Commit Graph

22302 Commits

Author SHA1 Message Date
Duncan P. N. Exon Smith
b5f4854fb4 DIBuilder: Create a getHeaderIterator() helper, NFC
Extract this so it can be reused.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226770 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-22 03:00:01 +00:00
Chris Bieneman
ce93603b11 Making deleted copy constructors and operators to be private for better diagnostics when deleted is not available.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226769 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-22 02:51:33 +00:00
Chris Bieneman
e84c7b1116 Assigning and copying command line option objects shouldn't be allowed.
Summary:
The default copy and assignment operators for these objects probably don't actually do what the clients intend, so they should be deleted.

Places using the assignment operator to set the value of an option should cast to the option's data type first to call into the override for operator=. Places using the copy constructor just need to be changed to not copy (i.e. passing by const reference instead of value).

Reviewers: dexonsmith, chandlerc

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D7114

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226762 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-22 01:49:59 +00:00
Adrian Prantl
f51d86f02c Rewrite DIExpression::Verify() using an iterator. NFC.
Addresses review comments for r226627.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226747 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-22 00:00:52 +00:00
Matthias Braun
9a43e3d47f LiveIntervalAnalysis: Mark subregister defs as undef when we determined they are only reading a dead superregister value
This was not necessary before as this case can only be detected when the
liveness analysis is at subregister level.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226733 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-21 22:55:13 +00:00
Chris Bieneman
f04568139a Adding a new cl::HideUnrelatedOptions API to allow clang to migrate off cl::getRegisteredOptions.
Summary: cl::getRegisteredOptions really exposes some of the innards of how command line parsing is implemented. Exposing new APIs that allow us to disentangle client code from implementation details will allow us to make more extensive changes to command line parsing.

Reviewers: chandlerc, dexonsmith, beanz

Reviewed By: dexonsmith

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D7100

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226729 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-21 22:45:52 +00:00
Matthias Braun
7d3ec5af28 LiveIntervalAnalysis: Factor out code to update liveness on vreg def removal
This cleans up code and is more in line with the general philosophy of
modifying LiveIntervals through LiveIntervalAnalysis instead of changing
them directly.

This also fixes a case where SplitEditor::removeBackCopies() would miss
the subregister ranges.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226690 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-21 19:02:30 +00:00
Matthias Braun
a955eabc7b LiveIntervalAnalysis: document removePhysRegDefAt() function.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226689 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-21 19:02:26 +00:00
Matthias Braun
1458e05967 LiveIntervalAnalysis: Factor out code to update liveness on physreg def removal
This cleans up code and is more in line with the general philosophy of
modifying LiveIntervals through LiveIntervalAnalysis instead of changing
them directly.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226687 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-21 18:50:21 +00:00
Matthias Braun
5a9462587d LiveIntervalAnalysis: Remove unused pruneValue() variant.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226686 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-21 18:45:57 +00:00
Chandler Carruth
b67fc33fa5 [PM] Replace an abuse of inheritance to override a single function with
a more direct approach: a type-erased glorified function pointer. Now we
can pass a function pointer into this for the easy case and we can even
pass a lambda into it in the interesting case in the instruction
combiner.

I'll be using this shortly to simplify the interfaces to InstCombiner,
but this helps pave the way and seems like a better design for the
libcall simplifier utility.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226640 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-21 02:11:59 +00:00
Adrian Prantl
4d569edd37 Make DIExpression::Verify() stricter by checking that the number of
elements and the ordering is sane and cleanup the accessors.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226627 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-21 00:59:20 +00:00
Chandler Carruth
622a4bdaa7 [PM] Separate the InstCombiner from its pass.
This creates a small internal pass which runs the InstCombiner over
a function. This is the hard part of porting InstCombine to the new pass
manager, as at this point none of the code in InstCombine has access to
a Pass object any longer.

The resulting interface for the InstCombiner is pretty terrible. I'm not
planning on leaving it that way. The key thing missing is that we need
to separate the worklist from the combiner a touch more. Once that's
done, it should be possible for *any* part of LLVM to just create
a worklist with instructions, populate it, and then combine it until
empty. The pass will just be the (obvious and important) special case of
doing that for an entire function body.

For now, this is the first increment of factoring to make all of this
work.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226618 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-20 22:44:35 +00:00
Manman Ren
0d12d4ebc6 [llvm link] Destroy ConstantArrays in LLVMContext if they are not used.
ConstantArrays constructed during linking can cause quadratic memory
explosion. An example is the ConstantArrays constructed when linking in
GlobalVariables with appending linkage.

