Commit Graph

531 Commits

Author SHA1 Message Date
Diana Picus ca6a890d7f [ARM] GlobalISel: Lower double precision FP args
For the hard float calling convention, we just use the D registers.

For the soft-fp calling convention, we use the R registers and move values
to/from the D registers by means of G_SEQUENCE/G_EXTRACT. While doing so, we
make sure to honor the endianness of the target, since the CCAssignFn doesn't do
that for us.

For pure soft float targets, we still bail out because we don't support the
libcalls yet.

llvm-svn: 295295
2017-02-16 07:53:07 +00:00
Tim Northover 9136617a3f GlobalISel: legalize va_arg on AArch64.
Uses a Custom implementation because the slot sizes being a multiple of the
pointer size isn't really universal, even for the architectures that do have a
simple "void *" va_list.

llvm-svn: 295255
2017-02-15 23:22:50 +00:00
Tim Northover 4a652227dd GlobalISel: support translating va_arg
Since (say) i128 and [16 x i8] map to the same type in generic MIR, we also
need to attach the required alignment info.

llvm-svn: 295254
2017-02-15 23:22:33 +00:00
Tim Northover c2f8956313 GlobalISel: introduce G_PTR_MASK to simplify alloca handling.
This instruction clears the low bits of a pointer without requiring (possibly
dodgy if pointers aren't ints) conversions to and from an integer. Since (as
far as I'm aware) all masks are statically known, the instruction takes an
immediate operand rather than a register to specify the mask.

llvm-svn: 295103
2017-02-14 20:56:18 +00:00
Tim Northover 48dfa1a6ed GlobalISel: represent atomic loads & stores via the MachineMemOperand.
Also make sure the AArch64 backend doesn't try to convert them into normal
loads and stores.

llvm-svn: 294993
2017-02-13 22:14:16 +00:00
Tim Northover 0e01170c79 GlobalISel: drop lifetime intrinsics during translation.
We don't use them yet and they just cause problems.

llvm-svn: 294770
2017-02-10 19:10:38 +00:00
Tim Northover e041841811 GlobalISel: legalize G_FPOW to a libcall on AArch64.
There's no instruction to implement it.

llvm-svn: 294531
2017-02-08 23:23:39 +00:00
Tim Northover b38b4e2464 GlobalISel: translate @llvm.pow intrinsic to G_FPOW.
It'll usually be immediately legalized back to a libcall, but occasionally
something can be done with it so we'd just as well enable that flexibility from
the start.

llvm-svn: 294530
2017-02-08 23:23:32 +00:00
Tim Northover 0a9b27933a GlobalISel: expand mul-with-overflow into mul-hi on AArch64.
AArch64 has specific instructions to multiply two numbers at double the width
and produce the high part of the result. These can be used to implement LLVM's
mul.with.overflow instructions fairly simply. Helps with C++ operator new[].

llvm-svn: 294519
2017-02-08 21:22:15 +00:00
Tim Northover f19d467ff6 GlobalISel: translate @llvm.va_start intrinsic.
Because we need to preserve the memory access being performed we need a
separate instruction to represent this.

llvm-svn: 294492
2017-02-08 17:57:20 +00:00
Tim Northover d0d025ae45 GlobalISel: translate @llvm.va_end intrinsic.
Turns out no-one actually cares about this one (at least) in tree so we can
just drop it entirely.

llvm-svn: 294345
2017-02-07 20:08:59 +00:00
Tim Northover 868332d6bf GlobalISel: legalize narrow G_SELECTS on AArch64.
Otherwise there aren't any patterns to select them.

llvm-svn: 294261
2017-02-06 23:41:27 +00:00
Tim Northover 0e6afbdd77 GlobalISel: legalize G_INSERT instructions
We don't handle all cases yet (see arm64-fallback.ll for an example), but this
is enough to cover most common C++ code so it's a good place to start.

llvm-svn: 294247
2017-02-06 21:56:47 +00:00
Tim Northover c3e3f59d12 GlobalISel: translate dynamic alloca instructions.
llvm-svn: 294022
2017-02-03 18:22:45 +00:00
Tim Northover c6bfa481cf GlobalISel: the translation of an invoke must branch to the good block.
Otherwise bad things happen if the basic block order isn't trivial after an
invoke.

llvm-svn: 293679
2017-01-31 20:12:18 +00:00
Tim Northover 293f74355b GlobalISel: merge invoke and call translation paths.
Well, sort of. But the lower-level code that invoke used to be using completely
botched the handling of varargs functions, which hopefully won't be possible if
they're using the same code.

llvm-svn: 293670
2017-01-31 18:36:11 +00:00
Tim Northover 2bf8c9d381 GlobalISel: correctly translate invoke when callee is a register.
This should fix the GlobalISel verifier.

llvm-svn: 293550
2017-01-30 21:45:21 +00:00
Tim Northover c944970484 GlobalISel: account for differing exception selector sizes.
For some reason the exception selector register must be a pointer (that's
assumed by SDag); on the other hand, it gets moved into an IR-level type which
might be entirely different (i32 on AArch64). IRTranslator needs to be aware of
this.

llvm-svn: 293546
2017-01-30 20:52:42 +00:00
Tim Northover c94d70336b GlobalISel: tidy up def/use test. NFC.
llvm-svn: 293545
2017-01-30 20:52:37 +00:00
Tim Northover 79f43f195c GlobalISel: translate memset & memmove.
llvm-svn: 293541
2017-01-30 19:33:07 +00:00
Tim Northover 480609d0f3 GlobalISel: permit unused vregs without a register-class after ISel.
This can happen if earlier combining has removed all uses of some VReg, which
is fine and shouldn't flag an error.

llvm-svn: 293537
2017-01-30 19:12:50 +00:00
David Blaikie a66696f210 unique_ptrify some containers in GlobalISel::RegisterBankInfo
To simplify/clarify memory ownership, make leaks (as one was found/fixed
recently) harder to write, etc.

(also, while I was there - removed a duplicate lookup in a container)

llvm-svn: 293506
2017-01-30 17:13:56 +00:00
Kristof Beyls 65a12c012f [GlobalISel] Add support for indirectbr
Differential Revision: https://reviews.llvm.org/D28079

llvm-svn: 293470
2017-01-30 09:13:18 +00:00
Quentin Colombet 8cf1163c4f [RegisterBankInfo] Emit proper type for remapped registers.
When the OperandsMapper creates virtual registers, it used to just create
plain scalar register with the right size. This may confuse the
instruction selector because we lose the information of the instruction
using those registers what supposed to do. The MachineVerifier complains
about that already.

With this patch, the OperandsMapper still creates plain scalar register,
but the expectation is for the mapping function to remap the type
properly. The default mapping function has been updated to do that.

rdar://problem/30231850

llvm-svn: 293362
2017-01-28 02:23:48 +00:00
Matthias Braun 8c209aa877 Cleanup dump() functions.
We had various variants of defining dump() functions in LLVM. Normalize
them (this should just consistently implement the things discussed in
http://lists.llvm.org/pipermail/cfe-dev/2014-January/034323.html

For reference:
- Public headers should just declare the dump() method but not use
  LLVM_DUMP_METHOD or #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
- The definition of a dump method should look like this:
  #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
  LLVM_DUMP_METHOD void MyClass::dump() {
    // print stuff to dbgs()...
  }
  #endif

llvm-svn: 293359
2017-01-28 02:02:38 +00:00
Evgeniy Stepanov d0852873e5 Fix memory leak in globalisel.
#0 0x89cdeb in operator new[](unsigned long) /code/llvm/projects/compiler-rt/lib/asan/asan_new_delete.cc:84:37
    #1 0x4ec87c4 in llvm::RegisterBankInfo::ValueMapping const* llvm::RegisterBankInfo::getOperandsMapping<llvm::RegisterBankInfo::ValueMapping const* const*>(llvm::RegisterBankInfo::ValueMapping const* const*, llvm::RegisterBankInfo::ValueMapping const* const*) const /code/llvm/lib/CodeGen/GlobalISel/RegisterBankInfo.cpp:297:9
    #2 0x9327ee in llvm::AArch64RegisterBankInfo::getInstrMapping(llvm::MachineInstr const&) const /code/llvm/lib/Target/AArch64/AArch64RegisterBankInfo.cpp:540:30
    #3 0x4eb8d07 in llvm::RegBankSelect::assignInstr(llvm::MachineInstr&) /code/llvm/lib/CodeGen/GlobalISel/RegBankSelect.cpp:546:24
    #4 0x4eb9dd2 in llvm::RegBankSelect::runOnMachineFunction(llvm::MachineFunction&) /code/llvm/lib/CodeGen/GlobalISel/RegBankSelect.cpp:624:12
    #5 0x3141875 in llvm::MachineFunctionPass::runOnFunction(llvm::Function&) /code/llvm/lib/CodeGen/MachineFunctionPass.cpp:62:13
    #6 0x396128d in llvm::FPPassManager::runOnFunction(llvm::Function&) /code/llvm/lib/IR/LegacyPassManager.cpp:1513:27
    #7 0x3961832 in llvm::FPPassManager::runOnModule(llvm::Module&) /code/llvm/lib/IR/LegacyPassManager.cpp:1534:16
    #8 0x3962540 in runOnModule /code/llvm/lib/IR/LegacyPassManager.cpp:1590:27
    #9 0x3962540 in llvm::legacy::PassManagerImpl::run(llvm::Module&) /code/llvm/lib/IR/LegacyPassManager.cpp:1693
    #10 0x8ae368 in compileModule(char**, llvm::LLVMContext&) /code/llvm/tools/llc/llc.cpp:562:8
    #11 0x8a7a1b in main /code/llvm/tools/llc/llc.cpp:316:22

llvm-svn: 293351
2017-01-28 00:46:30 +00:00
Tim Northover 12bd22fbee GlobalISel: don't leak super-entry BB when merging with IR-level one.
We have to delete the block manually or it leaks. That triggers failures in
-fsanitize=leak bots (unsurprisingly), which should be fixed by this patch.

llvm-svn: 293347
2017-01-27 23:54:31 +00:00
Tim Northover d8b85584f2 GlobalISel: set correct regclass for LOAD_STACK_GUARD.
Since it's not actually a generic MI, its register operands need a RegClass,
which is conveniently the target's pointer RegClass.

llvm-svn: 293335
2017-01-27 21:31:24 +00:00
Tim Northover c9bc8a5580 GlobalISel: mark incoming landing-pad registers as live.
Should fix machine verifier failures.

llvm-svn: 293334
2017-01-27 21:31:17 +00:00
Tim Northover 09aac4ad2a GlobalISel: support debug intrinsics.
The translation scheme is mostly cribbed from FastISel, and it's not entirely
convincing semantically. But it does seem to work in the common cases and allow
variables to be printed so it can't be all wrong.

llvm-svn: 293228
2017-01-26 23:39:14 +00:00
Tim Northover 9e35f1e21c GlobalISel: rework getOrCreateVReg to avoid double lookup. NFC.
Thanks to Quentin for suggesting the refactoring.

llvm-svn: 293087
2017-01-25 20:58:22 +00:00
Justin Bogner 4844573eb1 GlobalISel: Fix typo in error message
llvm-svn: 293023
2017-01-25 06:02:10 +00:00
Ahmed Bougacha eb185e1f64 Try to prevent build breakage by touching a CMakeLists.txt.
Looks like our cmake goop for handling .inc->td dependencies doesn't
track the .td files.

This manifests as cmake complaining about missing files since r293009.

Force a rerun to avoid that.

llvm-svn: 293012
2017-01-25 02:55:24 +00:00
Justin Bogner a029531e10 GlobalISel: Use the correct types when translating landingpad instructions
There was a bug here where we were using p0 instead of s32 for the
selector type in the landingpad. Instead of hardcoding these types we
should get the types from the landingpad instruction directly.

Note that we replicate an assert from SDAG here to only support
two-valued landingpads.

llvm-svn: 292995
2017-01-25 00:16:53 +00:00
Ahmed Bougacha b6137063eb [AArch64][GlobalISel] Legalize narrow scalar fp->int conversions.
Since we're now avoiding operations using narrow scalar integer types,
we have to legalize the integer side of the FP conversions.

This requires teaching the legalizer how to do that.

llvm-svn: 292828
2017-01-23 21:10:14 +00:00
Tim Northover 7f3ad2e07b GlobalISel: prevent heap use-after-free when looking up VReg.
Translating the constant can create more VRegs, which can invalidate the
reference into the DenseMap. So we have to look up the value again after all
that's happened.

llvm-svn: 292675
2017-01-20 23:25:17 +00:00
Ahmed Bougacha d294823930 [AArch64][GlobalISel] Widen scalar int->fp conversions.
It's incorrect to ignore the higher bits of the integer source.
Teach the legalizer how to widen it.

llvm-svn: 292563
2017-01-20 01:37:24 +00:00
Justin Bogner e094cc4372 GlobalISel: Add a note about how we're being a bit loose with memory operands
The logic in r292461 is conservatively correct, but we should revisit
this later. Add a TODO so we don't forget.

llvm-svn: 292553
2017-01-20 00:30:17 +00:00
Justin Bogner 680663931c GlobalISel: Only set FailedISel on dropped dbg intrinsics when using fallback
It's easier to test the non-fallback path if we just drop these
intrinsics for now, like we did before we added the fallback path.
We'll obviously need to fix this properly, but the fixme for that is
already here.

llvm-svn: 292547
2017-01-20 00:24:30 +00:00
Justin Bogner 23acaf07de GlobalISel: Pass the MachineFunction in to reportSelectionError directly
Rather than trying to find MF based on the possibly-null MI we've
passed in here, just pass it in directly. It's already available at
all callers anyway.

llvm-svn: 292544
2017-01-20 00:16:19 +00:00
Tim Northover 3babfef11d AArch64: fall back to DAG ISel for inline assembly.
We can't currently handle "calls" to inlineasm strings so it's better to let
the DAG handle it than generate rubbish.

llvm-svn: 292540
2017-01-19 23:59:35 +00:00
Daniel Sanders d64d5024a4 Re-commit: [globalisel] Tablegen-erate current Register Bank Information
Summary:
Adds a RegisterBank tablegen class that can be used to declare the register
banks and an associated tablegen pass to generate the necessary code.

Changes since first commit attempt:
* Added missing guards
* Added more missing guards
* Found and fixed a use-after-free bug involving Twine locals

Reviewers: t.p.northover, ab, rovka, qcolombet

Reviewed By: qcolombet

Subscribers: aditya_nandakumar, rengolin, kristof.beyls, vkalintiris, mgorny, dberris, llvm-commits, rovka

Differential Revision: https://reviews.llvm.org/D27338

llvm-svn: 292478
2017-01-19 11:15:55 +00:00
Justin Bogner ddb80aee7e GlobalISel: Implement widening for shifts
llvm-svn: 292476
2017-01-19 07:51:17 +00:00
Justin Bogner d09c3ce6c0 GlobalISel: Implement narrowing for G_LOAD
llvm-svn: 292461
2017-01-19 01:05:48 +00:00
Justin Bogner 1f5c505437 GlobalISel: Fix text wrapping in a comment. NFC
llvm-svn: 292460
2017-01-19 01:04:46 +00:00
Justin Bogner fde0104649 GlobalISel: Implement narrowing for G_STORE
Legalize stores of types that are too wide by breaking them up into
sequences of smaller stores.

llvm-svn: 292412
2017-01-18 17:29:54 +00:00
Daniel Sanders af76f989b5 Re-revert: [globalisel] Tablegen-erate current Register Bank Information
More missing guards. My build didn't notice it due to a stale file left over
from a Global ISel build.

llvm-svn: 292369
2017-01-18 14:26:12 +00:00
Daniel Sanders 517b61cb69 Re-commit: [globalisel] Tablegen-erate current Register Bank Information
Summary:
Adds a RegisterBank tablegen class that can be used to declare the register
banks and an associated tablegen pass to generate the necessary code.

Changes since last commit:
The new tablegen pass is now correctly guarded by LLVM_BUILD_GLOBAL_ISEL and
this should fix the buildbots however it may not be the whole fix. The previous
buildbot failures suggest there may be a memory bug lurking that I'm unable to
reproduce (including when using asan) or spot in the source. If they re-occur
on this commit then I'll need assistance from the bot owners to track it down.

Reviewers: t.p.northover, ab, rovka, qcolombet

Reviewed By: qcolombet

Subscribers: aditya_nandakumar, rengolin, kristof.beyls, vkalintiris, mgorny, dberris, llvm-commits, rovka

Differential Revision: https://reviews.llvm.org/D27338

llvm-svn: 292367
2017-01-18 14:17:50 +00:00
Tim Northover d943354216 GlobalISel: correctly handle varargs
Some platforms (notably iOS) use a different calling convention for unnamed vs
named parameters in varargs functions, so we need to keep track of this
information when translating calls.

Since not many platforms are involved, the guts of the special handling is in
the ValueHandler class (with a generic implementation that should work for most
targets).

llvm-svn: 292283
2017-01-17 22:30:10 +00:00
Tim Northover b6636fd392 [GlobalISel] track predecessor mapping during switch lowering.
Correctly populating Machine PHIs relies on knowing exactly how the IR level
CFG was lowered to MachineIR. This needs to be tracked by any translation
phases that meddle (currently only SwitchInst handling).

This reapplies r291973 which was reverted because of testing failures. Fixes:

 + Don't return an ArrayRef to a local temporary.
 + Incorporate Kristof's suggested comment improvements.

llvm-svn: 292278
2017-01-17 22:13:50 +00:00
Daniel Sanders a83a1a69c5 Revert r292132: [globalisel] Tablegen-erate current Register Bank Information'...
Several buildbots encountered a crash in tablegen when building this commit.
Reverting while I investigate the cause.

llvm-svn: 292136
2017-01-16 15:34:43 +00:00
Daniel Sanders ab8194def0 [globalisel] Tablegen-erate current Register Bank Information
Summary:
Adds a RegisterBank tablegen class that can be used to declare the register
banks and an associated tablegen pass to generate the necessary code.

Reviewers: t.p.northover, ab, rovka, qcolombet

Subscribers: aditya_nandakumar, rengolin, kristof.beyls, vkalintiris, mgorny, dberris, llvm-commits, rovka

Differential Revision: https://reviews.llvm.org/D27338

llvm-svn: 292132
2017-01-16 15:20:43 +00:00
Daniel Jasper bf56ad36cb Revert "[GlobalISel] track predecessor mapping during switch lowering."
This reverts commit r291973.

