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Commit Graph

1641 Commits

Author SHA1 Message Date
Daniel Dunbar
2c99d47702 TargetRegistry: Fix create{AsmInfo,MCDisassembler} to return non-const objects.
llvm-svn: 99097
2010-03-20 22:36:22 +00:00
Daniel Dunbar
c687bf7cb4 MC: Add TargetAsmBackend::createObjectWriter.
- MCAssembler is now object-file independent, although we will surely need more work to fully support ELF/COFF.

llvm-svn: 98955
2010-03-19 10:43:26 +00:00
Daniel Dunbar
287ff291e3 MC: Add TargetAsmBackend::isVirtualSection hook.
llvm-svn: 98950
2010-03-19 09:29:03 +00:00
Daniel Dunbar
3444d755d2 MCAssembler: Move ApplyFixup to the TargetAsmBackend, this is a target specific not object writer specific task.
llvm-svn: 98947
2010-03-19 09:28:12 +00:00
Chris Lattner
6b395fca87 add a new SDNPVariadic SDNP node flag, and use it in
dag isel gen instead of instruction properties.  This
allows the oh-so-useful behavior of matching a variadic
non-root node.

llvm-svn: 98934
2010-03-19 05:07:09 +00:00
Chris Lattner
d678e362d2 use ins/outs
llvm-svn: 98867
2010-03-18 20:55:31 +00:00
Daniel Dunbar
571a3eb0b6 MC/AsmMatcher: Add support for target specific "instruction cleanup" functions,
to allow custom post-processing of matched instructions.

llvm-svn: 98857
2010-03-18 20:05:56 +00:00
Daniel Dunbar
26cbc4b1a3 MC/Darwin: Add a new target hook for whether the target uses "reliable" symbol differences, basically whether the assembler should attempt to understand atoms when using scattered symbols.
Also, avoid some virtual call overhead.

llvm-svn: 98789
2010-03-18 00:58:53 +00:00
Bob Wilson
950964e4d0 Remove an unnecessary (and misspelled) typedef. Tweak whitespace.
llvm-svn: 98753
2010-03-17 18:43:25 +00:00
Chris Lattner
e933062ae9 remove dead variable, patch by Nathan Howell!
llvm-svn: 98704
2010-03-17 01:45:17 +00:00
Daniel Dunbar
476b525e01 MC/Mach-O/x86_64: Temporary labels in cstring sections require symbols (and external relocations, but we don't have x86_64 relocations yet).
llvm-svn: 98583
2010-03-15 21:56:50 +00:00
Anton Korobeynikov
2cb4451ae6 Make default expansion for FP16 <-> FP32 nodes into libcalls
llvm-svn: 98501
2010-03-14 18:42:24 +00:00
Chris Lattner
e7538fa303 rearrange MCContext ownership. Before LLVMTargetMachine created it
and passing off ownership to AsmPrinter.  Now MachineModuleInfo
creates it and owns it by value.  This allows us to use MCSymbols
more consistently throughout the rest of the code generator, and
simplifies a bit of code.  This also allows MachineFunction to 
keep an MCContext reference handy, and cleans up the TargetRegistry
interfaces for AsmPrinters.

llvm-svn: 98450
2010-03-13 20:55:24 +00:00
Chris Lattner
c101ad818c give Mangler access to TargetData.
llvm-svn: 98378
2010-03-12 20:47:28 +00:00
Chris Lattner
01e70df9b2 finally give Mangler a getSymbol method, which returns an MCSymbol
for a global instead of messing around with string buffers.

llvm-svn: 98366
2010-03-12 18:55:20 +00:00
Chris Lattner
956582f876 make the mangler take an MCContext instead of an MAI.
No functionality change.

llvm-svn: 98363
2010-03-12 18:44:54 +00:00
Chris Lattner
07e124cec5 make TargetLoweringObjectFile::getExprForDwarfReference
just make unnamed temp symbols instead of having to come
up with its own names.

llvm-svn: 98324
2010-03-12 01:56:43 +00:00
Chris Lattner
5aefaeb42e fix a fixme in TargetLoweringObjectFile::getExprForDwarfReference
where we used ot create an MCSymbol for ".".  Now emit an assembler
temporary label and reference it instead of "." textually.

rdar://7739457

llvm-svn: 98292
2010-03-11 21:55:20 +00:00
Dan Gohman
6b1b9e37d7 Remove getWidenVectorType, which is no longer used.
llvm-svn: 98289
2010-03-11 21:39:57 +00:00
Chris Lattner
1ce9dfd498 rename getSymbolForDwarf* to getExprForDwarf* since it returns
an MCExpr and not an MCSymbol.  Change it to take an MCStreamer,
which is currently unused.

