diff options
Diffstat (limited to 'llvm')
| -rw-r--r-- | llvm/docs/ReleaseNotes.html | 418 |
1 files changed, 222 insertions, 196 deletions
diff --git a/llvm/docs/ReleaseNotes.html b/llvm/docs/ReleaseNotes.html index 7568575d9be..d756fb3576e 100644 --- a/llvm/docs/ReleaseNotes.html +++ b/llvm/docs/ReleaseNotes.html @@ -743,210 +743,54 @@ be used to verify some algorithms. loop dependence analysis CorrelatedValuePropagation lib/Transforms/IPO/MergeFunctions.cpp => consider for 3.1. - --> + Integrated assembler on by default for arm/thumb? -<p><b>llvm-gcc is gone</b>. LLVM's configure script doesn't depend on llvm-gcc anymore, clean layering.</p> + --> -<p>LLVM 3.0 includes several major new capabilities:</p> - -<!-- Near dead: + <!-- Near dead: Analysis/RegionInfo.h + Dom Frontiers SparseBitVector: used in LiveVar. llvm/lib/Archive - replace with lib object? - --> - -<!-- - Type system rewrite: http://blog.llvm.org/2011/11/llvm-30-type-system-rewrite.html - Better performance for Neon code in clang due to SRoA improvements. - New regalloc on by default. Lin scan going away in 3.1 - PGO / builtin_expect improvements (summary needed) - Big EH rewrite. - AVX support, assembler, compiler and disassembler. - IndVar improvements: andy - PTX backend improvements: Justin - llvm-rtdyld & MC JIT: JimG - InstAliases now automatically used in the asmprinter where they are shorter. - Integrated assembler on by default for arm/thumb? - PostOrder Dominator frontiers were removed. - Line Profiling / gcov support - EH and debug information produced with CFI directives, yielding smaller executables: http://blog.mozilla.com/respindola/2011/05/12/cfi-directives/ - X86-64 generates smaller and faster code at -O0 (fast isel improvements) - Better code generation for Cortex-A9 - Many APIs take ArrayRef's now. - Pass manager extension API. - ARM inline asm constraints implemented. - LangRef.html#fnattrs uwtable attribute for asynch unwind tables. - better performance for indirect gotos. - llvm.prefetch now takes a 4th argument that specifies whether the prefetch happens to the icache or dcache. - New PackedVector, TinyPtrVector class (see Programmer's Manual) - New nonlazybind function attribute. - ARC language specific optimizer (Transforms/ObjCARC) a decent example of language-specific transformation. - LLVM 3.0 removes support for reading LLVM 2.8 and earlier files. Aim to maintain compatibility all the way back to 3.0 "forever". - - New llvm.expect intrinsic. - Table generated MC expansion logic for pseudo instructions that expand to multiple MC instructions through the PseudoInstExpansion class. (JimG) - New llvm.fma intrinsic. - - Euro dev meeting and main one too. - New atomics instructions, "#i_fence" instruction, cmpxchg, atomicrmw too. What target support (X86/ARM)? Also 'atomic load/store'. See Atomics.html - X86: inline assembler supports .code32 and .code64. - Exception handling rewrite: new landingpad and resume instruction. Unwind gone. - LowerSetJmp pass removed, unused. - llvm-objdump / dwarf parser library / llvm-dwarfdump (d0k) - object file parsing stuff and llvm-size (mspencer) - llvm-cov (devang) - Old arm disassembler replaced with a new one based on autogenerated encoding information from ARM .td files. - Frontend tests removed from llvm/test/Frontend* (was this completed for 3.0?) - Segmented stack support (X86 only?) Rafael and Sanjoy Das: docs/SegmentedStacks.html should be in CodeGen.html status table? - X86 backend support for NaCl (David Meyer / Nick L) - Codegen now supports vector "select" operations on vector comparisons, turning - them into various optimized code sequences (e.g. using the SSE4/AVX "blend" - instructions). - #line directives in integrated assembler - SSE domain fixing code enabled for AVX (Bruno/Jakob). Domain fixing pass is - now target independent (ExecutionDepsFix pass). (Jakob) - X86 backend synthesizes horizontal add/sub instructions from generic code. - returns_twice attribute (rafael) - Tablegen has been split into a library, clang tblgen pieces now live in clang. - The llvm version is now named llvm-tblgen instead of tblgen. - X86: Tons of encoding improvements and new instructions (e.g. Atom, Ivy Bridge, - and BMI instructions) - added to assembler and disassembler (Craig Topper) - data layout string can encode the natural alignment of the target's stack for better optimization (LangRef.html#datalayout) - --> - -<ul> - -<!