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add some more notes
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@27822 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -87,7 +87,8 @@ bug</a>. In addition, llvm-gcc4 implements support for many new features,
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including GCC inline assembly, generic vector support, SSE and Altivec
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intrinsics, and several new GCC attributes. In addition, llvm-gcc4 is
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significantly faster than llvm-gcc3, respects -O options, its -c/-S options
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correspond to GCC's (they emit native code).</p>
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correspond to GCC's (they emit native code), and it has debugging support well
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underway.</p>
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<p>If you can use it, llvm-gcc4 is offers significant new functionality, and we
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hope that it will replace llvm-gcc3 completely in a future release.
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@ -172,7 +173,7 @@ are used.
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</div>
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<!--_________________________________________________________________________-->
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<div class="doc_subsubsection"><a name="othernew">Optimizer
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<div class="doc_subsubsection"><a name="optimizernew">Optimizer
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Improvements</a></div>
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<div class="doc_text">
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@ -187,23 +188,56 @@ Improvements</a></div>
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bits are demanded or not.</li>
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<li>The Scalar Replacement of Aggregates pass (<tt>-scalarrepl</tt>) can now
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promote simple unions to registers.</li>
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<li>The Reassociation pass (<tt>-reassociate</tt>) can now
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factor expressions, e.g. turning "A*A+A*B" into "A*(A+B)".</li>
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<li>Several LLVM passes are <a href="http://llvm.org/PR681">significantly
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faster</a>.</li>
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</ul>
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</div>
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<!--_________________________________________________________________________-->
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<div class="doc_subsubsection"><a name="codgennew">Code Generator
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Improvements</a></div>
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<div class="doc_text">
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<ul>
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<li>LLVM has a new prepass (before register allocation) list scheduler, which
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supports bottom-up and top-down scheduling, pluggable priority functions and
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pluggable hazard recognizers. The X86 backend uses this to reduce register
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pressure and RISC targets schedule based on operation latency.</li>
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<li>The tblgen-based target description framework introduced in LLVM 1.6 has
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several new features, useful for targets that can fold loads and stores into
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operations, and features that make the .td files more expressive.</li>
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<li>The instruction selector is significantly faster in 1.7 than in 1.6.</li>
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<li>The X86, Alpha and Itanium backends use new DAG-DAG instruction selectors,
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making them easier to maintain and generate slightly better code.</li>
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<li>The X86 backend now supports generation of Scalar SSE code for scalar FP
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expressions. LLVM provides significantly better performance with Scalar SSE
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instructions than it does with the Intel floating point stack
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instructions.</li>
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<li>The Itanium backend now has a bundling pass, which improves performance
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by ~10% and reduces code size (previously it unconditionally inserted a stop
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bit after every instruction).</li>
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</ul>
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</div>
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<!--_________________________________________________________________________-->
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<div class="doc_subsubsection"><a name="othernew">Other New Features</a></div>
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<div class="doc_text">
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<ul>
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<li>The Mac OS/X PowerPC and X86 backends now have initial support Darwin DWARF
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debugging information, however, debug info generation has been disabled for
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the 1.7 release in llvmgcc4.</li>
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<li>LLVM includes the new <a href="docs/CommandGuide/html/llvm-config.html">
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llvm-config</a> utility, which makes it easier to build and link programs
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against the LLVM libraries when not using the LLVM makefiles.</li>
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<li>LLVM now supports first class global ctor/dtor initialization lists, no
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longer forcing targets to use "__main".</li>
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<li>LLVM supports assigning globals and functions to a particular section
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in the result executable using the GCC section attribute.</li>
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<li><a href="ExtendingLLVM.html">Adding intrinsics to LLVM</a> is now
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significantly easier.</li>
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significantly easier.</li>
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<li>llvmgcc4 now fully supports C99 Variable Length Arrays, including dynamic
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stack deallocation.</li>
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@ -218,6 +252,8 @@ significantly easier.</li>
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<div class="doc_text">
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<ul>
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<li>The official LLVM URL is now <a href="http://llvm.org/">
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http://llvm.org/</a>.</li>
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<li>The LLVM intrinsics used to be overloaded based on type: for example,
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<a href="LangRef.html#int_ctpop"><tt>llvm.ctpop</tt></a> could work with any
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integer datatype. They are now separated into different intrinsics with
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