Turning off SRA
I’m working on performance tuning a gcc 8.3 port and wanted to turn off SRA for an experiment. But passing both -fno-tree-sra -fno-ipa-sra but it’s still tagging compiled functions with a “_isra” suffix, which would seem to indicate that it’s still running that optimization. Is there a bigger hammer I’m missing? Alan Lehotsky https://codegentllc.com
Re: Turning off SRA
On Thu, Jan 21, 2021 at 3:31 PM Alan Lehotsky wrote: > > I’m working on performance tuning a gcc 8.3 port and wanted to turn off SRA > for an experiment. But passing both > > -fno-tree-sra > -fno-ipa-sra > > but it’s still tagging compiled functions with a “_isra” suffix, which would > seem to indicate that it’s still running that optimization. > > Is there a bigger hammer I’m missing? Nope, that should do the trick already. Richard. > > Alan Lehotsky > https://codegentllc.com > > >
Re: RFC: Add GNU_PROPERTY_UINT32_AND_XXX/GNU_PROPERTY_UINT32_OR_XXX
On Wed, Jan 13, 2021 at 9:06 AM H.J. Lu wrote: > > 1. GNU_PROPERTY_UINT32_AND_LO..GNU_PROPERTY_UINT32_AND_HI > > #define GNU_PROPERTY_UINT32_AND_LO 0xb000 > #define GNU_PROPERTY_UINT32_AND_HI 0xb0007fff > > A bit in the output pr_data field is set only if it is set in all > relocatable input pr_data fields. If all bits in the the output > pr_data field are zero, this property should be removed from output. > > If the bit is 1, all input relocatables have the feature. If the > bit is 0 or the property is missing, the info is unknown. > > 2. GNU_PROPERTY_UINT32_OR_LO..GNU_PROPERTY_UINT32_OR_HI > > #define GNU_PROPERTY_UINT32_OR_LO 0xb0008000 > #define GNU_PROPERTY_UINT32_OR_HI 0xb000 > > A bit in the output pr_data field is set if it is set in any > relocatable input pr_data fields. If all bits in the the output > pr_data field are zero, this property should be removed from output. > > If the bit is 1, some input relocatables have the feature. If the > bit is 0 or the property is missing, the info is unknown. > > The PDF is at > > https://gitlab.com/x86-psABIs/Linux-ABI/-/wikis/uploads/0690db0a3b7e5d8a44e0271a4be54aa7/linux-gABI-and-or-2021-01-13.pdf > > -- > H.J. Here is the binutils patch to implement it. -- H.J. From 347b7c47ac6c2149b7e6bfb318bd85a030ce2096 Mon Sep 17 00:00:00 2001 From: "H.J. Lu" Date: Sat, 16 Jan 2021 05:35:46 -0800 Subject: [PATCH] elf: Add GNU_PROPERTY_UINT32_AND_XXX/GNU_PROPERTY_UINT32_OR_XXX Implement GNU_PROPERTY_UINT32_AND_XXX/GNU_PROPERTY_UINT32_OR_XXX: https://sourceware.org/pipermail/gnu-gabi/2021q1/000467.html 1. GNU_PROPERTY_UINT32_AND_LO..GNU_PROPERTY_UINT32_AND_HI #define GNU_PROPERTY_UINT32_AND_LO 0xb000 #define GNU_PROPERTY_UINT32_AND_HI 0xb0007fff A bit in the output pr_data field is set only if it is set in all relocatable input pr_data fields. If all bits in the the output pr_data field are zero, this property should be removed from output. If the bit is 1, all input relocatables have the feature. If the bit is 0 or the property is missing, the info is unknown. 2. GNU_PROPERTY_UINT32_OR_LO..GNU_PROPERTY_UINT32_OR_HI #define GNU_PROPERTY_UINT32_OR_LO 0xb0008000 #define GNU_PROPERTY_UINT32_OR_HI 0xb000 A bit in the output pr_data field is set if it is set in any relocatable input pr_data fields. If all bits in the the output pr_data field are zero, this property should be removed from output. If the bit is 1, some input relocatables have the feature. If the bit is 0 or the property is missing, the info is unknown. bfd/ * elf-properties.c (_bfd_elf_parse_gnu_properties): Handle GNU_PROPERTY_UINT32_AND_LO, GNU_PROPERTY_UINT32_AND_HI, GNU_PROPERTY_UINT32_OR_LO and GNU_PROPERTY_UINT32_OR_HI. (elf_merge_gnu_properties): Likewise. binutils/ * readelf.c (print_gnu_property_note): Handle