-- -<li></li> ---> - -</ul> - -</div> + --> -<!--=========================================================================--> - -<!-- EH details: to be moved to a blog post: - +<p>LLVM 3.0 includes several major changes:</p> +<ul> +<li>llvm-gcc is no longer supported, and not included in the release. We + recommend switching to <a + href="http://clang.llvm.org/">Clang</a> or <a + href="http://dragonegg.llvm.org/">DragonEgg</a>.</li> + +<li>The linear scan register allocator has been replaced with a new "greedy" + register allocator, enabling live range splitting and many other + optimizations that lead to better code quality. Please see its <a + href="http://blog.llvm.org/2011/09/greedy-register-allocation-in-llvm-30.html">blog post</a> or its talk at the <a + href="http://llvm.org/devmtg/2011-11/">Developer Meeting</a> + for more information.</li> +<li> New <a href="Atomics.html">atomics</a> instructions, "#i_fence" instruction, cmpxchg, atomicrmw too. What target support (X86/ARM)? Also 'atomic load/store'. +</li> +<li>The LLVM IR exception handling representation has been redesigned and + reimplemented, making it more elegant, fixing a huge number of bugs, and + enabling inlining and other optimizations. Please see its blog post (XXX + not yet) for more information.</li> +<li>The LLVM IR Type system has been redesigned and reimplemented, making it + faster and solving some long-standing problems. + Please see its <a + href="http://blog.llvm.org/2011/11/llvm-30-type-system-rewrite.html">blog + post</a> for more information.</li> +<li>The MIPS backend has made major leaps in this release, going from an + experimental target to being virtually production quality that supports a + wide variety of MIPS subtargets. See the <a href="#MIPS">MIPS section</a> + below for more information.</li> -<p>One of the biggest changes is that 3.0 has a new exception handling - system. The old system used LLVM intrinsics to convey the exception handling - information to the code generator. It worked in most cases, but not - all. Inlining was especially difficult to get right. Also, the intrinsics - could be moved away from the <code>invoke</code> instruction, making it hard - to recover that information.</p> - -<p>The new EH system makes exception handling a first-class member of the IR. It - adds two new instructions:</p> - -<ul> - <li><a href="LangRef.html#i_landingpad"><code>landingpad</code></a> — - this instruction defines a landing pad basic block. It contains all of the - information that's needed by the code generator. It's also required to be - the first non-PHI instruction in the landing pad. In addition, a landing - pad may be jumped to only by the unwind edge of an <code>invoke</code> - instruction.</li> - - <li><a href="LangRef.html#i_resume"><code>resume</code></a> — this - instruction causes the current exception to resume traveling up the - stack. It replaces the <code>@llvm.eh.resume</code> intrinsic.</li> +<li>The optimizer and code generator now supports gprof and gcov-style coverage + and profiling information, and includes a new llvm-cov tool. Clang exposes + this through GCC-compatible command line options.</li> </ul> -<p>Converting from the old EH API to the new EH API is rather simple, because a - lot of complexity has been removed. The two intrinsics, - <code>@llvm.eh.exception</code> and <code>@llvm.eh.selector</code> have been - superseded by the <code>landingpad</code> instruction. Instead of generating - a call to <code>@llvm.eh.exception</code> and <code>@llvm.eh.selector</code>: - -<div class="doc_code"> -<pre> -Function *ExcIntr = Intrinsic::getDeclaration(TheModule, - Intrinsic::eh_exception); -Function *SlctrIntr = Intrinsic::getDeclaration(TheModule, - Intrinsic::eh_selector); - -// The exception pointer. -Value *ExnPtr = Builder.CreateCall(ExcIntr, "exc_ptr"); - -std::vector<Value*> Args; -Args.push_back(ExnPtr); -Args.push_back(Builder.CreateBitCast(Personality, - Type::getInt8PtrTy(Context))); - -<i>// Add selector clauses to Args.