No functionality change.

llvm-svn: 98278
2010-03-11 19:41:58 +00:00
Daniel Dunbar
fe8914f6b6 Fix (unused) RegisterAsmBackend template, clang++ isn't happy about this.
llvm-svn: 98226
2010-03-11 02:28:52 +00:00
Daniel Dunbar
687d99cfa8 MC: Provide MCAssembler with a TargetAsmBackend.
llvm-svn: 98222
2010-03-11 01:34:27 +00:00
Daniel Dunbar
f7f88fba2d MC: Sketch some TargetAsmBackend hooks we are going to need.
llvm-svn: 98221
2010-03-11 01:34:21 +00:00
Daniel Dunbar
10c975db78 MC: Provide the target triple to AsmBackend constructors.
llvm-svn: 98220
2010-03-11 01:34:16 +00:00
Chris Lattner
e34dde1e83 move three lowering hooks from MAI to TLOF and make one of them
semantic instead of syntactic.  This completes MCization of
darwin/x86[-64]!

llvm-svn: 98145
2010-03-10 07:20:42 +00:00
Jim Grosbach
f328c5334f Change the Value argument to eliminateFrameIndex to a type-tagged value. This
is preparatory to having PEI's scavenged frame index value reuse logic
properly distinguish types of frame values (e.g., whether the value is
stack-pointer relative or frame-pointer relative).

No functionality change.

llvm-svn: 98086
2010-03-09 21:45:49 +00:00
Chris Lattner
f3ee582f23 Use Other as a sentinel instead of iAny.
llvm-svn: 97914
2010-03-07 07:45:08 +00:00
Evan Cheng
70b7ecdef9 - Change MachineInstr::isIdenticalTo to take a new option that determines whether it should skip checking defs or at least virtual register defs. This subsumes part of the TargetInstrInfo::isIdentical functionality.
- Eliminate TargetInstrInfo::isIdentical and replace it with produceSameValue. In the default case, produceSameValue just checks whether two machine instructions are identical (except for virtual register defs). But targets may override it to check for unusual cases (e.g. ARM pic loads from constant pools).

llvm-svn: 97628
2010-03-03 01:44:33 +00:00
Bill Wendling
5990930d72 Remove dead parameter passing.
llvm-svn: 97536
2010-03-02 01:55:18 +00:00
Dan Gohman
5cffef564c Use Doxygen comment syntax.
llvm-svn: 97451
2010-03-01 17:45:15 +00:00
Dan Gohman
4b0dac5a8d Add a flag to addPassesToEmit* to disable the Verifier pass run
after LSR, so that clients can opt in.

llvm-svn: 97357
2010-02-28 00:41:59 +00:00
Dan Gohman
99c6bcbc13 The mayHaveSideEffects flag is no longer used.
llvm-svn: 97348
2010-02-27 23:47:46 +00:00
Chris Lattner
f179abcb3a remove a dead PatLeaf, I previously changed all uses to use -1 instead.
llvm-svn: 97148
2010-02-25 17:39:34 +00:00
Dan Gohman
084112437d Revert r97064. Duncan pointed out that bitcasts are defined in
terms of store and load, which means bitcasting between scalar
integer and vector has endian-specific results, which undermines
this whole approach.

llvm-svn: 97137
2010-02-25 15:20:39 +00:00
Dan Gohman
424e8f22d0 Make getTypeSizeInBits work correctly for array types; it should return
the number of value bits, not the number of bits of allocation for in-memory
storage.

Make getTypeStoreSize and getTypeAllocSize work consistently for arrays and
vectors.

Fix several places in CodeGen which compute offsets into in-memory vectors
to use TargetData information.