Releasing all unused constants can cause a 20% LTO compile-time
slowdown for a large application. So this commit releases unused ConstantArrays
only.

rdar://19040716. It reduces memory footprint from 20+G to 6+G.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226592 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-20 19:24:59 +00:00
Chandler Carruth
30dd113d6f [PM] Don't spend time making self moves no-ops. They're allowed to leave
the object in a moved-from state, and its simpler to write the code that
way.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226589 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-20 18:54:16 +00:00
Duncan P. N. Exon Smith
0b4f175141 Revert "IR: Specify underlying type instead of r226570, NFC"
This reverts commit r226571.  GCC really doesn't like it [1].

[1]: http://bb.pgr.jp/builders/cmake-llvm-x86_64-linux/builds/20260

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226579 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-20 17:04:56 +00:00
Duncan P. N. Exon Smith
c7fa62b126 IR: Specify underlying type instead of r226570, NFC
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226571 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-20 16:03:09 +00:00
Duncan P. N. Exon Smith
aafcbcd045 IR: Store StorageType as an unsigned bitfield
Use `unsigned` instead of `StorageType` for the bitfield to prevent MSVC
from treating the top bit of the bitfield as a sign bit.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226570 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-20 15:51:14 +00:00
Chandler Carruth
a37512049c [PM] Port LoopInfo to the new pass manager, adding both a LoopAnalysis
pass and a LoopPrinterPass with the expected associated wiring.

I've added a RUN line to the only test case (!!!) we have that actually
prints loops. Everything seems to be working.

This is somewhat exciting as this is the first analysis using another
analysis to go in for the new pass manager. =D I also believe it is the
last analysis necessary for porting instcombine, but of course I may yet
discover more.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226560 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-20 10:58:50 +00:00
Chandler Carruth
1540633fdb [PM] Make the LoopInfoBase and LoopInfo objects movable so that they can
be used as results in the new pass manager.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226559 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-20 10:58:38 +00:00
Chandler Carruth
934e884ae7 [PM] Fix a moderately scary typo in the deleted copy constructor
I noticed when adding move semantics to LoopInfo.

Hopefully not relevant, but still scary. =]

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226556 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-20 10:20:52 +00:00
Chandler Carruth
94a37a364e [PM] Use range-based for and auto to clean up some of the LoopInfo code.
No functionality changed.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226555 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-20 10:02:49 +00:00
Duncan P. N. Exon Smith
749d6fbf7e IR: Move MDNode clone() methods from ValueMapper to MDNode, NFC
Now that the clone methods used by `MapMetadata()` don't do any
remapping (and return a temporary), they make more sense as member
functions on `MDNode` (and subclasses).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226541 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-20 02:56:57 +00:00
Chandler Carruth
ccfacf7182 [PM] Replace the Pass argument in MergeBasicBlockIntoOnlyPred with
a DominatorTree argument as that is the analysis that it wants to
update.

This removes the last non-loop utility function in Utils/ which accepts
a raw Pass argument.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226537 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-20 01:37:09 +00:00
Duncan P. N. Exon Smith
c10ef2df5c IR: Detect whether to call recalculateHash() via SFINAE, NFC
Rather than relying on updating switch statements correctly, detect
whether `setHash()` exists in the subclass.  If so, call
`recalculateHash()` and `setHash(0)` appropriately.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226531 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-20 00:57:33 +00:00
Duncan P. N. Exon Smith
0a9f921686 IR: Introduce GenericDwarfNode
As part of PR22235, introduce `DwarfNode` and `GenericDwarfNode`.  The
former is a metadata node with a DWARF tag.  The latter matches our
current (generic) schema of a header with string (and stringified
integer) data and an arbitrary number of operands.

