similar to: security and Authentication

On Nov 9, 2011, at 11:34 AM, Rafael Espíndola wrote: >>> 1) [Requires ABI change] We emit dynamic initialization code for weak globals >>> (even in TUs where static initialization is required to be performed), unless >>> we can prove that every translation unit will use static initialization. We >>> emit the global plus its guard variable as a single object so

Hi Sanjoy, Thanks for feedback! As for memory effects, currently I use " inaccessiblememonly " for it. It allows to prove that it doesn't alias with any other load/store in the function, but doesn't allow CSE to eliminate it. It is not actually super-cool, because there is no way that we can safely hoist it out of loop (and sometimes we want to, for example to make unswitching).

Hi all, TL;DR: Should the loop guard branch be part of the canonical loop structure? Background: ----------- While working on the next set of improvements to loop fusion, we discovered that loop rotation will put a guard around a loop if it cannot prove the loop will execute at least once, as seen in the following (simplified) example: entry: br i1 %cmp1, label %for.body.lr.ph, label

On Hexagon, unguarded loops cannot be converted to hardware loops. If the loop's latch branch alone handles the iteration count, including the possibility of 0, then the loop cannot be converted to a hardware loop, because hardware loops must iterate at least once. If the entire loop is guarded against zero iteration count, we can put the loop setup in the preheader, since at that point the

Hello Everyone, I want to raise a discussion about @llvm.experimental.guard intrinsic and reasons why we should give up using it. Here is an alternative approach to representation of guards that resolves some of fundamental flaws that the current guards have. Basically, this intrinsic was introduced to model the following situation: we want to check that some condition is true, and if it's

Hi all, Apparently some people had trouble joining today. I also had trouble using the attendee ID provided by webex. I've canceled the meeting series and will be scheduling a new one with an updated link. Please remember to update your calendars with the new invite. My apologies to those who couldn't join today, and to everyone for the churn. Today's Meeting Minutes:

On Mon, November 7, 2011 16:31, Eli Friedman wrote: > 2011/11/7 Rafael Espíndola <rafael.espindola at gmail.com>: >> I tried a small variation: >> >> >> struct S {  static const int x; >> }; >> template<typename T> struct U {  static const int k; >> }; >> template<typename T> const int U<T>::k = T::x; >> >>

Replies inline. At a high level, it feels like we'll eventually need a new instruction to represent the kind of control flow a guard entails (to be clear: we should probably still start with an intrinsic) -- they are fairly well-behaved, i.e. readonly, nounwind etc. as far as the immediate "physical" caller is concerned, but not so as far as its callers's callers are concerned.

Hello developeRs, Apologies in advance for a rather long email, but to describe the problem, I need to step through many details. I have been working on a new dispatching system (futile.paradigm on CRAN) based on functional programming concepts that is an alternative to S3 and S4 dispatching. I use a declarative syntax using guard statements to control the dispatching between function variants. I

On Nov 7, 2011, at 9:47 AM, Richard Smith wrote: >> In cases where the C++ standard requires static initialization, >> introducing a write violates the guarantees of the C++ standard for static >> initialization. Therefore, I'm not sure the whole "make the constant >> writable" approach is actually viable. > > There is another problem which afflicts

All, TLDR: guards currently require reasoning about implicit control flow.  LLVM struggles with implicit control flow within a basic block.  We should redesign guards to admit this rather than trying to boil the ocean. As you may be aware, LLVM currently has experimental support for a construct called a "guard".  A guard is like a branch to a potential deoptimzation point, except

Hi all, Guard intrinsics[0] are similar in nature to Assume intrinsics, in that the condition passed to a guard intrinsic call is known to be true at locations dominated (but *not* post-dominated) by the call[1]. I'd like to re-use the AssumptionCache infrastructure that already exists to teach the mid level optimizer to exploit this property. The steps I want to take are (not necessarily

>> 1) [Requires ABI change] We emit dynamic initialization code for weak globals >> (even in TUs where static initialization is required to be performed), unless >> we can prove that every translation unit will use static initialization. We >> emit the global plus its guard variable as a single object so the linker can't >> separate them (this is the ABI change).

Hi all, There might be a bug in DeadStoreElimination.cpp. This pass eliminates stores backwards aggressively in an end BB. It does not check dependencies on stores in an end BB though. For example, in this code snippet: ... 1. %sum.safe_r47.pre-phi = phi i64* [ %sum.safe_r47.pre, %entry.for.end_crit_edge ], [ %sum.safe_r42, %for.body ] 2. %call9 = call i32 @gettimeofday(%struct.timeval* %end,

Hi, I was building LLVM with gcc 6.1.1 recently and it was spitting out some warnings relating to misleading indention that caught my eye. This wasn't a fresh build so I may have missed some. I've CC'ed the authors of the potentially misleading lines so they can decide what do about the warnings (if anything). I'm wondering if clang-format is making some inappropriate choices

Sanjoy gave the long answer, let me give the short one. :) "deopt" argument bundles are used in the middle end, they are lowered into a statepoint, and generate the existing stackmap format. i.e. one builds on the other. On 02/18/2016 11:43 AM, Eric Christopher wrote: > Hi Sanjoy, > > A quick question here. With the bailing to the interpreter support > that you're

Hi, I have problem with IRBuilderBase::InsertPointGuard class that simply does not work in the release build of my project. The class does not restore the IRBuilder's insert point correctly when NDEBUG macro is set. It happens on OSX system only, trunk version of the LLVM built with brew. I suspect it is the ABI problem. InsertPointGuard uses AssertingVT for debug builds. LLDB gets confused

On Fri, Sep 11, 2020 at 04:49:55PM -0500, Eric Blake wrote: > The next strict knob: allow the user to pass unknown flags across the > wire (this is different than passing a known flag at the wrong time). > > It is interesting to note that NBD only permits 16 bits of flags, but > we have a signature that takes uint32_t; if we wanted, we could pack > libnbd-specific flags in the

Hi Andy, Thanks for replying, responses inline below: On Fri, Feb 19, 2016 at 11:12 AM, Andrew Trick <atrick at apple.com> wrote: > This clearly doesn't need operand bundles, but using an intrinsic > would permit special code motion semantics. It could be hoisted and > merged with other traps, but the condition could never be widened > beyond the union of the original

On Thu, Oct 6, 2011 at 2:20 PM, Eli Friedman <eli.friedman at gmail.com> wrote: > On Thu, Oct 6, 2011 at 2:12 PM, Zeng Bin <ezengbin at gmail.com> wrote: >> Hi all, >> >> There might be a bug in DeadStoreElimination.cpp. This pass eliminates >> stores backwards aggressively in an end BB. It does not check dependencies >> on stores in an end BB though.