LLVM 3.1 Release Notes

This document contains the release notes for the LLVM Compiler - Infrastructure, release 3.1. Here we describe the status of LLVM, including + Infrastructure, release 3.2. Here we describe the status of LLVM, including major improvements from the previous release, improvements in various - subprojects of LLVM, and some of the current users of the code. - All LLVM releases may be downloaded from - the LLVM releases web site.

+ subprojects of LLVM, and some of the current users of the code. All LLVM + releases may be downloaded from the LLVM + releases web site.

For more information about LLVM, including information about the latest release, please check out the main LLVM web @@ -72,11 +72,11 @@ Release Notes.

The LLVM 3.1 distribution currently consists of code from the core LLVM - repository (which roughly includes the LLVM optimizers, code generators and - supporting tools), and the Clang repository. In - addition to this code, the LLVM Project includes other sub-projects that are - in development. Here we include updates on these subprojects.

The LLVM 3.2 distribution currently consists of code from the core LLVM + repository, which roughly includes the LLVM optimizers, code generators and + supporting tools, and the Clang repository. In addition to this code, the + LLVM Project includes other sub-projects that are in development. Here we + include updates on these subprojects.

@@ -94,23 +94,15 @@ Release Notes.

production-quality compiler for C, Objective-C, C++ and Objective-C++ on x86 (32- and 64-bit), and for Darwin/ARM targets.

In the LLVM 3.1 time-frame, the Clang team has made many improvements. +

In the LLVM 3.2 time-frame, the Clang team has made many improvements. Highlights include:

Greatly expanded C++11 - support including lambdas, initializer lists, constexpr, user-defined - literals, and atomics.
A new tooling - library to ease building of clang-based standalone tools.
Extended support for - literals in - Objective C.
...

For more details about the changes to Clang since the 3.0 release, see the -Clang release notes -

- +

For more details about the changes to Clang since the 3.1 release, see the + Clang release + notes.

If Clang rejects your code but another compiler accepts it, please take a look at the language @@ -125,6 +117,7 @@ Release Notes.

DragonEgg is a gcc plugin that replaces GCC's optimizers and code generators with LLVM's. It works with gcc-4.5 and gcc-4.6 @@ -133,25 +126,10 @@ Release Notes. Linux and OpenBSD platforms. It fully supports Ada, C, C++ and Fortran. It has partial support for Go, Java, Obj-C and Obj-C++.

The 3.1 release has the following notable changes:

- -

Partial support for gcc-4.7. Ada support is poor, but other languages work - fairly well.
Support for ARM processors. Some essential gcc headers that are needed to - build DragonEgg for ARM are not installed by gcc. To work around this, - copy the missing headers from the gcc source tree.
Better optimization for Fortran by exploiting the fact that Fortran scalar - arguments have 'restrict' semantics.
Better optimization for all languages by passing information about type - aliasing and type ranges to the LLVM optimizers.
A regression test-suite was added.

The 3.2 release has the following notable changes:

@@ -168,11 +146,15 @@ Release Notes. target-specific hooks required by code generation and other runtime components. For example, when compiling for a 32-bit target, converting a double to a 64-bit unsigned integer is compiled into a runtime call to the - "__fixunsdfdi" function. The compiler-rt library provides highly optimized - implementations of this and other low-level routines (some are 3x faster than - the equivalent libgcc routines).

+ __fixunsdfdi function. The compiler-rt library provides highly + optimized implementations of this and other low-level routines (some are 3x + faster than the equivalent libgcc routines).

+ +

The 3.2 release has the following notable changes:

....

@@ -189,7 +171,11 @@ Release Notes. expression parsing (particularly for C++) and uses the LLVM JIT for target support.

...

