kernel/git - git - PowerEL Git System

Commit Graph

Author	SHA1	Message	Date
Atousa Pahlevan Duprat	3bc72fde3f	sha1: provide another level of indirection for the SHA-1 functions The git source uses git_SHA1_Update() and friends to call into the code that computes the hashes. Traditionally, we used to map these directly to underlying implementation of the SHA-1 hash (e.g. SHA1_Update() from OpenSSL or blk_SHA1_Update() from block-sha1/). This arrangement however makes it hard to tweak behaviour of the underlying implementation without fully replacing. If we want to introduce a tweaked_SHA1_Update() wrapper to implement the "Update" in a slightly different way, for example, the implementation of the wrapper still would want to call into the underlying implementation, but tweaked_SHA1_Update() cannot call git_SHA1_Update() to get to the underlying implementation (often but not always SHA1_Update()). Add another level of indirection that maps platform_SHA1_Update() and friends to their underlying implementations, and by default make git_SHA1_Update() and friends map to platform_SHA1_* functions. Doing it this way will later allow us to map git_SHA1_Update() to tweaked_SHA1_Update(), and the latter can use platform_SHA1_Update() in its implementation. Signed-off-by: Atousa Pahlevan Duprat <apahlevan@ieee.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>	9 years ago
Jeff King	802b123366	block-sha1: factor out get_be and put_be wrappers The BLK_SHA1 code has optimized wrappers for doing endian conversions on memory that may not be aligned. Let's pull them out so that we can use them elsewhere, especially the time-tested list of platforms that prefer each strategy. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>	11 years ago
Junio C Hamano	6b2dd0e56b	block-sha1/sha1.c: have SP around arithmetic operators Signed-off-by: Junio C Hamano <gitster@pobox.com>	11 years ago
Jonathan Nieder	23119ffb4e	block-sha1: put expanded macro parameters in parentheses 't' is currently always a numeric constant, but it can't hurt to prepare for the day that it becomes useful for a caller to pass in a more complex expression. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	12 years ago
Jonathan Nieder	5f6a11259a	block-sha1: avoid pointer conversion that violates alignment constraints With `660231aa` (block-sha1: support for architectures with memory alignment restrictions, 2009-08-12), blk_SHA1_Update was modified to access 32-bit chunks of memory one byte at a time on arches that prefer that: #define get_be32(p) ( \ (((unsigned char )(p) + 0) << 24) \| \ (((unsigned char )(p) + 1) << 16) \| \ (((unsigned char )(p) + 2) << 8) \| \ (((unsigned char )(p) + 3) << 0) ) The code previously accessed these values by just using htonl(p). Unfortunately, Michael noticed on an Alpha machine that git was using plain 32-bit reads anyway. As soon as we convert a pointer to int , the compiler can assume that the object pointed to is correctly aligned as an int (C99 section 6.3.2.3 "pointer conversions" paragraph 7), and gcc takes full advantage by using a single 32-bit load, resulting in a whole bunch of unaligned access traps. So we need to obey the alignment constraints even when only dealing with pointers instead of actual values. Do so by changing the type of 'data' to void *. This patch renames 'data' to 'block' at the same time to make sure all references are updated to reflect the new type. Reported-tested-and-explained-by: Michael Cree <mcree@orcon.net.nz> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>	12 years ago
Ramsay Jones	078e9bce1e	msvc: Select the "fast" definition of the {get,put}_be32() macros On Intel machines, the msvc compiler defines the CPU architecture macros _M_IX86 and _M_X64 (equivalent to __i386__ and __x86_64__ respectively). Use these macros in the pre-processor expression to select the "fast" definition of the {get,put}_be32() macros. Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk> Acked-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	15 years ago
Ramsay Jones	9eafa1201b	msvc: Fix some compiler warnings In particular, using the normal (or production) compiler warning level (-W3), msvc complains as follows: .../sha1.c(244) : warning C4018: '<' : signed/unsigned mismatch .../sha1.c(270) : warning C4244: 'function' : conversion from \ 'unsigned __int64' to 'unsigned long', possible loss of data .../sha1.c(271) : warning C4244: 'function' : conversion from \ 'unsigned __int64' to 'unsigned long', possible loss of data Note that gcc issues a similar complaint about line 244 when compiling with -Wextra. Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk> Signed-off-by: Junio C Hamano <gitster@pobox.com>	15 years ago
