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distribute content out to the appropriate sections
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128968 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner
parent
b48c791515
commit
1efe27eb79
@ -102,7 +102,7 @@ standards, fast compilation, and low memory use. Like LLVM, Clang provides a
|
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modular, library-based architecture that makes it suitable for creating or
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integrating with other development tools. Clang is considered a
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production-quality compiler for C, Objective-C, C++ and Objective-C++ on x86
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(32- and 64-bit), and for darwin-arm targets.</p>
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(32- and 64-bit), and for darwin/arm targets.</p>
|
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|
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<p>In the LLVM 2.9 time-frame, the Clang team has made many improvements in C,
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C++ and Objective-C support. C++ support is now generally rock solid, has
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@ -293,196 +293,26 @@ in this section.
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<p>LLVM 2.9 includes several major new capabilities:</p>
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<ul>
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<li><pre>
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last release for llvm-gcc
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TBAA: On by default in clang. Disable it with -fno-strict-aliasing.
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<li>
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TBAA: On by default in clang. Disable it with -fno-strict-aliasing.
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Could be more aggressive for structs.
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</li>
|
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|
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<li>New Nvidia PTX backend, not generally useful in 2.9 though.</li>
|
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|
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Triple::normalize is new, llvm triples are always stored in normalized form internally.
|
||||
|
||||
Triple x86_64--mingw64 is obsoleted. Use x86_64--mingw32 instead.
|
||||
|
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MC Assembler: X86 now generates much better diagnostics for common errors,
|
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is much faster at matching instructions, is much more bug-compatible with
|
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the GAS assembler, and is now generally useful for a broad range of X86
|
||||
assembly.
|
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|
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New Nvidia PTX backend, not generally useful in 2.9 though.
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|
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<li>
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Much better debug info generated, particularly in optimized code situations.
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</li>
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ARM Fast ISel
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|
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ELF MC support: on by default in clang. There are still known missing features
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for human written assembly.
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|
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X86: Reimplemented all of MMX to introduce a new LLVM IR x86_mmx type. Now
|
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random types like <2 x i32> are not iseld to mmx without emms. The
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-disable-mmx flag is gone now.
|
||||
|
||||
Some basic <a href="CodeGenerator.html#mc">internals documentation</a> for MC.
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MC Assembler support for .file and .loc.
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<li>
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inline asm multiple alternative constraint support.
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</li>
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LoopIdiom: memset/memcpy formation and memset_pattern on darwin. Build with
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-ffreestanding or -fno-builtin if your memcpy is being compiled into infinite
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recursion.
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|
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<li>
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New naming rules in coding standards: CodingStandards.html#ll_naming
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</li>
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|
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TargetLibraryInfo
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|
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X86 support for FS/GS relative loads and stores using address space 256/257 are
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reliable now.
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|
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ARM: New code placement pass.
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|
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unnamed_addr + PR8927
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|
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PointerTracking has been removed from mainline, moved to ClamAV.
|
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|
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EarlyCSE pass.
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LoopInstSimplify pass.
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|
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- DIBuilder provides simpler interface for front ends like Clang to encode debug info in LLVM IR.
|
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- This interface hides implementation details (e.g. DIDerivedType, existence of compile unit etc..) that any front end should not know about.
|
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For example, DIFactory DebugFactory;
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Ty = DebugFactory.CreateDerivedType(DW_TAG_volatile_type,
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findRegion(TYPE_CONTEXT(type)),
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StringRef(),
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getOrCreateFile(main_input_filename),
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0 /*line no*/,
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NodeSizeInBits(type),
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NodeAlignInBits(type),
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0 /*offset */,
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0 /* flags */,
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MainTy);
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can be replaced by
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DbgTy = DBuilder.createQualifiedType(DW_TAG_volatile_type, MainTy);
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||||
DIFactory is gone now.
|
||||
|
||||
PPC: Switched to MCInstPrinter, and MCCodeEmitter. Ready to implement support
|
||||
for directly writing out mach-o object files, but noone seems interested.
|
||||
|
||||
ARM: Improved code generation for Cortex-A8 and Cortex-A9 CPUs.
|
||||
|
||||
Scheduler now models operand latency and pipeline forwarding.
|
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|
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Can optimize printf to iprintf when no floating point is used, for embedded
|
||||
targets with smaller iprintf implementation.
|
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|
||||
error_code + libsystem + PathV2 changes
|
||||
The system_error header from C++0x was added.
|
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* Use if (error_code ec = function()) to check for error conditions
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from functions which return it.
