Commit Graph

476 Commits

Author SHA1 Message Date
Peter Collingbourne d4135bbc30 DebugInfo: New metadata representation for global variables.
This patch reverses the edge from DIGlobalVariable to GlobalVariable.
This will allow us to more easily preserve debug info metadata when
manipulating global variables.

Fixes PR30362. A program for upgrading test cases is attached to that
bug.

Differential Revision: http://reviews.llvm.org/D20147

llvm-svn: 281284
2016-09-13 01:12:59 +00:00
David Blaikie a01f295322 DebugInfo: Add flag to CU to disable emission of inline debug info into the skeleton CU
In cases where .dwo/.dwp files are guaranteed to be available, skipping
the extra online (in the .o file) inline info can save a substantial
amount of space - see the original r221306 for more details there.

llvm-svn: 279650
2016-08-24 18:29:49 +00:00
Adrian Prantl c19dee734f Support the DW_AT_noreturn DWARF flag.
This is used to mark functions with the C++11 [[ noreturn ]] or C11 _Noreturn
attributes.

Patch by Victor Leschuk!

https://reviews.llvm.org/D23167

llvm-svn: 278940
2016-08-17 16:02:43 +00:00
Mehdi Amini 8c629ecf3a Revert "Revert "Invariant start/end intrinsics overloaded for address space""
This reverts commit 32fc6488e48eafc0ca1bac1bd9cbf0008224d530.

llvm-svn: 278609
2016-08-13 23:31:24 +00:00
Mehdi Amini 164ac651da Revert "Invariant start/end intrinsics overloaded for address space"
This reverts commit r276447.

llvm-svn: 278608
2016-08-13 23:27:32 +00:00
Anna Thomas 0be4a0e6a4 Invariant start/end intrinsics overloaded for address space
Summary:
The llvm.invariant.start and llvm.invariant.end intrinsics currently
support specifying invariant memory objects only in the default address
space.

With this change, these intrinsics are overloaded for any adddress space
for memory objects
and we can use these llvm invariant intrinsics in non-default address
spaces.

Example: llvm.invariant.start.p1i8(i64 4, i8 addrspace(1)* %ptr)

This overloaded intrinsic is needed for representing final or invariant
memory in managed languages.

Reviewers: apilipenko, reames

Subscribers: llvm-commits
llvm-svn: 276447
2016-07-22 17:49:40 +00:00
Anna Thomas c858faa244 Revert "Invariant start/end intrinsics overloaded for address space"
This reverts commit r276316.

llvm-svn: 276320
2016-07-21 19:06:28 +00:00
Anna Thomas 29b24dfe44 Invariant start/end intrinsics overloaded for address space
Summary:
The llvm.invariant.start and llvm.invariant.end intrinsics currently
support specifying invariant memory objects only in the default address space.

With this change, these intrinsics are overloaded for any adddress space for memory objects
and we can use these llvm invariant intrinsics in non-default address spaces.

Example: llvm.invariant.start.p1i8(i64 4, i8 addrspace(1)* %ptr)

This overloaded intrinsic is needed for representing final or invariant memory in managed languages.

Reviewers: tstellarAMD, reames, apilipenko

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D22519

llvm-svn: 276316
2016-07-21 18:41:44 +00:00
David Majnemer a7b6c973e5 [ConstantFold] Don't incorrectly infer inbounds on array GEP
The many levels of nesting inside the responsible code made it easy for
bugs to sneak in.  Flattening the logic makes it easier to see what's
going on.

llvm-svn: 275244
2016-07-13 03:24:41 +00:00
Reid Kleckner b5af11dfa3 [codeview] Add DISubprogram::ThisAdjustment
Summary:
This represents the adjustment applied to the implicit 'this' parameter
in the prologue of a virtual method in the MS C++ ABI. The adjustment is
always zero unless multiple inheritance is involved.

This increases the size of DISubprogram by 8 bytes, unfortunately. The
adjustment really is a signed 32-bit integer. If this size increase is
too much, we could probably win it back by splitting out a subclass with
info specific to virtual methods (virtuality, vindex, thisadjustment,
containingType).

Reviewers: aprantl, dexonsmith

Subscribers: aaboud, amccarth, llvm-commits

Differential Revision: http://reviews.llvm.org/D21614

llvm-svn: 274325
2016-07-01 02:41:21 +00:00
Artur Pilipenko 7ad95ec22d Support arbitrary addrspace pointers in masked load/store intrinsics
This is a resubmittion of 263158 change after fixing the existing problem with intrinsics mangling (see LTO and intrinsics mangling llvm-dev thread for details).

