search for: vtable

Using relative offsets applies to more than just vtables. It would do wonders for constant strings too. -- Sean Silva On Mon, Feb 29, 2016 at 1:53 PM, Peter Collingbourne via cfe-dev < cfe-dev at lists.llvm.org> wrote: > Hi all, > > I'd like to make a proposal to implement the new vtable ABI described in > PR26723, which I'l...

Hi all, I'd like to make a proposal to implement the new vtable ABI described in PR26723, which I'll call the relative ABI. That bug gives more details and justification for that ABI. The user interface for the new ABI would be that -fwhole-program-vtables would take an optional value indicating which aspects of the program have whole-program scope. For ex...

Hi all, I’ve been working on a Java-esque object-oriented language Bolt that targets LLVM IR. I’m agonisingly close to getting a virtual table working, and was hoping one of you could point out the gap in my understanding. I’ve linked the C++ code snippets relevant to the vtable below. Example IR generated (partially displayed below): https://github.com/mukul-rathi/bolt/blob/vtable/examples/vtable/foo.ll <https://github.com/mukul-rathi/bolt/blob/vtable/examples/vtable/foo.ll> And the Bolt source code that compiles to it- https://github.com/mukul-rathi/bolt/blob/vt...

Dear Mailing List, This might sound unconventional, but I am trying to access a C++ objects vtable to pass as an argument to a function call for a library function I created. Creating & inserting a function call at the correct location in LLVM is done. I have learned that C++ objects are represented as struct types. But I'm just not quite sure how to get at the vtable pointer within, wh...

Hi Peter, Thanks for your answer! > On Jan 28, 2016, at 10:17 AM, Peter Collingbourne <peter at pcc.me.uk> wrote: > > Hans wrote: >> (and start-up time if we can drop the vtables and >> void the dynamic relocations). > > On Thu, Jan 28, 2016 at 09:15:05AM -0800, Mehdi Amini wrote: >> Hi, >> >> I just thought about another use case: VTable compression. >> If you know that an entry in the Vtable is never used, just remove it! >> I’...

Hi, I just thought about another use case: VTable compression. If you know that an entry in the Vtable is never used, just remove it! I’d hope we could even eliminate some unused virtual functions from the final binary. — Mehdi > On Jan 27, 2016, at 10:29 PM, Mehdi Amini via llvm-dev <llvm-dev at lists.llvm.org> wrote: > > Hi P...

...xtend ThinLTO to allow a bitcode module to embed another bitcode module containing summary information. The purpose of doing so is to support CFI and whole-program devirtualization optimizations under ThinLTO. Overview The CFI and whole-program devirtualization optimizations work by transforming vtables according to the class hierarchy. For example, if a class A has two derived classes B and C, CFI will lay out the vtables for A, B and C consecutively, so that clients can check that a vtable refers to a derived class of A by performing arithmetic on the virtual function pointer. For more details,...

Hi all, I would like to propose a mechanism that allows IR modules to co-operatively build a pointer set corresponding to addresses within a given set of globals. The specific use case I have in mind is to provide a mechanism for a C++ program to efficiently verify (at each call site) that a vtable pointer is in the set of valid vtable pointers for the class or its derived classes. One way of doing this is for a toolchain component to build, for each class, a bit set that maps to the memory region allocated for the vtables, such that each 1 bit in the bit set maps to a valid vtable for that c...

Hi, Can someone help me with how to dump the vtable and the vptr addresses within it? Thanks, Dami -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20170529/5dc7e058/attachment.html>

...isOfType(Base::kDerived); } We can make the observation that if the type hierarchy is known to be closed and the definition of each virtual function and each virtual call is visible to the compiler, calls to either of these functions can be implemented more efficiently by loading directly from the vtable (we refer to this as virtual constant propagation): struct Base_VTable { bool isDerived : 1, isOfTypeBase : 1, isOfTypeDerived : 1; }; Base_VTable base_vtable{false, true, false}; Derived_VTable derived_vtable{true, false, true}; bool f(Base *b) { return b->vtable->isDerived; } bool g(Ba...

...ence to `typeinfo for llvm::cl::GenericOptionValue' This seems to be due to the (mis-)use of "anchor" methods in CommandLine. I commited r183830, with a removal of the anchor method for GenericOptionValue, which solved my link problem. Also, the commit didn't change the number of vtables, as measured by: find -name \*.o | xargs nm -C | grep 'V vtable' | grep OptionValue | wc The current LLVM developer policy text regarding "anchor" methods is: "If a class is defined in a header file and has a vtable (either it has virtual methods or it derives from class...