This fixes PR1784.

llvm-svn: 97064
2010-02-24 22:05:23 +00:00
Jim Grosbach
c4ab116a90 Updated version of r96634 (which was reverted due to failing 176.gcc and
126.gcc nightly tests. These failures uncovered latent bugs that machine DCE
could remove one half of a stack adjust down/up pair, causing PEI to assert.
This update fixes that, and the tests now pass.

llvm-svn: 96822
2010-02-22 23:10:38 +00:00
Dan Gohman
835086ef52 Fix various doxygen warnings.
llvm-svn: 96779
2010-02-22 04:10:52 +00:00
Daniel Dunbar
b6b58bff88 MC: Sketch registry support for target specific assembler backends.
llvm-svn: 96762
2010-02-21 21:53:53 +00:00
Daniel Dunbar
518e9cbe46 Formatting tweaks (trailing whitespace, ordering, comments).
llvm-svn: 96761
2010-02-21 21:53:37 +00:00
Chris Lattner
ad9fa2075b Eliminate some uses of immAllOnes, just use -1, it does
the same thing and is more efficient for the matcher.

llvm-svn: 96713
2010-02-21 03:13:10 +00:00
Bob Wilson
df432a30b2 Revert 96634. It causes assertion failures for 126.gcc and 176.gcc in
the armv6 nightly tests.

llvm-svn: 96691
2010-02-19 18:59:53 +00:00
Jim Grosbach
53ef05fa82 Radar 7636153. In the presence of large call frames, it's not sufficient
for ARM to just check if a function has a FP to determine if it's safe
to simplify the stack adjustment pseudo ops prior to eliminating frame
indices. Allow targets to override the default behavior and does so for ARM
and Thumb2.

llvm-svn: 96634
2010-02-19 00:16:24 +00:00
Eric Christopher
88fe6775de Fix a few unused parameter warnings.
llvm-svn: 96533
2010-02-17 23:55:26 +00:00
Anton Korobeynikov
ef1862e256 Move TLOF implementations to libCodegen to resolve layering violation.
llvm-svn: 96288
2010-02-15 22:37:53 +00:00
Anton Korobeynikov
dccd240998 Preliminary patch to improve dwarf EH generation - Hooks to return Personality / FDE / LSDA / TType encoding depending on target / options (e.g. code model / relocation model) - MCIzation of Dwarf EH printer to use encoding information - Stub generation for ELF target (needed for indirect references) - Some other small changes here and there
llvm-svn: 96285
2010-02-15 22:35:59 +00:00
Chris Lattner
946403d05f give MCCodeEmitters access to the current MCContext.
llvm-svn: 96038
2010-02-12 23:12:47 +00:00
Chris Lattner
63870006bf refactor x86 conditional branches to use a multipattern
that generates the 1-byte and 4-byte immediate versions
from one definition.

llvm-svn: 95902
2010-02-11 19:31:22 +00:00
Mon P Wang
c17e781f35 The previous fix of widening divides that trap was too fragile as it depends on custom
lowering and requires that certain types exist in ValueTypes.h.  Modified widening to
check if an op can trap and if so, the widening algorithm will apply only the op on
the defined elements.  It is safer to do this in widening because the optimizer can't
guarantee removing unused ops in some cases.

llvm-svn: 95823
2010-02-10 23:37:45 +00:00
Dan Gohman
92b6122204 Fix "the the" and similar typos.
llvm-svn: 95781
2010-02-10 16:03:48 +00:00
Chris Lattner
7acf9be6c4 move target-independent opcodes out of TargetInstrInfo
into TargetOpcodes.h.  #include the new TargetOpcodes.h
into MachineInstr.  Add new inline accessors (like isPHI())
to MachineInstr, and start using them throughout the 
codebase.

llvm-svn: 95687
2010-02-09 19:54:29 +00:00
Dan Gohman
f45b7c6795 Rename the PerformTailCallOpt variable to GuaranteedTailCallOpt to reflect
its current purpose.

llvm-svn: 95564
2010-02-08 20:27:50 +00:00
Chris Lattner
e8811c3222 change addPassesToEmitFile to return true on failure instead of its input,
add -filetype=null for performance testing and remove -filetype=dynlib,
which isn't planned to be implemented.

llvm-svn: 95202
2010-02-03 05:55:08 +00:00
Evan Cheng
9057fea7ef Revert 95130.
llvm-svn: 95160
2010-02-02 23:55:14 +00:00
Chris Lattner
643f2f9bc4 refactor code so that LLVMTargetMachine creates the asmstreamer and
mccontext instead of having AsmPrinter do it.  This allows other 
types of MCStreamer's to be passed in.