This patch fixes the problem which occurs when loop-vectorize tries to use @llvm.masked.load/store intrinsic for a non-default addrspace pointer. It fails with "Calling a function with a bad signature!" assertion in CallInst constructor because it tries to pass a non-default addrspace pointer to the pointer argument which has default addrspace.

The fix is to add pointer type as another overloaded type to @llvm.masked.load/store intrinsics.

Reviewed By: reames

Differential Revision: http://reviews.llvm.org/D17270

llvm-svn: 274043
2016-06-28 18:27:25 +00:00
Artur Pilipenko 72f76b8805 Revert -r273892 "Support arbitrary addrspace pointers in masked load/store intrinsics" since some of the clang tests don't expect to see the updated signatures.
llvm-svn: 273895
2016-06-27 16:54:33 +00:00
Artur Pilipenko a36aa41519 Support arbitrary addrspace pointers in masked load/store intrinsics
This is a resubmittion of 263158 change after fixing the existing problem with intrinsics mangling (see LTO and intrinsics mangling llvm-dev thread for details).

This patch fixes the problem which occurs when loop-vectorize tries to use @llvm.masked.load/store intrinsic for a non-default addrspace pointer. It fails with "Calling a function with a bad signature!" assertion in CallInst constructor because it tries to pass a non-default addrspace pointer to the pointer argument which has default addrspace.

The fix is to add pointer type as another overloaded type to @llvm.masked.load/store intrinsics.

Reviewed By: reames

Differential Revision: http://reviews.llvm.org/D17270

llvm-svn: 273892
2016-06-27 16:29:26 +00:00
Peter Collingbourne 21521891a2 IR: Allow metadata attachments on declarations, and fix lazy loaded metadata issue with globals.
This change is motivated by an upcoming change to the metadata representation
used for CFI. The indirect function call checker needs type information for
external function declarations in order to correctly generate jump table
entries for such declarations. We currently associate such type information
with declarations using a global metadata node, but I plan [1] to move all
such metadata to global object attachments.

In bitcode, metadata attachments for function declarations appear in the
global metadata block. This seems reasonable to me because I expect metadata
attachments on declarations to be uncommon. In the long term I'd also expect
this to be the case for CFI, because we'd want to use some specialized bitcode
format for this metadata that could be read as part of the ThinLTO thin-link
phase, which would mean that it would not appear in the global metadata block.

To solve the lazy loaded metadata issue I was seeing with D20147, I use the
same bitcode representation for metadata attachments for global variables as I
do for function declarations. Since there's a use case for metadata attachments
in the global metadata block, we might as well use that representation for
global variables as well, at least until we have a mechanism for lazy loading
global variables.

In the assembly format, the metadata attachments appear after the "declare"
keyword in order to avoid a parsing ambiguity.

[1] http://lists.llvm.org/pipermail/llvm-dev/2016-June/100462.html

Differential Revision: http://reviews.llvm.org/D21052

llvm-svn: 273336
2016-06-21 23:42:48 +00:00
Peter Collingbourne 96efdd6107 IR: Introduce local_unnamed_addr attribute.
If a local_unnamed_addr attribute is attached to a global, the address
is known to be insignificant within the module. It is distinct from the
existing unnamed_addr attribute in that it only describes a local property
of the module rather than a global property of the symbol.

This attribute is intended to be used by the code generator and LTO to allow
the linker to decide whether the global needs to be in the symbol table. It is
possible to exclude a global from the symbol table if three things are true:
- This attribute is present on every instance of the global (which means that
  the normal rule that the global must have a unique address can be broken without
  being observable by the program by performing comparisons against the global's
  address)
- The global has linkonce_odr linkage (which means that each linkage unit must have
  its own copy of the global if it requires one, and the copy in each linkage unit
  must be the same)
- It is a constant or a function (which means that the program cannot observe that
  the unique-address rule has been broken by writing to the global)

Although this attribute could in principle be computed from the module
contents, LTO clients (i.e. linkers) will normally need to be able to compute
this property as part of symbol resolution, and it would be inefficient to
materialize every module just to compute it.

See:
http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20160509/356401.html
http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20160516/356738.html
for earlier discussion.

Part of the fix for PR27553.