A question about the layout of structs: I decided to make my vtables out of structs rather than arrays. In other words, instead of being a table of opaque pointers, I decided to individually declare each entry with the correct type for that method. I figure that the various optimizers could do a better job if I preserve the type info. OK, so we come to the iss...

...me he wrote this policy - and, as I said in my previous email, I wouldn't mind seeing some justification or just seeing the rule go away & drop the anchors I added previously (or, if we're going to keep it, we could add more anchors & actually get to the point where we're -Wweak-vtable clean & enable that warning)) On Wed, Jun 12, 2013 at 1:44 PM, Patrik Hägglund H <patrik.h.hagglund at ericsson.com> wrote: > I tried to build LLVM with ’gcc-4.8.1 –flto’, and when linking unittest > programs, I got the following error: > > > > /tmp/cc8pMk84.ltrans30.lt...

...lso to allow bitcode objects to be shared between links of targets with differing valid LTO visibility. This utilizes the !vcall_visibility metadata added for Dead Virtual Function Elimination. The summary of changes required are (these are described in more detail later): 1) When -fwhole-program-vtables is specified, always insert type test assumes for virtual calls, and additionally add !vcall_visibility metadata to vtable definitions (which will be summarized in the ThinLTO index). 2) At LTO link time, apply hidden LTO visibility to vtable definition vcall_visibility metadata (or summary) when...

...se a mechanism that allows IR modules to >> co-operatively >> build a pointer set corresponding to addresses within a given set of >> globals. The specific use case I have in mind is to provide a mechanism >> for a C++ program to efficiently verify (at each call site) that a vtable >> pointer is in the set of valid vtable pointers for the class or its >> derived >> classes. One way of doing this is for a toolchain component to build, for >> each >> class, a bit set that maps to the memory region allocated for the vtables, >> such that each...

Hello, In an effort to help LLVM-style projects save memory, I’ve been toying with some macros that provide an alternative to C++ vtables that use LLVM-style RTTI design patterns instead. Is this something that LLVM or sub-projects think is worth pursuing? Or are the macros below too ugly/problematic? Feedback would be appreciated. Thanks, Dave //===- llvm/Support/VTable.h - LLVM-style vtables ---------------*- C++ -*-===// //...

Hello xapian users, The server I'm compiling on is a little odd. SunOS on a sun4 architecture. Fails when linking, gives the following, memcpy 0x10 /usr/local/gcc-3.3.2/lib/./libstdc++.a(ctype.o) ld: fatal: relocations remain against allocatable but non-writable sections collect2: ld returned 1 exit status *** Error code 1 make: Fatal error:

...mpatible versions. I am using libtool 2.2.6b, GNU ld 2.20.2010303. I know gcc 3.3.2 is a little behind the times, but I see the the documentation the minimum requirement is 3.1. I also see James Aylett reported compiling Xapian version 1.0.5 on the Solaris 9 with platform with gcc 3.3. Any ideas? vtable for __cxxabiv1::__vmi_class_type_info0x4 /usr/local/gcc-3.3.2/lib/./libstdc++.a(tinfo.o) vtable for __cxxabiv1::__vmi_class_type_info0xc /usr/local/gcc-3.3.2/lib/./libstdc++.a(tinfo.o) vtable for __cxxabiv1::__vmi_class_type_info0x4 /usr/local/gcc-3.3.2/lib/./libstdc++.a(tinfo.o) vtable for __cxxab...

...>> co-operatively > > >> build a pointer set corresponding to addresses within a given set of > > >> globals. The specific use case I have in mind is to provide a > mechanism > > >> for a C++ program to efficiently verify (at each call site) that a > vtable > > >> pointer is in the set of valid vtable pointers for the class or its > > >> derived > > >> classes. One way of doing this is for a toolchain component to build, > for > > >> each > > >> class, a bit set that maps to the memory reg...

...I would like to propose a mechanism that allows IR modules to co-operatively > build a pointer set corresponding to addresses within a given set of > globals. The specific use case I have in mind is to provide a mechanism > for a C++ program to efficiently verify (at each call site) that a vtable > pointer is in the set of valid vtable pointers for the class or its derived > classes. One way of doing this is for a toolchain component to build, for each > class, a bit set that maps to the memory region allocated for the vtables, > such that each 1 bit in the bit set maps to a val...