GNU_PROPERTY_UINT32_AND_LO, GNU_PROPERTY_UINT32_AND_HI, GNU_PROPERTY_UINT32_OR_LO and GNU_PROPERTY_UINT32_OR_HI. include/ * elf/common.h (GNU_PROPERTY_UINT32_AND_LO): New. (GNU_PROPERTY_UINT32_AND_HI): Likewise. (GNU_PROPERTY_UINT32_OR_LO): Likewise. (GNU_PROPERTY_UINT32_OR_HI): Likewise. ld/ * testsuite/ld-elf/property-and-1.d: New file. * testsuite/ld-elf/property-and-1.s: Likewise. * testsuite/ld-elf/property-and-2.d: Likewise. * testsuite/ld-elf/property-and-2.s: Likewise. * testsuite/ld-elf/property-and-3.d: Likewise. * testsuite/ld-elf/property-and-3.s: Likewise. * testsuite/ld-elf/property-and-4.d: Likewise. * testsuite/ld-elf/property-and-empty.s: Likewise. * testsuite/ld-elf/property-or-1.d: Likewise. * testsuite/ld-elf/property-or-1.s: Likewise. * testsuite/ld-elf/property-or-2.d: Likewise. * testsuite/ld-elf/property-or-2.s: Likewise. * testsuite/ld-elf/property-or-3.d: Likewise. * testsuite/ld-elf/property-or-3.s: Likewise. * testsuite/ld-elf/property-or-4.d: Likewise. * testsuite/ld-elf/property-or-empty.s: Likewise. --- bfd/elf-properties.c | 90 binutils/readelf.c | 15 include/elf/common.h | 10 +++ ld/testsuite/ld-elf/property-and-1.d | 7 ++ ld/testsuite/ld-elf/property-and-1.s | 15 ld/testsuite/ld-elf/property-and-2.d | 8 +++ ld/testsuite/ld-elf/property-and-2.s | 15 ld/testsuite/ld-elf/property-and-3.d | 8 +++ ld/testsuite/ld-elf/property-and-3.s | 15 ld/testsuite/ld-elf/property-and-4.d | 12 ld/testsuite/ld-elf/property-and-empty.s | 15 ld/testsuite/ld-elf/property-or-1.d | 11 +++ ld/testsuite/ld-elf/property-or-1.s | 15 ld/testsuite/ld-elf/property-or-2.d | 12 ld/testsuite/ld-elf/property-or-2.s | 15 ld/testsuite/ld-elf/property-or-3.d | 12 ld/testsuite/ld-elf/property-or-3.s | 15 ld/testsuite/ld-elf/property-or-4.d | 12 ld/testsuite/ld-elf/property-or-empty.s | 15 19 files changed, 317 insertions(+) create mode 100644 ld/testsuite/ld-elf/property-and-1.d create
Request for contribution to your project
Ma'am I am a 1st year computer science engineering undergraduate student at krishna engineering college (affiliated to Dr. A.P.J. Abdul Kalam Technical University (AKTU)) . I am actively looking for some GSoC organisation to contribute . I actively contribute 2 years to a website name livecultureofindia.com ( WordPress ) and have worked with html , c ,c++ . I am interested to contribute in your project and your view to change world by making others life easy . I saw your organisation in GSoC and thought of asking you if system can be a good organisation for me to start . If yes please guide me how to begin and let me know how can I contact you for further help. Hoping to hear from you soon Thank you
Re: RFC: Add GNU_PROPERTY_UINT32_AND_XXX/GNU_PROPERTY_UINT32_OR_XXX
On 2021-01-21, H.J. Lu via Gnu-gabi wrote: On Wed, Jan 13, 2021 at 9:06 AM H.J. Lu wrote: 1. GNU_PROPERTY_UINT32_AND_LO..GNU_PROPERTY_UINT32_AND_HI #define GNU_PROPERTY_UINT32_AND_LO 0xb000 #define GNU_PROPERTY_UINT32_AND_HI 0xb0007fff A bit in the output pr_data field is set only if it is set in all relocatable input pr_data fields. If all bits in the the output pr_data field are zero, this property should be removed from output. If the bit is 1, all input relocatables have the feature. If the bit is 0 or the property is missing, the info is unknown. 