The test fails in a Release build with LLVM_BUILD_GLOBAL_ISEL enabled.
AFAICT, llc segfaults. I'll add a few more details to the original
commit.

llvm-svn: 292061
2017-01-15 09:41:49 +00:00
Tim Northover 2b57987827 [GlobalISel] track predecessor mapping during switch lowering.
Correctly populating Machine PHIs relies on knowing exactly how the IR level
CFG was lowered to MachineIR. This needs to be tracked by any translation
phases that meddle (currently only SwitchInst handling).

llvm-svn: 291973
2017-01-13 23:11:37 +00:00
Benjamin Kramer 061f4a5fe6 Apply clang-tidy's performance-unnecessary-value-param to LLVM.
With some minor manual fixes for using function_ref instead of
std::function. No functional change intended.

llvm-svn: 291904
2017-01-13 14:39:03 +00:00
Daniel Sanders b7391dd3b4 [globalisel] Move as much RegisterBank initialization to the constructor as possible
Summary:
The register bank is now entirely initialized in the constructor. However,
we still have the hardcoded number of register classes which will be
dealt with in the TableGen patch (D27338) since we do not have access
to this information to resolve this at this stage. The number of register
classes is known to the TRI and to TableGen but the RegisterBank
constructor is too early for the former and too late for the latter.
This will be fixed when the data is tablegen-erated.

Reviewers: t.p.northover, ab, rovka, qcolombet

Subscribers: aditya_nandakumar, kristof.beyls, vkalintiris, llvm-commits, dberris

Differential Revision: https://reviews.llvm.org/D27809

llvm-svn: 291770
2017-01-12 16:11:23 +00:00
Daniel Sanders ae03595bfb [globalisel] Initialize RegisterBanks with static data.
Summary:
Refactor the RegisterBank initialization to use static data. This requires
GlobalISel implementations to rewrite calls to createRegisterBank() and
addRegBankCoverage() into a call to setRegBankData().

Out of tree targets can use diff 4 of D27807
(https://reviews.llvm.org/D27807?id=84117) to have addRegBankCoverage() dump
the register classes and other data that needs to be provided to
setRegBankData(). This is the method that was used to generate the static data
in this patch.

Tablegen-eration of this static data will follow after some refactoring.

Reviewers: t.p.northover, ab, rovka, qcolombet

Subscribers: aditya_nandakumar, kristof.beyls, vkalintiris, llvm-commits, dberris

Differential Revision: https://reviews.llvm.org/D27807
Differential Revision: https://reviews.llvm.org/D27808

llvm-svn: 291768
2017-01-12 15:32:10 +00:00
Tim Northover 778d0816ab GlobalISel: only print debug info with -debug. NFC.
Turns out DEBUG(...) has uses even inside NDEBUG checks.

llvm-svn: 291685
2017-01-11 17:33:37 +00:00
Quentin Colombet 0b63b31b2e [RegBankSelect] Improve the output of the debug messages.
Add more information about mapping cost and chosen solution.

llvm-svn: 291629
2017-01-11 00:48:41 +00:00
Daniel Sanders 12360efa76 [globalisel] Stop requiring -debug/-debug-only=registerbankinfo for assertions.
Summary:
I've noticed that these assertions don't trigger when the condition is false.
The problem is that the DEBUG(x) macro only executes x when the pass is
emitting debug output via the -debug and -debug-only=registerbankinfo command
line arguments.

Debug builds should always execute the assertions so use '#ifndef NDEBUG' instead.

Also removed an assertion that is only true the first time it's tested. <Target>RegisterBankInfo's constructor will re-use register banks causing them to be valid on subsequent tests. That
assertion will fail on the first test too in the near future.

Reviewers: t.p.northover, ab, rovka, qcolombet

Subscribers: dberris, llvm-commits, kristof.beyls

Differential Revision: https://reviews.llvm.org/D28358

llvm-svn: 291235
2017-01-06 14:29:34 +00:00
Kristof Beyls a983e7c4a4 [GlobalISel] Add support for address-taken basic blocks
To make this work, pointers from the MachineBasicBlock to the LLVM-IR-level
basic blocks need to be initialized, as the AsmPrinter uses this link to be
able to print out labels for the basic blocks that are address-taken.

Most of the changes in this commit are about adapting existing tests to include
the basic block name that is now printed out in the MIR format, now that the
name becomes available as the link to the LLVM-IR basic block is initialized.
The relevant test change for the functionality added in this patch are the
added "(address-taken)" strings in
test/CodeGen/AArch64/GlobalISel/arm64-irtranslator.ll.

Differential Revision: https://reviews.llvm.org/D28123

llvm-svn: 291105
2017-01-05 13:27:52 +00:00
Kristof Beyls eced071e88 [GlobalISel] Add support for switch statements
This commit does this using a trivial chain of conditional branches.  In the
future, we probably want to reuse the optimized switch lowering used in
SelectionDAG.

Differential Revision: https://reviews.llvm.org/D28176

llvm-svn: 291099
2017-01-05 11:28:51 +00:00
Quentin Colombet 7e1f66d6f5 [RegisterBankInfo] Allow to set a register class when nothing else is set
This is going to be needed to be able to constraint register class on
target specific instruction while the RegBankSelect pass did not run
yet.

llvm-svn: 290375
2016-12-22 21:56:26 +00:00
Quentin Colombet b4e71185b2 [GlobalISel] Refactor the logic to constraint registers.
Move the logic to constraint register from InstructionSelector to a
utility function. It will be required by other passes in the GlobalISel
pipeline.

llvm-svn: 290374
2016-12-22 21:56:19 +00:00
Diana Picus 812caee65a [ARM] GlobalISel: Select add i32, i32
Add the minimal support necessary to select a function that returns the sum of
two i32 values.

This includes some support for argument/return lowering of i32 values through
registers, as well as the handling of copy and add instructions throughout the
GlobalISel pipeline.

Differential Revision: https://reviews.llvm.org/D26677

llvm-svn: 289940
2016-12-16 12:54:46 +00:00
Quentin Colombet 327f942876 [IRTranslator] Merge the entry and ABI lowering blocks.
The IRTranslator uses an additional block before the LLVM-IR entry block
to perform all the ABI lowering and the constant hoisting. Thus, this
block is the actual entry block and it falls through the LLVM-IR entry
block. However, with such representation, we end up with two basic
blocks that are not maximal.

Therefore, this patch adds a bit of canonicalization by merging both the
LLVM-IR entry block and the ABI lowering/constants hoisting into one
block, making the resulting block more likely to be maximal (indeed the
LLVM-IR entry block might not have been maximal).

llvm-svn: 289891
2016-12-15 23:32:25 +00:00
Diana Picus 2d9adbf524 [GlobalISel] Move extendRegister where it belongs. NFCI
Apparently I missed this one when I moved ValueHandler back in r288658. Sorry!

llvm-svn: 289528
2016-12-13 10:46:12 +00:00
Tim Northover b58346f2f2 GlobalISel: fall back gracefully for debug intrinsics.
Supporting them properly is a reasonably complex chunk of work, so to allow bot
testing before then we should at least be able to fall back to DAG ISel.

llvm-svn: 289150
2016-12-08 22:44:13 +00:00
Tim Northover 1e656ec137 GlobalISel: factor overflow handling into separate function. NFC.
llvm-svn: 289149
2016-12-08 22:44:00 +00:00
Tim Northover c53606ef02 GlobalISel: use correct builder for ConstantExprs.
ConstantExpr instances were emitting code into the current block rather than
the entry block. This meant they didn't necessarily dominate all uses, which is
clearly wrong.

llvm-svn: 288985
2016-12-07 21:29:15 +00:00
Tim Northover 50db7f416c GlobalISel: store the current MachineFunction as direct state. NFC.
Having to ask the MIRBuilder for the current function is a little awkward, and
I'm intending to improve how that's threaded through anyway.

llvm-svn: 288983
2016-12-07 21:17:47 +00:00
Tim Northover 05cc4859ad GlobalISel: simplify MachineIRBuilder interface.
MachineIRBuilder had weird before/after and beginning/end flags for the insert
point. Unfortunately the non-default means that instructions will be inserted
in reverse order which is almost never what anyone wants.

Really, I think we just want (like IRBuilder has) the ability to insert at any
C++ iterator-style point (i.e. before any instruction or before MBB.end()). So
this fixes MIRBuilders to behave like IRBuilders in this respect.

llvm-svn: 288980
2016-12-07 21:05:38 +00:00
Tim Northover 14ceb45fb4 GlobalISel: correctly handle small args via memory.
We were rounding size in bits down rather than up, leading to 0-sized slots for
i1 (assert!) and bugs for other types not byte-aligned.

llvm-svn: 288848
2016-12-06 21:02:19 +00:00
Tim Northover 0a683e7bfd GlobalISel: fall back gracefully when we hit unhandled legalizer default.
llvm-svn: 288840
2016-12-06 19:02:15 +00:00
Tim Northover c1a23854f3 GlobalISel: handle G_SEQUENCE fallbacks gracefully.
There were two problems:
  + AArch64 was reusing random data from its binary op tables, which is
    complete nonsense for G_SEQUENCE.
  + Even when AArch64 gave up and said it couldn't handle G_SEQUENCE,
    the generic code asserted.

llvm-svn: 288836
2016-12-06 18:38:38 +00:00
Tim Northover f50f2f3d32 GlobalISel: allow G_SELECT instructions for pointers.
llvm-svn: 288835
2016-12-06 18:38:34 +00:00
Tim Northover 405e25cd6a GlobalISel: stop the legalizer from trying to handle oddly-sized types.
It'll almost immediately fail because it always tries to half/double the size
until it finds a legal one. Unfortunately, this triggers an assertion
preventing the DAG fallback from being possible.

llvm-svn: 288834
2016-12-06 18:38:29 +00:00
Sam McCall 03435f57aa Add missing parens in assert.
Summary: Add missing parens in assert, which warn in GCC.

