Commit Graph

1858 Commits

Author SHA1 Message Date
Jakub Staszak 225d3ab801 Simplify code. No functionality change.
llvm-svn: 249335
2015-10-05 18:53:30 +00:00
Teresa Johnson 403a787e03 Support for function summary index bitcode sections and files.
Summary:
The bitcode format is described in this document:
  https://drive.google.com/file/d/0B036uwnWM6RWdnBLakxmeDdOeXc/view
For more info on ThinLTO see:
  https://sites.google.com/site/llvmthinlto

The first customer is ThinLTO, however the data structures are designed
and named more generally based on prior feedback. There are a few
comments regarding how certain interfaces are used by ThinLTO, and the
options added here to gold currently have ThinLTO-specific names as the
behavior they provoke is currently ThinLTO-specific.

This patch includes support for generating per-module function indexes,
the combined index file via the gold plugin, and several tests
(more are included with the associated clang patch D11908).

Reviewers: dexonsmith, davidxl, joker.eph

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D13107

llvm-svn: 249270
2015-10-04 14:33:43 +00:00
Evgeniy Stepanov f608111d1b Fix debug info with SafeStack.
llvm-svn: 248933
2015-09-30 19:55:43 +00:00
Jeroen Ketema ab99b59e8c [ARM][NEON] Use address space in vld([1234]|[234]lane) and vst([1234]|[234]lane) instructions
This commit changes the interface of the vld[1234], vld[234]lane, and vst[1234],
vst[234]lane ARM neon intrinsics and associates an address space with the
pointer that these intrinsics take. This changes, e.g.,

<2 x i32> @llvm.arm.neon.vld1.v2i32(i8*, i32)

to

<2 x i32> @llvm.arm.neon.vld1.v2i32.p0i8(i8*, i32)

This change ensures that address spaces are fully taken into account in the ARM
target during lowering of interleaved loads and stores.

Differential Revision: http://reviews.llvm.org/D12985

llvm-svn: 248887
2015-09-30 10:56:37 +00:00
Maksim Panchenko cce239c45d HHVM calling conventions.
HHVM calling convention, hhvmcc, is used by HHVM JIT for
functions in translated cache. We currently support LLVM back end to
generate code for X86-64 and may support other architectures in the
future.

In HHVM calling convention any GP register could be used to pass and
return values, with the exception of R12 which is reserved for
thread-local area and is callee-saved. Other than R12, we always
pass RBX and RBP as args, which are our virtual machine's stack pointer
and frame pointer respectively.

When we enter translation cache via hhvmcc function, we expect
the stack to be aligned at 16 bytes, i.e. skewed by 8 bytes as opposed
to standard ABI alignment. This affects stack object alignment and stack
adjustments for function calls.

One extra calling convention, hhvm_ccc, is used to call C++ helpers from
HHVM's translation cache. It is almost identical to standard C calling
convention with an exception of first argument which is passed in RBP
(before we use RDI, RSI, etc.)

Differential Revision: http://reviews.llvm.org/D12681

llvm-svn: 248832
2015-09-29 22:09:16 +00:00
Artur Pilipenko b4d009042b Introduce !align metadata for load instruction
Reviewed By: hfinkel

Differential Revision: http://reviews.llvm.org/D12853

llvm-svn: 248721
2015-09-28 17:41:08 +00:00
Justin Bogner d7d1a72f66 AsmWriter: Print the argument names in declarations while debugging
When llvm declarations have argument names, it's helpful to actually
print those names when debugging. Arguably, it'd be nice to print them
all the time, but that would mean the IR we output wouldn't round trip
through bitcode, which doesn't store the names.

Make the varous print() methods in AsmWriter optionally print "for
debug" and set that flag in the dump() methods. The only thing this
does differently for now is print the argument names in declarations.

llvm-svn: 248692
2015-09-27 22:38:50 +00:00
Sanjoy Das b513a9fa4f [Bitcode][Asm] Teach LLVM to read and write operand bundles.
Summary:
This also adds the first set of tests for operand bundles.

The optimizer has not been audited to ensure that it does the right
thing with operand bundles.

Depends on D12456.

Reviewers: reames, chandlerc, majnemer, dexonsmith, kmod, JosephTremoulet, rnk, bogner

Subscribers: maksfb, llvm-commits

Differential Revision: http://reviews.llvm.org/D12457

llvm-svn: 248551
2015-09-24 23:34:52 +00:00
Sanjoy Das 9303c24650 [IR] Add operand bundles to CallInst and InvokeInst.
Summary:
This change teaches `CallInst`s and `InvokeInst`s to maintain a set of
operand bundles as part of its operands.  `CallInst`s and `InvokeInst`s
with operand bundles co-allocate some space before their `Use` array to
hold meta information about which of its operands are part of an operand
bundle.

The strings corresponding to the bundle tags are interned into
`LLVMContextImpl::BundleTagCache`

This change does not include any parsing / bitcode support.  That's the
next change.

Depends on D12455.

Reviewers: reames, chandlerc, majnemer, dexonsmith, kmod, JosephTremoulet, rnk, bogner

Subscribers: MatzeB, sanjoy, llvm-commits

Differential Revision: http://reviews.llvm.org/D12456

llvm-svn: 248527
2015-09-24 19:14:18 +00:00
Sanjoy Das b07fc572bd [IR] Teach `llvm::User` to co-allocate a descriptor.
Summary:
With this change, subclasses of `llvm::User` will be able to co-allocate
a variable number of bytes (called a "descriptor") with the `llvm::User`
instance.  The co-allocated descriptor can later be accessed using
`llvm::User::getDescriptor`.  This will be used in later changes to
implement operand bundles.

This change steals one bit from `NumUserOperands`, but given that it is
still 28 bits wide I don't think this will be a practical issue.

This change does not allow allocating hung off uses with descriptors.
This only for simplicity, not for any fundamental reason; and we can
easily add this functionality later if needed.

Reviewers: reames, chandlerc, dexonsmith, kmod, majnemer, pete, JosephTremoulet

Subscribers: pete, sanjoy, llvm-commits

Differential Revision: http://reviews.llvm.org/D12455

llvm-svn: 248453
2015-09-24 01:00:49 +00:00
Philip Reames d63df5107e Remove handling of AddrSpaceCast in stripAndAccumulateInBoundsConstantOffsets
Patch by: simoncook

Unlike BitCasts, AddrSpaceCasts do not always produce an output the same size as its input, which was previously assumed. This fixes cases where two address spaces do not have the same size pointer, as an assertion failure would occur when trying to prove deferenceability.  LoopUnswitch is used in the particular test, but LICM also exhibits the same problem.

Differential Revision: http://reviews.llvm.org/D13008

llvm-svn: 248422
2015-09-23 19:48:43 +00:00
Simon Pilgrim 9cb018b6b6 [X86][SSE] Replace 128-bit SSE41 PMOVSX intrinsics with native IR
This patches removes the x86.sse41.pmovsx* intrinsics, provides a suitable upgrade path and updates relevant tests to sign extend a subvector instead.

LLVM counterpart to D12835

Differential Revision: http://reviews.llvm.org/D13002

llvm-svn: 248368
2015-09-23 08:48:33 +00:00
Stephen Canon b12db0e42c Remove roundingMode argument in APFloat::mod
Because mod is always exact, this function should have never taken a rounding mode argument.  The actual implementation still has issues, which I'll look at resolving in a subsequent patch.

llvm-svn: 248195
2015-09-21 19:29:25 +00:00
Piotr Padlewski ea09288ee7 Added MD_invariant_group to LLVMContext
http://reviews.llvm.org/D12926

llvm-svn: 247931
2015-09-17 20:25:07 +00:00
David Blaikie 798f3079d4 [opaque pointer types] Add an explicit value type to GlobalObject
This is needed by all GlobalObjects (GlobalAlias, Function,
GlobalVariable), see the GlobalObject::getValueType which is used in
many places. If at some point that can be removed, then we can remove
this member.

llvm-svn: 247621
2015-09-14 21:47:27 +00:00
David Blaikie 16a2f3e302 Revert "[opaque pointer type] Pass GlobalAlias the actual pointer type rather than decomposing it into pointee type + address space"
This was a flawed change - it just caused the getElementType call to be
deferred until later, when we really need to remove it. Now that the IR
for GlobalAliases has been updated, the root cause is addressed that way
instead and this change is no longer needed (and in fact gets in the way
- because we want to pass the pointee type directly down further).

Follow up patches to push this through GlobalValue, bitcode format, etc,
will come along soon.

This reverts commit 236160.

llvm-svn: 247585
2015-09-14 18:01:59 +00:00
Bruce Mitchener e9ffb45b60 Fix typos.
Summary: This fixes a variety of typos in docs, code and headers.