2. GNU_PROPERTY_UINT32_OR_LO..GNU_PROPERTY_UINT32_OR_HI #define GNU_PROPERTY_UINT32_OR_LO 0xb0008000 #define GNU_PROPERTY_UINT32_OR_HI 0xb000 A bit in the output pr_data field is set if it is set in any relocatable input pr_data fields. If all bits in the the output pr_data field are zero, this property should be removed from output. If the bit is 1, some input relocatables have the feature. If the bit is 0 or the property is missing, the info is unknown. The PDF is at https://gitlab.com/x86-psABIs/Linux-ABI/-/wikis/uploads/0690db0a3b7e5d8a44e0271a4be54aa7/linux-gABI-and-or-2021-01-13.pdf -- H.J. Here is the binutils patch to implement it. -- H.J. Hi, H.J. Thank you for CCing llvm-dev:) In the past various GNU ABI proposals went unnoticed by LLVM folks who don't happen to subscribe to GNU lists. (A lot! I personally subscribe to some lists and check the discussion just in case I miss something important:) ) I have researched a bit and observed that the following GNU_PROPERTY values are currently used by compilers/linkers: Bitwise OR for relocatable links. Bitwise AND for executable/shared object links. * GNU_PROPERTY_X86_FEATURE_1_AND = GNU_PROPERTY_X86_UINT32_AND_LO + 0, * used by Intel Indirect branch tracking and Shadow Stack * GNU_PROPERTY_AARCH64_FEATURE_1_AND, used by AArch64 Branch Target * Identification and Pointer Authentication Bitwise OR for all links. * GNU_PROPERTY_X86_ISA_1_NEEDED = GNU_PROPERTY_X86_UINT32_OR_LO + 2, * used by GCC -mneeded (for -march=x86-64-v[234]) There appear to be another type of AND/OR bits which are not defined in ABIs (AFAICT): * GNU_PROPERTY_X86_ISA_1_USED = GNU_PROPERTY_X86_UINT32_OR_AND_LO + 2 * GNU_PROPERTY_X86_FEATURE_2_USED = GNU_PROPERTY_X86_UINT32_OR_AND_LO + * 1 I think generalizing the AND/OR idea to all architectures probably requires us to think about these questions: * What's the impending usage of the generic AND/OR ranges? ifunc? :) * Does the concept generalize well to other architectures? If we * consider AArch64/x86 FEATURE_1_AND to be the same thing, the current * usage is purely x86 specific. * Is AND/OR encoding expressive enough to represent the required states? * I've asked two folks and they expressed concerns. I think the three * AND/OR usage above speak for themselves. * Szabolcs Nagy mentioned that GNU_PROPERTY is an OS-specific mechanism * (GNU), but the features are oftentimes arch specific which make sense * to other OSes or bare-metal. * Szabolcs: Do we need any versioning mechanism? The feature selection and compatibility checking mechanism has some overlap with GNU/arch-specific attributes (e.g .ARM.attributes, .riscv.attributes). If I understand correctly, GNU_PROPERTY has an associated program header so it can be checked by loaders (kernel/ld.so/emulator) while Attributes don't have program headers so they are largely assembler/linker protocols. In an inflexible way that such feature bits can affect observable states to loaders as well, e.g. .ARM.attributes can affect e_flags (soft/hard float). .MIPS.abiflags has an associated program header PT_MIPS_ABIFLAGS (I know nearly nothing about mips) Some thoughts from mips folks would be useful. Last, I think a feature selection and compatibility checking mechanism is assuredly useful, but whether the current AND/OR scheme can perfectly satisfy that goal I am unsure. Having the proposal is a very good start, though:) Thanks a lot for driving the discussion:)
gcc-8-20210121 is now available
Snapshot gcc-8-20210121 is now available on https://gcc.gnu.org/pub/gcc/snapshots/8-20210121/ and on various mirrors, see http://gcc.gnu.org/mirrors.html for details. This snapshot has been generated from the GCC 8 git branch with the following options: git://gcc.gnu.org/git/gcc.git branch releases/gcc-8 revision c9569046bd8ba2671833d600b3bdbdb7de593873 You'll find: gcc-8-20210121.tar.xzComplete GCC SHA256=7b0afce5e5ca8643adfdd69dd88af7603389868c33b40be6d70c4b6d6b94272f SHA1=0192d83e0e85e27eccd8f8f4825055a484f03f4c Diffs from 8-20210114 are available in the diffs/ subdirectory. When a particular snapshot is ready for public consumption the LATEST-8 link is updated and a message is sent to the gcc list. Please do not use a snapshot before it has been announced that way.