llvm-svn: 95155
2010-02-02 23:37:42 +00:00
Chris Lattner
7dd4ad3ced Remove a bunch of stuff around the edges of the ELF writer.
Now the only use of the ELF writer is the JIT, which won't be
easy to fix in the short term. :( :(

llvm-svn: 95148
2010-02-02 22:31:11 +00:00
Chris Lattner
21bcba21e7 eliminate all the dead addSimpleCodeEmitter implementations.
eliminate random "code emitter" stuff in Alpha, except for
the JIT path.  Next up, remove the template cruft.

llvm-svn: 95131
2010-02-02 21:31:47 +00:00
Evan Cheng
48375fbf4f Pass callsite return type to TargetLowering::LowerCall and use that to check sibcall eligibility.
llvm-svn: 95130
2010-02-02 21:29:10 +00:00
Chris Lattner
7d162688a9 eliminate FileModel::Model, just use CodeGenFileType. The client
of the code generator shouldn't care what object format a target
uses.

llvm-svn: 95124
2010-02-02 21:06:45 +00:00
Chris Lattner
cb4d0d0df4 remove the remnants of TargetMachOWriterInfo.
llvm-svn: 95114
2010-02-02 19:41:23 +00:00
Chris Lattner
ff8ba8fc79 eliminate all forms of addPassesToEmitMachineCode except
the one used by the JIT.  Remove all forms of
addPassesToEmitFileFinish except the one used by the static
code generator.  Inline the remaining version of
addPassesToEmitFileFinish into its only caller.

llvm-svn: 95109
2010-02-02 19:14:27 +00:00
Chris Lattner
fa04a6e968 Inline addAssemblyEmitter into its one real caller and delete
the -print-emitted-asm option.  The JIT shouldn't have to pull
in the asmprinter.

llvm-svn: 95100
2010-02-02 18:44:12 +00:00
Nate Begeman
4d489ea053 Kill the Mach-O writer, and temporarily make filetype=obj an error.
The MCStreamer based assemblers will take over for this functionality.

llvm-svn: 95033
2010-02-01 23:56:58 +00:00
Sean Callanan
5458663492 Moved InstallLexer() from the X86-specific AsmLexer
to the TargetAsmLexer class so that clients can
actually use the TargetAsmLexer they get from a
Target.

llvm-svn: 94940
2010-01-31 02:28:18 +00:00
Evan Cheng
a5cb4213ac Remove a dead target hook.
llvm-svn: 94646
2010-01-27 01:44:40 +00:00
Evan Cheng
237629e476 Eliminate target hook IsEligibleForTailCallOptimization.
Target independent isel should always pass along the "tail call" property. Change
target hook LowerCall's parameter "isTailCall" into a refernce. If the target
decides it's impossible to honor the tail call request, it should set isTailCall
to false to make target independent isel happy.

llvm-svn: 94626
2010-01-27 00:07:07 +00:00
Chris Lattner
278075333e constify a method argument.
llvm-svn: 94612
2010-01-26 23:15:09 +00:00
Bill Wendling
d4a402c2aa Remove warning about non return on a non-void function.
llvm-svn: 94532
2010-01-26 08:27:24 +00:00
Chris Lattner
967a37fb26 eliminate the TargetLowering::UsesGlobalOffsetTable bool, which is
subsumed by TargetLowering::getJumpTableEncoding().  Change uses of
it to be more specific.

llvm-svn: 94529
2010-01-26 06:53:37 +00:00
Chris Lattner
d87c50833a Move getJTISymbol from MachineJumpTableInfo to MachineFunction,
which is more convenient, and change getPICJumpTableRelocBaseExpr
to take a MachineFunction to match.

Next, move the X86 code that create a PICBase symbol to
X86TargetLowering::getPICBaseSymbol from 
X86MCInstLower::GetPICBaseSymbol, which was an asmprinter specific 
library.  This eliminates a 'gross hack', and allows us to
implement X86ISelLowering::getPICJumpTableRelocBaseExpr which now
calls it.