Subscribers: jholewinski, sanjoy, arsenm, llvm-commits

Differential Revision: http://reviews.llvm.org/D12626

llvm-svn: 247495
2015-09-12 01:17:08 +00:00
Reid Kleckner 5dbee7baef [IR] Print the label operands of a catchpad like an invoke
The rest of the EH pads are fine, since they have at most one label and
take fewer operands for the personality.

Old catchpad vs. new:
  %5 = catchpad [i8* bitcast (i32 ()* @"\01?filt$0@0@main@@" to i8*)] to label %__except.ret.10 unwind label %catchendblock.9
-----
  %5 = catchpad [i8* bitcast (i32 ()* @"\01?filt$0@0@main@@" to i8*)]
          to label %__except.ret.10 unwind label %catchendblock.9

llvm-svn: 247433
2015-09-11 17:27:52 +00:00
NAKAMURA Takumi 25b5bd27ea [PR24785] Appease MSC18 to tweak optimizations.
This brings a warning.

  cl : Command line warning D9035: option 'Og-' has been deprecated and will be removed in a future release

We should resolve PR11951 to remove this tweak.

llvm-svn: 247427
2015-09-11 17:08:02 +00:00
David Blaikie 2f40830dde [opaque pointer type] Add textual IR support for explicit type parameter for global aliases
update.py:
import fileinput
import sys
import re

alias_match_prefix = r"(.*(?:=|:|^)\s*(?:external |)(?:(?:private|internal|linkonce|linkonce_odr|weak|weak_odr|common|appending|extern_weak|available_externally) )?(?:default |hidden |protected )?(?:dllimport |dllexport )?(?:unnamed_addr |)(?:thread_local(?:\([a-z]*\))? )?alias"
plain = re.compile(alias_match_prefix + r" (.*?))(| addrspace\(\d+\) *)\*($| *(?:%|@|null|undef|blockaddress|addrspacecast|\[\[[a-zA-Z]|\{\{).*$)")
cast  = re.compile(alias_match_prefix + r") ((?:bitcast|inttoptr|addrspacecast)\s*\(.* to (.*?)(| addrspace\(\d+\) *)\*\)\s*(?:;.*)?$)")
gep   = re.compile(alias_match_prefix + r") ((?:getelementptr)\s*(?:inbounds)?\s*\((?P<type>.*), (?P=type)(?:\s*addrspace\(\d+\)\s*)?\* .*\)\s*(?:;.*)?$)")

def conv(line):
  m = re.match(cast, line)
  if m:
    return m.group(1) + " " + m.group(3) + ", " + m.group(2)
  m = re.match(gep, line)
  if m:
    return m.group(1) + " " + m.group(3) + ", " + m.group(2)
  m = re.match(plain, line)
  if m:
    return m.group(1) + ", " + m.group(2) + m.group(3) + "*" + m.group(4) + "\n"
  return line

for line in sys.stdin:
  sys.stdout.write(conv(line))

apply.sh:
for name in "$@"
do
  python3 `dirname "$0"`/update.py < "$name" > "$name.tmp" && mv "$name.tmp" "$name"
  rm -f "$name.tmp"
done

The actual commands:
From llvm/src:
find test/ -name *.ll | xargs ./apply.sh
From llvm/src/tools/clang:
find test/ -name *.mm -o -name *.m -o -name *.cpp -o -name *.c | xargs -I '{}' ../../apply.sh "{}"
From llvm/src/tools/polly:
find test/ -name *.ll | xargs ./apply.sh

llvm-svn: 247378
2015-09-11 03:22:04 +00:00
Duncan P. N. Exon Smith adc5456da0 AsmWriter: Avoid O(N^2) processing of metadata
Fix embarrassing bugs I introduced to the `SlotTracker` in or around
r235785.  I had us iterating through every instruction in a function
(and hitting a map in the LLVMContext) for every basic block in the
function.

While there, completely avoid the call to
`SlotTracker::processFunctionMetadata()` from
`SlotTracker::processFunction()` if we've speculatively done this
already in `SlotTracker::processModule()` by checking
`ShouldInitializeAllMetadata` (this wasn't an algorithmic problem, but
it's touching the same line of code).

Fixes PR24699.

llvm-svn: 247372
2015-09-11 01:34:59 +00:00
David Majnemer 880c2cb097 [IR] Conservatively mark 'catchpad' as accessing memory
The exact semantics of 'catchpad' are really in the hands of the
personality routine so we shouldn't assume that they have no side
effects.

llvm-svn: 247322
2015-09-10 18:50:09 +00:00
Chandler Carruth 87275186d1 [LPM] Simplify this code and fix a compile error for compilers that
don't correctly implement the scoping rules of C++11 range based for
loops. This kind of aliasing isn't a good idea anyways (and wasn't
really intended).

llvm-svn: 247241
2015-09-10 04:22:36 +00:00
Chandler Carruth b1e3a9ae8d [LPM] Use a map from analysis ID to immutable passes in the legacy pass
manager to avoid a slow linear scan of every immutable pass and on every
attempt to find an analysis pass.

This speeds up 'check-llvm' on an unoptimized build for me by 15%, YMMV.
It should also help (a tiny bit) other folks that are really
bottlenecked on repeated runs of tiny pass pipelines across small IR
files.

llvm-svn: 247240
2015-09-10 02:31:42 +00:00
Matt Arsenault acd68b58ae SelectionDAG: Support Expand of f16 extloads
Currently this hits an assert that extload should
always be supported, which assumes integer extloads.

This moves a hack out of SI's argument lowering and
is covered by existing tests.

llvm-svn: 247113
2015-09-09 01:12:27 +00:00
Sanjoy Das 88d0fdeb00 [IR] Have AttrBuilder::clear clear `TargetDepAttrs`.
Test case attached -- currently the parser smears the "foo bar" to all
of the formal arguments.

llvm-svn: 246812
2015-09-03 22:27:42 +00:00
Karl Schimpf f04a5d5978 Fix SEGV in InlineAsm::ConstraintInfo::Parse.
Summary:
Fixes bug 24646. Previous code was not checking if an index into a vector
was valid, resulting in a SEGV. Fixed by assuming the construct can't
be parsed when given this input.

Reformat and add test.

Differential Revision: http://reviews.llvm.org/D12539

llvm-svn: 246774
2015-09-03 15:41:37 +00:00
Karl Schimpf 388fd5ae2f Fix SEGV in InlineAsm::ConstraintInfo::Parse.
Fixes bug 24646. Previous code was not checking if an index into a vector
was valid, resulting in a SEGV. Fixed by assuming the construct can't
be parsed when given this input.

llvm-svn: 246773
2015-09-03 15:41:34 +00:00
Joseph Tremoulet 61efbc32a6 [WinEH] Add llvm.eh.exceptionpointer intrinsic
Summary:
This intrinsic can be used to extract a pointer to the exception caught by
a given catchpad.  Its argument has token type and must be a `catchpad`.

Also clarify ExtendingLLVM documentation regarding overloaded intrinsics.


Reviewers: majnemer, andrew.w.kaylor, sanjoy, rnk

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D12533

llvm-svn: 246752
2015-09-03 09:15:32 +00:00
Joseph Tremoulet 9ce71f76b9 [WinEH] Add cleanupendpad instruction
Summary:
Add a `cleanupendpad` instruction, used to mark exceptional exits out of
cleanups (for languages/targets that can abort a cleanup with another
exception).  The `cleanupendpad` instruction is similar to the `catchendpad`
instruction in that it is an EH pad which is the target of unwind edges in
the handler and which itself has an unwind edge to the next EH action.
The `cleanupendpad` instruction, similar to `cleanupret` has a `cleanuppad`
argument indicating which cleanup it exits.  The unwind successors of a
`cleanuppad`'s `cleanupendpad`s must agree with each other and with its
`cleanupret`s.

Update WinEHPrepare (and docs/tests) to accomodate `cleanupendpad`.

Reviewers: rnk, andrew.w.kaylor, majnemer

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D12433

llvm-svn: 246751
2015-09-03 09:09:43 +00:00
Ahmed Bougacha b03ea02479 [X86] Require 32-byte alignment for 32-byte VMOVNTs.
We used to accept (and even test, and generate) 16-byte alignment
for 32-byte nontemporal stores, but they require 32-byte alignment,
per SDM. Found by inspection.

Instead of hardcoding 16 in the patfrag, check for natural alignment.
Also fix the autoupgrade and the various tests.

