similar to: [LLVMdev] Memcpy / Memset for address spaces >= 256

Hi David, sorry for sending you the mail two times, I forgot to send to the list the first time. On 2014-03-12 09:48, David Chisnall wrote: > I have some patches that automatically expand all memcpy and similar > if the operands are not in AS 0. I think this is probably not quite > the right approach though, and we should be asking the back end for > the function that does a memcpy

Hello, Is there a script to update those test cases? I see mention of a sed script in the commit message but when I try it (see attached) on sed I get the following error: sed: file script line 2: invalid reference \3 on `s' command's RHS Did I lose something in a copy-paste? Is it not really a sed script? How do I run it? On Fri, Jan 19, 2018 at 9:15 AM, Daniel Neilson via

Hi Alexandre, The script uses extended-sed syntax, so you need to run sed with the -E option. For example, when preparing the patch I created a file ( script.sed ) containing all of the lines that I copied into the commit message. Then, I ran this bash one-liner from the test directory: for f in $(find . -name '*.ll'); do sed -E -i ‘.sedbak' -f script.sed $f; done When I was happy

Thanks, that worked like a charm except for the following: llvm generate: call void @llvm.memcpy.p3i8.p1i8.i64(i8 addrspace(3)* align 1 bitcast ([512 x float] addrspace(3)* @a_scratchpad to i8 addrspace(3)*), i8 addrspace(1)* align 1 %0, i64 2048, i1 false) And we expected: call void @llvm.memcpy.p3i8.p1i8.i64(i8 addrspace(3)* bitcast ([512 x float] addrspace(3)* [[SPM0]] to i8

Good day all, I’ve spent a few days resurrecting the circa-2015 work on removing the explicit alignment argument (4th arg) from the @llvm.memcpy/memmove/memset intrinsics in favour of using the alignment attribute on the pointer args of calls to the intrinsic. This work was first proposed back in August 2015 by Lang Hames: http://lists.llvm.org/pipermail/llvm-dev/2015-August/089384.html (item

On 3 Dec 2014, at 23:36, Robert Lougher <rob.lougher at gmail.com> wrote: > On 2 December 2014 at 22:18, Alex Rosenberg <alexr at leftfield.org> wrote: >> >> Our C library amplifies this problem by being in a dynamic library, so the >> call has additional overhead, which for small trip counts swamps the >> copy/set. >> > > I can't imagine

Hi all, A quick note just to let people know that as of this past Friday my go at this work has been fully landed. It ended up being a back-burner item, so it took longer than I would have liked to get completed. None the less, the changes made were: 1) The IRBuilders in LLVM, Clang, and Polly were all updated to create only the new form of the memory intrinsics. 2) All LLVM passes to understand

Hi Alexandre, Before the change you would have been expecting one of the following, correct? a) call void @llvm.memcpy.p3i8.p1i8.i64(i8 addrspace(3)* bitcast ([512 x float] addrspace(3)* [[SPM0]] to i8 addrspace(3)*), i8 addrspace(1)* [[APTR]], i64 2048, i32 0, i1 false) b) call void @llvm.memcpy.p3i8.p1i8.i64(i8 addrspace(3)* bitcast ([512 x float] addrspace(3)* [[SPM0]] to i8 addrspace(3)*), i8

Yes, all that is correct. My question is more a long term question: why do the .ll printer specify the alignment if it is equivalent to the default one? That is, it seems the sed script expect the printer to not specify it (this would match the load/store behavior), but the ll-printer does specify it, which either means the printer is not ideal on this case and I should fix it, or in this case

Good question. AFAIK, the IR-printer doesn’t understand the semantics of parameter attributes. In this case, it only knows that there is an attribute on the parameter that is integer valued (with value 1) and that has the name “align”, so it prints it out. If we don’t want it printing out ‘align 1’ then it’s up to us to not set the alignment parameter attribute to a value if that value would be 1.

Hi Daniel, a quick question (and kind-of a follow-up to <https://lists.llvm.org/pipermail/llvm-dev/2017-July/115665.html>): Do the pointers have to be aligned even if the size is 0? It would be nice to have this stated explicitly in the LangRef. Kind regards, Ralf On 26.03.2018 22:43, Daniel Neilson via llvm-dev wrote: > Hi all, >  A quick note just to let people know that as of

There are a large number of ways to lose information in translating loops into memset/memcpy calls, alignment is one of them. As previously mentioned, loop-trip-count is another. Another is size of accesses. For example, the loop may have originally been using int64_t sized copies. This has definite impact on what the best memset/memcpy expansion is, because effectively, the loop knows that it

Hi, LLVM's memory intrinsics are quite useful for performing various optimizations with frequently used memory operations. Unfortunately this intrinsics are not applicable for languages with guaranteed atomicity for their memory accesses (like Java for example). In order to overcome this limitation I'm thinking about adding set of intrinsics which will execute as a series of unordered

On Dec 3, 2014, at 6:12 AM, Eric Christopher <echristo at gmail.com> wrote: > > > >> On Tue Dec 02 2014 at 12:12:01 PM Robert Lougher <rob.lougher at gmail.com> wrote: >> On 2 December 2014 at 19:57, Joerg Sonnenberger <joerg at britannica.bec.de> wrote: >> > On Tue, Dec 02, 2014 at 07:23:01PM +0000, Robert Lougher wrote: >> >> In

As reported in an earlier thread (http://clang-developers.42468.n3.nabble.com/Disable-memset-synthesis-tp4057810.html), we noticed in some cases that the llvm.memset intrinsic, if lowered to stores, could help with performance. Here's a test case: If LIMIT is > 8, I see that a call to memset is emitted for arm & aarch64, but not for x86 target. typedef struct { int v0[100]; }

Hi all, This change has been reviewed, and appears to be ready to land (review available here if anyone still wants to chime in: https://reviews.llvm.org/D41675 ). The process that we’re going to use for landing this will take a few steps. To wit: Step 1) Remove align argument, and add align attribute to pointer args. Require that src & dest have the same alignment via verifier rule. Also

Hal, I appreciate the clarification. That was what I was expecting (that the transformation uses intrinsics), Intel compiler does the same thing internally, and like LLVM it is into an internal intrinsic, not a plain library call. Nevertheless, there are a huge number of ways (In machine code) to write "the best" memory copy or memory set sort of code if, as a programmer, you are able

On Jan 18, 2018, at 10:48 PM, Chris Lattner <clattner at nondot.org<mailto:clattner at nondot.org>> wrote: On Jan 18, 2018, at 7:45 AM, Daniel Neilson via llvm-dev <llvm-dev at lists.llvm.org<mailto:llvm-dev at lists.llvm.org>> wrote: Hi all, This change has been reviewed, and appears to be ready to land (review available here if anyone still wants to chime in:

> On Jan 18, 2018, at 7:45 AM, Daniel Neilson via llvm-dev <llvm-dev at lists.llvm.org> wrote: > > > Hi all, > This change has been reviewed, and appears to be ready to land (review available here if anyone still wants to chime in: https://reviews.llvm.org/D41675 <https://reviews.llvm.org/D41675> ). The process that we’re going to use for landing this will take a few

As of earlier this year, we now explicitly ignore the nonnull attributes that glibc puts on memcpy (and other stdlib functions). I don't know how LLVM feels about dangling or underaligned pointers in particular, but AFAICT, we do try hard to make sure that memcpy(NULL, _, 0) works as the user probably intends. Here's the thread I read about it: