Commit Graph

111811 Commits

Author SHA1 Message Date
Duncan P. N. Exon Smith
2912990d86 IR: Separate out decrementUnresolvedOperandCount(), NFC
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225667 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-12 19:43:15 +00:00
Duncan P. N. Exon Smith
aea8ab800f IR: Prevent handleChangedOperand() recursion
Instead of returning early on `handleChangedOperand()` recursion
(finally identified (and test added) in r225657), prevent it upfront by
releasing operands before RAUW.

Aside from massively different program flow, there should be no
functionality change ;).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225665 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-12 19:36:35 +00:00
Tom Stellard
d275e025d2 R600/SI: Use RegisterOperands to specify which operands can accept immediates
There are some operands which can take either immediates or registers
and we were previously using different register class to distinguish
between operands that could take immediates and those that could not.

This patch switches to using RegisterOperands which should simplify the
backend by reducing the number of register classes and also make it
easier to implement the assembler.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225662 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-12 19:33:18 +00:00
Tom Stellard
b461e8304c Target: Allow target specific operand types
This adds two new fields to the RegisterOperand TableGen class:

string OperandNamespace = "MCOI";
string OperandType = "OPERAND_REGISTER";

These fields can be used to specify a target specific operand type,
which will be stored in the OperandType member of the MCOperandInfo
object.

This can be useful for targets that need to store some extra information
about operands that cannot be expressed using the target independent
types.  For example, in the R600 backend, there are operands which
can take either registers or immediates and it is convenient to be able
to specify this in the TableGen definitions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225661 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-12 19:33:09 +00:00
Sanjay Patel
2211d38267 GVN: propagate equalities for floating point compares
Allow optimizations based on FP comparison values in the same way
as integers. 

This resolves PR17713:
http://llvm.org/bugs/show_bug.cgi?id=17713

Differential Revision: http://reviews.llvm.org/D6911



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225660 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-12 19:29:48 +00:00
Duncan P. N. Exon Smith
728315adf4 IR: Add test for handleChangedOperand() recursion
Turns out this can happen.  Remove the `FIXME` and add a testcase that
crashes without the extra logic.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225657 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-12 19:22:04 +00:00
Duncan P. N. Exon Smith
6205b21cf5 IR: Separate out recalculateHash(), NFC
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225655 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-12 19:16:34 +00:00
Duncan P. N. Exon Smith
7826807958 IR: Separate out helper: resolveAfterOperandChange(), NFC
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225654 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-12 19:14:15 +00:00
Duncan P. N. Exon Smith
b8e8faf480 IR: Use SubclassData32 directly, NFC
Simplify some logic by accessing `SubclassData32` directly instead of
relying on API.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225653 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-12 19:12:37 +00:00
Matthias Braun
095ca8f493 RegisterCoalescer: Turn some impossible conditions into asserts
This is a fixed version of reverted r225500. It fixes the too early
if() continue; of the last patch and adds a comment to the unorthodox
loop.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225652 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-12 19:10:17 +00:00
Duncan P. N. Exon Smith
54b53edbd9 IR: Don't allow operands to become unresolved
Operands shouldn't change from being resolved to unresolved during graph
construction.  Simplify the logic based on that assumption.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225649 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-12 18:59:40 +00:00
Duncan P. N. Exon Smith
1478aabb18 IR: Remove redundant comment, NFC
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225648 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-12 18:45:32 +00:00
Duncan P. N. Exon Smith
0315eb0bcb IR: Simplify code, NFC
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225647 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-12 18:45:01 +00:00
Duncan P. N. Exon Smith
28184c10c9 IR: Make temporary nodes distinct
Change the return of `MDNode::isDistinct()` for `MDNode::getTemporary()`
to `true`.  They aren't uniqued.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225646 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-12 18:41:26 +00:00
Rafael Espindola
5512415ade Add r224985 back with two fixes.
One is that AArch64 has additional restrictions on when local relocations can
be used. We have to take those into consideration when deciding to put a L
symbol in the symbol table or not.

The other is that ld64 requires the relocations to cstring to use linker
visible symbols on AArch64.

Thanks to Michael Zolotukhin for testing this!

Remove doesSectionRequireSymbols.

In an assembly expression like

bar:
.long L0 + 1

the intended semantics is that bar will contain a pointer one byte past L0.

In sections that are merged by content (strings, 4 byte constants, etc), a
single position in the section doesn't give the linker enough information.
For example, it would not be able to tell a relocation must point to the
end of a string, since that would look just like the start of the next.

The solution used in ELF to use relocation with symbols if there is a non-zero
addend.

In MachO before this patch we would just keep all symbols in some sections.

This would miss some cases (only cstrings on x86_64 were implemented) and was
inefficient since most relocations have an addend of 0 and can be represented
without the symbol.

This patch implements the non-zero addend logic for MachO too.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225644 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-12 18:13:07 +00:00
Duncan P. N. Exon Smith
e5e4a9a4df IR: Simplify replaceOperandWith(), NFC
This will call `handleChangedOperand()` less frequently, but in that
case (i.e., `isStoredDistinctInContext()`) it has identical logic to
here.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225643 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-12 18:01:45 +00:00
Duncan P. N. Exon Smith
21245280cc IR: Remove redundant calls to MDNode::setHash(), NFC
`storeDistinctInContext()` already calls `setHash(0)`.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225642 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-12 17:57:38 +00:00
Timur Iskhodzhanov
de4190697a [ASan] Move the shadow on Windows 32-bit from 0x20000000 to 0x40000000
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225641 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-12 17:38:58 +00:00
Ahmed Bougacha
2cec3e9c11 [SimplifyLibCalls] Factor out fortified libcall handling.
This lets us remove CGP duplicate.

Differential Revision: http://reviews.llvm.org/D6541


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225640 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-12 17:22:43 +00:00
Ahmed Bougacha
fe2d64e0f6 [SimplifyLibCalls] Factor out str/mem libcall optimizations.
Put them in a separate function, so we can reuse them to further
simplify fortified libcalls as well.

Differential Revision: http://reviews.llvm.org/D6540


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225639 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-12 17:20:06 +00:00
Ahmed Bougacha
aebee0ee62 [SimplifyLibCalls] Factor out signature checks for fortifiable libcalls.
The checks are the same for fortified counterparts to the libcalls, so
we might as well do them in a single place.

Differential Revision: http://reviews.llvm.org/D6539


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225638 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-12 17:18:19 +00:00
Jozef Kolek
ad017096fc [mips][microMIPS] Implement BEQZ16 and BNEZ16 instructions
Differential Revision: http://reviews.llvm.org/D5271


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225627 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-12 12:03:34 +00:00
Richard Smith
7a95c03b1d Put this test's input in the Inputs directory where it belongs, rather than
reusing a file from a different test directory.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225621 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-12 08:50:47 +00:00
Chandler Carruth
ecf84c1124 Add a new utility script that helps update very simple regression tests.
This script is currently specific to x86 and limited to use with very
small regression or feature tests using 'llc' and 'FileCheck' in
a reasonably canonical way. It is in no way general purpose or robust at
this point. However, it works quite well for simple examples. Here is
the intended workflow:

- Make a change that requires updating N test files and M functions'
  assertions within those files.
- Stash the change.
- Update those N test files' RUN-lines to look "canonical"[1].
- Refresh the FileCheck lines for either the entire file or select
  functions by running this script.
  - The script will parse the RUN lines and run the 'llc' binary you
    give it according to each line, collecting the asm.
  - It will then annotate each function with the appropriate FileCheck
    comments to check every instruction from the start of the first
    basic block to the last return.
  - There will be numerous cases where the script either fails to remove
    the old lines, or inserts checks which need to be manually editted,
    but the manual edits tend to be deletions or replacements of
    registers with FileCheck variables which are fast manual edits.
  - A common pattern is to have the script insert complete checking of
    every instruction, and then edit it down to only check the relevant
    ones.
  - Be careful to do all of these cleanups though! The script is
    designed to make transferring and formatting the asm output of llc
    into a test case fast, it is *not* designed to be authoratitive
    about what constitutes a good test!
- Commit the nice fresh baseline of checks.
- Unstash your change and rebuild llc.
- Re-run script to regenerate the FileCheck annotations
  - Remember to re-cleanup these annotations!!!
- Check the diff to make sure this is sane, checking the things you
  expected it to, and check that the newly updated tests actually pass.
- Profit!

Also, I'm *terrible* at writing Python, and frankly I didn't spend a lot
of time making this script beautiful or well engineered. But it's useful
to me and may be useful to others so I thought I'd send it out.

http://reviews.llvm.org/D5546

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225618 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-12 04:43:18 +00:00
Hal Finkel
b6bb7db62b [PowerPC] Fix calls to non-function objects
Looking at r225438 inspired me to see how the PowerPC backend handled the
situation (calling a bitcasted TLS global), and it turns out we also produced
an error (cannot select ...). What it means to "call" something that is not a
function is implementation and platform specific, but in the name of doing
something (besides crashing), this makes sure we do what GCC does (treat all
such calls as calls through a function pointer -- meaning that the pointer is
assumed, as is the convention on PPC, to point to a function descriptor
structure holding the actual code address along with the function's TOC pointer
and environment pointer). As GCC does, we now do the same for calling regular
(non-TLS) non-function globals too.