Also, use explicit -mattr instead of -mcpu: I stared at the output
several minutes wondering why I get 2x movntps for the unaligned
case (which is the ideal output, but needs some work: see FIXME),
until I remembered corei7-avx implies +slow-unaligned-mem-32.

llvm-svn: 246733
2015-09-02 23:25:39 +00:00
Justin Bogner 0ffea9d47f IR: Remove an unused AssemblyWriter constructor. NFC
llvm-svn: 246729
2015-09-02 22:46:15 +00:00
Justin Bogner 7fe2469150 IR: Remove a redundant function. NFC
Function::print isn't interestingly different from Value::print. Just
let the only caller (in PrintCallGraphPass) call the Value version.

llvm-svn: 246720
2015-09-02 22:28:47 +00:00
Piotr Padlewski 28ffcbe1cc Constant propagation after hitting assume(cmp) bugfix
Last time code run into assertion `BBE.isSingleEdge()` in
lib/IR/Dominators.cpp:200.

http://reviews.llvm.org/D12170

llvm-svn: 246696
2015-09-02 19:59:59 +00:00
Sanjay Patel a99ab1f536 add unpredictable metadata type for control flow
This patch defines 'unpredictable' metadata. This metadata can be used to signal to the optimizer
or backend that a branch or switch is unpredictable, and therefore, it's probably better to not
split a compound predicate into multiple branches such as in CodeGenPrepare::splitBranchCondition().

This was discussed in:
https://llvm.org/bugs/show_bug.cgi?id=23827

Dependent patches to alter codegen and expose this in clang to follow.

Differential Revision; http://reviews.llvm.org/D12341

llvm-svn: 246688
2015-09-02 19:06:43 +00:00
Justin Bogner 58e0823ee9 IR: Invert a condition to make it more legible. NFC
Also updates the style to more modern conventions.

llvm-svn: 246681
2015-09-02 17:54:41 +00:00
Joseph Tremoulet 917c7382c1 [TableGen] Allow TokenTy in intrinsic signatures
Summary:
Add the necessary plumbing so that llvm_token_ty can be used as an
argument/return type in intrinsic definitions and correspondingly require
TokenTy in function types.  TokenTy is an opaque type that has no target
lowering, but can be used in machine-independent intrinsics.  It is
required for the upcoming llvm.eh.padparam intrinsic.

Reviewers: majnemer, rnk

Subscribers: stoklund, llvm-commits

Differential Revision: http://reviews.llvm.org/D12532

llvm-svn: 246651
2015-09-02 13:36:25 +00:00
Naomi Musgrave 21c1bc46ae Rollback of commit "Repress sanitization on User dtor."
This would have suppressed bug 24578, about use-after-
destroy on User and MDNode. Rolled back suppression for
the sake of code cleanliness, in preferance for bug
tracking to keep track of this issue.

This reverts commit 6ff2baabc4625d5b0a8dccf76aa0f72d930ea6c0.

llvm-svn: 246484
2015-08-31 21:06:08 +00:00
Naomi Musgrave 763468baec Undo reversion on commit: Revert "Revert "Repress sanitization on User dtor.
Modify msan macros for applying attribute""

This reverts commit 020e70a79878c96457e6882bcdfaf6628baf32b7.

llvm-svn: 246470
2015-08-31 18:49:31 +00:00
Naomi Musgrave 5f79c6653d Revert "Repress sanitization on User dtor. Modify msan macros for applying attribute"
This reverts commit 5e3bfbb38eb3fb6f568b107f6b239e0aa4c5f334.

llvm-svn: 246450
2015-08-31 16:26:44 +00:00
Naomi Musgrave d8c1a064e5 Repress sanitization on User dtor. Modify msan macros for applying attribute
to repress sanitization. Move attribute for repressing sanitization to
operator delete for User, MDNode.

Summary: In response to bug 24578, reported against failing LLVM test.

Reviewers: chandlerc, rsmith, eugenis

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D12335

llvm-svn: 246449
2015-08-31 15:57:40 +00:00
Duncan P. N. Exon Smith b09eb9f1c2 DI: Set DILexicalBlock columns >= 65536 to 0/unknown
This fixes PR24621 and matches what we do for `DILocation`.  Although
the limit seems somewhat artificial, there are places in the backend
that also assume 16-bit columns, so we may as well just be consistent
about the limits.

llvm-svn: 246349
2015-08-28 22:58:50 +00:00
Duncan P. N. Exon Smith b56b5af4c3 DI: Add Function::getSubprogram()
Add `Function::setSubprogram()` and `Function::getSubprogram()`,
convenience methods to forward to `setMetadata()` and `getMetadata()`,
respectively, and deal in `DISubprogram` instead of `MDNode`.

Also add a verifier check to enforce that `!dbg` attachments are always
subprograms.

