+KLEE is a symbolic execution framework for +programs in LLVM bitcode form. KLEE tries to symbolically evaluate "all" paths +through the application and records state transitions that lead to fault +states. This allows it to construct testcases that lead to faults and can even +be used to verify some algorithms. +

+ +

Although KLEE does not have any major new features as of 2.8, we have made +various minor improvements, particular to ease development:

Added support for LLVM 2.8. KLEE currently maintains compatibility with + LLVM 2.6, 2.7, and 2.8.
Added a buildbot for 2.6, 2.7, and trunk. A 2.8 buildbot will be coming + soon following release.
Fixed many C++ code issues to allow building with Clang++. Mostly + complete, except for the version of MiniSAT which is inside the KLEE STP + version.
Improved support for building with separate source and build + directories.
Added support for "long double" on x86.
Initial work on KLEE support for using 'lit' test runner instead of + DejaGNU.
Added configure support for using an external version of + STP.

+ +

-Clam AntiVirus is an open source (GPL) +Clam AntiVirus is an open source (GPL) anti-virus toolkit for UNIX, designed especially for e-mail scanning on mail gateways. Since version 0.96 it has bytecode signatures that allow writing detections for complex malware. It uses LLVM's JIT to speed up the execution of bytecode on -X86,X86-64,PPC32/64, falling back to its own interpreter otherwise. -The git version was updated to work with LLVM 2.8 +X86, X86-64, PPC32/64, falling back to its own interpreter otherwise. +The git version was updated to work with LLVM 2.8.

The

Jade project is hosted as part of the Open @@ -490,14 +543,14 @@ builds on LLVM 2.8.

DTMC provides support for Transactional Memory, which is an easy-to-use and efficient way to synchronize accesses to shared memory. Transactions can contain normal C/C++ code (e.g., -__transaction { list.remove(x); x.refCount--; }) and will be executed +__transaction { list.remove(x); x.refCount--; }) and will be executed virtually atomically and isolated from other transactions.

-Kai Interpreter +Kai Programming Language

-LLVM Community Changes -

Major New Features @@ -574,8 +610,16 @@ organization changes have happened:

LLVM 2.8 includes several major new capabilities:

llvm-diff
Direct .o file writing support for darwin/x86[64].
As mentioned above, libc++ and LLDB are major new additions to the LLVM collective.
LLVM 2.8 now has pretty decent support for debugging optimized code. You + should be able to reliably get debug info for function arguments, assuming + that the value is actually available where you have stopped.
A new 'llvm-diff' tool is available that does a semantic diff of .ll + files.
The MC subproject has made major progress in this release. + Direct .o file writing support for darwin/x86[-64] is now reliable and + support for other targets and object file formats are in progress.

-Interpreter and JIT Improvements -

Target Independent Code Generator Improvements @@ -697,35 +751,57 @@ infrastructure, which allows us to implement more aggressive algorithms and make it run faster:

The clang/gcc -momit-leaf-frame-pointer argument is now supported.
The clang/gcc -ffunction-sections and -fdata-sections arguments are now + supported on ELF targets (like GCC).
The MachineCSE pass is now tuned and on by default. It eliminates common + subexpressions that are exposed when lowering to machine instructions.
The "local" register allocator was replaced by a new "fast" register + allocator. This new allocator (which is often used at -O0) is substantially + faster and produces better code than the old local register allocator.
A new LLC "-regalloc=default" option is available, which automatically + chooses a register allocator based on the -O optimization level.
The common code generator code was modified to promote illegal argument and + return value vectors to wider ones when possible instead of scalarizing + them. For example, <3 x float> will now pass in one SSE register + instead of 3 on X86. This generates substantially better code since the + rest of the code generator was already expecting this.
The code generator uses a new "COPY" machine instruction. This speeds up + the code generator and eliminates the need for targets to implement the + isMoveInstr hook. Also, the copyRegToReg hook was renamed to copyPhysReg + and simplified.
The code generator now has a "LocalStackSlotPass", which optimizes stack + slot access for targets (like ARM) that have limited stack displacement + addressing.
A new "PeepholeOptimizer" is available, which eliminates sign and zero + extends, and optimizes away compare instructions when the condition result + is available from a previous instruction.
Atomic operations now get legalized into simpler atomic operations if not + natively supported, easing the implementation burden on targets.
We have added two new bottom-up pre-allocation register pressure aware schedulers: +
1. The hybrid scheduler schedules aggressively to minimize schedule length when registers are available and avoid overscheduling in high pressure situations.
2. The instruction-level-parallelism scheduler schedules for maximum ILP when registers are available and avoid overscheduling in high pressure situations.
The tblgen type inference algorithm was rewritten to be more consistent and + diagnose more target bugs. If you have an out-of-tree backend, you may + find that it finds bugs in your target description. This support also + allows limited support for writing patterns for instructions that return + multiple results (e.g. a virtual register and a flag result). The + 'parallel' modifier in tblgen was removed, you should use the new support + for multiple results instead.
A new (experimental) "-rendermf" pass is available which renders a + MachineFunction into HTML, showing live ranges and other useful + details.
The new SubRegIndex tablegen class allows subregisters to be indexed + symbolically instead of numerically. If your target uses subregisters you + will need to adapt to use SubRegIndex when you upgrade to 2.8.
The -fast-isel instruction selection path (used at -O0 on X86) was rewritten + to work bottom-up on basic blocks instead of top down. This makes it + slightly faster (because the MachineDCE pass is not needed any longer) and + allows it to generate better code in some cases.

New features of the X86 target include: +

New features and major changes in the X86 target include:

The X86 backend now supports holding X87 floating point stack values in registers across basic blocks, dramatically improving performance of code - that uses long double, and when targetting CPUs that don't support SSE.
The X86 backend now uses a SSEDomainFix pass to optimize SSE operations. On + Nehalem ("Core i7") and newer CPUs there is a 2 cycle latency penalty on + using a register in a different domain than where it was defined. This pass + optimizes away these stalls.
The X86 backend now promotes 16-bit integer operations to 32-bits when + possible. This avoids 0x66 prefixes, which are slow on some + microarchitectures and bloat the code on all of them.
The X86 backend now supports the Microsoft "thiscall" calling convention, + and a calling convention to support + ghc.
The X86 backend supports a new "llvm.x86.int" intrinsic, which maps onto + the X86 "int $42" and "int3" instructions.
At the IR level, the <2 x float> datatype is now promoted and passed + around as a <4 x float> instead of being passed and returned as an MMX + vector. If you have a frontend that uses this, please pass and return a + <2 x i32> instead (using bitcasts).
When printing .s files in verbose assembly mode (the default for clang -S), + the X86 backend now decodes X86 shuffle instructions and prints human + readable comments after the most inscrutable of them, e.g.: + +
```
+  insertps $113, %xmm3, %xmm0 # xmm0 = zero,xmm0[1,2],xmm3[1]
+  unpcklps %xmm1, %xmm0       # xmm0 = xmm0[0],xmm1[0],xmm0[1],xmm1[1]
+  pshufd   $1, %xmm1, %xmm1   # xmm1 = xmm1[1,0,0,0]
+
```
+