more updates.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@57466 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2008-10-13 20:59:32 +00:00
parent 7b8e96401c
commit 7752d1ac04

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@ -193,12 +193,13 @@ front-ends and driver with the LLVM optimizer and code generator. It currently
includes support for the C, C++, Objective-C, Ada, and Fortran front-ends.</p>
<ul>
<li>LLVM 2.4 supports the full set of atomic __sync builtins. LLVM 2.3 only
supported those used by OpenMP, but 2.4 supports them all. Not all targets
support all builtins, but X86 and PowerPC do.</li>
<li>LLVM 2.4 supports the full set of atomic <tt>__sync_*</tt> builtins. LLVM
2.3 only supported those used by OpenMP, but 2.4 supports them all. While
llvm-gcc supports all of these builtins, note that not all targets do. X86 and
PowerPC are known to support them all in both 32-bit and 64-bit mode.</li>
<li>llvm-gcc now supports an -flimited-precision option, which tells the
compiler that it is ok to use low-precision approximations of certain libm
<li>llvm-gcc now supports an <tt>-flimited-precision</tt> option, which tells
the compiler that it is ok to use low-precision approximations of certain libm
functions (like tan, log, etc). This allows you to get high performance if you
only need (say) 14-bits of precision.</li>
@ -229,15 +230,39 @@ Previously, LTO could only be used with -O4, which implied optimizations in
</p>
<ul>
<li>vector shifts in the IR: no codegen support yet</li>
<li>use diet patch landed: saved 15% IR memory footprint</li>
<li>A major change to the "Use" class landed, which shrank it by 25%. Since
this is a pervasive part of the LLVM, it ended up reducing the memory use of
LLVM IR in general by 15% for most programs.</li>
<li>Values with no names are now pretty printed by <tt>llvm-dis</tt> more
nicely. They now print as "<tt>%3 = add i32 %A, 4</tt>" instead of
"<tt>add i32 %A, 4 ; &lt;i32&gt;:3</tt>", which makes it much easier to read.
</li>
<li>LLVM 2.4 includes some changes for better vector support. First, the shift
operations (<tt>shl</tt>, <tt>ashr</tt>, <tt>lshr</tt>) now all support vectors
and do an element-by-element shift (shifts of the whole vector can be
accomplished by bitcasting the vector to &lt;1 x i128&gt; for example). Second,
there is support in development for vector comparisons. LLVM 2.4 actually
supports two ways to do vector comparisons: the vicmp/vfcmp instructions and the
icmp/fcmp instructions. The vicmp/vfcmp instructions are temporary and will be
removed (do not use them). The icmp/fcmp instructions compare two vectors and
return a vector of i1's for each result. Note that there is very little codegen
support available for any of these IR features though.</li>
<li>A new <tt>DebugInfoBuilder</tt> class is available, which makes it much
easier for front-ends to create debug info descriptors, similar to the way that
IRBuilder makes it easier to create LLVM IR.</li>
<li>LLVM now supports "function attributes", which allows us to seperate return
value attributes from function attributes. LLVM now supports attributes on a
function itself, a return value, and its parameters. New supported function
attributes include noinline/alwaysinline and the "opt-size" flag which says the
function should be optimized for code size.</li>
<li>LLVM IR now directly represents "common" linkage, instead of
representing it as a form of weak linkage.</li>
<li>DebugInfoBuilder</li>
<li>.ll printing format change: %3 = add i32 4, 2</li>
<li>opt-size, noinline, alwaysinline function attributes</li>
<li>Attrs: function, return, param.</p></li>
<li>...</li>
</ul>
</div>