</i> - -// The selector call. -Builder.CreateCall(SlctrIntr, Args, "exc_sel"); -</pre> -</div> - -<p>You should instead generate a <code>landingpad</code> instruction, that - returns an exception object and selector value:</p> - -<div class="doc_code"> -<pre> -LandingPadInst *LPadInst = - Builder.CreateLandingPad(StructType::get(Int8PtrTy, Int32Ty, NULL), - Personality, 0); - -Value *LPadExn = Builder.CreateExtractValue(LPadInst, 0); -Builder.CreateStore(LPadExn, getExceptionSlot()); - -Value *LPadSel = Builder.CreateExtractValue(LPadInst, 1); -Builder.CreateStore(LPadSel, getEHSelectorSlot()); -</pre> </div> -<p>It's now trivial to add the individual clauses to the <code>landingpad</code> - instruction.</p> - -<div class="doc_code"> -<pre> -<i><b>// Adding a catch clause</b></i> -Constant *TypeInfo = getTypeInfo(); -LPadInst->addClause(TypeInfo); - -<i><b>// Adding a C++ catch-all</b></i> -LPadInst->addClause(Constant::getNullValue(Builder.getInt8PtrTy())); - -<i><b>// Adding a cleanup</b></i> -LPadInst->setCleanup(true); - -<i><b>// Adding a filter clause</b></i> -std::vector<Constant*> TypeInfos; -Constant *TypeInfo = getFilterTypeInfo(); -TypeInfos.push_back(Builder.CreateBitCast(TypeInfo, Builder.getInt8PtrTy())); - -ArrayType *FilterTy = ArrayType::get(Int8PtrTy, TypeInfos.size()); -LPadInst->addClause(ConstantArray::get(FilterTy, TypeInfos)); -</pre> -</div> - -<p>Converting from using the <code>@llvm.eh.resume</code> intrinsic to - the <code>resume</code> instruction is trivial. It takes the exception - pointer and exception selector values returned by - the <code>landingpad</code> instruction:</p> - -<div class="doc_code"> -<pre> -Type *UnwindDataTy = StructType::get(Builder.getInt8PtrTy(), - Builder.getInt32Ty(), NULL); -Value *UnwindData = UndefValue::get(UnwindDataTy); -Value *ExcPtr = Builder.CreateLoad(getExceptionObjSlot()); -Value *ExcSel = Builder.CreateLoad(getExceptionSelSlot()); -UnwindData = Builder.CreateInsertValue(UnwindData, ExcPtr, 0, "exc_ptr"); -UnwindData = Builder.CreateInsertValue(UnwindData, ExcSel, 1, "exc_sel"); -Builder.CreateResume(UnwindData); -</pre> -</div> - - - - - --> <!--=========================================================================--> <h3> @@ -958,8 +802,15 @@ Builder.CreateResume(UnwindData); <p>LLVM IR has several new features for better support of new targets and that expose new optimization opportunities:</p> - - + New llvm.expect intrinsic. + New llvm.fma intrinsic. + + LangRef.html#fnattrs uwtable attribute for asynch unwind tables. + llvm.prefetch now takes a 4th argument that specifies whether the prefetch happens to the icache or dcache. + New nonlazybind function attribute. + data layout string can encode the natural alignment of the target's stack for better optimization (LangRef.html#datalayout) + returns_twice attribute (rafael) + </div> <!--=========================================================================--> @@ -997,6 +848,8 @@ Builder.CreateResume(UnwindData); optimizers:</p> <ul> + Pass manager extension API. + <li>Information about <a href="BranchWeightMetadata.html">branch probability</a> and basic block frequency is now available within LLVM, based on a combination of static branch prediction heuristics and @@ -1004,7 +857,9 @@ Builder.CreateResume(UnwindData); register spill placement and if-conversion, with additional optimizations planned for future releases. The same framework is intended for eventual use with profile-guided optimization.</li> -</li> + + ARC language specific optimizer (Transforms/ObjCARC) a decent example of language-specific transformation. + </ul> @@ -1038,6 +893,17 @@ compiler and provides better integration with the platform ABI as a result.</p> the <a href="http://blog.llvm.org/2010/04/intro-to-llvm-mc-project.html">Intro to the LLVM MC Project Blog Post</a>.