Commit Graph

6100 Commits

Author SHA1 Message Date
Simon Pilgrim
4ed5a81a43 Document the LLVM_ENABLE_EXPENSIVE_CHECKS cmake option introduced in r268050
llvm-svn: 268197
2016-05-01 15:27:47 +00:00
Sanjoy Das
0d28098245 [LowerGuardIntrinsics] Keep track of !make.implicit metadata
If a guard call being lowered by LowerGuardIntrinsics has the
`!make.implicit` metadata attached, then reattach the metadata to the
branch in the resulting expanded form of the intrinsic.  This allows us
to implement null checks as guards and still get the benefit of implicit
null checks.

llvm-svn: 268148
2016-04-30 00:55:59 +00:00
Chris Bieneman
9c4f3cfc37 [Docs] Refer to the CMakePrimer from CMake doc
The "Building LLVM with CMake" document should have a reference to the CMakePrimer.

llvm-svn: 268109
2016-04-29 21:23:24 +00:00
Chris Bieneman
6fb260949c [Docs] Add CMake Primer document
This document is intended to provide a basic overview of the CMake scripting language for LLVM developers. It was unorthodoxly reviewed for accuracy and content on the CMake developer list:

http://public.kitware.com/pipermail/cmake-developers/2016-April/028300.html

llvm-svn: 268096
2016-04-29 20:34:54 +00:00
Kostya Serebryany
d357a30eb0 [libFuzzer] fix docs
llvm-svn: 268092
2016-04-29 19:28:24 +00:00
Kostya Serebryany
6e5d1a22c3 [libFuzzer] enable detect_leaks=1, add proper docs
llvm-svn: 268088
2016-04-29 18:49:55 +00:00
Sanjoy Das
e12c5af2ac Remove stale documentation on -no-aa
The pass itself was removed in rL247167.

llvm-svn: 267978
2016-04-29 03:01:49 +00:00
Kostya Serebryany
f69f881341 [libFuzzer] Improve documentation
Reviewers: kcc

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D19585

llvm-svn: 267892
2016-04-28 15:19:05 +00:00
Adam Nemet
083815b3cc Fixed sphinx warning from r267672
llvm-svn: 267675
2016-04-27 05:59:51 +00:00
Adam Nemet
ededcfa020 [LoopDist] Add llvm.loop.distribute.enable loop metadata
Summary:
D19403 adds a new pragma for loop distribution.  This change adds
support for the corresponding metadata that the pragma is translated to
by the FE.

As part of this I had to rethink the flag -enable-loop-distribute.  My
goal was to be backward compatible with the existing behavior:

  A1. pass is off by default from the optimization pipeline
  unless -enable-loop-distribute is specified

  A2. pass is on when invoked directly from opt (e.g. for unit-testing)

The new pragma/metadata overrides these defaults so the new behavior is:

  B1. A1 + enable distribution for individual loop with the pragma/metadata

  B2. A2 + disable distribution for individual loop with the pragma/metadata

The default value whether the pass is on or off comes from the initiator
of the pass.  From the PassManagerBuilder the default is off, from opt
it's on.

I moved -enable-loop-distribute under the pass.  If the flag is
specified it overrides the default from above.

Then the pragma/metadata can further modifies this per loop.

As a side-effect, we can now also use -enable-loop-distribute=0 from opt
to emulate the default from the optimization pipeline.  So to be precise
this is the new behavior:

  C1. pass is off by default from the optimization pipeline
  unless -enable-loop-distribute or the pragma/metadata enables it

  C2. pass is on when invoked directly from opt
  unless -enable-loop-distribute=0 or the pragma/metadata disables it

Reviewers: hfinkel

Subscribers: joker.eph, mzolotukhin, llvm-commits

Differential Revision: http://reviews.llvm.org/D19431

llvm-svn: 267672
2016-04-27 05:28:18 +00:00
Adam Nemet
9d448b66bc [Docs] Try to clarify the concept of domains for noalias scope
Summary:
This tries to anchor down the concept of domains a bit better.  I had
trouble initially relating this to anything.  Also talking to David
Majnemer on IRC suggested that I wasn't the only one.

