Commit Graph

428 Commits

Author SHA1 Message Date
Reid Kleckner
ae44e871cd Revert "Revert "Revert r248959, "[WinEH] Emit int3 after noreturn calls on Win64"""
This reverts commit r249794.

Apparently my checkouts are full of unexpected surprises today.

llvm-svn: 249796
2015-10-09 01:13:17 +00:00
Reid Kleckner
b510401785 Revert "Revert r248959, "[WinEH] Emit int3 after noreturn calls on Win64""
This reverts commit r249032.

TODO write commit msg

llvm-svn: 249794
2015-10-09 01:11:37 +00:00
NAKAMURA Takumi
1ed20db720 Revert r248959, "[WinEH] Emit int3 after noreturn calls on Win64"
It broke; LLVM :: CodeGen__Generic__2009-11-16-BadKillsCrash.ll

llvm-svn: 249032
2015-10-01 17:00:56 +00:00
Reid Kleckner
6dec87a8a0 [WinEH] Emit int3 after noreturn calls on Win64
The Win64 unwinder disassembles forwards from each PC to try to
determine if this PC is in an epilogue. If so, it skips calling the EH
personality function for that frame. Typically, this means you cannot
catch an exception in the same frame that you threw it, because 'throw'
calls a noreturn runtime function.

Previously we avoided this problem with the TrapUnreachable
TargetOption, but that's a much bigger hammer than we need. All we need
is a 1 byte non-epilogue instruction right after the call.  Instead,
what we got was an unconditional branch to a shared block containing the
ud2, potentially 7 bytes instead of 1. So, this reverts r206684, which
added TrapUnreachable, and replaces it with something better.

The new code pattern matches for invoke/call followed by unreachable and
inserts an int3 into the DAG. To be 100% watertight, we would need to
insert SEH_Epilogue instructions into all basic blocks ending in a call
with no terminators or successors, but in practice this is unlikely to
come up.

llvm-svn: 248959
2015-09-30 23:09:23 +00:00
Matthias Braun
4816b18d86 FastISel: Avoid adding a successor block twice for degenerate IR.
This fixes http://llvm.org/PR24581

Differential Revision: http://reviews.llvm.org/D12350

llvm-svn: 246074
2015-08-26 20:46:49 +00:00
Matthias Braun
17af607796 FastISel: Factor out common code; NFC intended
This should be no functional change but for the record: For three cases
in X86FastISel this will change the order in which the FalseMBB and
TrueMBB of a conditional branch is addedd to the successor/predecessor
lists.

llvm-svn: 245997
2015-08-26 01:38:00 +00:00
Dan Gohman
7b63484b99 [WebAssembly] Skeleton FastISel support
llvm-svn: 245860
2015-08-24 18:44:37 +00:00
Alex Lorenz
2f43dd5a12 StackMap: FastISel: Add an appropriate number of immediate operands to the
frame setup instruction.

This commit ensures that the stack map lowering code in FastISel adds an
appropriate number of immediate operands to the frame setup instruction.

The previous code added just one immediate operand, which was fine for a target
like AArch64, but on X86 the ADJCALLSTACKDOWN64 instruction needs two explicit
operands. This caused the machine verifier to report an error when the old code
added just one.

Reviewers: Juergen Ributzka

Differential Revision: http://reviews.llvm.org/D11853

llvm-svn: 244508
2015-08-10 21:27:03 +00:00
Mehdi Amini
5c183d5239 Make getByValTypeAlignment() taking DataLayout as an argument
Summary:
This change is part of a series of commits dedicated to have a single
DataLayout during compilation by using always the one owned by the
module.

Reviewers: echristo

Subscribers: yaron.keren, rafael, llvm-commits, jholewinski

Differential Revision: http://reviews.llvm.org/D11038

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 241777
2015-07-09 02:09:28 +00:00
Mehdi Amini
44ede33a69 Make TargetLowering::getPointerTy() taking DataLayout as an argument
Summary:
This change is part of a series of commits dedicated to have a single
DataLayout during compilation by using always the one owned by the
module.

Reviewers: echristo

Subscribers: jholewinski, ted, yaron.keren, rafael, llvm-commits

Differential Revision: http://reviews.llvm.org/D11028

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 241775
2015-07-09 02:09:04 +00:00
Mehdi Amini
56228dabfa Redirect DataLayout from TargetMachine to Module in ComputeValueVTs()
Summary:
Avoid using the TargetMachine owned DataLayout and use the Module owned
one instead. This requires passing the DataLayout up the stack to
ComputeValueVTs().

This change is part of a series of commits dedicated to have a single
DataLayout during compilation by using always the one owned by the
module.

Reviewers: echristo

Subscribers: jholewinski, yaron.keren, rafael, llvm-commits

Differential Revision: http://reviews.llvm.org/D11019

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 241773
2015-07-09 01:57:34 +00:00
Mehdi Amini
7da8b536f4 Redirect DataLayout from TargetMachine to Module in FastISel
Summary:
This change is part of a series of commits dedicated to have a single
DataLayout during compilation by using always the one owned by the
module.

Reviewers: echristo

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D10985

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 241613
2015-07-07 18:39:02 +00:00
Akira Hatanaka
56c70441dc Use function attribute "trap-func-name" and remove TargetOptions::TrapFuncName.
This commit changes normal isel and fast isel to read the user-defined trap
function name from function attribute "trap-func-name" attached to llvm.trap or
llvm.debugtrap instead of from TargetOptions::TrapFuncName. This is needed to
use clang's command line option "-ftrap-function" for LTO and enable changing
the trap function name on a per-call-site basis.

Out-of-tree projects currently using TargetOptions::TrapFuncName to specify the
trap function name should attach attribute "trap-func-name" to the call sites
of llvm.trap and llvm.debugtrap instead.

rdar://problem/21225723

Differential Revision: http://reviews.llvm.org/D10832

llvm-svn: 241305
2015-07-02 22:13:27 +00:00
Rafael Espindola
ce4c2bc1d6 Use MCSymbols for FastISel.
The summary is that it moves the mangling earlier and replaces a few
calls to .addExternalSymbol with addSym.

I originally wanted to replace all the uses of addExternalSymbol with
addSym, but noticed it was a lot of work and doesn't need to be done
all at once.

llvm-svn: 240395
2015-06-23 12:21:54 +00:00
Pete Cooper
d54fb89901 [Fast-ISel] Don't mark the first use of a remat constant as killed.
When emitting something like 'add x, 1000' if we remat the 1000 then we should be able to
mark the vreg containing 1000 as killed.  Given that we go bottom up in fast-isel, a later
use of 1000 will be higher up in the BB and won't kill it, or be impacted by the lower kill.

However, rematerialised constant expressions aren't generated bottom up.  The local value save area
grows downwards.  This means that if you remat 2 constant expressions which both use 1000 then the
first will kill it, then the second, which is *lower* in the BB will read a killed register.

This is the case in the attached test where the 2 GEPs both need to generate 'add x, 6680' for the constant offset.

Note that this commit only makes kill flag generation conservative.  There's nothing else obviously wrong with
the local value save area growing downwards, and in fact it needs to for handling arbitrarily complex constant expressions.

However, it would be nice if there was a solution which would let us generate more accurate kill flags, or just kill flags completely.

llvm-svn: 236922
2015-05-09 00:51:03 +00:00
Pete Cooper
54085cdc7b Fix incorrect kill flags in fastisel.
If called twice in the same BB on the same constant, FastISel::fastEmit_ri_ was marking the materialized vreg as killed on each use, instead of only the last use.

Change this to only mark the last use as killed by making earlier uses check if the vreg is already used elsewhere.

llvm-svn: 236650
2015-05-06 22:09:29 +00:00
Lang Hames
65613a634a [patchpoint] Add support for symbolic patchpoint targets to SelectionDAG and the
X86 backend.

The code generated for symbolic targets is identical to the code generated for
constant targets, except that a relocation is emitted to fix up the actual
target address at link-time. This allows IR and object files containing
patchpoints to be cached across JIT-invocations where the target address may
change.

llvm-svn: 235483
2015-04-22 06:02:31 +00:00
Duncan P. N. Exon Smith
d4a19a396d DebugInfo: Assert dbg.declare/value insts are valid
Remove early returns for when `getVariable()` is null, and just assert
that it never happens.  The Verifier already confirms that there's a
valid variable on these intrinsics, so we should assume the debug info
isn't broken.  I also updated a check for a `!dbg` attachment, which the
Verifier similarly guarantees.

llvm-svn: 235400
2015-04-21 18:24:23 +00:00
Duncan P. N. Exon Smith
e686f1591f CodeGen: Stop using DIDescriptor::is*() and auto-casting
Same as r234255, but for lib/CodeGen and lib/Target.

llvm-svn: 234258
2015-04-06 23:27:40 +00:00
Rafael Espindola
d58de064b8 Use sext in fast isel.
Fast isel used to zero extends immediates to 64 bits. This normally goes
unnoticed because the value is truncated to 32 bits for output.