Differential Revision: http://reviews.llvm.org/D20348

llvm-svn: 272709
2016-06-14 21:01:22 +00:00
Reid Kleckner de3d8b500f [DebugInfo] Add calling convention support for DWARF and CodeView
Summary:
Now DISubroutineType has a 'cc' field which should be a DW_CC_ enum.  If
it is present and non-zero, the backend will emit it as a
DW_AT_calling_convention attribute. On the CodeView side, we translate
it to the appropriate enum for the LF_PROCEDURE record.

I added a new LLVM vendor specific enum to the list of DWARF calling
conventions. DWARF does not appear to attempt to standardize these, so I
assume it's OK to do this until we coordinate with GCC on how to emit
vectorcall convention functions.

Reviewers: dexonsmith, majnemer, aaboud, amccarth

Subscribers: mehdi_amini, llvm-commits

Differential Revision: http://reviews.llvm.org/D21114

llvm-svn: 272197
2016-06-08 20:34:29 +00:00
Peter Collingbourne 382d81cacf IR: Allow multiple global metadata attachments with the same type.
This will be necessary to allow the global merge pass to attach
multiple debug info metadata nodes to global variables once we reverse
the edge from DIGlobalVariable to GlobalVariable.

Differential Revision: http://reviews.llvm.org/D20414

llvm-svn: 271358
2016-06-01 01:17:57 +00:00
Peter Collingbourne cceae7feda Add support for metadata attachments for global variables.
This patch adds an IR, assembly and bitcode representation for metadata
attachments for globals. Future patches will port existing features to use
these new attachments.

Differential Revision: http://reviews.llvm.org/D20074

llvm-svn: 271348
2016-05-31 23:01:54 +00:00
Matt Arsenault 2907e51246 Fix constant folding of addrspacecast of null
This should not be making assumptions on the value of
the casted pointer.

llvm-svn: 270293
2016-05-21 00:14:04 +00:00
Rafael Espindola 32483a7641 Make "@name =" mandatory for globals in .ll files.
An oddity of the .ll syntax is that the "@var = " in

@var = global i32 42

is optional. Writing just

global i32 42

is equivalent to

@0 = global i32 42

This means that there is a pretty big First set at the top level. The
current implementation maintains it manually. I was trying to refactor
it, but then started wondering why keep it a all. I personally find the
above syntax confusing. It looks like something is missing.

This patch removes the feature and simplifies the parser.

llvm-svn: 269096
2016-05-10 18:22:45 +00:00
Duncan P. N. Exon Smith a59d3e5af8 DebugInfo: Remove MDString-based type references
Eliminate DITypeIdentifierMap and make DITypeRef a thin wrapper around
DIType*.  It is no longer legal to refer to a DICompositeType by its
'identifier:', and DIBuilder no longer retains all types with an
'identifier:' automatically.

Aside from the bitcode upgrade, this is mainly removing logic to resolve
an MDString-based reference to an actualy DIType.  The commits leading
up to this have made the implicit type map in DICompileUnit's
'retainedTypes:' field superfluous.

This does not remove DITypeRef, DIScopeRef, DINodeRef, and
DITypeRefArray, or stop using them in DI-related metadata.  Although as
of this commit they aren't serving a useful purpose, there are patchces
under review to reuse them for CodeView support.

The tests in LLVM were updated with deref-typerefs.sh, which is attached
to the thread "[RFC] Lazy-loading of debug info metadata":

  http://lists.llvm.org/pipermail/llvm-dev/2016-April/098318.html

llvm-svn: 267296
2016-04-23 21:08:00 +00:00
Marcin Koscielnicki 3fdc257d6a [AArch64] [ARM] Make a target-independent llvm.thread.pointer intrinsic.
Both AArch64 and ARM support llvm.<arch>.thread.pointer intrinsics that
just return the thread pointer.  I have a pending patch that does the same
for SystemZ (D19054), and there are many more targets that could benefit
from one.

This patch merges the ARM and AArch64 intrinsics into a single target
independent one that will also be used by subsequent targets.

Differential Revision: http://reviews.llvm.org/D19098

llvm-svn: 266818
2016-04-19 20:51:05 +00:00
Duncan P. N. Exon Smith 2c7cd4afab IR: Fix type-refs in testcase from r266548
There's a hole in the verifier right now: if a module has no compile
units, it never checks that all the string-based DITypeRefs get
resolved.  As a result, this testcase didn't fail the verifier, even
there were references to `!"has-uuid"` instead of `!"uuid"` (the former
was a composite type's 'name:' field, the latter its 'identifier:'
field).

I'm currently working on removing string-based type refs entirely, and
this testcase started failing (because the upgrade script can't resolve
the type refs).  Rather than fixing the (about-to-be-removed) hole in
the verifier, I'm just going to fix the test so that my upgrade script
handles it.

llvm-svn: 266553
2016-04-17 06:42:30 +00:00
Duncan P. N. Exon Smith 05ebfd0938 IR: Use ODR to unique DICompositeType members
Merge members that are describing the same member of the same ODR type,
even if other bits differ.  If the file or line differ, we don't care;
if anything else differs, it's an ODR violation (and we still don't
really care).

For DISubprogram declarations, this looks at the LinkageName and Scope.
For DW_TAG_member instances of DIDerivedType, this looks at the Name and
Scope.  In both cases, we know that the Scope follows ODR rules if it
has a non-empty identifier.

llvm-svn: 266548
2016-04-17 02:30:20 +00:00
Adrian Prantl 75819aedf6 [PR27284] Reverse the ownership between DICompileUnit and DISubprogram.
Currently each Function points to a DISubprogram and DISubprogram has a
scope field. For member functions the scope is a DICompositeType. DIScopes
point to the DICompileUnit to facilitate type uniquing.

Distinct DISubprograms (with isDefinition: true) are not part of the type
hierarchy and cannot be uniqued. This change removes the subprograms
list from DICompileUnit and instead adds a pointer to the owning compile
unit to distinct DISubprograms. This would make it easy for ThinLTO to
strip unneeded DISubprograms and their transitively referenced debug info.

Motivation
----------

Materializing DISubprograms is currently the most expensive operation when
doing a ThinLTO build of clang.

We want the DISubprogram to be stored in a separate Bitcode block (or the
same block as the function body) so we can avoid having to expensively
deserialize all DISubprograms together with the global metadata. If a
function has been inlined into another subprogram we need to store a
reference the block containing the inlined subprogram.

Attached to https://llvm.org/bugs/show_bug.cgi?id=27284 is a python script
that updates LLVM IR testcases to the new format.

http://reviews.llvm.org/D19034
<rdar://problem/25256815>

llvm-svn: 266446
2016-04-15 15:57:41 +00:00
Adam Nemet 7aab648831 Revert "Support arbitrary addrspace pointers in masked load/store intrinsics"
This reverts commit r266086.

It breaks the LTO build of gcc in SPEC2000.

llvm-svn: 266282
2016-04-14 08:47:17 +00:00
Artur Pilipenko dbe0bc8df4 Support arbitrary addrspace pointers in masked load/store intrinsics
This is a resubmittion of 263158 change.

This patch fixes the problem which occurs when loop-vectorize tries to use @llvm.masked.load/store intrinsic for a non-default addrspace pointer. It fails with "Calling a function with a bad signature!" assertion in CallInst constructor because it tries to pass a non-default addrspace pointer to the pointer argument which has default addrspace.

The fix is to add pointer type as another overloaded type to @llvm.masked.load/store intrinsics.

Reviewed By: reames

Differential Revision: http://reviews.llvm.org/D17270

llvm-svn: 266086
2016-04-12 15:58:04 +00:00
Tim Shen 0012756489 [SSP] Remove llvm.stackprotectorcheck.
This is a cleanup patch for SSP support in LLVM. There is no functional change.
llvm.stackprotectorcheck is not needed, because SelectionDAG isn't
actually lowering it in SelectBasicBlock; rather, it adds check code in
FinishBasicBlock, ignoring the position where the intrinsic is inserted
(See FindSplitPointForStackProtector()).

llvm-svn: 265851
2016-04-08 21:26:31 +00:00
Dmitry Polukhin 24c4f28ac9 [IFUNC] Fix ifunc-asm.ll test
It seems that llc cannot be called used in assembler tests so test that
checks asm for particular target needs to be moved to codegen.

llvm-svn: 265770
2016-04-08 06:45:19 +00:00
Dmitry Polukhin af16b958c0 Fix test/Assembler/ifunc-asm.ll test on hexagon-elf bots
Temporary disable llc test, it seems that such test should be in some
other directory.

llvm-svn: 265669
2016-04-07 13:18:43 +00:00
Dmitry Polukhin a1feff7024 [GCC] Attribute ifunc support in llvm
This patch add support for GCC attribute((ifunc("resolver"))) for
targets that use ELF as object file format. In general ifunc is a
special kind of function alias with type @gnu_indirect_function. Patch
for Clang http://reviews.llvm.org/D15524