This in turn allows us to eliminate the 
X86AsmPrinter::printPICJumpTableSetLabel method, which was the
only overload of printPICJumpTableSetLabel.

llvm-svn: 94526
2010-01-26 06:28:43 +00:00
Chris Lattner
3b2bf7ab66 stub out a new target hook, need some refactoring before I can
implement it.

llvm-svn: 94521
2010-01-26 05:30:30 +00:00
Chris Lattner
41f661d2c2 this hook should be const.
llvm-svn: 94508
2010-01-26 04:19:00 +00:00
Chris Lattner
5ee5b62838 Add support for target-specific 32-bit custom-lowered
jump table entries.

llvm-svn: 94505
2010-01-26 04:05:28 +00:00
Chris Lattner
efdc572e44 Rearrange handling of jump tables. Highlights:
1. MachineJumpTableInfo is now created lazily for a function the first time
   it actually makes a jump table instead of for every function.
2. The encoding of jump table entries is now described by the
   MachineJumpTableInfo::JTEntryKind enum.  This enum is determined by the
   TLI::getJumpTableEncoding() hook, instead of by lots of code scattered
   throughout the compiler that "knows" that jump table entries are always
   32-bits in pic mode (for example).
3. The size and alignment of jump table entries is now calculated based on
   their kind, instead of at machinefunction creation time.

Future work includes using the EntryKind in more places in the compiler,
eliminating other logic that "knows" the layout of jump tables in various
situations.

llvm-svn: 94470
2010-01-25 23:26:13 +00:00
Chris Lattner
00ba9a5343 add a method to get the alignment of an integer type even
when we don't have one laying around.  Useful if you don't
have an llvmcontext handy.

llvm-svn: 94468
2010-01-25 23:18:11 +00:00
Sean Callanan
7b52485bbd Filled out the skeleton of the TargetAsmLexer to behave
exactly like an MCAsmLexer.  (The difference is that the
TargetAsmLexer knows how to handle target-specific stuff
like registers, whereas the MCAsmLexer is fully generic.)

llvm-svn: 94237
2010-01-22 22:35:01 +00:00
Evan Cheng
8e25244a48 Add two target hooks to determine whether two loads are near and should be scheduled together.
llvm-svn: 94147
2010-01-22 03:34:51 +00:00
Chris Lattner
8cd569a4b0 allow registering target lexers.
llvm-svn: 94127
2010-01-22 01:10:40 +00:00
Chris Lattner
2b19da4fa0 stub out a new TargetAsmLexer interface.
llvm-svn: 94125
2010-01-22 00:58:59 +00:00
Chris Lattner
0ce1aa4aa6 remove a couple of asserts that use RTTI.
llvm-svn: 94068
2010-01-21 06:11:03 +00:00
Chris Lattner
15e2a64ec2 stop using the .lcomm pseudoop on darwin, instead, directly use the
.zerofill directive.  Streamerize its generation.

llvm-svn: 93868
2010-01-19 06:25:51 +00:00
Chris Lattner
b5e64bd377 use BSSLocal classifier to identify 'lcomm' data instead of
duplicating the logic (differently) in lots of different targets.

llvm-svn: 93847
2010-01-19 04:21:20 +00:00
Chris Lattner
53d8210a69 change an accessor to a predicate.
llvm-svn: 93839
2010-01-19 02:13:06 +00:00
Chris Lattner
816fcd1287 Cleanup handling of .zerofill on darwin:
1. TargetLoweringObjectFileMachO should decide if something
   goes in zerofill instead of having every target do it.
2. TargetLoweringObjectFileMachO should assign said symbols to
   the right MCSection, the asmprinters should just emit to the
   right section.
3. Since all zerofill stuff goes through mcstreamer anymore,
   MAI can have a bool "haszerofill" instead of having the textual
   directive to emit.

llvm-svn: 93838
2010-01-19 02:09:44 +00:00
Bill Wendling
58d26c105b - Add getLSDAEncoding to the PowerPC backend.
- Greatly improve the comments to the getLSDAEncoding method.

llvm-svn: 93796
2010-01-18 22:36:35 +00:00
Bill Wendling
5678a9711b - Add a comment to the callback indicating that it's *extremely* not a good
idea, but unfortunately necessary.
- Default to using 4-bytes for the LSDA pointer encoding to agree with the
  encoded value in the CIE.

llvm-svn: 93753
2010-01-18 19:36:27 +00:00
Benjamin Kramer
35bf21a0d2 Unnamed symbol index should be >= 1. This was lost during the mangler refactoring. Fixes PR6067.
llvm-svn: 93724
2010-01-18 14:39:20 +00:00
Chris Lattner
c2047ba3e4 stop the CBE from using Mangler::appendMangledName, which is a private function, it is mangling types, which don't matter how they are done.
llvm-svn: 93692
2010-01-17 19:32:29 +00:00
Chris Lattner
5607355614 fix uninit member, thanks to Benjamin Kramer for identifying the bug.
llvm-svn: 93691
2010-01-17 19:24:35 +00:00
Chris Lattner
f7c6508544 Get MCSymbol out of the mangling business, and move all the logic
to Mangler.  Now MCSymbol just decides whether to slap quotes around
a symbol when printing it.

