similar to: [LLVMdev] stackrestore

Hi, I have two problems regarding the llvm.stackrestore intrinsic. I'm running on 3.0, but a quick test on trunk also showed the same behavior. First problem: --------------- I have code like: tmp1 = call llvm.stacksave() tmp2 = alloca [do some stuff with tmp2] call llvm.stackrestore(tmp1) [some other stuff] tmp3 = call llvm.stacksave() tmp4 = alloca [do some stuff

Hi, I've tracked the first problem (mentioned in my previous email, quoted below) down further, ending up in the handling of alloca in LoopRotation.cpp (from trunk): // If the instruction's operands are invariant and it doesn't read or write // memory, then it is safe to hoist. Doing this doesn't change the order of // execution in the preheader, but does

Bringing this back up for discussion on handling exceptions. According to the inalloca design <https://llvm.org/docs/InAlloca.html>, there should be a stackrestore after an invoke in both the non-exceptional and exceptional case (that doesn't seem to be happening in some cases as we've seen, but that's beside the point). Does it make sense to model a preallocated call as

On Sat, Mar 28, 2020 at 2:20 PM Eli Friedman <efriedma at quicinc.com> wrote: > This would specifically be for cases where we try to rewrite the > signature? I would assume we should forbid rewriting the signature of a > call with an operand bundle. And once some optimization drops the bundle > and preallocated marking, to allow such rewriting, the signature doesn’t > need

On Mon, Jan 27, 2020 at 4:31 PM Eli Friedman <efriedma at quicinc.com> wrote: > I assume by “drop support”, you mean reject it in the bitcode reader/IR > parser? We can’t reasonably support a complex feature like inalloca if > nobody is testing it. If we can’t reasonably upgrade it, and we don’t think > there are any users other than clang targeting 32-bit Windows, probably

2012/2/3 Patrik Hägglund <patrik.h.hagglund at ericsson.com>: > Hi, > > I've tracked the first problem (mentioned in my previous email, quoted > below) down further, ending up in the handling of alloca in > LoopRotation.cpp (from trunk): > >      // If the instruction's operands are invariant and it doesn't read > or write >      // memory, then it is

Sorry for the delay. Arthur Eubanks has started working on the design here: https://reviews.llvm.org/D74651 I felt I should follow up here about that. On Mon, Jan 27, 2020 at 6:47 PM Eli Friedman <efriedma at quicinc.com> wrote: > It doesn’t seem like multiple call sites should be a problem if they’re > sufficiently similar? If the argument layout for each callsite is the > same,

Thanks all. David why do you say it is particularly bad IR (other than not having gone through SROA). Is it the multiple blocks for early returns? That is how I'm supporting early returns in the middle of a basic block. I couldn't find any other way. On Sun, Apr 5, 2015 at 6:24 AM, David Jones <djones at xtreme-eda.com> wrote: > Data point: > > I use (rarely) alloca in

Hi LLVM folks, To properly implement pass-by-value in the Microsoft C++ ABI, we need to be able to take the address of an outgoing call argument slot. This is http://llvm.org/PR5064 . Problem ------- On Windows, C structs are pushed right onto the stack in line with the other arguments. In LLVM, we use byval to model this, and it works for C structs. However, C++ records are also passed this

Hi! Sorry for delay, just returned from vacation. On 12/11/15 23:44, Kostya Serebryany via llvm-dev wrote: > +Maxim and Yuri, as I think this is their code. > > On Thu, Nov 12, 2015 at 3:02 AM, Jay Foad <jay.foad at gmail.com > <mailto:jay.foad at gmail.com>> wrote: > > (Resending with the correct mailing list address.) > > Hi, > > Currently

Jay, do you have a PowerPC64 target? If so, could you please check attached patch on PPC box? This is a draft patch, but it would be nice to make sure that we are moving to right direction here. Thanks, -Maxim On 18/11/15 00:12, Jay Foad wrote: >>> Currently test/asan/TestCases/alloca_vla_interact.cc is XFAILed for >>> powerpc64. I've had a look at why it

(Resending with the correct mailing list address.) Hi, Currently test/asan/TestCases/alloca_vla_interact.cc is XFAILed for powerpc64. I've had a look at why it doesn't work. I think the only problem is in the call to __asan_allocas_unpoison that is inserted at the end of the "for" loop (just before a stackrestore instruction). The call function is created something like this

In LowerGET_DYNAMIC_AREA_OFFSET() you're calling MFI->getMaxCallFrameSize(), but it looks like that doesn't return useful information until after the PrologEpilogInserter's PEI::calculateCallsInformation() has run. So maybe the lowering has to be done as part of frame index elimination? (I'm not too familiar with this code.) Jay. On 23 November 2015 at 13:07, Jay Foad

How do you handle this during codegen? One problem is avoid stack changes (like spills). Another is coordinating things that are using allocas and those that are not but end up in the stack. Consider void foo(int arg1, int arg2, int arg3, ....CXXTypeWithCopyConstructor argn, int argp1...) You will need an alloca for argn, but the ABI also requires it to be next to the plain integers that

I wanted to mention that I'm planning to start writing and sending out patches for this. Naming the attribute 'alloca' was really confusing, so I'd like to change it to 'inalloca', which follows the preposition pattern of inreg and byval. After discussion, we decided it was silly to add stackbase uses to alloca instructions. They should stay simple. Instead, we'll

Nyx wrote: > Hello, > > I would just like to ask if it's possible to explicitly free allocas. This > is because I need to call functions that take structs of different sizes as > input, (possibly inside of loops) and I would rather avoid a stack overflow. You can't explicitly free a specific alloca, but you can use the llvm.stacksave and llvm.stackrestore intrinsics to

Chris Lattner schrieb: > On Aug 21, 2009, at 3:04 AM, Marc Brünink wrote: >>> This isn't really possible. The issue is that MemDep doesn't just >>> "analyze your function". It is designed to be as lazy as possible, >>> which means that it only does analysis when a query is performed. This >>> means that if you have

Hi everyone, I'm curious about the constraints that come with the usage of llvm.stacksave/llvm.stackrestore. Specifically I was wondering what the contract of their usage was with respect to SSA variables defined after llvm.stacksave. It seems to me that they could get spilled to a stack slot, which I'm concerned stackrestore might mess up. Is this a valid concern? Thanks, Keno

Hi all, I just noticed that LICM does not hoist/sink the following store out of the loop: int array[20]; int i; for (i = 0; i<100; i++) { array [0] = 0; } The getElementPtr instruction is hoisted out of the loop; the store is not. Did I miss something obvious? Bitcode file attached. Generated using LLVM 2.5 and llvm-gcc -c -emit-llvm

On 2018-05-11 02:28, Andrew Kelley via llvm-dev wrote: > In the Zig frontend, we know at compile-time the entire call graph. > This means we know stack size for all functions and therefore the > upper bound stack usage. > > [snip] > 1. Is there a way to accomplish this with existing LLVM API? You should use the @llvm.stacksave and @llvm.stackrestore intrinsic. It is only legal