search for: d19904

...d like to be able to reference the >> whole array with a single symbol (or two, one to mark the start and the >> other to mark the end). I'm trying to get this to work initially on x86 and >> Linux (ELF). >> >> What I've got currently in http://reviews.llvm.org/D19904 creates this >> section (.xray_instr_map) and defines two globals in that section named >> "__xray_instr_map" and "__xray_instr_map_end". The problem inevitably with >> this approach is that having multiple object files have these definitions >> cause iss...

Just to close this out, I've updated http://reviews.llvm.org/D19904 to use named ELF groups per-function, and have the runtime library use __start_xray_instr_map and __stop_xray_instr_map as weak symbols from the C++ side. I've sent a patch to make creating these COMDAT/Group sections easier when lowering through the MCStreamer interface ( http://reviews.llvm.o...

Dean Michael Berris via llvm-dev <llvm-dev at lists.llvm.org> writes: > Just to close this out, I've updated http://reviews.llvm.org/D19904 to use > named ELF groups per-function, and have the runtime library use > __start_xray_instr_map and __stop_xray_instr_map as weak symbols from the > C++ side. In case you're not aware, the __start_/__stop_ trick isn't portable. You may want to look at compiler-rt/lib/profile/Ins...

...sts.llvm.org/pipermail/llvm-dev/2016-April/098901.html). > > Matthias beat me to it! >From reading the RFC, it seems that some of what XRay is doing on the instrumentation side is very similar to what CSI enables. The current implementation I'm working with (in http://reviews.llvm.org/D19904) requires some very deep integration with the LLVM compiler infrastructure (essentially a machine function pass, and instruction lowering on a per-platform basis). The development of XRay has a few trade-offs for code-size effect and runtime overhead, which I suspect are unique to XRay's targe...

...are concatenated. The trick though is I'd like to be able to reference the whole array with a single symbol (or two, one to mark the start and the other to mark the end). I'm trying to get this to work initially on x86 and Linux (ELF). What I've got currently in http://reviews.llvm.org/D19904 creates this section (.xray_instr_map) and defines two globals in that section named "__xray_instr_map" and "__xray_instr_map_end". The problem inevitably with this approach is that having multiple object files have these definitions cause issues with multiple definition violati...

I have a bit of a riddle: In http://reviews.llvm.org/D19904 I'm trying to spell the following assembly: .palign 2, 0x90 jmp +0x9 nopw 512(%rax,%rax,1) // rest of the code I try the following snippet to accomplish this: OutStreamer->EmitLabel(CurSled); OutStreamer->EmitCodeAlignment(4); auto Target = OutContext.createLinkerPrivateT...

...track of the instrumentation points marked by the lowered pseudo-instructions and generate a per-function COMDAT/ELF Group section, merged into a special section (xray_instr_map). We only currently implement the lowering for x86_64 ELF. All these changes are implemented in http://reviews.llvm.org/D19904. Challenges ========= This implementation approach poses two major challenges just on the LLVM (core) side of the implementation: 1) The pseudo-instructions need to be handled especially for each platform on which XRay would be ported. At this time we're exploring implementing (and acceptin...

Hi, The following three patches, when applied cleanly to LLVM+Clang+compiler-rt will now allow for building and running binaries with a very simple version of XRay included: http://reviews.llvm.org/D21612 (compiler-rt) http://reviews.llvm.org/D20352 (clang) http://reviews.llvm.org/D19904 (llvm) To use this on x86_64-unknown-linux-gnu you'd need to set the flags '-fxray-instrument' and if you'd like to instrument all functions, set '-fxray-instruction-threshold=1'. Apply those flags to all your object files, and link statically for best effect. Now, some qu...

I am very glad this project reached the state where we can start the public code review. Please shoot the patches for review when ready. --kcc On Thu, Jun 16, 2016 at 12:14 PM, TB Schardl via llvm-dev < llvm-dev at lists.llvm.org> wrote: > CC'ing the mailing list for the CSI project. > > On Thu, Jun 16, 2016 at 12:01 PM, TB Schardl <neboat at mit.edu> wrote: >