The 3.2 release has the following notable changes:

+ +

Polly is an experimental +

Polly is an experimental optimizer for data locality and parallelism. It currently provides high-level loop optimizations and automatic parallelisation (using the OpenMP run time). Work in the area of automatic SIMD and accelerator code generation was - started. - -

Within the LLVM 3.1 time-frame there were the following highlights:

- -

Polly became an official LLVM project
Polly can be loaded directly into clang (Enabled by '-O3 -mllvm -polly' - )
An automatic scheduling optimizer (derived from Pluto) was integrated. It - performs loop transformations to optimize for data-locality and parallelism. - The transformations include, but are not limited to interchange, fusion, - fission, skewing and tiling. -

+ started.

+ +

Within the LLVM 3.2 time-frame there were the following highlights:

+ +

- External Open Source Projects Using LLVM 3.1 + External Open Source Projects Using LLVM 3.2

An exciting aspect of LLVM is that it is used as an enabling technology for - a lot of other language and tools projects. This section lists some of the - projects that have already been updated to work with LLVM 3.1.

+ a lot of other language and tools projects. This section lists some of the + projects that have already been updated to work with LLVM 3.2.

+ +

Crack

+ +

Crack aims to provide + the ease of development of a scripting language with the performance of a + compiled language. The language derives concepts from C++, Java and Python, + incorporating object-oriented programming, operator overloading and strong + typing.

+ +

FAUST

@@ -402,14 +395,14 @@ Release Notes.

- What's New in LLVM 3.1? + What's New in LLVM 3.2?

This release includes a huge number of bug fixes, performance tweaks and - minor improvements. Some of the major improvements and new features are + minor improvements. Some of the major improvements and new features are listed in this section.

@@ -419,13 +412,13 @@ Release Notes.

- @@ -436,18 +429,10 @@ Release Notes. llvm/lib/Archive - replace with lib object? --> -

LLVM 3.1 includes several major changes and big features:

LLVM 3.2 includes several major changes and big features:

AddressSanitizer, - a fast memory error detector.
MachineInstr Bundles, - Support to model instruction bundling / packing.
ARM Integrated Assembler, - A full featured assembler and direct-to-object support for ARM.
Basic Block Placement - Probability driven basic block placement.
....
...

@@ -463,22 +448,12 @@ Release Notes.

LLVM IR has several new features for better support of new targets and that expose new optimization opportunities:

A new type representing 16 bit half floating point values has - been added.
IR now supports vectors of pointers, including vector GEPs.
Module flags have been introduced. They convey information about the - module as a whole to LLVM subsystems. This is currently used to encode - Objective C ABI information.
Loads can now have range metadata attached to them to describe the - possible values being loaded.
The llvm.ctlz and llvm.cttz intrinsics now have an - additional argument which indicates whether the behavior of the intrinsic - is undefined on a zero input. This can be used to generate more efficient - code on platforms that only have instructions which don't return the type - size when counting bits in 0.
....

Thread local variables may have a specified TLS model. See the + Language Reference Manual.
...

@@ -488,23 +463,11 @@ Release Notes.

In addition to many minor performance tweaks and bug fixes, this - release includes a few major enhancements and additions to the - optimizers:

In addition to many minor performance tweaks and bug fixes, this release + includes a few major enhancements and additions to the optimizers:

The loop unroll pass now is able to unroll loops with run-time trip counts. - This feature is turned off by default, and is enabled with the - -unroll-runtime flag.
A new basic-block autovectorization pass is available. Pass - -vectorize to run this pass along with some associated - post-vectorization cleanup passes. For more information, see the EuroLLVM - 2012 slides: - Autovectorization with LLVM.
Inline cost heuristics have been completely overhauled and now closely - model constant propagation through call sites, disregard trivially dead - code costs, and can model C++ STL iterator patterns.
....
...

@@ -519,15 +482,12 @@ Release Notes.

The LLVM Machine Code (aka MC) subsystem was created to solve a number of problems in the realm of assembly, disassembly, object file format handling, and a number of other related areas that CPU instruction-set level tools work - in. For more information, please see - the Intro - to the LLVM MC Project Blog Post.

+ in. For more information, please see the + Intro + to the LLVM MC Project Blog Post.

The integrated assembler can optionally emit debug information when - assembling a .s file. It can be enabled by passing the - -g option to llvm-mc.
....
...

