LLVM 1.9 Release Notes

This document contains the release notes for the LLVM compiler -infrastructure, release 1.9. Here we describe the status of LLVM, including any -known problems and major improvements from the previous release. The most -up-to-date version of this document (corresponding to LLVM CVS) can be found -on the LLVM releases web site. If you are -not reading this on the LLVM web pages, you should probably go there because -this document may be updated after the release.

+infrastructure, release 2.0. Here we describe the status of LLVM, including any +known problems and major improvements from the previous release. 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 @@ -61,8 +58,18 @@ href="http://llvm.org/releases/">releases page.

This is the tenth public release of the LLVM Compiler Infrastructure. This -release incorporates a large number of enhancements, new features, and bug +

This is the eleventh public release of the LLVM Compiler Infrastructure. +Being the first major release since 1.0, we took this as an opportunity to +break backwards compatibility with the LLVM 1.x bytecode and .ll file format. +If you have LLVM 1.9 .ll files that you would like to upgrade to LLVM 2.x, we +recommend the use of the stand alone llvm-upgrade +tool. We intend to keep compatibility with .ll and .bc formats within the 2.x +release series.

+ +

Note that while + This +release +incorporates a large number of enhancements, new features, and bug fixes. We recommend that all users of previous LLVM versions upgrade.

@@ -70,37 +77,7 @@ fixes. We recommend that all users of previous LLVM versions upgrade.

-New Features in LLVM 1.9 -

- - -

New X86-64 Backend

LLVM 1.9 now fully supports the x86-64 instruction set on Mac OS/X, and -supports it on Linux (and other operating systems) when compiling in -static -mode. LLVM includes JIT support for X86-64, and supports both Intel EMT-64T -and AMD-64 architectures. The X86-64 instruction set permits addressing a -64-bit addressing space and provides the compiler with twice the -number of integer registers to use.

- - -

Link-Time Optimization integration -with native linkers

LLVM now includes liblto which can -be used to integrate LLVM Link-Time Optimization support into a native linker. -This allows LLVM .bc to transparently participate with linking an application, -even when some .o files are in LLVM form and some are not.

- - -

DWARF debugging -support for Linux, Cygwin and MinGW on X86

llvm-gcc4 now supports generating debugging info for Linux, Cygwin and MinGW. -This extends the PPC/Darwin and X86/Darwin debugging support available in the -1.8 release. DWARF is a standard debugging format used on many platforms.

+New Features in LLVM 2.0

@@ -111,17 +88,7 @@ Improvements

Significant changes include:

LLVM includes a new 'predicate simplifier' pass, which - currently performs dominator tree-based optimizations.
The complete loop unroll pass now supports unrolling of - multiple basic block loops.
The 'globalopt' pass can now perform the scalar replacement of - aggregates transformation on some heap allocations.
The globalsmodref-aa alias analysis can now track 'indirect pointer - globals' more accurately.
The instruction combiner can now perform element propagation -analysis of vector expressions, eliminating computation of vector elements -that are not used.

In addition, the LLVM target description format has itself been extended in several ways:

Further, several significant target-specific enhancements are included in -LLVM 1.9:

This release includes many other improvements, including improvements to - the optimizers and code generators (improving the generated code) changes to - speed up the compiler in many ways (improving algorithms and fine tuning - code), and changes to reduce the code size of the compiler itself.

More specific changes include:

The llvm-test framework now supports SPEC2006.
LLVM now includes a FAQ about the -getelementptr instruction.
Bugpoint now supports a new "-find-bugs" mode. This mode makes - bugpoint permute pass sequences to try to expose bugs due to pass - sequencing.
The JIT now supports lazily streaming code from multiple modules at a - time, implicitly linking the code as it goes.

- -

Several significant API changes have been made. If you are maintaining -out-of-tree code, please be aware that:

- -

The ConstantSInt and ConstantUInt classes have been merged into the - ConstantInt class.
As a step towards making LLVM's integer types signless, several new -instructions have been added to LLVM. The Div instruction is now -UDiv, SDiv, and FDiv. The Rem instruction -is now URem, SRem and FRem. See the -Language Reference for details on these new -instructions.
-
ConstantBool::True and ConstantBool::False have been - renamed to ConstantBool::getTrue() and - ConstantBool::getFalse().
The 'analyze' tool has been merged into the 'opt' tool.