Two cases were it is noticed:

* We fail to use smaller encodings.
* If the original constant was smaller than i32.

In the tests using i1 constants, codegen would change to use -1, which is fine
(and matches what regular isel does) since only the lowest bit is then used.

Instead, this patch then changes the ir to use i8 constants, which looks more
like what clang produces.

llvm-svn: 234249
2015-04-06 22:29:07 +00:00
Duncan P. N. Exon Smith
3bef6a3803 CodeGen: Assert that inlined-at locations agree
As a follow-up to r234021, assert that a debug info intrinsic variable's
`MDLocalVariable::getInlinedAt()` always matches the
`MDLocation::getInlinedAt()` of its `!dbg` attachment.

The goal here is to get rid of `MDLocalVariable::getInlinedAt()`
entirely (PR22778), but I'll let these assertions bake for a while
first.

If you have an out-of-tree backend that just broke, you're probably
attaching the wrong `DebugLoc` to a `DBG_VALUE` instruction.  The one
you want is the location that was attached to the corresponding
`@llvm.dbg.declare` or `@llvm.dbg.value` call that you started with.

llvm-svn: 234038
2015-04-03 19:20:26 +00:00
David Majnemer
cde33036ed [WinEH] Run cleanup handlers when an exception is thrown
Generate tables in the .xdata section representing what actions to take
when an exception is thrown.  This currently fills in state for
cleanups, catch handlers are still unfinished.

llvm-svn: 233636
2015-03-30 22:58:10 +00:00
Benjamin Kramer
799003bf8c Re-sort includes with sort-includes.py and insert raw_ostream.h where it's used.
llvm-svn: 232998
2015-03-23 19:32:43 +00:00
Reid Kleckner
016c6b2104 Handle big index in getelementptr instruction
CodeGen incorrectly ignores (assert from APInt) constant index bigger
than 2^64 in getelementptr instruction. This is a test and fix for that.

Patch by Paweł Bylica!

Reviewed By: rnk

Subscribers: majnemer, rnk, mcrosier, resistor, llvm-commits

Differential Revision: http://reviews.llvm.org/D8219

llvm-svn: 231984
2015-03-11 23:36:10 +00:00
Eric Christopher
9deb75d176 Have getCallPreservedMask and getThisCallPreservedMask take a
MachineFunction argument so that we can grab subtarget specific
features off of it.

llvm-svn: 231979
2015-03-11 22:42:13 +00:00
Eric Christopher
8b7706517c Move DataLayout back to the TargetMachine from TargetSubtargetInfo
derived classes.

Since global data alignment, layout, and mangling is often based on the
DataLayout, move it to the TargetMachine. This ensures that global
data is going to be layed out and mangled consistently if the subtarget
changes on a per function basis. Prior to this all targets(*) have
had subtarget dependent code moved out and onto the TargetMachine.

*One target hasn't been migrated as part of this change: R600. The
R600 port has, as a subtarget feature, the size of pointers and
this affects global data layout. I've currently hacked in a FIXME
to enable progress, but the port needs to be updated to either pass
the 64-bitness to the TargetMachine, or fix the DataLayout to
avoid subtarget dependent features.

llvm-svn: 227113
2015-01-26 19:03:15 +00:00
Chandler Carruth
62d4215baa [PM] Move TargetLibraryInfo into the Analysis library.
While the term "Target" is in the name, it doesn't really have to do
with the LLVM Target library -- this isn't an abstraction which LLVM
targets generally need to implement or extend. It has much more to do
with modeling the various runtime libraries on different OSes and with
different runtime environments. The "target" in this sense is the more
general sense of a target of cross compilation.

This is in preparation for porting this analysis to the new pass
manager.

No functionality changed, and updates inbound for Clang and Polly.

llvm-svn: 226078
2015-01-15 02:16:27 +00:00
Chandler Carruth
d9903888d9 [cleanup] Re-sort all the #include lines in LLVM using
utils/sort_includes.py.