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* error_code::message returns a human readable description of the error.
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|
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PathV1 has been deprecated in favor of PathV2 (sorry I didn't finish
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this before the release).
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* No Path class, use a r-value convertible to a twine instead.
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* Assumes all paths are UTF-8.
|
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|
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new macho-dump tool
|
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|
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Major regalloc rewrite, not on by default for 2.9 and not advised to use it.
|
||||
* New basic register allocator that can be used as a safe fallback when
|
||||
debugging. Enable with -regalloc=basic.
|
||||
* New infrastructure for live range splitting. SplitKit can break a live
|
||||
interval into smaller pieces while preserving SSA form, and SpillPlacement
|
||||
can help find the best split points. This is a work in progress so the API
|
||||
is changing quickly.
|
||||
* The inline spiller has learned to clean up after live range splitting. It
|
||||
can hoist spills out of loops, and it can eliminate redundant spills.
|
||||
Rematerialization works with live range splitting.
|
||||
* New greedy register allocator using live range splitting. This will be the
|
||||
default register allocator in the next LLVM release, but it is not turned on
|
||||
by default in 2.9.
|
||||
|
||||
ARM: __builtin_prefetch turns into prefetch instructions.
|
||||
|
||||
MC assembler support for 3dNow! and 3DNowA instructions.
|
||||
|
||||
tblgen support for assembler aliases: <a
|
||||
href="CodeGenerator.html#na_instparsing">MnemonicAlias and InstAlias</a>
|
||||
|
||||
LoopIndexSplit pass was removed, unmaintained.
|
||||
LiveValues, SimplifyHalfPowrLibCalls, and GEPSplitter were removed.
|
||||
|
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include/llvm/System merged into include/llvm/Support.
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||||
|
||||
Win32 PE-COFF support in the MC assembler has made a lot of progress in the 2.9
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||||
timeframe, but is still not generally useful. Please see
|
||||
"http://llvm.org/bugs/showdependencytree.cgi?id=9100&hide_resolved=1" for open bugs?
|
||||
|
||||
New <a href="WritingAnLLVMPass.html#RegionPass">RegionPass</a> infrastructure
|
||||
for region-based optimizations.
|
||||
|
||||
MicroBlaze: major updates for aggressive delay slot filler, MC-based assembly
|
||||
printing, assembly instruction parsing, ELF .o file emission, and MC
|
||||
instruction disassembler.
|
||||
|
||||
Countless ARM microoptimizations.
|
||||
|
||||
Speedups to various mid-level passes:
|
||||
GVN is much faster on functions with deep dominator trees / lots of BBs.
|
||||
DomTree and DominatorFrontier are much faster to compute, and preserved by
|
||||
more passes (so they are computed less often)
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SRoA is also much faster and doesn't use DominanceFrontier.
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||||
|
||||
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new 'hotpatch' attribute: LangRef.html#fnattrs
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APInt API changes, see PR5207.
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|
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DSE is more aggressive with stores of different types: e.g. a large store
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following a small one to the same address.
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|
||||
New naming rules in coding standards: CodingStandards.html#ll_naming
|
||||
|
||||
LiveDebugVariables is a new pass that keeps track of debugging information for
|
||||
user variables that are kept in registers in optimized builds.
|
||||
|
||||
We now optimize various idioms for overflow detection into check of the flag
|
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register on various CPUs, e.g.:
|
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unsigned long t = a+b;
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||||
if (t < a) ...
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||||
into:
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addq %rdi, %rbx
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jno LBB0_2
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||||
|
||||
X86: Much better codegen for several cases using adc/sbb instead of cmovs for
|
||||
conditional increment and other idioms.
|
||||
|
||||
MVT::Flag renamed to MVT::Glue
|
||||
|
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Removed the PartialSpecialization pass, it was unmaintained and buggy.
|
||||
|
||||
SPARC: Many improvements, including using the Y registers for multiplications
|
||||
and addition of a simple delay slot filler.
|
||||
|
||||
|
||||
udiv, ashr, lshr, shl now have exact and nuw/nsw bits: PR8862 / LangRef.html
|
||||
|
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lib/Object and llvm-objdump
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||||
|
||||
|
||||
Target Independent Code Gen:
|
||||
The pre-register-allocation (preRA) instruction scheduler models register pressure
|
||||
much more accurately in some cases. This allows the adoption of more
|
||||
aggressive scheduling heuristics.