Originally (when I had the llvm-dev discussion back in April) I thought
I'd store a pointer directly on `llvm::Function` for these attachments
-- we frequently have debug info, and that's much cheaper than using map
in the context if there are no other function-level attachments -- but
for now I'm just using the generic infrastructure.  Let's add the extra
complexity only if this shows up in a profile.

llvm-svn: 246339
2015-08-28 21:55:35 +00:00
Duncan P. N. Exon Smith 0660bcda53 AsmPrinter: Allow null subroutine type
Currently the DWARF backend requires that subprograms have a type, and
the type is ignored if it has an empty type array.  The long term
direction here -- see PR23079 -- is instead to skip the type entirely if
there's no valid type.

It turns out we have cases in tree of missing types on subprograms, but
since they're not referenced by compile units, the backend never crashes
on them.  One option would be to add a Verifier check that subprograms
have types, and fix the bitrot.  However, this is a fair bit of churn
(20-30 testcases) that would be reversed anyway by PR23079.

I found this inconsistency because of a WIP patch and upgrade script for
PR23367 that started crashing on test/DebugInfo/2010-10-01-crash.ll.
This commit updates the testcase to reference the subprogram from the
compile unit, and fixes the resulting crash (in line with the direction
of PR23079).  This also updates `DIBuilder` to stop assuming a non-null
pointer for the subroutine types.

llvm-svn: 246333
2015-08-28 21:38:24 +00:00
Duncan P. N. Exon Smith 814b8e91c7 DI: Require subprogram definitions to be distinct
As a follow-up to r246098, require `DISubprogram` definitions
(`isDefinition: true`) to be 'distinct'.  Specifically, add an assembler
check, a verifier check, and bitcode upgrading logic to combat testcase
bitrot after the `DIBuilder` change.

While working on the testcases, I realized that
test/Linker/subprogram-linkonce-weak-odr.ll isn't relevant anymore.  Its
purpose was to check for a corner case in PR22792 where two subprogram
definitions match exactly and share the same metadata node.  The new
verifier check, requiring that subprogram definitions are 'distinct',
precludes that possibility.

I updated almost all the IR with the following script:

    git grep -l -E -e '= !DISubprogram\(.* isDefinition: true' |
    grep -v test/Bitcode |
    xargs sed -i '' -e 's/= \(!DISubprogram(.*, isDefinition: true\)/= distinct \1/'

Likely some variant of would work for out-of-tree testcases.

llvm-svn: 246327
2015-08-28 20:26:49 +00:00
Steven Wu 61db34d12e Revert r246244 and r246243
These two commits cause clang/llvm bootstrap to hang.

llvm-svn: 246279
2015-08-28 06:52:00 +00:00
Piotr Padlewski 3f81ec1e38 Constant propagation after hitting assume(cmp) bugfix
Last time code run into assertion `BBE.isSingleEdge()` in
lib/IR/Dominators.cpp:200.

http://reviews.llvm.org/D12170

llvm-svn: 246244
2015-08-28 01:02:00 +00:00
Duncan P. N. Exon Smith b2df64721c DI: Make Subprogram definitions 'distinct'
Change `DIBuilder` always to produce 'distinct' nodes when creating
`DISubprogram` definitions.  I measured a ~5% memory improvement in the
link step (of ld64) when using `-flto -g`.

`DISubprogram`s are used in two ways in the debug info graph.

Some are definitions, point at actual functions, and can't really be
shared between compile units.  With full debug info, these point down at
their variables, forming uniquing cycles.  These uniquing cycles are
expensive to link between modules, since all unique nodes that reference
them transitively need to be duplicated (see commit message for r244181
for more details).

Others are declarations, primarily used for member functions in the type
hierarchy.  Definitions never show up there; instead, a definition
points at its corresponding declaration node.

I started by making all subprograms 'distinct'.  However, that was too
big a hammer: memory usage *increased* ~5% (net increase vs. this patch
of ~10%) because the 'distinct' declarations undermine LTO type
uniquing.  This is a targeted fix for the definitions (where uniquing is
an observable problem).

A couple of notes:

  - There's an accompanying commit to update IRGen testcases in clang.
  - ^ That's what I'm using to test this commit.
  - In a follow-up, I'll change the verifier to require 'distinct' on
    definitions and add an upgrade to `BitcodeReader`.

llvm-svn: 246098
2015-08-26 22:50:16 +00:00
Sanjay Patel 4104337d9d fix typos; NFC
llvm-svn: 245899
2015-08-24 23:20:16 +00:00
Sanjay Patel 942b46a011 fix typo; NFC
llvm-svn: 245896
2015-08-24 23:18:44 +00:00