similar to: [LLVMdev] scalarrepl tuning

Hi all, Thanks for the answers! I feel like I've hijacked your thread now though Björn, sorry for that. But from the answers it sounds like there is agreement that it's reasonable to remove the duplicates as done in Björn's patch? --- A couple of more things around the problem I saw. On 09/19/2017 05:40 PM, Adrian Prantl wrote: > A dbg.declare describes a stack-allocated

On 31 Jan 2018, at 17:36, Jakub (Kuba) Kuderski via llvm-dev <llvm-dev at lists.llvm.org> wrote: > > If you want to get rid of memcpy altogether, you can take a look at this pass: https://github.com/seahorn/seahorn/blob/master/lib/Transforms/Scalar/PromoteMemcpy.cc . There are at least four different places in LLVM where memcpy intrinsics are expanded to either sequences of

Hal Finkel <hfinkel at anl.gov> wrote on 16.03.2015 17:56:20: > If you want to do it at a clang level, the right thing to do is to > fixup the ABI lowerings for pointers to keep them pointers in this case. > So this is an artifact of the way that we pass structures, and > constructing a general solution at the ABI level might be tricky. > I've cc'd Uli, who did most

=== PROBLEM === (See this bug https://llvm.org/bugs/show_bug.cgi?id=26445) IR contains code for loading a float from float * and storing it to a float * address. After canonicalization of load in InstCombine [1], new bitcasts are added to the IR (see bottom of the email for code samples). This prevents select speculation in SROA to work. Also after SROA we have bitcasts from int32 to float.

As a results of my investigations, the thread is also added to cfe-dev. The context : while porting my company code from the LLVM/Clang releases 3.1 to 3.2, I stumbled on a code size and performance regression. The testcase is : $ cat test.c #include <stdint.h> struct R { uint16_t a; uint16_t b; }; volatile struct R * const addr = (volatile struct R *) 416; void test(uint16_t a) {

Hi, Today I managed to link ioquake3, but generating a binary does not work yet. 1) On OSX, I get: Error: Code generator does not support intrinsic function 'llvm.ppc.altivec.lvsl'! when I do: llc file.bc -march=c -o file.c 2) On Linux X86, llc does not give any problem, but I get this while compiling the generated .c file: error: unknown register name 'S' in

Hi All, Using clang+llvm at head, I noticed a weird behaviour with the following reduced testcase : $ cat test.c #include <stdint.h> struct R { uint16_t a; uint16_t b; }; volatile struct R * const addr = (volatile struct R *) 416; void test(uint16_t a) { struct R r = { a, 1 }; *addr = r; } $ clang -O2 -o - -emit-llvm -S -c test.c ; ModuleID = 'test.c' target

I have a file for which clang-7 takes over 2 hours to compile with -O3. For the same file, clang-5 takes less than 2 minutes (which is also high IMHO). I will try to create a test case (but it is pretty simple, it only contains initializations of many arrays of structs where the structs are of the following form: struct Foo { EnumType1 e1; // there are 700+ enum labels std::string s1;

On Wed, Mar 16, 2016 at 8:34 AM, Mehdi Amini via llvm-dev < llvm-dev at lists.llvm.org> wrote: > Hi, > > How do it interact with the "typeless pointers" work? > Right - the goal of the typeless pointer work is to fix all these bugs related to "didn't look through bitcasts" in optimizations. Sometimes that's going to mean more work (because the code

On Mon, Sep 24, 2012 at 3:41 AM, David Tweed <david.tweed at arm.com> wrote: > Just a note that the following new regressions have started to show up on > ARM/Linux: > Thanks for letting me know! I know that there is one serious bug that would impact in BE system. I should have that fixed today, along with a crasher. I would appreciate help tracking down any issues once the one I

On Feb 17, 2015, at 1:58 PM, Chandler Carruth <chandlerc at gmail.com> wrote: > I'm not actually worried about this change though Chris, at least w.r.t. optimizer changes being necessary. There are a few reasons: > > 1) The old ScalarRepl pass cared a *lot* about pointer type, but the new SROA doesn't care at all, so the biggest offender is essentially handled. Why do you

I doubt you needed to add cfe-dev here. Sorry I hadn't seen this, this seems like an easy and simple deficiency in the IR intrinsic for memcpy. See below. On Sun, Jan 20, 2013 at 1:42 PM, Arnaud de Grandmaison < arnaud.allarddegrandmaison at parrot.com> wrote: > define void @test(i16 zeroext %a) nounwind uwtable { > %r.sroa.0 = alloca i16, align 2 > %r.sroa.1 = alloca i16,

On 1 Feb 2018, at 18:39, Friedman, Eli <efriedma at codeaurora.org> wrote: > > On 2/1/2018 2:03 AM, David Chisnall via llvm-dev wrote: >> In contrast, the padding between fields in non-packed structs disappears as soon as SROA runs. This can lead to violations of C semantics, where padding fields should not change (because C defines bitwise comparisons on structs using memcmp).

I can't think of a better way to do this, so I think it's ok. I also submitted a complementary patch on llvm-commits clarifying volatile semantics. -Andy On Jan 28, 2013, at 8:54 AM, Arnaud A. de Grandmaison <arnaud.allarddegrandmaison at parrot.com> wrote: > Hi All, > > In the language reference manual, the access behavior of the memcpy, > memmove and memset

Back to the discussion on the RFC, I still see some advantage in following the proposed solution. I see two paths forward: 1- Change canonical form, possibly lower memcpy to non-integer load and store in InstCombine. Then teach the backends to convert that to integer load and store if that is more profitable. Notice that we are talking about loads that have no use other than store. So it is a

After a lot of testing and help from Duncan, Benjamin, Joerg and others, I think the new SROA is ready for some broader testing. I've fixed all the crashers and miscompiles that Duncan and Joerg have been able to find (although I'm sure there are a few left I'll tackle when there are reports), and the LNT numbers look *really* good. Here is the latest LNT run we got by flipping it on

SROA optimization pass did some optimizations and transforms for memcpy function,such as ld/st operations.When someone has written down code like size>sizeof(dest) in memcpy(*dest,*src,size), there was much likely a wrong code generation.for example,considered as such testcase: int main() { char ch; short sh = 0x1234; memcpy(&ch,&sh,2); printf("ch=0x%02x\n",ch); } At

On Wed, Mar 16, 2016 at 11:00 AM, Ehsan Amiri <ehsanamiri at gmail.com> wrote: > David, > > Could you give us an update on the status of typeless pointer work? How > much work is left and when you think it might be ready? > It's a bit of an onion peel, really - since it will eventually involve generalizing/fixing every optimization that's currently leaning on typed

Hi Dan, > Oh, ok. So code that takes an alloca, bitcasts the address to a higher > alignment, Since alignment is not a property of a type, I don't think you can "bitcast to a higher alignment" as such. I still understand what you mean, though :-) > and then does a load or store at the higher alignment, is > invoking undefined behavior. The alignment attribute on a load

I don't know enough about the tradeoff for 1, but 2 seems like a bandaid for something that is not a correctness issue neither a regression. I'm not sure it justifies "bandaid patches" while there is a clear path forward, i.e. typeless pointers, unless there is an acknowledgement that typeless pointers won't be there before a couple of years. -- Mehdi > On Mar 22, 2016,