This also fixes some weirdness where two MCSymbols could be created
for the same symbol, if one needed to be mangled and got mangled to
the other one.

llvm-svn: 93690
2010-01-17 19:23:46 +00:00
Chris Lattner
57ac0be2b5 now that mangler is in libtarget, it can use MCAsmInfo instead of clients
having to pass various fields from it in.  Simplify.

llvm-svn: 93686
2010-01-17 18:22:35 +00:00
Chris Lattner
51e8abe640 move the mangler into libtarget from vmcore.
llvm-svn: 93664
2010-01-16 21:57:06 +00:00
Bill Wendling
d78fcdd332 Retrying r91337:
The CIE says that the LSDA point in the FDE section is an "sdata4". That's fine,
but we need it to actually be 4-bytes in the FDE for some platforms. Allow
individual platforms to decide for themselves.

llvm-svn: 93616
2010-01-16 01:40:55 +00:00
Dale Johannesen
7a3b1c5ffc DEBUG_VALUE is now variable sized, as it has a
target-dependent memory address representation in it.
Restore X86 printing of DEBUG_VALUE; lowering is
done in X86RegisterInfo using the normal algorithm.

llvm-svn: 93565
2010-01-15 22:22:35 +00:00
Nate Begeman
b6c8d75f62 Hook up llc's -filetype=obj to use MCStreamer if an MCCodeEmitter is available.
Remove most of old Mach-O Writer support, it has been replaced by MCMachOStreamer

Further refactoring to completely remove MachOWriter and drive the object file
writer with the AsmPrinter MCInst/MCSection logic is forthcoming.

llvm-svn: 93527
2010-01-15 18:51:18 +00:00
Dale Johannesen
c396179c7e Remove DEBUG_DECLARE, looks like we don't need it.
Also, DEBUG_VALUE has side effects.

llvm-svn: 93498
2010-01-15 01:50:44 +00:00
Chris Lattner
882cb240a6 Split the TargetAsmParser "ParseInstruction" interface in half:
the new ParseInstruction method just parses and returns a list of
target operands.  A new MatchInstruction interface is used to
turn the operand list into an MCInst.

This requires new/deleting all the operands, but it also gives 
targets the ability to use polymorphic operands if they want to. 

llvm-svn: 93469
2010-01-14 22:21:20 +00:00
Chris Lattner
ceabb11a5e prune #includes in TargetAsmParser.h
Pass in SMLoc of instr opcode into ParseInstruction.
Make AsmToken be a class, not a struct.

llvm-svn: 93457
2010-01-14 21:32:45 +00:00
Chris Lattner
3c2fad1fc6 change Mangler::makeNameProper to return its result in a SmallVector
instead of returning it in an std::string.  Based on this change:

1. Change TargetLoweringObjectFileCOFF::getCOFFSection to take a StringRef
2. Change a bunch of targets to call makeNameProper with a smallstring,
   making several of them *much* more efficient.
3. Rewrite Mangler::makeNameProper to not build names and then prepend
   prefixes, not use temporary std::strings, and to avoid other crimes.

llvm-svn: 93298
2010-01-13 06:38:18 +00:00
Dale Johannesen
ee679ebe05 Fix a comment.
llvm-svn: 93284
2010-01-13 01:39:38 +00:00
Evan Cheng
76db3bb18e Add a quick pass to optimize sign / zero extension instructions. For targets where the pre-extension values are available in the subreg of the result of the extension, replace the uses of the pre-extension value with the result + extract_subreg.
For now, this pass is fairly conservative. It only perform the replacement when both the pre- and post- extension values are used in the block. It will miss cases where the post-extension values are live, but not used.

llvm-svn: 93278
2010-01-13 00:30:23 +00:00