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D27448

llvm-svn: 288792
2016-12-06 10:14:36 +00:00
Tim Northover 800638fd67 GlobalISel: avoid looking too closely at PHIs when we bail.
The function used to finish off PHIs by adding the relevant basic blocks can
fail if we're aborting and still don't actually have the needed
MachineBasicBlocks. So avoid trying in that case.

llvm-svn: 288727
2016-12-05 23:10:19 +00:00
Tim Northover b566848d68 GlobalISel: place constants correctly in the entry block.
When the entry block was empty after arg lowering, we were always placing
constants at the end. This is probably hamrless while translating the same
block, but horribly wrong once its terminator has been translated. So switch to
inserting at the beginning.

llvm-svn: 288720
2016-12-05 22:40:13 +00:00
Tim Northover c0bd197c6b GlobalISel: handle pointer arguments that get assigned to the stack.
llvm-svn: 288717
2016-12-05 22:20:32 +00:00
Tim Northover cc35f90492 GlobalISel: translate constants larger than 64 bits.
llvm-svn: 288713
2016-12-05 21:54:17 +00:00
Tim Northover 9267ac5d47 GlobalISel: make G_CONSTANT take a ConstantInt rather than int64_t.
This makes it more similar to the floating-point constant, and also allows for
larger constants to be translated later. There's no real functional change in
this patch though, just syntax updates.

llvm-svn: 288712
2016-12-05 21:47:07 +00:00
Tim Northover 6ad7b9f837 GlobalISel: improve translation fallback for constants.
Returning 0 (NoReg) from getOrCreateVReg leads to unexpected situations later
in the translation. It's better to return a valid (if undefined) register and
let the rest of the instruction carry on as planned.

llvm-svn: 288709
2016-12-05 21:40:33 +00:00
Diana Picus f11f042ecb [GlobalISel] Extract handleAssignments out of AArch64CallLowering
This function seems target-independent so far: all the target-specific behaviour
is isolated in the CCAssignFn and the ValueHandler (which we're also extracting
into the generic CallLowering).

The intention is to use this in the ARM backend.

Differential Revision: https://reviews.llvm.org/D27045

llvm-svn: 288658
2016-12-05 10:40:33 +00:00
Peter Collingbourne 25a40759c1 Fix GlobalISel build.
llvm-svn: 288460
2016-12-02 02:55:30 +00:00
Matthias Braun d0ee66c2e9 Move most EH from MachineModuleInfo to MachineFunction
Recommitting r288293 with some extra fixes for GlobalISel code.

Most of the exception handling members in MachineModuleInfo is actually
per function data (talks about the "current function") so it is better
to keep it at the function instead of the module.

This is a necessary step to have machine module passes work properly.

Also:
- Rename TidyLandingPads() to tidyLandingPads()
- Use doxygen member groups instead of "//===- EH ---"... so it is clear
  where a group ends.
- I had to add an ugly const_cast at two places in the AsmPrinter
  because the available MachineFunction pointers are const, but the code
  wants to call tidyLandingPads() in between
  (markFunctionEnd()/endFunction()).

Differential Revision: https://reviews.llvm.org/D27227

llvm-svn: 288405
2016-12-01 19:32:15 +00:00
Tom Stellard df613198c0 GlobalISel: Fix unconditional fallback with global isel abort is disabled
Reviewers: t.p.northover, ab, qcolombet

Subscribers: mehdi_amini, vkalintiris, wdng, dberris, llvm-commits, rovka

Differential Revision: https://reviews.llvm.org/D26765

llvm-svn: 287344
2016-11-18 14:14:35 +00:00
Chris Bieneman 05c279fc4b [CMake] NFC. Updating CMake dependency specifications
This patch updates a bunch of places where add_dependencies was being explicitly called to add dependencies on intrinsics_gen to instead use the DEPENDS named parameter. This cleanup is needed for a patch I'm working on to add a dependency debugging mode to the build system.

llvm-svn: 287206
2016-11-17 04:36:50 +00:00
Ahmed Bougacha bd6ce9a247 [CodeGen] Pass references, not pointers, to MMI helpers. NFC.
While there, rename them to follow the coding style.

llvm-svn: 287169
2016-11-16 22:25:03 +00:00
Ahmed Bougacha 996961a461 Revert "Get GlobalISel to build on Linux after r286407"
This reverts commit r286962.

We want to avoid depending on SelectionDAG, and AddLandingPadInfo
lives in CodeGen now.

llvm-svn: 287168
2016-11-16 22:24:59 +00:00
Ahmed Bougacha 456dce8a84 [CodeGen] Pull MMI helpers from FunctionLoweringInfo to MMI. NFC.
They're not SelectionDAG- or FunctionLoweringInfo-specific.  They
are, however, specific to building MMI from IR.
We could make them members, but it's nice having MMI be a "simple" data
structure and this logic kept separate.

This also lets us reuse them from GlobalISel.

llvm-svn: 287167
2016-11-16 22:24:56 +00:00
Diana Picus 3776e76201 Get GlobalISel to build on Linux after r286407
r286407 has introduced calls to llvm::AddLandingPadInfo, which lives in the
SelectionDAG component. Add it to LLVMBuild to avoid linker failures on Linux.

llvm-svn: 286962
2016-11-15 14:11:11 +00:00
Diana Picus bda7276120 GlobalISel: Fix indentation. NFC
llvm-svn: 286808
2016-11-14 10:25:43 +00:00
Tim Northover 09dd2496b7 GlobalISel: fix typo. NFC
llvm-svn: 286408
2016-11-09 22:40:02 +00:00
Tim Northover a9105be437 GlobalISel: translate invoke and landingpad instructions
Pretty bare-bones support for exception handling (no weird MSVC stuff, no SjLj
etc), but it should get things going.

llvm-svn: 286407
2016-11-09 22:39:54 +00:00
David L. Jones e09ae201f2 GlobalISel: make sure debugging variables are appropriately elided in release builds.
Summary:
There are two variables here that break. This change constrains both of them to
debug builds (via DEBUG() or #ifndef NDEBUG).

Reviewers: bkramer, t.p.northover

Subscribers: mehdi_amini, vkalintiris

Differential Revision: https://reviews.llvm.org/D26421

llvm-svn: 286300
2016-11-08 22:03:23 +00:00
Tim Northover 6cddfc14f9 GlobalISel: allow CodeGen to fallback on VReg type/class issues.
After instruction selection we perform some checks on each VReg just before
discarding the type information. These checks were assertions before, but that
breaks the fallback path so this patch moves the logic into the main flow and
reports a better error on failure.

llvm-svn: 286289
2016-11-08 20:39:03 +00:00
Ahmed Bougacha 53a03a28c4 [GlobalISel] Dump all instructions inserted by selector.
This is helpful when multiple instructions are inserted.

llvm-svn: 286273
2016-11-08 19:27:13 +00:00
Ahmed Bougacha db273a1272 [GlobalISel] Permit select() to erase.
Erasing reverse_iterators is problematic; iterate manually.
While there, keep track of the range of inserted instructions.
It can miss instructions inserted elsewhere, but those are harder
to track.

Differential Revision: http://reviews.llvm.org/D22924

llvm-svn: 286272
2016-11-08 19:27:10 +00:00
Tim Northover 60f2349b50 GlobalISel: improve error diagnostics when IRTranslation fails.
llvm-svn: 286190
2016-11-08 01:12:17 +00:00
Tim Northover cdf23f1d93 GlobalISel: translate stack protector intrinsics
llvm-svn: 285614
2016-10-31 18:30:59 +00:00
Tim Northover e699929507 Revert r284604. A.K.A. "TMP"
Committed by mistake.

llvm-svn: 284606
2016-10-19 15:56:12 +00:00
Tim Northover 3d4cd3d930 TMP
llvm-svn: 284604
2016-10-19 15:55:09 +00:00
Tim Northover 7152dcaf77 GlobalISel: support translating volatile loads and stores.
llvm-svn: 284603
2016-10-19 15:55:06 +00:00
Tim Northover 6e9043009e GlobalISel: translate the @llvm.objectsize intrinsic.
llvm-svn: 284527
2016-10-18 20:03:51 +00:00
Tim Northover 3f18603c52 GlobalISel: translate memcpy intrinsics.
llvm-svn: 284525
2016-10-18 20:03:45 +00:00
Tim Northover 69fa84a6e9 GlobalISel: rename legalizer components to match others.
The previous names were both misleading (the MachineLegalizer actually
contained the info tables) and inconsistent with the selector & translator (in
having a "Machine") prefix. This should make everything sensible again.

The only functional change is the name of a couple of command-line options.

llvm-svn: 284287
2016-10-14 22:18:18 +00:00
Tim Northover bdf1624367 GlobalISel: select G_GLOBAL_VALUE uses on AArch64.
llvm-svn: 283809
2016-10-10 21:50:00 +00:00
Mehdi Amini 732afdd09a Turn cl::values() (for enum) from a vararg function to using C++ variadic template
The core of the change is supposed to be NFC, however it also fixes
what I believe was an undefined behavior when calling:

 va_start(ValueArgs, Desc);

with Desc being a StringRef.

Differential Revision: https://reviews.llvm.org/D25342

llvm-svn: 283671
2016-10-08 19:41:06 +00:00
Quentin Colombet 1b01677e61 [RegisterBankInfo] Change the default mapping for Copy and PHI.
Instead of producing a mapping for all the operands, we only generate a
mapping for the definition. Indeed, the other operands are not
constrained by the instruction and thus, we should leave the choice to
the actual definition to do the right thing.