Reviewers: hfinkel

Subscribers: llvm-commits, majnemer

Differential Revision: http://reviews.llvm.org/D18799

llvm-svn: 267647
2016-04-27 00:52:48 +00:00
Chuang-Yu Cheng
da7d0bf651 [ppc64] Reenable sibling call optimization on ppc64 since fixed tsan library tail-call issue
print-stack-trace.cc test failure of compiler-rt has been fixed by
r266869 (http://reviews.llvm.org/D19148), so reenable sibling call
optimization on ppc64

Reviewers: nemanjai kbarton
llvm-svn: 267527
2016-04-26 07:38:24 +00:00
Hal Finkel
7956f36dac [LoopVectorize] Don't consider conditional-load dereferenceability for marked parallel loops
I really thought we were doing this already, but we were not. Given this input:

void Test(int *res, int *c, int *d, int *p) {
  for (int i = 0; i < 16; i++)
    res[i] = (p[i] == 0) ? res[i] : res[i] + d[i];
}

we did not vectorize the loop. Even with "assume_safety" the check that we
don't if-convert conditionally-executed loads (to protect against
data-dependent deferenceability) was not elided.

One subtlety: As implemented, it will still prefer to use a masked-load
instrinsic (given target support) over the speculated load. The choice here
seems architecture specific; the best option depends on how expensive the
masked load is compared to a regular load. Ideally, using the masked load still
reduces unnecessary memory traffic, and so should be preferred. If we'd rather
do it the other way, flipping the order of the checks is easy.

The LangRef is updated to make explicit that llvm.mem.parallel_loop_access also
implies that if conversion is okay.

Differential Revision: http://reviews.llvm.org/D19512

llvm-svn: 267514
2016-04-26 02:00:36 +00:00
Duncan P. N. Exon Smith
94512f24de 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
Sanjoy Das
5fea8e874e Add some release notes about the fix for PR26774
As suggested by Chandler on the review thread for D18634.

llvm-svn: 267239
2016-04-22 22:45:23 +00:00
Peter Collingbourne
d04766ba20 Introduce llvm.load.relative intrinsic.
This intrinsic takes two arguments, ``%ptr`` and ``%offset``. It loads
a 32-bit value from the address ``%ptr + %offset``, adds ``%ptr`` to that
value and returns it. The constant folder specifically recognizes the form of
this intrinsic and the constant initializers it may load from; if a loaded
constant initializer is known to have the form ``i32 trunc(x - %ptr)``,
the intrinsic call is folded to ``x``.

LLVM provides that the calculation of such a constant initializer will
not overflow at link time under the medium code model if ``x`` is an
``unnamed_addr`` function. However, it does not provide this guarantee for
a constant initializer folded into a function body. This intrinsic can be
used to avoid the possibility of overflows when loading from such a constant.

Differential Revision: http://reviews.llvm.org/D18367

llvm-svn: 267223
2016-04-22 21:18:02 +00:00
Michael Kuperstein
8bf993fc77 Point link to CODE_OWNERS.txt to klaus instead of viewvc.
llvm-svn: 267176
2016-04-22 17:41:12 +00:00
Teresa Johnson
39da0c928b Document source_filename in LangRef.
Summary: Add documentation for new LLVM IR source_filename identifier.

Reviewers: joker.eph, majnemer

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D18857

llvm-svn: 267150
2016-04-22 13:09:17 +00:00
Amaury Sechet
8c1203a67d Add LLVMGetAttrKindID in the C API in order to facilitate migration away from LLVMAttribute
Summary:
LLVMAttribute has outlived its utility and is becoming a problem for C API users that what to use all the LLVM attributes. In order to help moving away from LLVMAttribute in a smooth manner, this diff introduce LLVMGetAttrKindIDInContext, which can be used instead of the enum values.

See D18749 for reference.

Reviewers: Wallbraker, whitequark, joker.eph, echristo, rafael

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D19081

llvm-svn: 266842
2016-04-20 01:02:12 +00:00
Kostya Serebryany
f4b1c52a7a [libFuzzer] more trophies
llvm-svn: 266830
2016-04-19 22:37:44 +00:00
Marcin Koscielnicki
0919e582e6 [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
Tim Shen
3a75cd4bf9 [SSP, 2/2] Create llvm.stackguard() intrinsic and lower it to LOAD_STACK_GUARD
With this change, ideally IR pass can always generate llvm.stackguard
call to get the stack guard; but for now there are still IR form stack
guard customizations around (see getIRStackGuard()). Future SSP
customization should go through LOAD_STACK_GUARD.

There is a behavior change: stack guard values are not CSEed anymore,
since we should never reuse the value in case that it has been spilled (and
corrupted). See ssp-guard-spill.ll. This also cause the change of stack
size and codegen in X86 and AArch64 test cases.