</p> + + InstAliases now automatically used in the asmprinter where they are shorter. + + Table generated MC expansion logic for pseudo instructions that expand to multiple MC instructions through the PseudoInstExpansion class. (JimG) + + #line directives in integrated assembler + + llvm-rtdyld: JimG + llvm-objdump / dwarf parser library / llvm-dwarfdump (d0k) + object file parsing stuff and llvm-size (mspencer) + </div> <!--=========================================================================--> @@ -1052,6 +918,17 @@ compiler and provides better integration with the platform ABI as a result.</p> make it run faster:</p> <ul> + + better performance for indirect gotos through new tail dup pass. + + Codegen now supports vector "select" operations on vector comparisons, turning + them into various optimized code sequences (e.g. using the SSE4/AVX "blend" + instructions). + + EH and debug information produced with CFI directives, yielding smaller executables: http://blog.mozilla.com/respindola/2011/05/12/cfi-directives/ + + Domain fixing pass is now target independent (ExecutionDepsFix pass). (Jakob) + <!-- <li></li> --> @@ -1081,6 +958,16 @@ compiler and provides better integration with the platform ABI as a result.</p> <code>@llvm.x86.sse42.crc32.32.[8|16|32]</code> and <code>@llvm.x86.sse42.crc32.64.[8|64]</code>.</li> + X86: inline assembler supports .code32 and .code64. + AVX support, assembler, compiler and disassembler. + X86 backend support for NaCl (David Meyer / Nick L) + SSE domain fixing code enabled for AVX (Bruno/Jakob). + X86 backend synthesizes horizontal add/sub instructions from generic code. + X86: Tons of encoding improvements and new instructions (e.g. Atom, Ivy Bridge, + and BMI instructions) + added to assembler and disassembler (Craig Topper) + X86-64 generates smaller and faster code at -O0 (fast isel improvements) + </ul> </div> @@ -1098,6 +985,12 @@ compiler and provides better integration with the platform ABI as a result.</p> <li>Reworked Set Jump Long Jump EH Lowering,</li> <li>improved support for Cortex-M series processors, and</li> <li>beta quality integrated assembler support.</li> + + Better code generation for Cortex-A9 + ARM inline asm constraints implemented. + Old arm disassembler replaced with a new one based on autogenerated encoding information from ARM .td files. + Better performance for Neon code in clang due to SRoA improvements. + </ul> </div> @@ -1181,6 +1074,15 @@ compiler and provides better integration with the platform ABI as a result.</p> from the previous release.</p> <ul> + <li>LLVM's configure script doesn't depend on llvm-gcc anymore, clean layering.</p> + LLVM 3.0 removes support for reading LLVM 2.8 and earlier files. Aim to maintain compatibility all the way back to 3.0 "forever". + Frontend tests removed from llvm/test/Frontend* + Tablegen has been split into a library, clang tblgen pieces now live in clang. + The llvm version is now named llvm-tblgen instead of tblgen. + PostOrder Dominator frontiers were removed. + LowerSetJmp pass removed, unused. + + <li>The <code>LLVMC</code> meta compiler driver was removed.</li> <li>The <code>LowerSetJmp</code> pass wasn't used effectively by any target and has been removed.</li> @@ -1343,8 +1245,8 @@ compiler and provides better integration with the platform ABI as a result.</p> <ul> <li>The Alpha, Blackfin, CellSPU, MSP430, PTX, SystemZ and - XCore backends are experimental, and several of these have already been - removed from mainline.</li> + XCore backends are experimental, and the Alpha, Blackfin and SystemZ + targets have already been removed from mainline.</li> <li>The integrated assembler, disassembler, and JIT is not supported by several targets. If an integrated assembler is not supported, then a @@ -1381,6 +1283,130 @@ compiler and provides better integration with the platform ABI as a result.</p> </div> +<!--=========================================================================--> + +<!