In pratice this is almost NFC, but with one advantage. We will have only
one instance of OperandsMapping for each copy and phi that map to one
register bank instead of one different instance for each different
number of operands for each copy and phi.

llvm-svn: 282756
2016-09-29 19:51:46 +00:00
Quentin Colombet 40cbc27ff3 [RegisterBankInfo] Uniquely generate OperandsMapping.
This is a step toward statically allocate InstructionMapping. Like the
previous few commits, the goal is to move toward a TableGen'ed like
structure with no dynamic allocation at all.

This should already improve compile time by getting rid of a bunch of
memmove of SmallVectors.

llvm-svn: 282643
2016-09-28 22:20:49 +00:00
Quentin Colombet 97d2d21d65 [RegisterBankInfo] Rework the APIs of ValueMapping.
This is a preparatory commit for more TableGen-like structure.
NFC

llvm-svn: 282642
2016-09-28 22:20:24 +00:00
Quentin Colombet d816bfb282 [RegisterBankInfo] Constify the member of the XXXMapping maps.
This makes it obvious that items in those maps behave like statically
created objects.

llvm-svn: 282327
2016-09-24 04:54:03 +00:00
Quentin Colombet a50813f608 [RegisterBankInfo] Add statistics for dynamic value mappings.
Like partial mappings, as we move toward TableGen'ed information, the
number should reach zero eventually.

llvm-svn: 282325
2016-09-24 04:53:55 +00:00
Quentin Colombet fd8c95adf4 [RegisterBankInfo] Uniquely generate ValueMapping.
This is a step toward statically allocate ValueMapping. Like the
previous few commits, the goal is to move toward a TableGen'ed like
structure with no dynamic allocation at all.

llvm-svn: 282324
2016-09-24 04:53:52 +00:00
Quentin Colombet 8159de4de9 [RegisterBankInfo] Keep valid pointers for PartialMappings.
Previously we were using the address of the unique instance of a partial
mapping in the related map to access this instance. However, when the
map grows, the whole set of instances may be moved elsewhere and the
previous addresses are not valid anymore.

Instead, keep the address of the unique heap allocated instance of a
partial mapping.

Note: I did not see any actual bugs for that problem as the number of
partial mappings dynamically allocated is small (<= 4).

llvm-svn: 282323
2016-09-24 04:53:48 +00:00
Quentin Colombet d4c02437c1 [RegisterBankInfo] Add statistics for dynamic partial mappings.
Collect statistics about the number of partial mappings dynamically
allocated and accessed. Ultimately, when the whole TableGen
infrastructure is set, those numbers should be zero.

llvm-svn: 282274
2016-09-23 18:38:06 +00:00
Quentin Colombet c13ea88a14 [RegBankSelect] Use DEBUG_TYPE instead of repeating the name of the pass
NFC

llvm-svn: 282267
2016-09-23 17:50:06 +00:00
Quentin Colombet 09a9edcc26 [RegisterBank] Mark the dump method with LLVM_DUMP_METHOD.
NFC

llvm-svn: 282266
2016-09-23 17:50:03 +00:00
Quentin Colombet ceb71c2f43 [RegisterBankInfo] Mark the dump methods with LLVM_DUMP_METHOD.
NFC

llvm-svn: 282221
2016-09-23 00:59:12 +00:00
Quentin Colombet 1946580cf2 [RegisterBankInfo] Check that the mapping covers the interesting bits.
In the verify method of the ValueMapping class we used to check that the
mapping exactly matches the bits of the input value. This is problematic
for statically allocated mappings because we would need a different
mapping for each different size of the value that maps on one
instruction. For instance, with such scheme, we would need a different
mapping for a value of size 1, 5, 23 whereas they all end up on a 32-bit
wide instruction.

Therefore, change the verifier to check that the meaningful bits are
covered by the mapping instead of matching them.

llvm-svn: 282214
2016-09-23 00:14:34 +00:00
Quentin Colombet 0afa7d6b82 [RegisterBankInfo] Use array instead of SmallVector for BreakDown.
This is another step toward TableGen'ed like structures. The BreakDown of
the mapping of the value will be statically computed by TableGen, thus
we only have to point to the right entry in the table instead of
dynamically allocate the mapping for each instruction.

We still support the dynamic allocation through a factory of
PartialMapping to ease the bring-up of the targets while the TableGen
backend is not available.

llvm-svn: 282213
2016-09-23 00:14:30 +00:00
Tim Northover a5e38fa00d GlobalISel: handle stack-based parameters on AArch64.
llvm-svn: 282153
2016-09-22 13:49:25 +00:00
Quentin Colombet 6a76323c64 [RegisterBankInfo] Move to statically allocated RegisterBank.
This commit is basically the first step toward what will
RegisterBankInfo look when it gets TableGen'ed.

It introduces a XXXGenRegisterBankInfo.def file that is what TableGen
will issue at some point. Moreover, the RegBanks field in
RegisterBankInfo changed to reflect the static (compile time) aspect of
the information.

llvm-svn: 282131
2016-09-22 02:10:37 +00:00
Quentin Colombet b202eb88aa [RegisterBankInfo] Take advantage of the extra argument of SmallVector::resize.
When initializing an instance of OperandsMapper, instead of using
SmallVector::resize followed by std::fill, use the function that
directly does that in SmallVector.

llvm-svn: 282130
2016-09-22 02:10:32 +00:00
Tim Northover 9a46718378 GlobalISel: produce correct code for signext/zeroext ABI flags.
We still don't really have an equivalent of "AssertXExt" in DAG, so we don't
exploit the guarantees on the receiving side yet, but this should produce
conservatively correct code on iOS ABIs.

llvm-svn: 282069
2016-09-21 12:57:45 +00:00
Tim Northover 862758ec14 GlobalISel: pass Function to lowerFormalArguments directly (NFC).
The only implementation that exists immediately looks it up anyway, and the
information is needed to handle various parameter attributes (stored on the
function itself).

llvm-svn: 282068
2016-09-21 12:57:35 +00:00
Tim Northover b18ea162df GlobalISel: split aggregates for PCS lowering
This should match the existing behaviour for passing complicated struct and
array types, in particular HFAs come through like that from Clang.

For C & C++ we still need to somehow support all the weird ABI flags, or at
least those that are present in the IR (signext, byval, ...), and stack-based
parameter passing.

llvm-svn: 281977
2016-09-20 15:20:36 +00:00
Quentin Colombet ae273b6ba2 [RegisterBankInfo] Adapt call to std::fill due to use of SmallVector.
This was meant to be commited with my previous commit.

llvm-svn: 281948
2016-09-19 23:18:47 +00:00
Quentin Colombet a7330ba5ac [RegisterBankInfo] Avoid heap allocation in most cases.
The OperandsMapper class is used heavy in RegBankSelect and each
instantiation triggered a heap allocation for the array of operands.
Instead, use a SmallVector with a big enough size such that most of the
cases do not have to use dynamically allocated memory.

This improves the compile time of the RegBankSelect pass.

llvm-svn: 281916
2016-09-19 17:33:55 +00:00
Ahmed Bougacha 74db8faa71 [AArch64][GlobalISel] Test default regbank mapping for G_ICMP.
Also relax a RegisterBankInfo verifier check that's incompatible with
1-bit mappings.

llvm-svn: 281735
2016-09-16 14:44:54 +00:00
Tim Northover 22d82cf179 GlobalISel: legalize GEP instructions with small offsets.
llvm-svn: 281602
2016-09-15 11:02:19 +00:00
Tim Northover 4cf0a482bc GlobalISel: relax type constraints on G_ICMP to allow pointers.
llvm-svn: 281600
2016-09-15 10:40:38 +00:00
Tim Northover 32a078ad1a GlobalISel: remove "unsized" LLT
It was only really there as a sentinel when instructions had to have precisely
one type. Now that registers are typed, each register really has to have a type
that is sized.

llvm-svn: 281599
2016-09-15 10:09:59 +00:00
Tim Northover 5ae8350af6 GlobalISel: cache pointer sizes in LLT
Otherwise everything that needs to work out what size they are has to keep a
DataLayout handy, which is a bit silly and very annoying.

llvm-svn: 281597
2016-09-15 09:20:34 +00:00
Tim Northover 032548fc5e GlobalISel: support translation of global addresses.
llvm-svn: 281207
2016-09-12 12:10:41 +00:00
Tim Northover a7653b3919 GlobalISel: translate GEP instructions.
Unlike SDag, we use a separate G_GEP instruction (much simplified, only taking
a single byte offset) to preserve the pointer type information through
selection.

llvm-svn: 281205
2016-09-12 11:20:22 +00:00
Rui Ueyama a5edf655af Fix another -Wunused-variable for non-assert build.
llvm-svn: 281073
2016-09-09 18:37:08 +00:00
Rui Ueyama 47320da1ee Fix -Wunused-variable for non-assert build.
llvm-svn: 281069
2016-09-09 18:07:33 +00:00
Tim Northover 25d1286e5a GlobalISel: remove G_TYPE and G_PHI
These instructions were only necessary when type information was stored in the
MachineInstr (because only generic MachineInstrs possessed a type). Now that
it's in MachineRegisterInfo, COPY and PHI work fine.

llvm-svn: 281037
2016-09-09 11:47:31 +00:00
Tim Northover 1f8b1db93e GlobalISel: fix comments and add assertions for valid instructions.
llvm-svn: 281036
2016-09-09 11:46:58 +00:00
Tim Northover 0f140c769a GlobalISel: move type information to MachineRegisterInfo.
We want each register to have a canonical type, which means the best place to
store this is in MachineRegisterInfo rather than on every MachineInstr that
happens to use or define that register.

