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Cling version 0.2
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@vgvassilev vgvassilev released this 05 Aug 08:37
· 2215 commits to master since this release
v0.2
2b41279

Introduction

This document contains the release notes for the interactive C++ interpreter Cling, release 0.2. Cling is built on top of Clang and LLVM compiler infrastructure Here we describe the status of Cling in some detail, including major improvements from the previous release and new feature work.

Note that if you are reading this file from a git checkout or the main Cling web page, this document applies to the next release, not the current one.

What's New in Cling 0.2?

Some of the major new features and improvements to Cling are listed here. Generic improvements to Cling as a whole or to its underlying infrastructure are described first.

Major New Features

  • Switch Cling's execution engine to use LLVM's Orc JIT. The new JIT allows Cling to support:

    • ARM and PowerPC architectures.

    • Exceptions. Cling can throw and catch exceptions from interpreted and compiled code.

      [cling]$ throw new std::exception();
Exception occurred. Recovering...

    • Inline assembly. Cling can execute asm statements.

      [cling]$ extern "C" int printf(const char*, ...);
[cling]$ int arg1=1, arg2=2, add;
[cling]$ asm ("addl %%ebx, %%eax;" : "=a" (add) : "a" (arg1) , "b" (arg2));
[cling]$ printf( "%d + %d = %d\n", arg1, arg2, add );
1 + 2 = 3

  • Reduce memory usage caused by excessive memory allocations in Cling lookup routines.

  • Stabilize error recovery caused by handling of templated declarations.

  • Implement a user-extendable value streaming engine.

  • Implement shebang support.

  • Protect against invalid pointer dereferences.

     [cling]$ struct S{ int a; };
 [cling]$ ((S*)0x123)->a;
 input_line_4:2:2: warning: invalid memory pointer passed to a callee:
 ((S*)0x123)->a;
 ^~~~~~~~~~~
 [cling]$ ((S*)0)->a;
 input_line_5:2:2: warning: null passed to a callee that requires a non-null argument [-Wnonnull]
 ((S*)0)->a;
 ^~~~~~~

  • Redirect stderr and stdout. Cling's users can redirect the output streams.

     [cling]$ // Redirects stdout to /tmp/outfile.txt
 [cling]$ .> /tmp/outfile.txt
 [cling]$ // Toggles back to the prompt
 [cling]$ .>
 [cling]$ // Redirects stderr to /tmp/errfile.txt
 [cling]$ .2> /tmp/errfile.txt
 [cling]$ // Redirects stdout and stderr to /tmp/bothfile.txt
 [cling]$ .&> /tmp/bothfile.txt

  • Add #pragma cling directives:

    • #pragma cling add_include_path("/include/path/")
    • #pragma cling add_library_path("/library/path/")
    • #pragma cling load("libUserLib")

  • Add .@ metacommand to cancel multiline user input.

  • Add .debug [Constant] metacommand to tune the generated debug information.

Cling as a Library

  • Implement a generator of forward declarations from a given AST declaration.
  • Improve string-to-decl lookup helper.
  • Support of parent-children (multiple) interpreters.

External Dependencies

  • Upgrade to LLVM r272382.
  • Upgrade to CMake 3.4.3 (following LLVM requirements)

Misc

Experimental Features

  • Code unloading:
    • Generate one module per transaction, which simplifies unloading of llvm::Modules and machine code.
    • Add support for unloading few STL header files.
  • Dynamic Scopes:
    • Handle of errors occurred when synthesizing AST nodes.

Fixed Bugs:

ROOT-4760 ROOT-5467 ROOT-5607 ROOT-5698 ROOT-5844 ROOT-6153 ROOT-6185 ROOT-6345 ROOT-6365 ROOT-6385 ROOT-6611 ROOT-6625 ROOT-6650 ROOT-6692 ROOT-6695 ROOT-6705 ROOT-6712 ROOT-6719 ROOT-6755 ROOT-6791 ROOT-6824 ROOT-6832 ROOT-6909 ROOT-6942 ROOT-6976 ROOT-7031 ROOT-7037 ROOT-7041 ROOT-7090 ROOT-7092 ROOT-7095 ROOT-7114 ROOT-7159 ROOT-7163 ROOT-7184 ROOT-7269 ROOT-7276 ROOT-7295 ROOT-7310 ROOT-7364 ROOT-7426 ROOT-7462 ROOT-7614 ROOT-7619 ROOT-7673 ROOT-7737 ROOT-7744 ROOT-7837 ROOT-7840 ROOT-7918 ROOT-8034 ROOT-8056 ROOT-8096 ROOT-8111

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