I clearly haven't done this in a while, so more changed than usual. This
even uncovered a missing include from the InstrProf library that I've
added. No functionality changed here, just mechanical cleanup of the
include order.

llvm-svn: 225974
2015-01-14 11:23:27 +00:00
Hal Finkel
0ad96c818c [StackMaps] Mark in CallLoweringInfo when lowering a patchpoint
While, generally speaking, the process of lowering arguments for a patchpoint
is the same as lowering a regular indirect call, on some targets it may not be
exactly the same. Targets may not, for example, want to add additional register
dependencies that apply only to making cross-DSO calls through linker stubs,
may not want to load additional registers out of function descriptors, and may
not want to add additional side-effect-causing instructions that cannot be
removed later with the call itself being generated.

The PowerPC target will use this in a future commit (for all of the reasons
stated above).

llvm-svn: 225806
2015-01-13 17:48:04 +00:00
David Blaikie
70573dcd9f Update SetVector to rely on the underlying set's insert to return a pair<iterator, bool>
This is to be consistent with StringSet and ultimately with the standard
library's associative container insert function.

This lead to updating SmallSet::insert to return pair<iterator, bool>,
and then to update SmallPtrSet::insert to return pair<iterator, bool>,
and then to update all the existing users of those functions...

llvm-svn: 222334
2014-11-19 07:49:26 +00:00
Duncan P. N. Exon Smith
de36e8040f Revert "IR: MDNode => Value"
Instead, we're going to separate metadata from the Value hierarchy.  See
PR21532.

This reverts commit r221375.
This reverts commit r221373.
This reverts commit r221359.
This reverts commit r221167.
This reverts commit r221027.
This reverts commit r221024.
This reverts commit r221023.
This reverts commit r220995.
This reverts commit r220994.

llvm-svn: 221711
2014-11-11 21:30:22 +00:00
Duncan P. N. Exon Smith
3872d0084c IR: MDNode => Value: Instruction::getMetadata()
Change `Instruction::getMetadata()` to return `Value` as part of
PR21433.

Update most callers to use `Instruction::getMDNode()`, which wraps the
result in a `cast_or_null<MDNode>`.

llvm-svn: 221024
2014-11-01 00:10:31 +00:00
Philip Reames
5a3f5f751b Introduce enum values for previously defined metadata types. (NFC)
Our metadata scheme lazily assigns IDs to string metadata, but we have a mechanism to preassign them as well.  Using a preassigned ID is helpful since we get compile time type checking, and avoid some (minimal) string construction and comparison.  This change adds enum value for three existing metadata types:
+    MD_nontemporal = 9, // "nontemporal"
+    MD_mem_parallel_loop_access = 10, // "llvm.mem.parallel_loop_access"
+    MD_nonnull = 11 // "nonnull"

I went through an updated various uses as well.  I made no attempt to get all uses; I focused on the ones which were easily grepable and easily to translate.  For example, there were several items in LoopInfo.cpp I chose not to update.

llvm-svn: 220248
2014-10-21 00:13:20 +00:00
Eric Christopher
4e3d6ded99 Remove getSubtargetImpl calls from FastISel, we can get it from
the MachineFunction where it's already cached.

llvm-svn: 219366
2014-10-08 23:38:33 +00:00
Eric Christopher
ffcbe9b048 Remove dead call to getTypeToTransformTo. The result is
unused.

llvm-svn: 219347
2014-10-08 22:25:45 +00:00
Adrian Prantl
87b7eb9d0f Move the complex address expression out of DIVariable and into an extra
argument of the llvm.dbg.declare/llvm.dbg.value intrinsics.

Previously, DIVariable was a variable-length field that has an optional
reference to a Metadata array consisting of a variable number of
complex address expressions. In the case of OpPiece expressions this is
wasting a lot of storage in IR, because when an aggregate type is, e.g.,
SROA'd into all of its n individual members, the IR will contain n copies
of the DIVariable, all alike, only differing in the complex address
reference at the end.

By making the complex address into an extra argument of the
dbg.value/dbg.declare intrinsics, all of the pieces can reference the
same variable and the complex address expressions can be uniqued across
the CU, too.
Down the road, this will allow us to move other flags, such as
"indirection" out of the DIVariable, too.

The new intrinsics look like this:
declare void @llvm.dbg.declare(metadata %storage, metadata %var, metadata %expr)
declare void @llvm.dbg.value(metadata %storage, i64 %offset, metadata %var, metadata %expr)

This patch adds a new LLVM-local tag to DIExpressions, so we can detect
and pretty-print DIExpression metadata nodes.

What this patch doesn't do:

This patch does not touch the "Indirect" field in DIVariable; but moving
that into the expression would be a natural next step.

http://reviews.llvm.org/D4919
rdar://problem/17994491

Thanks to dblaikie and dexonsmith for reviewing this patch!