Ideally we'd like to know if the guard created in llvm.stackprotector() gets
spilled or not. If the value is spilled, discard the value and reload
stack guard; otherwise reuse the value. This can be done by teaching
register allocator to know how to rematerialize LOAD_STACK_GUARD and
force a rematerialization (which seems hard), or check for spilling in
expandPostRAPseudo. It only makes sense when the stack guard is a global
variable, which requires more instructions to load. Anyway, this seems to go out
of the scope of the current patch.

llvm-svn: 266806
2016-04-19 19:40:37 +00:00
Sanjoy Das
91fd65c3a6 Introduce a "patchable-function" function attribute
Summary:
The `"patchable-function"` attribute can be used by an LLVM client to
influence LLVM's code generation in ways that makes the generated code
easily patchable at runtime (for instance, to redirect control).
Right now only one patchability scheme is supported,
`"prologue-short-redirect"`, but this can be expanded in the future.

Reviewers: joker.eph, rnk, echristo, dberris

Subscribers: joker.eph, echristo, mcrosier, llvm-commits

Differential Revision: http://reviews.llvm.org/D19046

llvm-svn: 266715
2016-04-19 05:24:47 +00:00
Kostya Serebryany
b5ecf4df2a [libFuzzer] add fresh openssl trophies
llvm-svn: 266649
2016-04-18 18:41:25 +00:00
Duncan P. N. Exon Smith
0c4233db2f IR: Use an explicit map for debug info type uniquing
Rather than relying on the structural equivalence of DICompositeType to
merge type definitions, use an explicit map on the LLVMContext that
LLParser and BitcodeReader consult when constructing new nodes.
Each non-forward-declaration DICompositeType with a non-empty
'identifier:' field is stored/loaded from the type map, and the first
definiton will "win".

This map is opt-in: clients that expect ODR types from different modules
to be merged must call LLVMContext::ensureDITypeMap.

  - Clients that just happen to load more than one Module in the same
    LLVMContext won't magically merge types.

  - Clients (like LTO) that want to continue to merge types based on ODR
    identifiers should opt-in immediately.

I have updated LTOCodeGenerator.cpp, the two "linking" spots in
gold-plugin.cpp, and llvm-link (unless -disable-debug-info-type-map) to
set this.

With this in place, it will be straightforward to remove the DITypeRef
concept (i.e., referencing types by their 'identifier:' string rather
than pointing at them directly).

llvm-svn: 266549
2016-04-17 03:58:21 +00:00
Duncan P. N. Exon Smith
a1404a67fa 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
Duncan P. N. Exon Smith
0e96399288 LangRef: Removed some outdated text about DIDerivedType
This text is also incorrect (much like r266540).  It looks like I missed
updating some of what I moved from SourceLevelDebugging.rst in r232566.

llvm-svn: 266544
2016-04-17 00:45:00 +00:00
Duncan P. N. Exon Smith
dcf69939b8 LangRef: Fix some bugs in debug info descriptions
Fix descriptions of DICompositeType and DIDerivedType.

llvm-svn: 266540
2016-04-16 22:46:47 +00:00
Kostya Serebryany
5c9ea3ceb9 [libFuzzer] menion the git mirror in the docs
llvm-svn: 266476
2016-04-15 21:10:27 +00:00
Mehdi Amini
ea195a382e Remove every uses of getGlobalContext() in LLVM (but the C API)
At the same time, fixes InstructionsTest::CastInst unittest: yes
you can leave the IR in an invalid state and exit when you don't
destroy the context (like the global one), no longer now.

This is the first part of http://reviews.llvm.org/D19094

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 266379
2016-04-14 21:59:01 +00:00
Adam Nemet
aa40b369a6 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
James Y Knight
b06645b66f Update psabi link for x86-64. Add link to linux gabi supplement.
llvm-svn: 266137
2016-04-12 21:54:57 +00:00
James Y Knight
a55b68a75e Add __atomic_* lowering to AtomicExpandPass.
(Recommit of r266002, with r266011, r266016, and not accidentally
including an extra unused/uninitialized element in LibcallRoutineNames)

AtomicExpandPass can now lower atomic load, atomic store, atomicrmw, and
cmpxchg instructions to __atomic_* library calls, when the target
doesn't support atomics of a given size.

This is the first step towards moving all atomic lowering from clang
into llvm. When all is done, the behavior of __sync_* builtins,
__atomic_* builtins, and C11 atomics will be unified.