|
||||
|
||||
The X86 backend has adopted a new preRA scheduling
|
||||
mode, "list-ilp", to shorten the height of instruction schedules
|
||||
without inducing register spills.
|
||||
|
||||
The ARM backend preRA scheduler now models machine resources at cycle
|
||||
granularity. This allows the scheduler to both accurately model
|
||||
instruction latency and avoid overcommitting functional units.
|
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|
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</pre></li>
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</ul>
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|
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</div>
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@ -497,6 +327,13 @@ lib/Object and llvm-objdump
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expose new optimization opportunities:</p>
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|
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<ul>
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<li>udiv, ashr, lshr, shl now have exact and nuw/nsw bits:
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PR8862 / LangRef.html</li>
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|
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unnamed_addr + PR8927
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|
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new 'hotpatch' attribute: LangRef.html#fnattrs
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||||
|
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</ul>
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||||
|
||||
</div>
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@ -512,9 +349,44 @@ expose new optimization opportunities:</p>
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release includes a few major enhancements and additions to the optimizers:</p>
|
||||
|
||||
<ul>
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<li>TBAA.</li>
|
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<li>LTO has been improved to use MC for parsing inline asm and now
|
||||
can build large programs like Firefox 4 on both OS X and Linux.</li>
|
||||
|
||||
|
||||
LoopIdiom: memset/memcpy formation and memset_pattern on darwin. Build with
|
||||
-ffreestanding or -fno-builtin if your memcpy is being compiled into infinite
|
||||
recursion.
|
||||
|
||||
TargetLibraryInfo
|
||||
|
||||
EarlyCSE pass.
|
||||
LoopInstSimplify pass.
|
||||
|
||||
New <a href="WritingAnLLVMPass.html#RegionPass">RegionPass</a> infrastructure
|
||||
for region-based optimizations.
|
||||
|
||||
Can optimize printf to iprintf when no floating point is used, for embedded
|
||||
targets with smaller iprintf implementation.
|
||||
|
||||
Speedups to various mid-level passes:
|
||||
GVN is much faster on functions with deep dominator trees / lots of BBs.
|
||||
DomTree and DominatorFrontier are much faster to compute, and preserved by
|
||||
more passes (so they are computed less often)
|
||||
SRoA is also much faster and doesn't use DominanceFrontier.
|
||||
|
||||
DSE is more aggressive with stores of different types: e.g. a large store
|
||||
following a small one to the same address.
|
||||
|
||||
|
||||
We now optimize various idioms for overflow detection into check of the flag
|
||||
register on various CPUs, e.g.:
|
||||
unsigned long t = a+b;
|
||||
if (t < a) ...
|
||||
into:
|
||||
addq %rdi, %rbx
|
||||
jno LBB0_2
|
||||
|
||||
|
||||
</ul>
|
||||
|
||||
<!--
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||||
@ -547,6 +419,39 @@ in.</p>
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<li>MC supports the <tt>.cfi_*</tt> directives for producing DWARF
|
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frame information, but it is still not used by CodeGen by default.</li>
|
||||
<li>COFF support?</li>
|
||||
|
||||
|
||||
MC Assembler: X86 now generates much better diagnostics for common errors,
|
||||
is much faster at matching instructions, is much more bug-compatible with
|
||||
the GAS assembler, and is now generally useful for a broad range of X86
|
||||
assembly.
|
||||
|
||||
|
||||
ELF MC support: on by default in clang. There are still known missing features
|
||||
for human written assembly.
|
||||
|
||||
|
||||
Some basic <a href="CodeGenerator.html#mc">internals documentation</a> for MC.
|
||||
|
||||
MC Assembler support for .file and .loc.
|
||||
|
||||
tblgen support for assembler aliases: <a
|
||||
href="CodeGenerator.html#na_instparsing">MnemonicAlias and InstAlias</a>
|
||||
|
||||
Win32 PE-COFF support in the MC assembler has made a lot of progress in the 2.9
|
||||
timeframe, but is still not generally useful. Please see
|
||||
"http://llvm.org/bugs/showdependencytree.cgi?id=9100&hide_resolved=1" for open bugs?