Nicolas Pitre	30ae47b4cc	remove ARM and Mozilla SHA1 implementations They are both slower than the new BLK_SHA1 implementation, so it is pointless to keep them around. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>	15 years ago
Nicolas Pitre	e9c5dcd131	block-sha1: guard gcc extensions with __GNUC__ With this, the code should now be portable to any C compiler. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>	15 years ago
Nicolas Pitre	51ea55190b	make sure byte swapping is optimal for git We rely on ntohl() and htonl() to perform byte swapping in many places. However, some platforms have libraries providing really poor implementations of those which might cause significant performance issues, especially with the block-sha1 code. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>	15 years ago
Nicolas Pitre	d5f6a96fa4	block-sha1: make the size member first in the context struct This is a 64-bit value, hence having it first provides a better alignment. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>	15 years ago
Brandon Casey	a12218572f	block-sha1/sha1.c: silence compiler complaints by casting void * to char * Some compilers produce errors when arithmetic is attempted on pointers to void. We want computations done on byte addresses, so cast them to char * to work them around. Signed-off-by: Brandon Casey <casey@nrlssc.navy.mil> Signed-off-by: Junio C Hamano <gitster@pobox.com>	15 years ago
Nicolas Pitre	ee7dc310af	block-sha1: more good unaligned memory access candidates In addition to X86, PowerPC and S390 are capable of unaligned memory accesses. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>	15 years ago
Nicolas Pitre	660231aa97	block-sha1: support for architectures with memory alignment restrictions This is needed on architectures with poor or non-existent unaligned memory support and/or no fast byte swap instruction (such as ARM) by using byte accesses to memory and shifting the result together. This also makes the code portable, therefore the byte access methods are the defaults. Any architecture that properly supports unaligned word accesses in hardware simply has to enable the alternative methods. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>	15 years ago
Nicolas Pitre	dc52fd2973	block-sha1: split the different "hacks" to be individually selected This is to make it easier for them to be selected individually depending on the architecture instead of the other way around i.e. having each architecture select a list of hacks up front. That makes for clearer documentation as well. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>	15 years ago
Nicolas Pitre	30ba0de726	block-sha1: move code around Move the code around so specific architecture hacks are defined first. Also make one line comments actually one line. No code change. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>	15 years ago
Linus Torvalds	926172c5e4	block-sha1: improve code on large-register-set machines For x86 performance (especially in 32-bit mode) I added that hack to write the SHA1 internal temporary hash using a volatile pointer, in order to get gcc to not try to cache the array contents. Because gcc will do all the wrong things, and then spill things in insane random ways. But on architectures like PPC, where you have 32 registers, it's actually perfectly reasonable to put the whole temporary array[] into the register set, and gcc can do so. So make the 'volatile unsigned int ' cast be dependent on a SMALL_REGISTER_SET preprocessor symbol, and enable it (currently) on just x86 and x86-64. With that, the routine is fairly reasonable even when compared to the hand-scheduled PPC version. Ben Herrenschmidt reports on a G5: Paulus asm version: about 3.67s * Yours with no change: about 5.74s * Yours without "volatile": about 3.78s so with this the C version is within about 3% of the asm one. And add a lot of commentary on what the heck is going on. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>	15 years ago
