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@ -62,10 +62,9 @@ href="http://llvm.cs.uiuc.edu/releases/">releases page</a>.</p>
<p>This is the sixth public release of the LLVM Compiler Infrastructure.</p>
<p> At this time, LLVM is known to correctly compile a wide range of C and C++
programs, including the SPEC CPU95 &amp; 2000 suite. It includes bug fixes for
those problems found since the 1.4 release and a large number of new features
and enhancements, described below.</p>
<p>LLVM 1.5 is known to correctly compile a wide range of C and C++ programs,
includes bug fixes for those problems found since the 1.4 release, and includes
a large number of new features and enhancements, described below.</p>
</div>
@ -101,7 +100,7 @@ easy to get wrong) details of writing the instruction selector, such as
generating efficient code for <a
href="LangRef.html#i_getelementptr">getelementptr</a> instructions, promoting
small integer types to larger types (e.g. for RISC targets with one size of
integer registers), expanding 64-bit integer operations for 32-bit hosts, etc.
integer registers), expanding 64-bit integer operations for 32-bit targets, etc.
Currently, the X86, PowerPC, Alpha, and IA-64 backends use this framework. The
SPARC backends will be migrated when time permits.
</p>
@ -138,7 +137,7 @@ Proper Tail Calls</a></div>
href="http://doi.acm.org/10.1145/277650.277719">proper tail calls</a>, as
required to implement languages like Scheme. Tail calls make use of two
features: custom calling conventions (described above), which allow the code
generator to emit code for the caller to deallocate its own stack when it
generator to use a convention where the caller deallocates its stack before it
returns. The second feature is a flag on the <a href="LangRef.html#i_call">call
instruction</a>, which indicates that the callee does not access the caller's
stack frame (indicating that it is acceptable to deallocate the caller stack
@ -149,11 +148,11 @@ than the caller, etc. The only case not supported are varargs calls, but that
could be added if desired.
</p>
<p>In order for a front-end to get guaranteed tail call, it must mark functions
as "fastcc", mark calls with the 'tail' marker, and follow the call with a
return of the called value (or void). The optimizer and code generator attempt
to handle more general cases, but the simple case will always work if the code
generator supports tail calls. Here is a simple example:</p>
<p>In order for a front-end to get a guaranteed tail call, it must mark
functions as "fastcc", mark calls with the 'tail' marker, and follow the call
with a return of the called value (or void). The optimizer and code generator
attempt to handle more general cases, but the simple case will always work if
the code generator supports tail calls. Here is an example:</p>
<pre>
fastcc int %bar(int %X, int(double, int)* %FP) { ;<i> fastcc</i>
@ -198,7 +197,8 @@ multiple of 8 bytes in size.
<li>LLVM 1.5 is now about 15% faster than LLVM 1.4 and its core data
structures use about 30% less memory.</li>
<li>Support for Microsoft Visual Studio is improved, and <a
href="GettingStartedVS.html">now documented</a>.</li>
href="GettingStartedVS.html">now documented</a>. Most LLVM tools build
natively with Visual C++ now.</li>
<li><a href="GettingStarted.html#config">Configuring LLVM to build a subset
of the available targets</a> is now implemented, via the
<tt>--enable-targets=</tt> option.</li>
@ -215,7 +215,13 @@ multiple of 8 bytes in size.
<li>LLVM now includes workarounds in the code generator generator which
reduces the likelyhood of <a href="http://llvm.cs.uiuc.edu/PR448">GCC
hitting swap during optimized builds</a>.</li>
<li>The PowerPC backend generates far better code than in LLVM 1.4.</li>
<li>The <a href="http://llvm.cs.uiuc.edu/ProjectsWithLLVM/#llvmtv">LLVM
Transformation Visualizer</a> (llvm-tv) project has been updated to
work with LLVM CVS.</li>
<li>Nightly tester output is now archived on the <a
href="http://mail.cs.uiuc.edu/pipermail/llvm-testresults/">
llvm-testresults</a> mailing list.</li>
</ol>
</div>
@ -226,31 +232,62 @@ multiple of 8 bytes in size.
<div class="doc_text">
<ol>
<li>The -globalopt pass now promotes non-address-taken static globals that are
only accessed in main to SSA registers.</li>
<li>The new -simplify-libcalls pass improves code generated for well-known
library calls. The pass optimizes calls to many of the string, memory, and
standard I/O functions (e.g. replace the calls with simpler/faster calls) when
possible, given information known statically about the arguments to the call.
</li>
<li>The -globalopt pass now promotes non-address-taken static globals that are
only accessed in main to SSA registers.</li>
<li>Loops with trip counts based on array pointer comparisons (e.g. "<tt>for (i
= 0; &amp;A[i] != &amp;A[100]; ++i) ...</tt>") are optimized better than before,
= 0; &amp;A[i] != &amp;A[n]; ++i) ...</tt>") are optimized better than before,
which primarily helps iterator-intensive C++ codes.</li>
<li>The code generator now can provide and use information about commutative
two-address instructions when performing register allocation.</li>
<li>The optimizer now eliminates simple cases where redundant conditions exist
between neighboring blocks.</li>
between neighboring blocks.</li>
<li>The reassociation pass (which turns (1+X+3) into (X+1+3) among other
things), is more aggressive an intelligent.</li>
things), is more aggressive and intelligent.</li>
<li>The -prune-eh pass now detects no-return functions in addition to the
no-unwind functions it did before.</li>
<li>The -globalsmodref alias analysis generates more precise results in some
cases.</li>
</ol>
</div>
<!--=========================================================================-->
<div class="doc_subsection">
<a name="codequality">Code Generator Improvements in LLVM 1.5</a>
</div>
<div class="doc_text">
<ol>
<li>The code generator now can provide and use information about commutative
two-address instructions when performing register allocation.</li>
<li>The code generator now tracks function live-in registers explicitly,
instead of requiring the target to generate 'implicit defs' at the
entry to a function.</li>
<li>The code generator can lower integer division by a constant to
multiplication by a magic constant and multiplication by a constant into
shift/add sequences.</li>
<li>The code generator compiles fabs/fneg/sin/cos/sqrt to assembly instructions
when possible.</li>
<li>The PowerPC backend generates better code in many cases, making use of
FMA instructions and the recording ("dot") forms of various PowerPC
instructions.</li>
</ol>
</div>
<!--=========================================================================-->
<div class="doc_subsection">
<a name="bugfix">Significant Bugs Fixed in LLVM 1.5</a>
@ -266,7 +303,7 @@ things), is more aggressive an intelligent.</li>
<li><a href="http://llvm.cs.uiuc.edu/PR548">[instcombine] miscompilation of
setcc or setcc in one case</a></li>
<li>Transition code for LLVM 1.0 style varargs was removed from the .ll file
parser. LLVM 1.0 bytecode files are still supported. </li>
parser. LLVM 1.0 bytecode files are still supported. </li>
</ol>
<p>Code Generator Bugs:</p>
@ -277,6 +314,7 @@ things), is more aggressive an intelligent.</li>
respect 'volatile'</a>.</li>
<li>The JIT sometimes miscompiled globals and constant pool entries for
64-bit integer constants on 32-bit hosts.</li>
<li>The C backend should no longer produce code that crashes ICC 8.1.</li>
</ol>
<p>Bugs in the C/C++ front-end:</p>