This doesn't move it into place yet; that change will require a large
number of testcase updates.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226529 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-20 00:01:43 +00:00
Duncan P. N. Exon Smith
0d7ab29889 IR: Cleanup MDNode field use, NFC
Swap usage of `SubclassData32` and `MDNodeSubclassData`, and rename
`MDNodeSubclassData` to `NumUnresolved`.  Small drive-by cleanup to
`countUnresolvedOperands()` since otherwise the name clash with local
vars named `NumUnresolved` would be confusing.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226523 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-19 23:18:34 +00:00
Duncan P. N. Exon Smith
c062fbe4ca IR: Move replaceWithUniqued(), etc., to source file, NFC
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226522 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-19 23:17:09 +00:00
Duncan P. N. Exon Smith
b0617860b5 IR: Merge UniquableMDNode back into MDNode, NFC
As pointed out in r226501, the distinction between `MDNode` and
`UniquableMDNode` is confusing.  When we need subclasses of `MDNode`
that don't use all its functionality it might make sense to break it
apart again, but until then this makes the code clearer.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226520 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-19 23:13:14 +00:00
Duncan P. N. Exon Smith
ce8f144e00 IR: Simplify uniquifyImpl(), NFC
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226518 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-19 22:52:07 +00:00
Duncan P. N. Exon Smith
668bd8ccfe IR: Simplify erasing from uniquing store, NFC
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226517 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-19 22:47:08 +00:00
Duncan P. N. Exon Smith
05111848a0 Remove dead code, NFC
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226516 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-19 22:45:41 +00:00
Duncan P. N. Exon Smith
6744a8e53d Utils: Simplify MapMetadata(), NFC
Take advantage of the new ability of temporary nodes to mutate to
distinct and uniqued nodes to greatly simplify the `MapMetadata()`
helper functions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226511 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-19 22:39:07 +00:00
Duncan P. N. Exon Smith
37c7ccc40c IR: Allow temporary nodes to become uniqued or distinct
Add `MDNode::replaceWithUniqued()` and `MDNode::replaceWithDistinct()`,
which mutate temporary nodes to become uniqued or distinct.  On uniquing
collisions, the unique version is returned and the node is deleted.

This takes advantage of temporary nodes being folded back in, and should
let me clean up some awkward logic in `MapMetadata()`.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226510 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-19 22:24:52 +00:00
Duncan P. N. Exon Smith
65bb48b6fc IR: Remove templates from TempMDNodeDeleter, NFC
r226504 added `TempMDNodeDeleter` to help with `std::unique_ptr<>`-izing
the `MDNode::getTemporary()` interface.  It doesn't need to be
templated, though.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226509 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-19 22:21:15 +00:00
Duncan P. N. Exon Smith
0927997ce8 IR: Split out countUnresolvedOperands(), NFC
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226508 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-19 22:18:29 +00:00
Duncan P. N. Exon Smith
f9eaea701d IR: Return unique_ptr from MDNode::getTemporary()
Change `MDTuple::getTemporary()` and `MDLocation::getTemporary()` to
return (effectively) `std::unique_ptr<T, MDNode::deleteTemporary>`, and
clean up call sites.  (For now, `DIBuilder` call sites just call
`release()` immediately.)

There's an accompanying change in each of clang and polly to use the new
API.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226504 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-19 21:30:18 +00:00
Rafael Espindola
a23cc6a1ea Add r224985 back with fixes.
The fixes are to note that AArch64 has additional restrictions on when local
relocations can be used. In particular, ld64 requires that relocations to
cstring/cfstrings use linker visible symbols.

Original message:

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@226503 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-19 21:11:14 +00:00
Duncan P. N. Exon Smith
a7852bfa47 IR: Add MDLocation::getTemporary()
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226502 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-19 20:37:44 +00:00
Duncan P. N. Exon Smith
8ec0aee3b4 IR: Remove MDNodeFwdDecl
Remove `MDNodeFwdDecl` (as promised in r226481).  Aside from API
changes, there's no real functionality change here.
`MDNode::getTemporary()` now forwards to `MDTuple::getTemporary()`,
which returns a tuple with `isTemporary()` equal to true.

The main point is that we can now add temporaries of other `MDNode`
subclasses, needed for PR22235 (I introduced `MDNodeFwdDecl` in the
first place because I didn't recognize this need, and thought they were
only needed to handle forward references).

A few things left out of (or highlighted by) this commit:

  - I've had to remove the (few) uses of `std::unique_ptr<>` to deal
    with temporaries, since the destructor is no longer public.
    `getTemporary()` should probably return the equivalent of
    `std::unique_ptr<T, MDNode::deleteTemporary>`.
  - `MDLocation::getTemporary()` doesn't exist yet (worse, it actually
    does exist, but does the wrong thing: `MDNode::getTemporary()` is
    inherited and returns an `MDTuple`).
  - `MDNode` now only has one subclass, `UniquableMDNode`, and the
    distinction between them is actually somewhat confusing.