Differential Revision: http://reviews.llvm.org/D15525

llvm-svn: 265667
2016-04-07 12:32:19 +00:00
Duncan P. N. Exon Smith 29883866a4 AsmParser: Don't crash on unresolved !tbaa
Instead of crashing, give a nice error.  As a drive-by, fix the location
associated with the errors for unresolved metadata (the location was off
by one token).

llvm-svn: 265507
2016-04-06 02:06:40 +00:00
Davide Italiano ea04026c13 [DebugInfo] Fix tests so that each subprogram belongs to a CU.
llvm-svn: 265490
2016-04-05 23:37:08 +00:00
Davide Italiano a017306063 [DebugInfo] Fix tests in Assembler/
Each DISubprogram with isDefinition : true must
belong to a compile unit.

llvm-svn: 265281
2016-04-04 02:11:34 +00:00
Adrian Prantl b8089516a5 testcase gardening: update the emissionKind enum to the new syntax. (NFC)
llvm-svn: 265081
2016-04-01 00:16:49 +00:00
Adrian Prantl b939a25707 Move the DebugEmissionKind enum from DIBuilder into DICompileUnit.
This mostly cosmetic patch moves the DebugEmissionKind enum from DIBuilder
into DICompileUnit. DIBuilder is not the right place for this enum to live
in — a metadata consumer should not have to include DIBuilder.h.
I also added a Verifier check that checks that the emission kind of a
DICompileUnit is actually legal.

http://reviews.llvm.org/D18612
<rdar://problem/25427165>

llvm-svn: 265077
2016-03-31 23:56:58 +00:00
Teresa Johnson d8d94652b2 Use existing PrintEscapedString in AssemblyWriter
r264884 introduced a helper to escape the backslashes in the source file
path, but I since discovered an existing mechanism to escape strings.

llvm-svn: 264936
2016-03-30 22:17:28 +00:00
Teresa Johnson 83c517c44e Restore "[ThinLTO] Serialize the Module SourceFileName to/from LLVM assembly"
This restores commit 264869, with a fix for windows bots to properly
escape '\' in the path when serializing out. Added test.

llvm-svn: 264884
2016-03-30 18:15:08 +00:00
Teresa Johnson 20beeea24a Revert "[ThinLTO] Serialize the Module SourceFileName to/from LLVM assembly"
This reverts commit r264869. I am seeing Windows bot failures due to the
"\" in the path being mishandled at some point (seems to be interpreted
wrongly at some point and llvm-as | llvm-dis is yielding some junk
characters). Need to investigate.

llvm-svn: 264871
2016-03-30 15:16:04 +00:00
Teresa Johnson 832a6790f6 [ThinLTO] Serialize the Module SourceFileName to/from LLVM assembly
Summary:
This change serializes out and in the SourceFileName to LLVM assembly
so that it is preserved through "llvm-dis | llvm-as". This is
necessary to ensure that the global identifiers created for local values
in the module summary index are the same even if the bitcode is
streamed out and read back from LLVM assembly.

Serializing the summary itself to LLVM assembly is in progress.

Reviewers: joker.eph

Subscribers: llvm-commits, joker.eph

Differential Revision: http://reviews.llvm.org/D18588

llvm-svn: 264869
2016-03-30 14:00:02 +00:00
Duncan P. N. Exon Smith e8eb94a9a5 ADCE: Remove debug info intrinsics in dead scopes
During ADCE, track which debug info scopes still have live references
from the code, and delete debug info intrinsics for the dead ones.

These intrinsics describe the locations of variables (in registers or
stack slots).  If there's no code left corresponding to a variable's
scope, then there's no way to reference the variable in the debugger and
it doesn't matter what its value is.

I add a DEBUG printout when the described location in an SSA register,
in case it helps some trying to track down why locations get lost.
However, we still delete these; the scope itself isn't attached to any
real code, so the ship has already sailed.

llvm-svn: 264800
2016-03-29 22:57:12 +00:00
Adrian Prantl faebbb053d Add an IR Verifier check for orphaned DICompileUnits.
A DICompileUnit that is not listed in llvm.dbg.cu will cause assertion
failures and/or crashes in the backend. The Verifier should reject this.

rdar://problem/25369499

llvm-svn: 264657
2016-03-28 21:06:26 +00:00
Duncan P. N. Exon Smith efe16c8eb4 IR: Stop upgrading !llvm.loop attachments via MDString
Remove logic to upgrade !llvm.loop by changing the MDString tag
directly.  This old logic would check (and change) arbitrary strings
that had nothing to do with loop metadata.  Instead, check !llvm.loop
attachments directly, and change which strings get attached.