Linus Torvalds	66c9c6c0fb	block-sha1: improved SHA1 hashing I think I have found a way to avoid the gcc crazyness. Lookie here: # TIME[s] SPEED[MB/s] rfc3174 5.094 119.8 rfc3174 5.098 119.7 linus 1.462 417.5 linusas 2.008 304 linusas2 1.878 325 mozilla 5.566 109.6 mozillaas 5.866 104.1 openssl 1.609 379.3 spelvin 1.675 364.5 spelvina 1.601 381.3 nettle 1.591 383.6 notice? I outperform all the hand-tuned asm on 32-bit too. By quite a margin, in fact. Now, I didn't try a P4, and it's possible that it won't do that there, but the 32-bit code generation sure looks impressive on my Nehalem box. The magic? I force the stores to the 512-bit hash bucket to be done in order. That seems to help a lot. The diff is trivial (on top of the "rename registers with cpp" patch), as appended. And it does seem to fix the P4 issues too, although I can obviously (once again) only test Prescott, and only in 64-bit mode: # TIME[s] SPEED[MB/s] rfc3174 1.662 36.73 rfc3174 1.64 37.22 linus 0.2523 241.9 linusas 0.4367 139.8 linusas2 0.4487 136 mozilla 0.9704 62.9 mozillaas 0.9399 64.94 that's some really impressive improvement. All from just saying "do the stores in the order I told you to, dammit!" to the compiler. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>	15 years ago
Linus Torvalds	30d12d4c16	block-sha1: perform register rotation using cpp Instead of letting the compiler to figure out the optimal way to rotate register usage, explicitly rotate the register names with cpp. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>	15 years ago
Linus Torvalds	5d5210c35a	block-sha1: get rid of redundant 'lenW' context .. and simplify the ctx->size logic. We now count the size in bytes, which means that 'lenW' was always just the low 6 bits of the total size, so we don't carry it around separately any more. And we do the 'size in bits' shift at the end. Suggested by Nicolas Pitre and linux@horizon.com. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>	15 years ago
Linus Torvalds	e869e113c8	block-sha1: Use '(B&C)+(D&(B^C))' instead of '(B&C)\|(D&(B\|C))' in round 3 It's an equivalent expression, but the '+' gives us some freedom in instruction selection (for example, we can use 'lea' rather than 'add'), and associates with the other additions around it to give some minor scheduling freedom. Suggested-by: linux@horizon.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>	15 years ago
Linus Torvalds	ab14c823df	block-sha1: macroize the rounds a bit further Avoid repeating the shared parts of the different rounds by adding a macro layer or two. It was already more cpp than C. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>	15 years ago
Linus Torvalds	7b5075fcfb	block-sha1: re-use the temporary array as we calculate the SHA1 The mozilla-SHA1 code did this 80-word array for the 80 iterations. But the SHA1 state is really just 512 bits, and you can actually keep it in a kind of "circular queue" of just 16 words instead. This requires us to do the xor updates as we go along (rather than as a pre-phase), but that's really what we want to do anyway. This gets me really close to the OpenSSL performance on my Nehalem. Look ma, all C code (ok, there's the rol/ror hack, but that one doesn't strictly even matter on my Nehalem, it's just a local optimization). Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>	15 years ago
Linus Torvalds	139e3456ec	block-sha1: make the 'ntohl()' part of the first SHA1 loop This helps a teeny bit. But what I -really- want to do is to avoid the whole 80-array loop, and do the xor updates as I go along.. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>	15 years ago
Junio C Hamano	fd536d3439	block-sha1: minor fixups Bert Wesarg noticed non-x86 version of SHA_ROT() had a typo. Also spell in-line assembly as __asm__(), otherwise I seem to get error: implicit declaration of function 'asm' from my compiler. Signed-off-by: Junio C Hamano <gitster@pobox.com>	15 years ago
Linus Torvalds	b8e48a89b8	block-sha1: try to use rol/ror appropriately Use the one with the smaller constant. It _can_ generate slightly smaller code (a constant of 1 is special), but perhaps more importantly it's possibly faster on any uarch that does a rotate with a loop. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>	15 years ago
Junio C Hamano	b26a9d5089	block-sha1: undo ctx->size change Undo the change I picked up from the mailing list discussion suggested by Nico, not because it is wrong, but it will be done at the end of the follow-up series. Signed-off-by: Junio C Hamano <gitster@pobox.com>	15 years ago
Linus Torvalds	d7c208a92e	Add new optimized C 'block-sha1' routines Based on the mozilla SHA1 routine, but doing the input data accesses a word at a time and with 'htonl()' instead of loading bytes and shifting. It requires an architecture that is ok with unaligned 32-bit loads and a fast htonl(). Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>	15 years ago

30 Commits (aa6d7f93edc39361c926e1748fbee3b4243808f8)