Previously LLVM would pass everything through to the ISelLowering
code. There, unsupported atomic instructions would turn into __sync_*
library calls. Because of that behavior, Clang currently avoids emitting
llvm IR atomic instructions when this would happen, and emits __atomic_*
library functions itself, in the frontend.

This change makes LLVM able to emit __atomic_* libcalls, and thus will
eventually allow clang to depend on LLVM to do the right thing.

It is advantageous to do the new lowering to atomic libcalls in
AtomicExpandPass, before ISel time, because it's important that all
atomic operations for a given size either lower to __atomic_*
libcalls (which may use locks), or native instructions which won't. No
mixing and matching.

At the moment, this code is enabled only for SPARC, as a
demonstration. The next commit will expand support to all of the other
targets.

Differential Revision: http://reviews.llvm.org/D18200

llvm-svn: 266115
2016-04-12 20:18:48 +00:00
Artur Pilipenko
d9a8d9a1af 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
Matt Arsenault
73354d0f62 LangRef: Update example syntax for atomic load instruction
llvm-svn: 266077
2016-04-12 14:41:03 +00:00
Rafael Espindola
b04bc032f0 This reverts commit r266002, r266011 and r266016.
They broke the msan bot.

Original message:

Add __atomic_* lowering to AtomicExpandPass.

AtomicExpandPass can now lower atomic load, atomic store, atomicrmw,and
cmpxchg instructions to __atomic_* library calls, when the target
doesn't support atomics of a given size.

This is the first step towards moving all atomic lowering from clang
into llvm. When all is done, the behavior of __sync_* builtins,
__atomic_* builtins, and C11 atomics will be unified.

Previously LLVM would pass everything through to the ISelLowering
code. There, unsupported atomic instructions would turn into __sync_*
library calls. Because of that behavior, Clang currently avoids emitting
llvm IR atomic instructions when this would happen, and emits __atomic_*
library functions itself, in the frontend.

This change makes LLVM able to emit __atomic_* libcalls, and thus will
eventually allow clang to depend on LLVM to do the right thing.

It is advantageous to do the new lowering to atomic libcalls in
AtomicExpandPass, before ISel time, because it's important that all
atomic operations for a given size either lower to __atomic_*
libcalls (which may use locks), or native instructions which won't. No
mixing and matching.

At the moment, this code is enabled only for SPARC, as a
demonstration. The next commit will expand support to all of the other
targets.

Differential Revision: http://reviews.llvm.org/D18200

llvm-svn: 266062
2016-04-12 12:30:25 +00:00
George Burgess IV
4e2d8dca99 Add the allocsize attribute to LLVM.
`allocsize` is a function attribute that allows users to request that
LLVM treat arbitrary functions as allocation functions.

This patch makes LLVM accept the `allocsize` attribute, and makes
`@llvm.objectsize` recognize said attribute.

The review for this was split into two patches for ease of reviewing:
D18974 and D14933. As promised on the revisions, I'm landing both
patches as a single commit.

Differential Revision: http://reviews.llvm.org/D14933

llvm-svn: 266032
2016-04-12 01:05:35 +00:00
James Y Knight
003ee915ba Add __atomic_* lowering to AtomicExpandPass.
AtomicExpandPass can now lower atomic load, atomic store, atomicrmw, and
cmpxchg instructions to __atomic_* library calls, when the target
doesn't support atomics of a given size.

This is the first step towards moving all atomic lowering from clang
into llvm. When all is done, the behavior of __sync_* builtins,
__atomic_* builtins, and C11 atomics will be unified.

Previously LLVM would pass everything through to the ISelLowering
code. There, unsupported atomic instructions would turn into __sync_*
library calls. Because of that behavior, Clang currently avoids emitting
llvm IR atomic instructions when this would happen, and emits __atomic_*
library functions itself, in the frontend.

This change makes LLVM able to emit __atomic_* libcalls, and thus will
eventually allow clang to depend on LLVM to do the right thing.

It is advantageous to do the new lowering to atomic libcalls in
AtomicExpandPass, before ISel time, because it's important that all
atomic operations for a given size either lower to __atomic_*
libcalls (which may use locks), or native instructions which won't. No
mixing and matching.

At the moment, this code is enabled only for SPARC, as a
demonstration. The next commit will expand support to all of the other
targets.