Note: I accidentally committed a bogus older version of this patch previously.
llvm-svn: 218787
2014-10-01 18:55:02 +00:00
Adrian Prantl
b458dc2eee Revert r218778 while investigating buldbot breakage.
"Move the complex address expression out of DIVariable and into an extra"

llvm-svn: 218782
2014-10-01 18:10:54 +00:00
Adrian Prantl
25a7174e7a Move the complex address expression out of DIVariable and into an extra
argument of the llvm.dbg.declare/llvm.dbg.value intrinsics.

Previously, DIVariable was a variable-length field that has an optional
reference to a Metadata array consisting of a variable number of
complex address expressions. In the case of OpPiece expressions this is
wasting a lot of storage in IR, because when an aggregate type is, e.g.,
SROA'd into all of its n individual members, the IR will contain n copies
of the DIVariable, all alike, only differing in the complex address
reference at the end.

By making the complex address into an extra argument of the
dbg.value/dbg.declare intrinsics, all of the pieces can reference the
same variable and the complex address expressions can be uniqued across
the CU, too.
Down the road, this will allow us to move other flags, such as
"indirection" out of the DIVariable, too.

The new intrinsics look like this:
declare void @llvm.dbg.declare(metadata %storage, metadata %var, metadata %expr)
declare void @llvm.dbg.value(metadata %storage, i64 %offset, metadata %var, metadata %expr)

This patch adds a new LLVM-local tag to DIExpressions, so we can detect
and pretty-print DIExpression metadata nodes.

What this patch doesn't do:

This patch does not touch the "Indirect" field in DIVariable; but moving
that into the expression would be a natural next step.

http://reviews.llvm.org/D4919
rdar://problem/17994491

Thanks to dblaikie and dexonsmith for reviewing this patch!

llvm-svn: 218778
2014-10-01 17:55:39 +00:00
Juergen Ributzka
d111d29f90 [FastISel] Move optimizeCmpPredicate to FastISel base class. NFC.
Make the optimizeCmpPredicate function available to all targets.

llvm-svn: 217822
2014-09-15 20:47:13 +00:00
Hans Wennborg
18f0a986c1 Fast-ISel: Remove dead code after falling back from selecting call instructions (PR20863)
Previously, fast-isel would not clean up after failing to select a call
instruction, because it would have called flushLocalValueMap() which moves
the insertion point, making SavedInsertPt in selectInstruction() invalid.

Fixing this by making SavedInsertPt a member variable, and having
flushLocalValueMap() update it.

This removes some redundant code at -O0, and more importantly fixes PR20863.

Differential Revision: http://reviews.llvm.org/D5249

llvm-svn: 217401
2014-09-08 20:24:10 +00:00
Juergen Ributzka
88e32517c4 [FastISel][tblgen] Rename tblgen generated FastISel functions. NFC.
This is the final round of renaming. This changes tblgen to emit lower-case
function names for FastEmitInst_* and FastEmit_*, and updates all its uses
in the source code.

Reviewed by Eric

llvm-svn: 217075
2014-09-03 20:56:59 +00:00
Juergen Ributzka
5b8bb4d7dd [FastISel] Rename public visible FastISel functions. NFC.
This commit renames the following public FastISel functions:
LowerArguments -> lowerArguments
SelectInstruction -> selectInstruction
TargetSelectInstruction -> fastSelectInstruction
FastLowerArguments -> fastLowerArguments
FastLowerCall -> fastLowerCall
FastLowerIntrinsicCall -> fastLowerIntrinsicCall
FastEmitZExtFromI1 -> fastEmitZExtFromI1
FastEmitBranch -> fastEmitBranch
UpdateValueMap -> updateValueMap
TargetMaterializeConstant -> fastMaterializeConstant
TargetMaterializeAlloca -> fastMaterializeAlloca
TargetMaterializeFloatZero -> fastMaterializeFloatZero
LowerCallTo -> lowerCallTo

Reviewed by Eric

llvm-svn: 217074
2014-09-03 20:56:52 +00:00
Juergen Ributzka
7a76c2409e [FastISel] Some long overdue spring cleaning of FastISel.
Things got a little bit messy over the years and it is time for a little bit
spring cleaning.

This first commit is focused on the FastISel base class itself. It doxyfies all
comments, C++11fies the code where it makes sense, renames internal methods to
adhere to the coding standard, and clang-formats the files.

