning: deprecated conversion from string constant > to 'CHAR8* {aka char*}' [-Wwrite-strings] > gCVfrErrorHandle.PrintMsg (0, "Error", "Can not find the adjust offset in the > record."); ^ Thanks! Laszlo _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