Most changes following from this are pretty simple (you need an MRI anyway if
you're going to be doing any transformations, so just check the type there).
But legalization doesn't really want to check redundant operands (when, for
example, a G_ADD only ever has one type) so I've made use of MCInstrDesc's
operand type field to encode these constraints and limit legalization's work.

As an added bonus, more validation is possible, both in MachineVerifier and
MachineIRBuilder (coming soon).

llvm-svn: 281035
2016-09-09 11:46:34 +00:00
Tim Northover 8d8812c5d7 GlobalISel: add a G_PHI instruction to give phis a type.
They're another source of generic vregs, which are going to need a type on the
definition when we remove the register width from MachineRegisterInfo.

llvm-svn: 280412
2016-09-01 20:45:41 +00:00
Tim Northover 11a2354670 GlobalISel: use G_TYPE to annotate physregs with a type.
More preparation for dropping source types from MachineInstrs: regsters coming
out of already-selected code (i.e. non-generic instructions) don't have a type,
but that information is needed so we must add it manually.

This is done via a new G_TYPE instruction.

llvm-svn: 280292
2016-08-31 21:24:02 +00:00
Tim Northover 991b12bf09 GlobalISel: combine extracts & sequences created for legalization
Legalization ends up creating many G_SEQUENCE/G_EXTRACT pairs which leads to
inefficient codegen (even for -O0), so add a quick pass over the function to
remove them again.

llvm-svn: 280155
2016-08-30 20:51:25 +00:00
Tim Northover f8bab1ce0c GlobalISel: use multi-dimensional arrays for legalize actions.
Instead of putting all possible requests into a single table, we can perform
the extremely dense lookup based on opcode and type-index in constant time
using multi-dimensional array-like things.

This roughly halves the time spent doing legalization, which was dominated by
queries against the Actions table.

llvm-svn: 280011
2016-08-29 21:00:00 +00:00
Tim Northover ac5148ef41 GlobalISel: switch to SmallVector for pending legalizations.
std::queue was doing far to many heap allocations to be healthy.

llvm-svn: 279992
2016-08-29 19:27:20 +00:00
Tim Northover edb3c8ccb8 GlobalISel: legalize frem to a libcall on AArch64.
llvm-svn: 279988
2016-08-29 19:07:16 +00:00
Tim Northover fe5f89ba14 GlobalISel: rework CallLowering so that it can be used for libcalls too.
There should be no functional change here, I'm just making the implementation
of "frem" (to libcall) legalization easier for a followup.

llvm-svn: 279987
2016-08-29 19:07:08 +00:00
Haojian Wu 407f275894 [InstructionSelect] NumBlocks isn't defined in DEBUG build.
Summary: A follow-up fixing on http://llvm.org/viewvc/llvm-project?view=revision&revision=279905.

Reviewers: bkramer

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D23985

llvm-svn: 279959
2016-08-29 08:48:15 +00:00
Quentin Colombet acb857b831 [RegBankSelect] Do not abort when the target wants to fall back.
llvm-svn: 279906
2016-08-27 02:38:27 +00:00
Quentin Colombet 948abf0a0f [InstructionSelect] Do not abort when the target wants to fall back.
llvm-svn: 279905
2016-08-27 02:38:24 +00:00
Quentin Colombet 5e60bcdeaf [MachineLegalize] Do not abort when the target wants to fall back.
llvm-svn: 279904
2016-08-27 02:38:21 +00:00
Quentin Colombet 6049524d37 [GlobalISel] Teach the core pipeline not to run if ISel failed.
llvm-svn: 279889
2016-08-27 00:18:24 +00:00
Quentin Colombet 3bb32cc79c [IRTranslator] Do not abort when the target wants to fall back.
Every pass in the GlobalISel pipeline will need to do something similar.

llvm-svn: 279886
2016-08-26 23:49:05 +00:00
Quentin Colombet 1d0cb6f107 [IRTranslator][NFC] Use DEBUG_TYPE instead of repeating the name.
llvm-svn: 279878
2016-08-26 22:32:57 +00:00
Tim Northover 051b8ad3d9 GlobalISel: simplify G_ICMP legalization regime.
It's unclear how the old

    %res(32) = G_ICMP { s32, s32 } intpred(eq), %0, %1

is actually different from an s1 verison

    %res(1) = G_ICMP { s1, s32 } intpred(eq), %0, %1

so we'll remove it for now.

llvm-svn: 279843
2016-08-26 17:46:17 +00:00
Tim Northover cecee56abb GlobalISel: legalize sdiv and srem operations.
llvm-svn: 279842
2016-08-26 17:46:13 +00:00
Tim Northover 7a753d9bec GlobalISel: legalize under-width divisions.
llvm-svn: 279841
2016-08-26 17:46:06 +00:00
Tim Northover 6c43b850b7 GlobalISel: add missing type to G_UADDE instructions
llvm-svn: 279762
2016-08-25 17:37:44 +00:00
Tim Northover 438c77ca1a GlobalISel: perform multi-step legalization
llvm-svn: 279758
2016-08-25 17:37:32 +00:00
Richard Smith 84c4cc47f5 Don't use "return {...}" to initialize a std::tuple. This has only been valid
since 2015 (n4387), though it's allowed by a library DR so new implementations
accept it in their C++11 modes...

This should unbreak the build with libstdc++ 4.9.

llvm-svn: 279583
2016-08-23 22:21:58 +00:00
Richard Smith 418237bed8 #ifdef out validation code when asserts are disabled to remove unused variable
warnings.

llvm-svn: 279582
2016-08-23 22:14:15 +00:00
Tim Northover bdf67c9a00 GlobalISel: make truncate/extend casts uniform
They really should have both types represented, but early variants were created
before MachineInstrs could have multiple types so they're rather ambiguous.

llvm-svn: 279567
2016-08-23 21:01:33 +00:00
Tim Northover 6cd4b23a0f GlobalISel: legalize integer comparisons on AArch64.
Next step is doing both legalizations at the same time! Marvel at GlobalISel's
cunning.

llvm-svn: 279566
2016-08-23 21:01:26 +00:00
Tim Northover b3a0be4d38 GlobalISel: legalize conditional branches on AArch64.
llvm-svn: 279565
2016-08-23 21:01:20 +00:00
Tim Northover a01bece1dc GlobalISel: extend legalizer interface to handle multiple types.
Instructions like G_ICMP have multiple types that may need to be legalized (the
boolean output and nearly arbitrary inputs in this case). So the legalizer must
be capable of deciding what to do for each of them separately.

llvm-svn: 279554
2016-08-23 19:30:42 +00:00
Tim Northover 3c73e367c0 GlobalISel: legalize 1-bit load/store and mark 8/16 bit variants legal on AArch64.
llvm-svn: 279548
2016-08-23 18:20:09 +00:00
Tim Northover a11be04769 GlobalISel: support legalization of G_FCONSTANTs
llvm-svn: 279341
2016-08-19 22:40:08 +00:00
Tim Northover ea904f9424 GlobalISel: teach legalizer how to handle integer constants.
llvm-svn: 279340
2016-08-19 22:40:00 +00:00
Tim Northover d5c23bcfc9 GlobalISel: translate floating-point comparisons
llvm-svn: 279319
2016-08-19 20:48:16 +00:00
Tim Northover b16734fbaa GlobalISel: translate floating-point constants
llvm-svn: 279311
2016-08-19 20:09:15 +00:00
Tim Northover 5a28c3642f GlobalISel: support translating select instructions.
llvm-svn: 279309
2016-08-19 20:09:07 +00:00
Tim Northover b604622bba GlobalISel: fix insert/extract to work on ConstantExprs too.
No tests yet unfortunately (ConstantFolding reduces all supported constants to
ConstantInts before we get to translation). Soon.

llvm-svn: 279308
2016-08-19 20:09:03 +00:00
Tim Northover bbbfb1cfb8 GlobalISel: translate insertvalue instructions.
This adds a G_INSERT instruction, which technically makes G_SEQUENCE redundant
(it's equivalent to a G_INSERT into an IMPLICIT_DEF). We'll leave G_SEQUENCE
for now though: it's likely to be far more common as it's a fundamental part of
legalization, so avoiding the mess and bloat of the extra IMPLICIT_DEFs is
probably worthwhile.

llvm-svn: 279306
2016-08-19 20:08:55 +00:00
Tim Northover 26b76f2c59 GlobalISel: improve representation of G_SEQUENCE and G_EXTRACT
First, make sure all types involved are represented, rather than being implicit
from the register width.

Second, canonicalize all types to scalar. These operations just act in bits and
don't care about vectors.

Also standardize spelling of Indices in the MachineIRBuilder (NFC here).

llvm-svn: 279294
2016-08-19 18:32:14 +00:00
Tim Northover 2fa5fa391f GlobalISel: allow extractvalue to extract an aggregate.
llvm-svn: 279287
2016-08-19 18:09:41 +00:00
Tim Northover 6f80b08c64 GlobalISel: support translation of extractvalue instructions.
llvm-svn: 279285
2016-08-19 17:47:05 +00:00
Tim Northover 91c8173093 GlobalISel: support overflow arithmetic intrinsics.
Unsigned addition and subtraction can reuse the instructions created to
legalize large width operations (i.e. both produce and consume a carry flag).
Signed operations and multiplies get a dedicated op-with-overflow instruction.