Reviewed by Eric

llvm-svn: 217060
2014-09-03 18:46:45 +00:00
Juergen Ributzka
7e998fb5e6 [FastISel] Provide the option to skip target-independent instruction selection. NFC.
This allows the target to disable target-independent instruction selection and
jump directly into the target-dependent instruction selection code.

This can be beneficial for targets, such as AArch64, which could emit much
better code, but never got a chance to do so, because the target-independent
instruction selector was able to find an instruction sequence.

llvm-svn: 216947
2014-09-02 21:07:44 +00:00
Juergen Ributzka
31328168bb [FastISel] Undo phi node updates when falling-back to SelectionDAG.
The included test case would fail, because the MI PHI node would have two
operands from the same predecessor.

This problem occurs when a switch instruction couldn't be selected. This happens
always, because there is no default switch support for FastISel to begin with.

The problem was that FastISel would first add the operand to the PHI nodes and
then fall-back to SelectionDAG, which would then in turn add the same operands
to the PHI nodes again.

This fix removes these duplicate PHI node operands by reseting the
PHINodesToUpdate to its original state before FastISel tried to select the
instruction.

This fixes <rdar://problem/18155224>.

llvm-svn: 216640
2014-08-28 02:06:55 +00:00
Juergen Ributzka
4f1a54a41a [FastISel]
Currently instructions are folded very aggressively for AArch64 into the memory
operation, which can lead to the use of killed operands:
  %vreg1<def> = ADDXri %vreg0<kill>, 2
  %vreg2<def> = LDRBBui %vreg0, 2
  ... = ... %vreg1 ...

This usually happens when the result is also used by another non-memory
instruction in the same basic block, or any instruction in another basic block.

This fix teaches hasTrivialKill to not only check the LLVM IR that the value has
a single use, but also to check if the register that represents that value has
already been used. This can happen when the instruction with the use was folded
into another instruction (in this particular case a load instruction).

This fixes rdar://problem/18142857.

llvm-svn: 216634
2014-08-28 00:09:46 +00:00
Juergen Ributzka
833bc681e3 [FastISel] Fix a potential bug in FastEmitInst_ri
FastEmitInst_ri was constraining the first operand without checking if it is
a virtual register. Use constrainOperandRegClass as all the other
FastEmitInst_* functions.

llvm-svn: 216613
2014-08-27 20:47:33 +00:00
Juergen Ributzka
4bf6c01cdb Reapply [FastISel] Let the target decide first if it wants to materialize a constant (215588).
Note: This was originally reverted to track down a buildbot error. This commit
exposed a latent bug that was fixed in r215753. Therefore it is reapplied
without any modifications.

I run it through SPEC2k and SPEC2k6 for AArch64 and it didn't introduce any new
regeressions.

Original commit message:
This changes the order in which FastISel tries to materialize a constant.
Originally it would try to use a simple target-independent approach, which
can lead to the generation of inefficient code.

On X86 this would result in the use of movabsq to materialize any 64bit
integer constant - even for simple and small values such as 0 and 1. Also
some very funny floating-point materialization could be observed too.

On AArch64 it would materialize the constant 0 in a register even the
architecture has an actual "zero" register.

On ARM it would generate unnecessary mov instructions or not use mvn.

This change simply changes the order and always asks the target first if it
likes to materialize the constant. This doesn't fix all the issues
mentioned above, but it enables the targets to implement such
optimizations.

Related to <rdar://problem/17420988>.

llvm-svn: 216006
2014-08-19 19:05:24 +00:00
Juergen Ributzka
5b1dbec1b4 [FastISel] Remove an performance debugging assert.
As Jim pointed out this assert isn't really needed to test for correctness,
because the code right afterwards does the same check and falls-back to
SelectionDAG - as intended.

llvm-svn: 215735
2014-08-15 17:36:30 +00:00
Juergen Ributzka
790bacf232 Revert several FastISel commits to track down a buildbot error.
This reverts:
r215595 "[FastISel][X86] Add large code model support for materializing floating-point constants."
r215594 "[FastISel][X86] Use XOR to materialize the "0" value."
r215593 "[FastISel][X86] Emit more efficient instructions for integer constant materialization."
r215591 "[FastISel][AArch64] Make use of the zero register when possible."
r215588 "[FastISel] Let the target decide first if it wants to materialize a constant."
r215582 "[FastISel][AArch64] Cleanup constant materialization code. NFCI."

llvm-svn: 215673
2014-08-14 19:56:28 +00:00