-- EH details: to be moved to a blog post: + + + + +<p>One of the biggest changes is that 3.0 has a new exception handling + system. The old system used LLVM intrinsics to convey the exception handling + information to the code generator. It worked in most cases, but not + all. Inlining was especially difficult to get right. Also, the intrinsics + could be moved away from the <code>invoke</code> instruction, making it hard + to recover that information.</p> + +<p>The new EH system makes exception handling a first-class member of the IR. It + adds two new instructions:</p> + +<ul> + <li><a href="LangRef.html#i_landingpad"><code>landingpad</code></a> — + this instruction defines a landing pad basic block. It contains all of the + information that's needed by the code generator. It's also required to be + the first non-PHI instruction in the landing pad. In addition, a landing + pad may be jumped to only by the unwind edge of an <code>invoke</code> + instruction.</li> + + <li><a href="LangRef.html#i_resume"><code>resume</code></a> — this + instruction causes the current exception to resume traveling up the + stack. It replaces the <code>@llvm.eh.resume</code> intrinsic.</li> +</ul> + +<p>Converting from the old EH API to the new EH API is rather simple, because a + lot of complexity has been removed. The two intrinsics, + <code>@llvm.eh.exception</code> and <code>@llvm.eh.selector</code> have been + superseded by the <code>landingpad</code> instruction. Instead of generating + a call to <code>@llvm.eh.exception</code> and <code>@llvm.eh.selector</code>: + +<div class="doc_code"> +<pre> +Function *ExcIntr = Intrinsic::getDeclaration(TheModule, + Intrinsic::eh_exception); +Function *SlctrIntr = Intrinsic::getDeclaration(TheModule, + Intrinsic::eh_selector); + +// The exception pointer. +Value *ExnPtr = Builder.CreateCall(ExcIntr, "exc_ptr"); + +std::vector<Value*> Args; +Args.push_back(ExnPtr); +Args.push_back(Builder.CreateBitCast(Personality, + Type::getInt8PtrTy(Context))); + +<i>// Add selector clauses to Args.</i> + +// The selector call. +Builder.CreateCall(SlctrIntr, Args, "exc_sel"); +</pre> +</div> + +<p>You should instead generate a <code>landingpad</code> instruction, that + returns an exception object and selector value:</p> + +<div class="doc_code"> +<pre> +LandingPadInst *LPadInst = + Builder.CreateLandingPad(StructType::get(Int8PtrTy, Int32Ty, NULL), + Personality, 0); + +Value *LPadExn = Builder.CreateExtractValue(LPadInst, 0); +Builder.CreateStore(LPadExn, getExceptionSlot()); + +Value *LPadSel = Builder.CreateExtractValue(LPadInst, 1); +Builder.CreateStore(LPadSel, getEHSelectorSlot()); +</pre> +</div> + +<p>It's now trivial to add the individual clauses to the <code>landingpad</code> + instruction.</p> + +<div class="doc_code"> +<pre> +<i><b>// Adding a catch clause</b></i> +Constant *TypeInfo = getTypeInfo(); +LPadInst->addClause(TypeInfo); + +<i><b>// Adding a C++ catch-all</b></i> +LPadInst->addClause(Constant::getNullValue(Builder.getInt8PtrTy())); + +<i><b>// Adding a cleanup</b></i> +LPadInst->setCleanup(true); + +<i><b>// Adding a filter clause</b></i> +std::vector<Constant*> TypeInfos; +Constant *TypeInfo = getFilterTypeInfo(); +TypeInfos.push_back(Builder.CreateBitCast(TypeInfo, Builder.getInt8PtrTy())); + +ArrayType *FilterTy = ArrayType::get(Int8PtrTy, TypeInfos.size()); +LPadInst->addClause(ConstantArray::get(FilterTy, TypeInfos)); +</pre> +</div> + +<p>Converting from using the <code>@llvm.eh.resume</code> intrinsic to + the <code>resume</code> instruction is trivial. It takes the exception + pointer and exception selector values returned by + the <code>landingpad</code> instruction:</p> + +<div class="doc_code"> +<pre> +Type *UnwindDataTy = StructType::get(Builder.getInt8PtrTy(), + Builder.getInt32Ty(), NULL); +Value *UnwindData = UndefValue::get(UnwindDataTy); +Value *ExcPtr = Builder.CreateLoad(getExceptionObjSlot()); +Value *ExcSel = Builder.CreateLoad(getExceptionSelSlot()); +UnwindData = Builder.CreateInsertValue(UnwindData, ExcPtr, 0, "exc_ptr"); +UnwindData = Builder.CreateInsertValue(UnwindData, ExcSel, 1, "exc_sel"); +Builder.CreateResume(UnwindData); +</pre> +</div> + + + + + --> + + <!-- *********************************************************************** --> <hr> |