I'll fix those up next.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226501 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-19 20:36:39 +00:00
Duncan P. N. Exon Smith
e5afc6570f IR: Extract out and reuse storeImpl(), NFC
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226499 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-19 20:18:13 +00:00
Duncan P. N. Exon Smith
518025f8a1 IR: Reuse getImpl() for getDistinct(), NFC
Merge `getDistinct()`'s implementation with those of `get()` and
`getIfExists()` for both `MDTuple` and `MDLocation`.  This will make it
easier to scale to supporting temporaries.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226497 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-19 20:14:15 +00:00
Duncan P. N. Exon Smith
00a658dcdc IR: Move replaceAllUsesWith() back up to MDNode
Move `MDNodeFwdDecl::replaceAllUsesWith()` back up to `MDNode`, but
assert `isTemporary()`.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226495 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-19 19:35:21 +00:00
Duncan P. N. Exon Smith
c888b87713 IR: Be specific about what MDNode::get() returns, NFC
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226494 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-19 19:32:27 +00:00
Duncan P. N. Exon Smith
2973322cfa Remove dead code, NFC
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226493 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-19 19:31:09 +00:00
Duncan P. N. Exon Smith
c9a780aec5 IR: Unify code for MDNode::isResolved(), NFC
Unify the definitions of `MDNode::isResolved()` and
`UniquableMDNode::isResolved()`.  Previously, `UniquableMDNode` could
answer this question more efficiently, but now that RAUW support has
been unified with `MDNodeFwdDecl`, `MDNode` doesn't need any casts to
figure out the answer.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226485 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-19 19:03:18 +00:00
Duncan P. N. Exon Smith
641414a6c0 IR: Store RAUW support and Context in the same pointer, NFC
Add an `LLVMContext &` to `ReplaceableMetadataImpl`, create a class that
either holds a reference to an `LLVMContext` or owns a
`ReplaceableMetadataImpl`, and use the new class in `MDNode`.

  - This saves a pointer in `UniquableMDNode` at the cost of a pointer
    in `ValueAsMetadata` (which didn't used to store the `LLVMContext`).
    There are far more of the former.
  - Unifies RAUW support between `MDNodeFwdDecl` (which is going away,
    see r226481) and `UniquableMDNode`.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226484 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-19 19:02:06 +00:00
Duncan P. N. Exon Smith
1d72e18caa IR: Add isUniqued() and isTemporary()
Change `MDNode::isDistinct()` to only apply to 'distinct' nodes (not
temporaries), and introduce `MDNode::isUniqued()` and
`MDNode::isTemporary()` for the other two possibilities.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226482 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-19 18:45:35 +00:00
Duncan P. N. Exon Smith
5f50874b3d IR: Use an enum to describe Metadata storage, NFC
More clearly describe the type of storage used for `Metadata`.

  - `Uniqued`: uniqued, stored in the context.
  - `Distinct`: distinct, stored in the context.
  - `Temporary`: not owned by anyone.

This is the first in a series of commits to fix a design problem with
`MDNodeFwdDecl` that I need to solve for PR22235.  While `MDNodeFwdDecl`
works well as a forward declaration, we use `MDNode::getTemporary()` for
more than forward declarations -- we also need to create early versions
of nodes (with fields not filled in) that we'll fill out later (see
`DIBuilder::finalize()` and `CGDebugInfo::finalize()` for examples).
This was a blind spot I had when I introduced `MDNodeFwdDecl` (which
David Blaikie (indirectly) highlighted in an unrelated review [1]).

[1]: http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20150112/252381.html

In general, we need `MDTuple::getTemporary()` to give a temporary tuple
(like `MDNodeFwdDecl`), `MDLocation::getTemporary()` to give a temporary
location, and (the problem at hand) `GenericDebugMDNode::getTemporary()`
to give a temporary generic debug node.

So I need to fold the idea of "temporary" nodes back into
`UniquableMDNode`.  (More commits to follow as I refactor.)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226481 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-19 18:36:18 +00:00
Adrian Prantl
e240cc0b4b Remove support for DIVariable's FlagIndirectVariable and expect
frontends to use a DIExpression with a DW_OP_deref instead.

This is not only a much more natural place for this informationl; there
is also a technical reason: The FlagIndirectVariable is used to mark a
variable that is turned into a reference by virtue of the calling
convention; this happens for example to aggregate return values.
The inliner, for example, may actually need to undo this indirection to
correctly represent the value in its new context. This is impossible to
implement because the DIVariable can't be safely modified. We can however
safely construct a new DIExpression on the fly.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226476 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-19 17:57:29 +00:00