We added new TableGen infrastructure to support bundling for @@ -583,11 +529,14 @@ Release Notes.

Basic Block Placement

ARM Integrated Assembler

The ARM target now includes a full featured macro assembler, including -direct-to-object module support for clang. The assembler is currently enabled -by default for Darwin only pending testing and any additional necessary -platform specific support for Linux.

+ direct-to-object module support for clang. The assembler is currently enabled + by default for Darwin only pending testing and any additional necessary + platform specific support for Linux.

Full support is included for Thumb1, Thumb2 and ARM modes, along with -subtarget and CPU specific extensions for VFP2, VFP3 and NEON.

+ subtarget and CPU specific extensions for VFP2, VFP3 and NEON.

The assembler is Unified Syntax only (see ARM Architecural Reference Manual -for details). While there is some, and growing, support for pre-unfied (divided) -syntax, there are still significant gaps in that support.

+ for details). While there is some, and growing, support for pre-unfied + (divided) syntax, there are still significant gaps in that support.

MIPS Target Improvements @@ -653,26 +598,11 @@ syntax, there are still significant gaps in that support.

This release has seen major new work on just about every aspect of the MIPS - backend. Some of the major new features include:

New features and major changes in the MIPS target include:

....
...

- - -

-PTX Target Improvements -

If you're already an LLVM user or developer with out-of-tree changes based on - LLVM 3.1, this section lists some "gotchas" that you may run into upgrading + LLVM 3.2, this section lists some "gotchas" that you may run into upgrading from the previous release.

LLVM's build system now requires a python 2 interpreter to be present at - build time. A perl interpreter is no longer required.
The C backend has been removed. It had numerous problems, to the point of - not being able to compile any nontrivial program.
The Alpha, Blackfin and SystemZ targets have been removed due to lack of - maintenance.
LLVM 3.1 removes support for reading LLVM 2.9 bitcode files. Going - forward, we aim for all future versions of LLVM to read bitcode files and - .ll files produced by LLVM 3.0 and later.
The unwind instruction is now gone. With the introduction of the - new exception handling system in LLVM 3.0, the unwind instruction - became obsolete.
LLVM 3.0 and earlier automatically added the returns_twice fo functions - like setjmp based on the name. This functionality was removed in 3.1. - This affects Clang users, if -ffreestanding is used.
....
...

LLVM is generally a production quality compiler, and is used by a broad range of applications and shipping in many products. That said, not every subsystem is as mature as the aggregate, particularly the more obscure - targets. If you run into a problem, please check the LLVM bug database and submit a bug if - there isn't already one or ask on the LLVMdev - list.

LLVM 3.1 Release Notes

LLVM 3.2 Release Notes

These are in-progress notes for the upcoming LLVM 3.1 +

These are in-progress notes for the upcoming LLVM 3.2 release.
You may prefer the -LLVM 3.0 +LLVM 3.1 Release Notes.

@@ -94,23 +94,15 @@ Release Notes.

- External Open Source Projects Using LLVM 3.1 + External Open Source Projects Using LLVM 3.2

Crack

FAUST

- What's New in LLVM 3.1? + What's New in LLVM 3.2?

Basic Block Placement

ARM Integrated Assembler

-PTX Target Improvements -

LLVM 3.1 Release Notes

LLVM 3.2 Release Notes

These are in-progress notes for the upcoming LLVM 3.1 +

These are in-progress notes for the upcoming LLVM 3.2 release. You may prefer the -LLVM 3.0 +LLVM 3.1 Release Notes.

@@ -94,23 +94,15 @@ Release Notes.

- External Open Source Projects Using LLVM 3.1 + External Open Source Projects Using LLVM 3.2

Crack

FAUST

- What's New in LLVM 3.1? + What's New in LLVM 3.2?

Basic Block Placement

ARM Integrated Assembler

-PTX Target Improvements -

These are in-progress notes for the upcoming LLVM 3.2 release.
You may prefer the -LLVM 3.0 +LLVM 3.1 Release Notes.