|
||||
|
||||
|
||||
lib/Object and llvm-objdump
|
||||
Experimental format independent object file manipulation library.
|
||||
* Supports PE/COFF and ELF.
|
||||
* llvm-nm extended to work with object files. Exactly matches
|
||||
binutils-nm for the files I've tested.
|
||||
* llvm-objdump added with support for disassembly (no relocations displayed).
|
||||
|
||||
|
||||
|
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</ul>
|
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|
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<p>For more information, please see the <a
|
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@ -569,7 +474,34 @@ it run faster:</p>
|
||||
|
||||
<ul>
|
||||
<!-- SplitKit -->
|
||||
FastISel for ARM.
|
||||
|
||||
<li>The pre-register-allocation (preRA) instruction scheduler models register
|
||||
pressure much more accurately in some cases. This allows the adoption of more
|
||||
aggressive scheduling heuristics.
|
||||
</li>
|
||||
|
||||
LiveDebugVariables is a new pass that keeps track of debugging information for
|
||||
user variables that are kept in registers in optimized builds.
|
||||
|
||||
|
||||
Scheduler now models operand latency and pipeline forwarding.
|
||||
|
||||
Major regalloc rewrite, not on by default for 2.9 and not advised to use it.
|
||||
* New basic register allocator that can be used as a safe fallback when
|
||||
debugging. Enable with -regalloc=basic.
|
||||
* New infrastructure for live range splitting. SplitKit can break a live
|
||||
interval into smaller pieces while preserving SSA form, and SpillPlacement
|
||||
can help find the best split points. This is a work in progress so the API
|
||||
is changing quickly.
|
||||
* The inline spiller has learned to clean up after live range splitting. It
|
||||
can hoist spills out of loops, and it can eliminate redundant spills.
|
||||
Rematerialization works with live range splitting.
|
||||
* New greedy register allocator using live range splitting. This will be the
|
||||
default register allocator in the next LLVM release, but it is not turned on
|
||||
by default in 2.9.
|
||||
|
||||
|
||||
|
||||
</ul>
|
||||
</div>
|
||||
|
||||
@ -583,6 +515,30 @@ FastISel for ARM.
|
||||
</p>
|
||||
|
||||
<ul>
|
||||
<li>
|
||||
X86: Reimplemented all of MMX to introduce a new LLVM IR x86_mmx type. Now
|
||||
random types like <2 x i32> are not iseld to mmx without emms. The
|
||||
-disable-mmx flag is gone now.
|
||||
</li>
|
||||
|
||||
<li>
|
||||
X86 support for FS/GS relative loads and stores using address space 256/257 are
|
||||
reliable now.
|
||||
</li>
|
||||
|
||||
<li>
|
||||
X86: Much better codegen for several cases using adc/sbb instead of cmovs for
|
||||
conditional increment and other idioms.
|
||||
</li>
|
||||
|
||||
<li>
|
||||
The X86 backend has adopted a new preRA scheduling
|
||||
mode, "list-ilp", to shorten the height of instruction schedules
|
||||
without inducing register spills.
|
||||
</li>
|
||||
|
||||
MC assembler support for 3dNow! and 3DNowA instructions.
|
||||
|
||||
<li>Several bugs have been fixed for Windows x64 code generator.</li>
|
||||
</ul>
|
||||
|
||||
@ -598,9 +554,39 @@ FastISel for ARM.
|
||||
</p>
|
||||
|
||||
<ul>
|
||||
<li>ARM Fast ISel</li>
|
||||
<li>ARM: New code placement pass.</li>
|
||||
<li>ARM: Improved code generation for Cortex-A8 and Cortex-A9 CPUs.</li>
|
||||
<li>ARM: __builtin_prefetch turns into prefetch instructions.</li>
|
||||
<li>Countless ARM microoptimizations.</li>
|
||||
|
||||
<li> The ARM backend preRA scheduler now models machine resources at cycle
|
||||
granularity. This allows the scheduler to both accurately model
|
||||
instruction latency and avoid overcommitting functional units.</li>
|
||||
|
||||
|
||||
</ul>
|
||||
</div>
|
||||
|
||||
<!--=========================================================================-->
|
||||
<h2>
|
||||
<a name="OtherTS">Other Target Specific Improvements</a>
|
||||
</h2>
|
||||
|
||||
<div class="doc_text">
|
||||
<ul>
|
||||
PPC: Switched to MCInstPrinter, and MCCodeEmitter. Ready to implement support
|
||||
for directly writing out mach-o object files, but noone seems interested.