Differential Revision: http://reviews.llvm.org/D18200

llvm-svn: 266002
2016-04-11 22:22:33 +00:00
Tim Shen
8cac1d5c28 [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
Ehsan Amiri
12e9a7d1ed [PPC] Added a note to release notes
A draft line added to release notes for PPC, to keep a record of changes.
This is just a draft and will be rewritten towards the end of release.

llvm-svn: 265694
2016-04-07 16:47:35 +00:00
Dmitry Polukhin
9d54726038 [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
JF Bastien
f4f5b32f44 NFC: make AtomicOrdering an enum class
Summary:
In the context of http://wg21.link/lwg2445 C++ uses the concept of
'stronger' ordering but doesn't define it properly. This should be fixed
in C++17 barring a small question that's still open.

The code currently plays fast and loose with the AtomicOrdering
enum. Using an enum class is one step towards tightening things. I later
also want to tighten related enums, such as clang's
AtomicOrderingKind (which should be shared with LLVM as a 'C++ ABI'
enum).

This change touches a few lines of code which can be improved later, I'd
like to keep it as NFC for now as it's already quite complex. I have
related changes for clang.

As a follow-up I'll add:
  bool operator<(AtomicOrdering, AtomicOrdering) = delete;
  bool operator>(AtomicOrdering, AtomicOrdering) = delete;
  bool operator<=(AtomicOrdering, AtomicOrdering) = delete;
  bool operator>=(AtomicOrdering, AtomicOrdering) = delete;
This is separate so that clang and LLVM changes don't need to be in sync.

Reviewers: jyknight, reames

Subscribers: jyknight, llvm-commits

Differential Revision: http://reviews.llvm.org/D18775

llvm-svn: 265602
2016-04-06 21:19:33 +00:00
Tom Stellard
f352d0cd70 AMDGPU: Document address space mapping
Summary:
Address space mapping is described in lib/Target/AMDGPU/AMDGPU.h in
Doxygen comments. This patch adds the description to user guide for
AMDGPU back-end.

Patch By: Vedran Miletić

Reviewers: tstellarAMD, arsenm

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D17046

llvm-svn: 265500
2016-04-06 01:29:19 +00:00
Manman Ren
6e8ec540e6 Swift Calling Convention: swiftcc for ARM.
Differential Revision: http://reviews.llvm.org/D18769

llvm-svn: 265482
2016-04-05 22:44:44 +00:00
Manman Ren
d8f96bea63 Swift Calling Convention: add swiftcc.
Differential Revision: http://reviews.llvm.org/D17863

llvm-svn: 265480
2016-04-05 22:41:47 +00:00
JF Bastien
f164daa424 Docs: dampen story time for atomics
Story time was nice a few years ago, but by now it's nice to state how things are, rather than explain the diff from ye olden atomic history. These were dark times.

llvm-svn: 265369
2016-04-05 00:31:25 +00:00
Paul Robinson
a4abbe046e Document standard substitutions defined by lit.
Patch by Guilherme Bufolo!

Differential Revision: http://reviews.llvm.org/D18752

llvm-svn: 265314
2016-04-04 17:14:45 +00:00
Manman Ren
ad40523f14 Swift Calling Convention: add swifterror attribute.
A ``swifterror`` attribute can be applied to a function parameter or an
AllocaInst.

This commit does not include any target-specific change. The target-specific
optimization will come as a follow-up patch.

Differential Revision: http://reviews.llvm.org/D18092

llvm-svn: 265189
2016-04-01 21:41:15 +00:00
Adrian Prantl
1653aa9f14 testcase gardening: update the emissionKind enum to the new syntax. (NFC)
llvm-svn: 265081
2016-04-01 00:16:49 +00:00
Hans Wennborg
07d10a6e30 Change eliminateCallFramePseudoInstr() to return an iterator
This will become necessary in a subsequent change to make this method
merge adjacent stack adjustments, i.e. it might erase the previous
and/or next instruction.

It also greatly simplifies the calls to this function from Prolog-
EpilogInserter. Previously, that had a bunch of logic to resume iteration
after the call; now it just continues with the returned iterator.

Note that this changes the behaviour of PEI a little. Previously,
it attempted to re-visit the new instruction created by
eliminateCallFramePseudoInstr(). That code was added in r36625,
but I can't see any reason for it: the new instructions will obviously
not be pseudo instructions, they will not have FrameIndex operands,
and we have already accounted for the stack adjustment.

Differential Revision: http://reviews.llvm.org/D18627

llvm-svn: 265036
2016-03-31 18:33:38 +00:00