Rather than updating the assembly-based upgrade, drop it entirely.  It
has been quite a while since we supported upgrading textual IR.

llvm-svn: 264373
2016-03-25 00:56:13 +00:00
Matthias Braun 68bb2931cc Revert "Support arbitrary addrspace pointers in masked load/store intrinsics"
This commit broke LTO builds. Reverting it to unbreak the bots while the
issue is investigated. See also:

http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20160321/341002.html

This reverts r263158

llvm-svn: 264088
2016-03-22 20:24:34 +00:00
Peter Collingbourne a1f8625662 DebugInfo: Add ability to not emit DW_AT_vtable_elem_location for virtual functions.
A virtual index of -1u indicates that the subprogram's virtual index is
unrepresentable (for example, when using the relative vtable ABI), so do
not emit a DW_AT_vtable_elem_location attribute for it.

Differential Revision: http://reviews.llvm.org/D18236

llvm-svn: 263765
2016-03-17 23:58:03 +00:00
Chris Bieneman 671d0dda7d Upgrade TBAA *before* upgrading intrinsics
Summary: If TBAA is on an intrinsic and it gets upgraded and drops the TBAA we hit an odd assert. We should just upgrade the TBAA first because it doesn't have side-effects.

Reviewers: reames, apilipenko, manmanren

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D18229

llvm-svn: 263673
2016-03-16 23:17:54 +00:00
Artur Pilipenko 3c8fc57e16 Support arbitrary addrspace pointers in masked load/store intrinsics
This patch fixes the problem which occurs when loop-vectorize tries to use @llvm.masked.load/store intrinsic for a non-default addrspace pointer. It fails with "Calling a function with a bad signature!" assertion in CallInst constructor because it tries to pass a non-default addrspace pointer to the pointer argument which has default addrspace.

The fix is to add pointer type as another overloaded type to @llvm.masked.load/store intrinsics.

Reviewed By: reames

Differential Revision: http://reviews.llvm.org/D17270

llvm-svn: 263158
2016-03-10 20:39:22 +00:00
Manuel Jacob c784e6acd9 Fix constant folding of constant vector GEPs with undef or null as pointer argument.
Reviewers: eddyb

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D16321

llvm-svn: 258134
2016-01-19 16:34:31 +00:00
David Majnemer 59be1d653a [ConstantFold] Fix bitcast to gep constant folding transform.
Make sure to check that the destination type is sized.
A check was present but was incorrectly checking the source type
instead.

Patch by Amaury SECHET!

Differential Revision: http://reviews.llvm.org/D15264

llvm-svn: 255536
2015-12-14 19:30:32 +00:00
David Majnemer 8a1c45d6e8 [IR] Reformulate LLVM's EH funclet IR
While we have successfully implemented a funclet-oriented EH scheme on
top of LLVM IR, our scheme has some notable deficiencies:
- catchendpad and cleanupendpad are necessary in the current design
  but they are difficult to explain to others, even to seasoned LLVM
  experts.
- catchendpad and cleanupendpad are optimization barriers.  They cannot
  be split and force all potentially throwing call-sites to be invokes.
  This has a noticable effect on the quality of our code generation.
- catchpad, while similar in some aspects to invoke, is fairly awkward.
  It is unsplittable, starts a funclet, and has control flow to other
  funclets.
- The nesting relationship between funclets is currently a property of
  control flow edges.  Because of this, we are forced to carefully
  analyze the flow graph to see if there might potentially exist illegal
  nesting among funclets.  While we have logic to clone funclets when
  they are illegally nested, it would be nicer if we had a
  representation which forbade them upfront.

Let's clean this up a bit by doing the following:
- Instead, make catchpad more like cleanuppad and landingpad: no control
  flow, just a bunch of simple operands;  catchpad would be splittable.
- Introduce catchswitch, a control flow instruction designed to model
  the constraints of funclet oriented EH.
- Make funclet scoping explicit by having funclet instructions consume
  the token produced by the funclet which contains them.
- Remove catchendpad and cleanupendpad.  Their presence can be inferred
  implicitly using coloring information.

N.B.  The state numbering code for the CLR has been updated but the
veracity of it's output cannot be spoken for.  An expert should take a
look to make sure the results are reasonable.

Reviewers: rnk, JosephTremoulet, andrew.w.kaylor

Differential Revision: http://reviews.llvm.org/D15139

llvm-svn: 255422
2015-12-12 05:38:55 +00:00