I'm not sure whether this is the most useful way to define the behavior, but at
least we won't be alone.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225617 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-12 04:34:47 +00:00
Simon Pilgrim
dc5a2dabfe [X86][SSE] Minor fix to VPBLENDW AVX2 commutation.
D6015 / rL221313 enabled commutation for SSE immediate blend instructions, but due to a typo the AVX2 VPBLENDW ymm instructions weren't flagged as commutative along with the others in the tables, but were still being commuted in code and tested for.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225612 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-11 22:08:01 +00:00
Daniel Sanders
8da1635c6a Fix silly mistake in release notes for Mips.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225608 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-11 10:48:20 +00:00
Daniel Sanders
e7f28b2bb0 Added release notes for the Mips target.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225607 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-11 10:34:52 +00:00
David Majnemer
85a0cb9bf2 Revert most of r225597
We can't rely on a DataLayout enlightened constant folder.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225599 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-11 07:29:51 +00:00
David Majnemer
d2f4460ee7 X86: Properly decode shuffle masks when the constant pool type is weird
It's possible for the constant pool entry for the shuffle mask to come
from a completely different operation.  This occurs when Constants have
the same bit pattern but have different types.

Make DecodePSHUFBMask tolerant of types which, after a bitcast, are
appropriately sized vector types.

This fixes PR22188.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225597 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-11 05:08:57 +00:00
Saleem Abdulrasool
776673ea09 X86: teach X86TargetLowering about L,M,O constraints
Teach the ISelLowering for X86 about the L,M,O target specific constraints.
Although, for the moment, clang performs constraint validation and prevents
passing along inline asm which may have immediate constant constraints violated,
the backend should be able to cope with the invalid inline asm a bit better.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225596 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-11 04:39:24 +00:00
Saleem Abdulrasool
5e3c87ee1a ARM: add support for segment base relocations (SBREL)
This adds support for parsing and emitting the SBREL relocation variant for the
ARM target.  Handling this relocation variant is necessary for supporting the
full ARM ELF specification.  Addresses PR22128.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225595 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-11 04:39:18 +00:00
Chandler Carruth
561088eb5d [x86] Remove some windows line endings that snuck into the tests here.
Folks on Windows, remember to set up your subversion to strip these when
submitting...

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225593 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-11 01:36:20 +00:00
Chandler Carruth
6c92f6eb6a [ADT] Remove the unused default constructor for iterator_range.
This default constructor is a bit weird. It left the range in an invalid
state. That might be reasonable so that you can construct a local
iterator range and assign to it based on some logic to compute the range
you want. If folks would like to support that use case, I can add it
back, but in 238-odd usages none have actually wanted to do this. ;]

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225592 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-11 01:16:26 +00:00
Sanjoy Das
7f0da20b97 Fix PR22179.
We were incorrectly inferring nsw for certain SCEVs. We can be more
aggressive here (see Richard Smith's comment on
http://llvm.org/bugs/show_bug.cgi?id=22179) but this change just
focuses on correctness.

Differential Revision: http://reviews.llvm.org/D6914



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225591 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-10 23:41:24 +00:00
Joerg Sonnenberger
3073d3960a Revert r225500, it leads to infinite loops.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225590 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-10 21:49:36 +00:00
Simon Pilgrim
47abf0e3da [X86][SSE] Improved (v)insertps shuffle matching
In the current code we only attempt to match against insertps if we have exactly one element from the second input vector, irrespective of how much of the shuffle result is zeroable.

This patch checks to see if there is a single non-zeroable element from either input that requires insertion. It also supports matching of cases where only one of the inputs need to be referenced.

We also split insertps shuffle matching off into a new lowerVectorShuffleAsInsertPS function.

Differential Revision: http://reviews.llvm.org/D6879



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225589 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-10 19:45:33 +00:00
Ramkumar Ramachandra
dc857fefdc .gitignore: add some rules for tagging programs
Often, we miss committing new files, and 'arc diff' is supposed to warn
us about this. Unfortunately, because of the spurious output of the
command (due to unignored untracked files), we tend to ignore it and
lose information.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225588 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-10 19:11:29 +00:00
Hal Finkel
9ae5b7a40a [PowerPC] Mark zext of a small scalar load as free
This initial implementation of PPCTargetLowering::isZExtFree marks as free
zexts of small scalar loads (that are not sign-extending). This callback is
used by SelectionDAGBuilder's RegsForValue::getCopyToRegs, and thus to
determine whether a zext or an anyext is used to lower illegally-typed PHIs.
Because later truncates of zero-extended values are nops, this allows for the
elimination of later unnecessary truncations.

