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Merged in both release announcement guts.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@37131 91177308-0d34-0410-b5e6-96231b3b80d8
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Tanya Lattner 2007-05-16 23:25:46 +00:00
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@ -96,8 +96,58 @@ release series, like we did within the 1.x series.</li>
</p>
<ul>
<li>ding dong llvm-gcc3 is dead</li>
<li>bytecode -> bitcode</li>
<li>llvm-gcc3 is now officially unsupported. Users are required to
upgrade to llvm-gcc4. llvm-gcc4 includes many features over
llvm-gcc3, is faster, and is much easier to build.</li>
<li>Integer types are now completely signless. This means that we
have types like i8/i16/i32 instead of ubyte/sbyte/short/ushort/int
etc. LLVM operations that depend on sign have been split up into
separate instructions (<a href="http://llvm.org/PR950">PR950</a>).</li>
<li>Arbitrary bitwidth integers (e.g. i13, i36, i42, etc) are now
supported in the LLVM IR and optimizations. However, neither llvm-gcc nor
the native code generators support non-standard width integers
(<a href="http://llvm.org/PR1043">PR1043</a>).</li>
<li>'type planes' have been removed (<a href="http://llvm.org/PR411">PR411</a>).
It is no longer possible to have two values with the same name in the
same symbol table. This simplifies LLVM internals, allowing significant
speedups.</li>
<li>Global variables and functions in .ll files are now prefixed with
@ instead of % (<a href="http://llvm.org/PR645">PR645</a>).</li>
<li>The LLVM 1.x "bytecode" format has been replaced with a
completely new binary representation, named 'bitcode'. Because we
plan to maintain binary compatibility between LLVM 2.x ".bc" files,
this is an important change to get right. Bitcode brings a number of
advantages to the LLVM over the old bytecode format. It is denser
(files are smaller), more extensible, requires less memory to read,
is easier to keep backwards compatible (so LLVM 2.5 will read 2.0 .bc
files), and has many other nice features.</li>
<li>Support was added for alignment values on load and store
instructions (<a href="http://www.llvm.org/PR400">PR400</a>). This
allows the IR to express loads that are not
sufficiently aligned (e.g. due to pragma packed) or to capture extra
alignment information. </li>
<li>LLVM now has a new MSIL backend. llc - march=msil will now turn LLVM
into MSIL (".net") bytecode. This is still fairly early development
with a number of limitations.</li>
<li>Support has been added for 'protected visibility' in ELF.</li>
<li>Thread Local Storage with the __thread keyword was implemented along
with added codegen support for Linux on X86 and ARM.</li>
<li>ELF symbol aliases supported has been added.</li>
<li>Added support for 'polymorphic intrinsics', allowing things like
llvm.ctpop to work on arbitrary width integers.</li>
</ul>
</div>
@ -111,8 +161,30 @@ Improvements</a></div>
</p>
<ul>
<li>many new supported things</li>
<li>easier to configure on linux</li>
<li>Precompiled Headers (PCH) support has been implemented.</li>
<li>Support for external weak linkage and hidden visibility has been added.</li>
<li>Packed structure types are now supported , which allows LLVM to express
unaligned data more naturally.</li>
<li>Inline assembly support has been improved and many bugs were fixed.
The two large missing features are support for 80-bit floating point stack
registers on X86 (<a href="http://llvm.org/PR879">PR879</a>), and support for inline asm in the C backend (<a href="http://llvm.org/PR802">PR802</a>).</li>
<li>Ada support, such as nested functions, has been improved.</li>
<li>Tracking function parameter/result attributes is now possible.</li>
<li>Its is now easier to configure llvm-gcc for linux.</li>
<li>Many enhancements have been added, such as improvements to NON_LVALUE_EXPR,
arrays with non-zero base, structs with variable sized fields,
VIEW_CONVERT_EXPR, CEIL_DIV_EXPR, and many other things.</li>
<li>Improved "attribute packed" support in the CFE, and handle many
other obscure struct layout cases correctly.</li>
</ul>
</div>
@ -125,7 +197,29 @@ Improvements</a></div>
</p>
<ul>
<li></li>
<li>The pass manager has been entirely rewritten, making it significantly
smaller, simpler, and more extensible. Support has been added to run
FunctionPasses interlaced with CallGraphSCCPasses.</li>
<li>The -scalarrepl pass can now promote unions containing FP values into
a register, it can also handle unions of vectors of the same size.</li>
<li>The predicate simplifier pass has been improved, making it able to do
simple value range propagation and eliminate more conditionals.</li>
<li>There is a new new LoopPass class. The passmanager has been
modified to support it, and all existing loop xforms have been
converted to use it. </li>
<li>There is a new loop rotation pass, which converts "for loops" into
"do/while loops", where the condition is at the bottom of the loop.</li>
<li>ModulePasses may now use the result of FunctionPasses.</li>
<li>The [Post]DominatorSet classes have been removed from LLVM and clients switched to use the far-more-efficient ETForest class instead. </li>
<li>The ImmediateDominator class has also been removed, and clients have been switched to use DominatorTree instead.</li>
</ul>
</div>
@ -140,14 +234,64 @@ New features include:
</p>
<ul>
<li></li>
<li>Support for Zero-cost DWARF exception handling has been added. It is mostly
complete and just in need of continued bug fixes and optimizations at
this point.</li>
<li>Progress has been made on a direct Mach-o .o file writer. Many small
apps work, but it is not quite complete yet.</li>
<li>Support was added for software floating point routines.</li>
<li>DWARF debug information generation has been improved. LLVM now passes