Once this is produced the two values are combined into a struct register (which
will almost always be merged with a corresponding G_EXTRACT as part of
legalization).

llvm-svn: 279278
2016-08-19 17:17:06 +00:00
Tim Northover de3aea0412 GlobalISel: support irtranslation of icmp instructions.
llvm-svn: 278969
2016-08-17 20:25:25 +00:00
Ahmed Bougacha e4c03abddd [AArch64][GlobalISel] Select G_MUL.
llvm-svn: 278810
2016-08-16 14:37:46 +00:00
Ahmed Bougacha 0306b5ef07 [AArch64][GlobalISel] Select p0 G_FRAME_INDEX.
And mark it as legal.

llvm-svn: 278802
2016-08-16 14:02:42 +00:00
Tim Northover 28fdc4272d GlobalISel: support loads and stores of strange types.
Before we mischaracterized structs and i1 types as a scalar with size 0 in
various ways.

llvm-svn: 278744
2016-08-15 21:13:17 +00:00
Tim Northover 8e0c53a018 GlobalISel: support 'null' constant in translation.
It's sharing the integer G_CONSTANT for now since I don't *think* it creates
any ambiguity (even on weird archs). If that turns out wrong we can create a
G_PTRCONSTANT or something.

llvm-svn: 278423
2016-08-11 21:40:55 +00:00
Tim Northover 0d51044b69 GlobalISel: clear vreg mapping after translating each function
Otherwise we only materialize (shared) constants in the first function they
appear in. This doesn't go well.

llvm-svn: 278351
2016-08-11 16:21:29 +00:00
Tim Northover 357f1be2ca GlobalISel: support same ConstantExprs as Instructions.
It's more than just inttoptr, but the others can't be tested until we have
support for non-trivial constants (they currently get unavoidably folded to a
ConstantInt).

llvm-svn: 278303
2016-08-10 23:02:41 +00:00
Tim Northover 406024a108 GlobalISel: implement simple function calls on AArch64.
We're still limited in the arguments we support, but this at least handles the
basic cases.

llvm-svn: 278293
2016-08-10 21:44:01 +00:00
Tim Northover 7552ef5a00 GlobalISel: avoid inserting redundant COPYs for bitcasts.
If the value produced by the bitcast hasn't been referenced yet, we can simply
reuse the input register avoiding an unnecessary COPY instruction.

llvm-svn: 278245
2016-08-10 16:51:14 +00:00
Tim Northover d403a3d8ee GlobalISel: support 'undef' constant.
llvm-svn: 278174
2016-08-09 23:01:30 +00:00
Tim Northover 5ed648e509 GlobalISel: first translation support for Constants.
For now put them all in the entry block. This should be correct but may give
poor runtime performance. Hopefully MachineSinking combined with
isReMaterializable can solve those issues, but if not the interface is sound
enough to support alternatives.

llvm-svn: 278168
2016-08-09 21:28:04 +00:00
Tim Northover 14e7f73a0f GlobalISel: clear pending phis after MachineFunction translated
Test is just reordering the existing functions (it would trigger for any
function after one with a phi).

llvm-svn: 277841
2016-08-05 17:50:36 +00:00
Tim Northover 97d0cb3165 GlobalISel: IRTranslate PHI instructions
llvm-svn: 277835
2016-08-05 17:16:40 +00:00
Tim Northover 61c16142b4 GlobalISel: extend add widening to SUB, MUL, OR, AND and XOR.
These are the operations that are trivially identical. Division is omitted for
now because you need to use the correct sign/zero extension.

llvm-svn: 277775
2016-08-04 21:39:49 +00:00
Tim Northover 1cfa919b3d GlobalISel: add support for G_MUL
llvm-svn: 277774
2016-08-04 21:39:44 +00:00
Tim Northover 9656f1476c GlobalISel: implement narrowing for G_ADD.
llvm-svn: 277769
2016-08-04 20:54:13 +00:00
Tim Northover 06db18fbf8 GlobalISel: also add G_TRUNC to IRTranslator.
llvm-svn: 277749
2016-08-04 18:35:17 +00:00
Tim Northover 323358184e GlobalISel: add code to widen scalar G_ADD
llvm-svn: 277747
2016-08-04 18:35:11 +00:00
Ahmed Bougacha bfaddd999a [GlobalISel] Set the Selected MF property.
None of GlobalISel requires the property, but this lets us use the
verifier instead of rolling our own "all instructions selected" check.

llvm-svn: 277484
2016-08-02 16:49:25 +00:00
Ahmed Bougacha 24d0d4d2ec [GlobalISel] Set, require, and verify Legalized MF property.
RegBankSelect and InstructionSelect run after the legalizer and
require a Legalized function: check that all instructions are legal.

Note that this should be in the MachineVerifier, but it can't use the
MachineLegalizer as it's currently in the separate GlobalISel library.
Note that the RegBankSelect verifier checks have the same layering
problem, but we only use inline methods so end up not needing to link
against the GlobalISel library.

llvm-svn: 277472
2016-08-02 15:10:32 +00:00
Ahmed Bougacha 45eb3b94d4 [GlobalISel] Don't RegBankSelect target-specific instructions.
They don't have types and should be using register classes.

llvm-svn: 277447
2016-08-02 11:41:16 +00:00
Ahmed Bougacha faf8e9f8c6 [GlobalISel] Don't legalize non-generic instructions.
They don't have types and should be legal.

llvm-svn: 277446
2016-08-02 11:41:09 +00:00
Ahmed Bougacha f49ab9af2c [GlobalISel] Const-ify MachineInstrs passed to MachineLegalizer.
llvm-svn: 277445
2016-08-02 11:41:03 +00:00
Tim Northover 5fc93b75d9 GlobalISel: translate "unreachable" (into nothing)
Easiest instruction ever!

llvm-svn: 277225
2016-07-29 22:41:55 +00:00
Tim Northover 5fb414d870 GlobalISel: support translation of intrinsic calls.
These come in two variants for now: G_INTRINSIC and G_INTRINSIC_W_SIDE_EFFECTS.
We may decide to split the latter up with finer-grained restrictions later, if
necessary.

llvm-svn: 277224
2016-07-29 22:32:36 +00:00
Tim Northover 0d56e05a12 GlobalISel: make translate* functions take the most specialized class possible.
NFC.

llvm-svn: 277188
2016-07-29 18:11:21 +00:00
Tim Northover 69c2ba546f GlobalISel: add generic conditional branch.
Just the basic equivalent to DAG's condbr for now, we'll get to things like
br_cc when we start doing more legalization.

llvm-svn: 277184
2016-07-29 17:58:00 +00:00
Tim Northover a51575ffa2 CodeGen: improve MachineInstrBuilder & MachineIRBuilder interface
For MachineInstrBuilder, having to manually use RegState::Define is ugly and
makes register definitions clunkier than they need to be, so this adds two
convenience functions: addDef and addUse.

For MachineIRBuilder, we want to avoid BuildMI's first-reg-is-def rule because
it's hidden away and causes bugs. So this patch switches buildInstr to
returning a MachineInstrBuilder and adding *all* operands via addDef/addUse.

NFC.

llvm-svn: 277176
2016-07-29 17:43:52 +00:00
Ahmed Bougacha 784e3423e6 [GlobalISel] Add G_XOR.
llvm-svn: 277172
2016-07-29 16:56:20 +00:00
Ahmed Bougacha 7adfac56b3 [AArch64][GlobalISel] Select G_LOAD/G_STORE.
Mostly straightforward as we ignore addressing modes and just
use the base + unsigned immediate offset (always 0) variants.

This currently fails to select extloads because we have yet to
agree on a representation.

llvm-svn: 277171
2016-07-29 16:56:16 +00:00
Matthias Braun 93320393a4 Missed updating a GlobalISel bit in my last commit
GlobalISel isn't built by default so I missed it.

llvm-svn: 277030
2016-07-28 20:13:42 +00:00
Tim Northover 8d2f52e035 GlobalISel: support zero-sized allocas
All allocas must be at least 1 byte at the MachineIR level so we allocate just
one byte.

llvm-svn: 276897
2016-07-27 17:47:54 +00:00
Ahmed Bougacha 6756a2c953 [GlobalISel] Introduce an instruction selector.
And implement it for AArch64, supporting x/w ADD/OR.

Differential Revision: https://reviews.llvm.org/D22373

llvm-svn: 276875
2016-07-27 14:31:55 +00:00
Tim Northover ad2b717f2c GlobalISel: add generic load and store instructions.
Pretty straightforward, the only oddity is the MachineMemOperand (which it's
surprisingly difficult to share code for).

llvm-svn: 276799
2016-07-26 20:23:26 +00:00
Tim Northover ab395cb071 GlobalISel: add correct operand type to G_FRAME_INDEX instrs.
Frame indices should use "addFrameIndex", not "addImm".

llvm-svn: 276775
2016-07-26 17:42:40 +00:00
Tim Northover 756eca35cf GlobalISel: add specialized buildCopy function to MachineInstrBuilder.
NFC.

llvm-svn: 276763
2016-07-26 16:45:30 +00:00
Tim Northover cc5f76226b GlobalISel: give MachineInstrBuilder a uniform interface. NFC.
Instead of an ad-hoc collection of "buildInstr" functions with varying numbers
of registers, this uses variadic templates to provide for as many regs as
needed!