|
||||
|
||||
MicroBlaze: major updates for aggressive delay slot filler, MC-based assembly
|
||||
printing, assembly instruction parsing, ELF .o file emission, and MC
|
||||
instruction disassembler.
|
||||
|
||||
SPARC: Many improvements, including using the Y registers for multiplications
|
||||
and addition of a simple delay slot filler.
|
||||
|
||||
</ul>
|
||||
</div>
|
||||
|
||||
<!--=========================================================================-->
|
||||
<h2>
|
||||
@ -614,30 +600,78 @@ on LLVM 2.8, this section lists some "gotchas" that you may run into upgrading
|
||||
from the previous release.</p>
|
||||
|
||||
<ul>
|
||||
</ul>
|
||||
last release for llvm-gcc
|
||||
|
||||
- DIBuilder provides simpler interface for front ends like Clang to encode debug info in LLVM IR.
|
||||
- This interface hides implementation details (e.g. DIDerivedType, existence of compile unit etc..) that any front end should not know about.
|
||||
For example, DIFactory DebugFactory;
|
||||
Ty = DebugFactory.CreateDerivedType(DW_TAG_volatile_type,
|
||||
findRegion(TYPE_CONTEXT(type)),
|
||||
StringRef(),
|
||||
getOrCreateFile(main_input_filename),
|
||||
0 /*line no*/,
|
||||
NodeSizeInBits(type),
|
||||
NodeAlignInBits(type),
|
||||
0 /*offset */,
|
||||
0 /* flags */,
|
||||
MainTy);
|
||||
can be replaced by
|
||||
DbgTy = DBuilder.createQualifiedType(DW_TAG_volatile_type, MainTy);
|
||||
DIFactory is gone now.
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
<p>In addition, many APIs have changed in this release. Some of the major LLVM
|
||||
API changes are:</p>
|
||||
<ul>
|
||||
|
||||
LoopIndexSplit pass was removed, unmaintained.
|
||||
LiveValues, SimplifyHalfPowrLibCalls, and GEPSplitter were removed.
|
||||
Removed the PartialSpecialization pass, it was unmaintained and buggy.
|
||||
|
||||
DIFactory removed, use DIBuilder instead.
|
||||
|
||||
Triple::normalize is new, llvm triples are always stored in normalized form internally.
|
||||
|
||||
Triple x86_64--mingw64 is obsoleted. Use x86_64--mingw32 instead.
|
||||
|
||||
PointerTracking has been removed from mainline, moved to ClamAV.
|
||||
|
||||
</ul>
|
||||
|
||||
</div>
|
||||
|
||||
<!--=========================================================================-->
|
||||
<h2>
|
||||
<a name="devtree_changes">Development Infrastructure Changes</a>
|
||||
<a name="api_changes">Internal API Changes</a>
|
||||
</h2>
|
||||
|
||||
<div class="doc_text">
|
||||
|
||||
<p>This section lists changes to the LLVM development infrastructure. This
|
||||
mostly impacts users who actively work on LLVM or follow development on
|
||||
mainline, but may also impact users who leverage the LLVM build infrastructure
|
||||
or are interested in LLVM qualification.</p>
|
||||
<p>In addition, many APIs have changed in this release. Some of the major
|
||||
LLVM API changes are:</p>
|
||||
|
||||
<ul>
|
||||
|
||||
include/llvm/System merged into include/llvm/Support.
|
||||
|
||||
|
||||
APInt API changes, see PR5207.
|
||||
|
||||
MVT::Flag renamed to MVT::Glue
|
||||
|
||||
|
||||
error_code + libsystem + PathV2 changes
|
||||
The system_error header from C++0x was added.
|
||||
* Use if (error_code ec = function()) to check for error conditions
|
||||
from functions which return it.
|
||||
* error_code::message returns a human readable description of the error.
|
||||
|
||||
PathV1 has been deprecated in favor of PathV2 (sorry I didn't finish
|
||||
this before the release).
|
||||
* No Path class, use a r-value convertible to a twine instead.
|
||||
* Assumes all paths are UTF-8.
|
||||
|
||||
|
||||
</ul>
|
||||
</div>
|
||||
|
||||
|
||||
Loading…
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Reference in New Issue
Block a user