most of the GDB testsuite on MacOS and debug info is more dense.</li>
<li>A new register scavenger has been implemented, which is useful for
finding free registers after register allocation. This is useful when
rewriting frame references on RISC targets, for example.</li>
<li>Heuristics have been added to avoid coalescing vregs with very large live
ranges to physregs.</li>
<li>Support now exists for very simple (but still very useful)
rematerialization the register allocator, enough to move
instructions like "load immediate" and constant pool loads.</li>
<li>Significantly improved 'switch' lowering, improving codegen for
sparse switches that have dense subregions, and implemented support
for the shift/and trick.</li>
<li>The code generator now has more accurate and general hooks for
describing addressing modes ("isLegalAddressingMode") to
optimizations like loop strength reduction and code sinking.</li>
<li>The Loop Strength Reduction pass has been improved, and support added
for sinking expressions across blocks to reduce register pressure.</li>
<li>Added support for tracking physreg sub-registers and super-registers
in the code generator, as well as extensive register
allocator changes to track them.</li>
<li>There is initial support for virtreg sub-registers
(<a href="http://llvm.org/PR1350">PR1350</a>).</li>
</ul>
<p>In addition, the LLVM target description format has itself been extended in
several ways:</p>
<ul>
<li></li>
<li>Extended TargetData to support better target parameterization in
the .ll/.bc files, eliminating the 'pointersize/endianness' attributes
in the files (<a href="http://llvm.org/PR761">PR761</a>).</li>
<li>TargetData was generalized for finer grained alignment handling,
handling of vector alignment, and handling of preferred alignment</li>
<li>LLVM now supports describing target calling conventions
explicitly in .td files, reducing the amount of C++ code that needs
to be written for a port.</li>
</ul>
<p>Further, several significant target-specific enhancements are included in
@ -165,25 +309,110 @@ Improvements</a></div>
<div class="doc_text">
<p>New features include:
<p>X86-Specific Code Generator Enhancements:
</p>
<ul>
<li></li>
<li>The scheduler was improved to better reduce register pressure on
X86 and other targets that are register pressure sensitive</li>
<li>Linux/x86-64 support has been improved.</li>
<li>PIC support for linux/x86 has been added.</li>
<li>Support now exists for the GCC regparm attribute, and code in the X86
backend to respect it.</li>
<li>Various improvements have been made for the X86-64 JIT, allowing it to
generate code in the large code model</li>
<li>LLVM now supports inline asm with multiple constraint letters per operand
(like "ri") which is common in X86 inline asms.</li>
<li>Early support has been added for X86 inline asm in the C backend.</li>
<li>Added support for the X86 MMX instruction set.</li>
</ul>
<p>ARM-Specific Code Generator Enhancements:
</p>
<ul>
<li>Several improvements have been made to the ARM backend, including basic
inline asm support, weak linkage support, static ctor/dtor support and
many bug fixes.</li>
<li>There are major enhancements to the ARM backend, including support for ARM
v4-v6, vfp support, soft float, pre/postinc support, load/store multiple
generation, constant pool entry motion (to support large functions),
and enhancements to ARM constant island pass.
</li>
<li>Added support for Thumb code generation (an ARM subtarget).</li>
<li>More aggressive size analysis for ARM inline asm strings was
implemented.</li>
</ul>
</div>
<p>Other Target-Specific Code Generator Enhancements:
</p>
<ul>
<li>The PowerPC 64 JIT now supports addressing code loaded above the 2G
boundary.</li>
<li>Improved support for the Linux/ppc ABI and the linux/ppc JIT is fully
functional now. llvm-gcc and static compilation are not fully supported
yet though.<</li>
<li>Many bugs fixed for PowerPC 64.</li>
<li>Support was added for the ARM AAPCS and EABI ABIs and PIC codegen on
arm/linux.</li>
<li>Several bugs in DWARF debug emission on linux and cygwin/mingw were fixed.
Debugging basically works on these targets now.</li>
<li>Support has been added for the X86-64 large code model to the JIT,
which is useful if JIT'd function bodies are more than 2G away from
library functions.</li>
<li>Several bugs were fixed for DWARF debug info generation on arm/linux.</li>
</ul>
</div>
<!--_________________________________________________________________________-->
<div class="doc_subsubsection"><a name="other">Other Improvements</a></div>
<div class="doc_text">
<p></p>
<p>This release includes many other improvements, including
performance work, specifically designed to tune datastructure
usage. This makes several critical components faster.</p>
<p>More specific changes include:</p>
<ul>
<li></li>
<li>ConstantBool, ConstantIntegral and ConstantInt classes have been merged
together, we now just have ConstantInt</li>
<li>LLVM no longer relies on static destructors to shut itself down. Instead,
it lazily initializes itself and shuts down when llvm_shutdown() is
explicitly called.</li>
<li>LLVM now has significantly fewer static constructors, reducing startup time.
</li>
<li>Several classes have been refactored to reduce the amount of code that
gets linked into apps that use the JIT.</li>
<li>Construction of intrinsic function declarations has been simplified.</li>
<li>The llvm-upgrade tool now exists. This migrates LLVM 1.9 .ll files to
LLVM 2.0 syntax.</li>
<li>The gccas/gccld tools have been removed.</li>
<li>Support has been added to llvm-test for running on low-memory
or slow machines (make SMALL_PROBLEM_SIZE=1).</li>
<li>llvm-test is now more portable and should build with MS Visual Studio.</li>
</ul>
</div>