similar to: Capturing x86 %rax in prologue to use in body

Hi John, On 14 March 2018 at 18:28, John Reagan via llvm-dev <llvm-dev at lists.llvm.org> wrote: > However, we're struggling somewhat on the code in the prologue to > capture the %ah value to then be obtained by our "arg_count" compiler > builtin. We found where the 1st parameter is put into a virtual > register in the event that it has to be passed back in %rax

Hi all, We're at the point in our port of OpenVMS to x86-64 that we're working on the unwind code.  The current ABI and the current codebase doesn't have enough support for true asynchronous unwinding from any point (most notably in the prologue/epilogue) in the code that OpenVMS needs.  We're working on a set of changes to the compact unwind information to handle the additional

Hello, I'd like to introduce myself, my company, and our upcoming use of LLVM. My name is John Reagan. I've been working on compilers and assemblers since 1983 (yes, 31 years). Most of that time was spent on compilers for VAX/VMS (later renamed to OpenVMS), then OpenVMS on Alpha, and OpenVMS on Itanium. I've also worked with the HP NonStop platform and was directly involved

Yes. We currently build LLVM 3.4.2 on our OpenVMS Itanium box with an older EDG/Intel C++03 compiler to create legacy cross-compilers to our OpenVMS x86 box (well, VirtualBox). We do have a few tweaks to the relocations to access static data always through the GOT (including CodeGen's static data). Our linker sees references to code (which might be in 64-bit space) and creates trampolines

> -----Original Message----- > From: llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org] On Behalf Of JF > Bastien via llvm-dev > Sent: Thursday, June 13, 2019 12:25 PM > To: John Reagan > Cc: llvm-dev at lists.llvm.org > Subject: Re: [llvm-dev] [RFC] Coding Standards: "prefer `int` for, regular > arithmetic, use `unsigned` only for bitmask and when you, intend to

As one of the OS' without current CMake support, I'm closely watching this discussion. We currently have LLVM 3.4.2 hosted on OpenVMS Itanium (as a host only, x86 target) using configure/make with little hassle. We plan to port CMake to OpenVMS, but that has been trickier than you'd think (others have tried, I haven't found anybody who has done it). Looks like I'll want to

I'm not sure if they are doing an x86 to IA64 cross compile, but in any event I'm going to guess they may need an ancient version to avoid any C++11 dependencies. In terms of IA64 compilers you have afaik 3 choices HP compiler, Open64 and Intel? (Does gcc still support it and how up-to-date or EOL is the Intel compiler IA64 support?) I really hope nobody decides not to move to a more

On Wed, May 18, 2016 at 01:10:50PM +0000, Daniel Sanders via llvm-dev wrote: > It's my understanding that llvm-mc is intended to be a testing tool > for LLVM developers rather than an assembler for end users. Users > should be assembling with clang. Not all LLVM users are clang users. For example, we're using LLVM to build OpenVMS cross-compilers to x86 for our porting effort.

As part of our port of OpenVMS to x86-64, we are using LLVM with our own frontends on OpenVMS Itanium. We are writing a converter between our old backend's IR and the LLVM IR. We can cross-compile (hosted on OpenVMS Itanium) and link/execute on x86-64 CentOS. At present, we pass over 88% of our C test suite. Porting starts with being able to compile the code. Since we are stuck with a

I had thought about "used", but not aware of the @llvm.used, et al. I wrote some test programs with __attribute__((used)) but that felt like something you'd put on function definitions to force code to be generated regardless. In the worst case, I'll do some metadata hack (I've ready had to do that for BLISS' GLOBAL BIND feature). Thanks for the response. I'll let

As somebody who's currently hosting LLVM on a platform (OpenVMS Itanium) that has configure but not a working CMake (we're working to fix that but there are some tricky issues), I would appreciate if you didn't scrub the existence of configure from the source or the documentation. Perhaps keep pointers to the older pages and link to them from the downloads pages or something with an

> From: Tim Northover via llvm-dev <llvm-dev at lists.llvm.org> > Emitting directives in the epilogue is hard because the directives > apply to all instructions after in program-counter order. So if you > have an epilogue in the middle of a function and emit CFI directives > saying the registers are back where they were then the unwinder will > think that applies to the

I think it's valuable to have precise / asynchronous unwind information without adding support for non-call exceptions. Profilers and debuggers need to be able to unwind the stack from arbitrary instruction boundaries, but they don't need to run exception handlers. We can still declare that outside the model. Speaking of which, barring bugs, we do support precise unwind info on Win64.

We're at the point in our port of OpenVMS to x86 using LLVM to make choices on mcmodel. Given OpenVMS's history, our linker will allocate static data (ie, .data, .bss, .plt, GOT, etc.) in the bottom 32-bits of address space (ie, 00000000.xxxxxxxx). However, we support code anywhere in the 64-bit address space as PIC code (we do this on Itanium today using our own code-generator and

I'm defining an external function in the IR that has no uses at all. No calls, no address taken, nada. Such an unused declaration seems to be just dropped on the floor as not needed. Seems reasonable in most cases. However, one of my OpenVMS compilers (BLISS) has a language rule that expects such definitions to get into the ELF symbol table as a way to compel the linker to include certain

Amy, when you say "implement MSVC's extensions", is that MSVC/LLVM or are you going to add these to clang? OpenVMS has dual-sized pointers as well and want to see them in clang. One of my engineers noticed that address space 4 was a 32-bit pointer address space (or at least it used to be). I haven't seen any formal discussion of that over in the cfe dev list. I'm happy to

We use .note descriptors with ELF on OpenVMS.  We have self-describing entries with tags and lengths.  The compiler encodes stuff for the linker such as compiler version, compilation date-time, module name, final severity of the compilation, etc.  The linker itself then adds/modifies the .note entries to insert linker version, link date/time, etc.  We also use .notes to record floating point

When I worked on the HPE NonStop compilers for x86 (we used Open64, not LLVM), we adjusted our -O1 to make sure the source display didn't "bounce around" based on feedback from users. We disabled any optimization that would move things across statement boundaries. We also disabled/de-tuned dead store since our DWARF location list support was pretty basic and with the removed store,

On 19 Jan 2018, at 14:48, John Reagan via llvm-dev <llvm-dev at lists.llvm.org> wrote: > > OpenVMS' EH model is for full asynchronous prologue/epilogue EH. We do more > than just program-level EH, but have to deal with OS events (timers going off, > asynch I/O completion, mailboxes filled with data, etc.) which could result in > an unwind occurring. > >

That is basically what we do today to provide mixed sized pointers with our legacy frontends. They generate IR to our old code generator which has ADDR32 and ADDR64 datatypes. We use a 64-bit address data layout and then typecast the 32-bit forms to/from the underlying 64-bit addresses. I have been warned that such rampant typecasting might interfere with certain optimizations or TBAA data. We