Also make IRtranslator use new "buildBr" function instead of some weird generic
one that no-one else would really use.

llvm-svn: 276762
2016-07-26 16:45:26 +00:00
Tim Northover 884b47ecfd GlobalISel: remove redundant ';'s. NFC
llvm-svn: 276723
2016-07-26 03:29:18 +00:00
Tim Northover 7c9eba90ff GlobalISel: add generic casts to IRTranslator
This adds LLVM's 3 main cast instructions (inttoptr, ptrtoint, bitcast) to the
IRTranslator. The first two are direct translations (with 2 MachineInstr types
each). Since LLT discards information, a bitcast might become trivial and we
emit a COPY in those cases instead.

llvm-svn: 276690
2016-07-25 21:01:29 +00:00
Tim Northover 33b07d6725 GlobalISel: implement legalization pass, with just one transformation.
This adds the actual MachineLegalizeHelper to do the work and a trivial pass
wrapper that legalizes all instructions in a MachineFunction. Currently the
only transformation supported is splitting up a vector G_ADD into one acting on
smaller vectors.

llvm-svn: 276461
2016-07-22 20:03:43 +00:00
Tim Northover bd5054602e GlobalISel: implement alloca instruction
llvm-svn: 276433
2016-07-22 16:59:52 +00:00
Quentin Colombet 2b59eab79f [IRTranslator] Add G_SUB opcode.
This commit adds a generic SUB opcode to global-isel.

llvm-svn: 276308
2016-07-21 17:26:50 +00:00
Quentin Colombet 19df8a1aba [IRTranslator] Add comments to explain the ordering of the switch. NFC.
Group arithmetic operations, bitwise operations, and branch operations.

llvm-svn: 276305
2016-07-21 17:26:41 +00:00
Quentin Colombet 7bcc921dd8 [IRTranslator] Add G_AND opcode.
This commit adds a generic AND opcode to global-isel.

llvm-svn: 276297
2016-07-21 15:50:42 +00:00
Tim Northover 75ad077330 GlobalISel: implement Legalization querying framework.
This adds an (incomplete, inefficient) framework for deciding what to do with
some operation on a given type.

llvm-svn: 276184
2016-07-20 21:13:29 +00:00
Tim Northover 62ae568bbb GlobalISel: implement low-level type with just size & vector lanes.
This should be all the low-level instruction selection needs to determine how
to implement an operation, with the remaining context taken from the opcode
(e.g. G_ADD vs G_FADD) or other flags not based on type (e.g. fast-math).

llvm-svn: 276158
2016-07-20 19:09:30 +00:00
Ahmed Bougacha 0313a08a1a [GlobalISel] Simplify more RegClassOrRegBank is+get. NFC.
llvm-svn: 276011
2016-07-19 19:47:06 +00:00
Ahmed Bougacha 35e67e1b1f [GlobalISel] Fix #include ordering/spacing. NFC.
llvm-svn: 275423
2016-07-14 14:52:55 +00:00
Tim Northover 72eebfa4b0 GlobalISel: freeze reserved regs after IRTranslator.
We can freeze the registers after the MachineFrameInfo has been configured (by
telling it about calls, inline asm, ...). This doesn't happen at all yet, but
will be part of IR translation.

Fixes -verify-machineinstrs assertion.

llvm-svn: 275221
2016-07-12 22:23:42 +00:00
Quentin Colombet f2a1909bb5 [IRTranslator] Support the translation of or.
Now or instructions get translated into G_OR.

llvm-svn: 272433
2016-06-10 20:50:35 +00:00
Quentin Colombet 13c55e07ed [IRTranslator] Refactor to expose a translateBinaryOp method.
This method will be used for every binary operation.

NFC.

llvm-svn: 272431
2016-06-10 20:50:18 +00:00
Quentin Colombet 3340645771 [RegBankSelect] Print out the actual mapping of the operands.
This improves the debuggability of the pass.

llvm-svn: 272210
2016-06-08 21:55:30 +00:00
Quentin Colombet 9400bfbf42 [RegBankSelect] Remove a debug print of a potentially dead instruction.
For complex rewrittings, which do not occur currently, the related
machine instruction may have been deleted in the process. Therefore, do
not try to print it after the mapping is applied.

llvm-svn: 272209
2016-06-08 21:55:29 +00:00
Quentin Colombet 9f8e209c60 [RegisterBankInfo] Avoid code duplication in OperandsMapper for the computation of the end of range.
Refactor the code so that we do not compute in two different places the
end iterator for the range of new virtual registers for a given operand.
Although this refactoring was intended as NFC, this is not the case
because it actually fixes a bug where we were returning a range off by 1
(too long). Right now, this could not result in an actual bug because we
were accessing this range via the BreakDown size of the related operand.

llvm-svn: 272208
2016-06-08 21:55:26 +00:00
Quentin Colombet 9d26805f42 [RegisterBankInfo] Add dump/print methods for OperandsMapper.
Improve debuggability of the OperandsMapper helper class.

llvm-svn: 272207
2016-06-08 21:55:23 +00:00
Quentin Colombet 86be3748a6 [RegBankSelect] Silence an unused variable warning in release mode.
llvm-svn: 272177
2016-06-08 17:39:47 +00:00
Quentin Colombet d6886bd22c [RegBankSelect] Comment on how we could improve repairing with copies.
When repairing with a copy, instead of accounting for the cost of that
copy and actually inserting it, we may be able to use an alternative
source for the register to repair and just use it.

Make sure this is documented, so that we consider that opportunity at
some point.

llvm-svn: 272176
2016-06-08 17:39:43 +00:00
Quentin Colombet ec5c93d3a0 [RegBankSelect] Use RegisterBankInfo applyMapping method.
The RegBankSelect pass can now rely on the target to do the remapping of
the instructions.

llvm-svn: 272169
2016-06-08 16:45:04 +00:00
Quentin Colombet 574a329962 [RegisterBankInfo] Implement the method to apply a mapping.
Now, the target will be able to provide its how implementation to remap
an instruction. This open the way to crazier optimizations, but to
beginning with, we will be able to handle something else than the
default mapping.

llvm-svn: 272165
2016-06-08 16:39:21 +00:00
Quentin Colombet f33e36545b [RegBankSelect] Use the OperandMapper class to hold remap information.
Now that we have an entity that hold the remap information the
rewritting should be easier to do.

No functional changes.

llvm-svn: 272164
2016-06-08 16:30:55 +00:00
Quentin Colombet 06ef4e209d [RegBankSelect] Use const_iterator instead of iterator for repairReg.
The repairing code has no reason to change the source or destination of
the registers.

llvm-svn: 272163
2016-06-08 16:24:55 +00:00
Quentin Colombet 7a03de5210 [RegisterBankInfo] Introduce OperandsMapper class.
This helper class is used to encapsulate the necessary information
to remap an instruction.

llvm-svn: 272161
2016-06-08 16:18:13 +00:00
Quentin Colombet a41272fb48 [RegBankSelect] Introduce a command line option to override the running mode.
When the command line option is set, it overrides any thing that the
target may have set. The rationale is that we get what we asked for.

Options are respectively regbankselect-fast and regbankselect-greedy for
fast and greedy mode.

llvm-svn: 272158
2016-06-08 15:49:23 +00:00
Quentin Colombet 6feaf82088 [RegBankSelect] Explain what it would take to support non-copy
repairing.

Copies are easy because we repair only when there is a mismatch. For
non-copy repairing, i.e., cases that involves breaking down or gathering
up the value, one of the operand may not have a register bank yet. Thus,
derivate a cost from that, requires more work.

llvm-svn: 272157
2016-06-08 15:40:32 +00:00
Quentin Colombet cfbdee2312 [RegisterBankInfo] Add a size argument for the cost of copy.
The cost of a copy may be different based on how many bits we have to
copy around. E.g., a 8-bit copy may be different than a 32-bit copy.

llvm-svn: 272084
2016-06-08 01:11:03 +00:00
Quentin Colombet 123a7a55e7 [RegisterBankInfo] Move a hidden function into a static method. NFC.
This will allow code reuse in the coming commits.

llvm-svn: 272083
2016-06-08 01:04:32 +00:00
Quentin Colombet f2723a2a91 [RegBankSelect] Compute the repairing cost for copies.
Prior to this patch, we were using 1 for all the repairing costs.
Now, we use the information from the target to get this information.

llvm-svn: 270304
2016-05-21 01:43:25 +00:00
Quentin Colombet 79fe1bea6b [RegBankSelect] Look for the best mapping in greedy mode.
The Fast mode takes the first mapping, the greedy mode loops over all
the possible mapping for an instruction and choose the cheaper one.
Test case will come with target specific code, since we currently do not
have instructions that have several mappings.

llvm-svn: 270249
2016-05-20 18:37:33 +00:00
Quentin Colombet 4f147a54a1 [RegBankSelect] Get rid of a now dead method: setSafeInsertPoint.
This is now encapsulated in the RepairingPlacement class.

llvm-svn: 270247
2016-05-20 18:17:16 +00:00
Quentin Colombet 6e80dbcde3 [RegBankSelect] Take advantage of a potential best cost information in
computeMapping.

Computing the cost of a mapping takes some time.
Since in Fast mode, the cost is irrelevant, just spare some cycles by not
computing it.
In Greedy mode, we need to choose the best cost, that means that when
the local cost gets more expensive than the best cost, we can stop
computing the repairing and cost for the current mapping.

llvm-svn: 270245
2016-05-20 18:00:46 +00:00