Fixes the initial complaint associated with PR22120.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225584 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-10 08:21:59 +00:00
Justin Hibbits
8ab13c61ed Remove some whitespace.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225583 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-10 07:50:31 +00:00
Dmitri Gribenko
750f3160df ConvertUTFTest: fix misleading empty line
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225580 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-10 05:03:29 +00:00
Saleem Abdulrasool
9c4081dce4 tests: fix previous commit
The previous commit accidentally missed changes to the test output checking,
resulting in an errant failure.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225577 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-10 02:53:25 +00:00
Saleem Abdulrasool
e83fb8c282 test: merge ARM relocations test
There is a fair number of relocations that are part of the AAELF specification.
Simply merge the tests into a single test file, otherwise, we will end up with
far too many test files to test each relocation type.  NFC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225576 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-10 02:48:29 +00:00
Saleem Abdulrasool
cc597901e5 tests: convert a couple of ARM relocation tests to readobj
These tests are checking the relocation generation.  Use the readobj output as
it is much easier to follow when glancing over the tests.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225575 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-10 02:48:25 +00:00
Justin Hibbits
1c6936f6d7 Fully fix Bug #22115.
Summary:
In the previous commit, the register was saved, but space was not allocated.
This resulted in the parameter save area potentially clobbering r30, leading to
nasty results.

Test Plan: Tests updated

Reviewers: hfinkel

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D6906

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225573 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-10 01:57:21 +00:00
Alexey Samsonov
2ba0f89d9e Fix undefined behavior (shift of negative value) in RuntimeDyldMachOAArch64::encodeAddend.
Test Plan: regression test suite with/without UBSan.

Reviewers: lhames, ributzka

Subscribers: aemerson, llvm-commits

Differential Revision: http://reviews.llvm.org/D6908

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225568 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-10 00:46:38 +00:00
Hal Finkel
6829815d96 [PowerPC] Readjust the loop unrolling threshold
Now that the way that the partial unrolling threshold for small loops is used
to compute the unrolling factor as been corrected, a slightly smaller threshold
is preferable. This is expected; other targets may need to re-tune as well.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225566 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-10 00:31:10 +00:00
Hal Finkel
a14d6f1ea5 [LoopUnroll] Fix the partial unrolling threshold for small loop sizes
When we compute the size of a loop, we include the branch on the backedge and
the comparison feeding the conditional branch. Under normal circumstances,
these don't get replicated with the rest of the loop body when we unroll. This
led to the somewhat surprising behavior that really small loops would not get
unrolled enough -- they could be unrolled more and the resulting loop would be
below the threshold, because we were assuming they'd take
(LoopSize * UnrollingFactor) instructions after unrolling, instead of
(((LoopSize-2) * UnrollingFactor)+2) instructions. This fixes that computation.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225565 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-10 00:30:55 +00:00
Rafael Espindola
68016e0a6e Use the DiagnosticHandler to print diagnostics when reading bitcode.
The bitcode reading interface used std::error_code to report an error to the
callers and it is the callers job to print diagnostics.

This is not ideal for error handling or diagnostic reporting:

* For error handling, all that the callers care about is 3 possibilities:
  * It worked
  * The bitcode file is corrupted/invalid.
  * The file is not bitcode at all.

* For diagnostic, it is user friendly to include far more information
  about the invalid case so the user can find out what is wrong with the
  bitcode file. This comes up, for example, when a developer introduces a
  bug while extending the format.

The compromise we had was to have a lot of error codes.

With this patch we use the DiagnosticHandler to communicate with the
human and std::error_code to communicate with the caller.

This allows us to have far fewer error codes and adds the infrastructure to
print better diagnostics. This is so because the diagnostics are printed when
he issue is found. The code that detected the problem in alive in the stack and
can pass down as much context as needed. As an example the patch updates
test/Bitcode/invalid.ll.

Using a DiagnosticHandler also moves the fatal/non-fatal error decision to the
caller. A simple one like llvm-dis can just use fatal errors. The gold plugin
needs a bit more complex treatment because of being passed non-bitcode files. An
hypothetical interactive tool would make all bitcode errors non-fatal.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225562 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-10 00:07:30 +00:00
Alexey Samsonov
f79e2d40b2 Fix UBSan error reports in ValueMapCallbackVH and AssertingVH<T> empty/tombstone keys generation.
Summary:
One more attempt to fix UBSan reports: make sure DenseMapInfo::getEmptyKey()
and DenseMapInfo::getTombstoneKey() doesn't do any upcasts/downcasts to/from Value*.

Test Plan: check-llvm test suite with/without UBSan bootstrap

Reviewers: chandlerc, dexonsmith

Subscribers: llvm-commits, majnemer

Differential Revision: http://reviews.llvm.org/D6903

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225558 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-09 23:17:25 +00:00