Commit Graph

280 Commits

Author SHA1 Message Date
Akira Hatanaka f1b3fc7356 [CodeGen][ObjC] Use the type of the captured field of the enclosing
block or lambda.

This is a follow-up to r281682, which fixed a bug in computeBlockInfo
where the captured VarDecl's type, rather than the captured field type
of the enclosing lambda or block, was used to compute the layout of a
block.

This commit makes similar changes to enterBlockScope. This is necessary
to correctly determine whether a block capture requires cleanup.

rdar://problem/30388124

llvm-svn: 295034
2017-02-14 06:46:55 +00:00
Charles Li e1958a083a [test] Make Lit tests C++11 Compatible - Objective-C++
Set 5 Objective-C++ tests to run at gnu++98

Differential Revision: https://reviews.llvm.org/D29739

llvm-svn: 294997
2017-02-13 23:09:56 +00:00
Alex Lorenz c1608f7f69 Add -f[no-]strict-return flag that can be used to avoid undefined behaviour
in non-void functions that fall off at the end without returning a value when
compiling C++.

Clang uses the new compiler flag to determine when it should treat control flow
paths that fall off the end of a non-void function as unreachable. If
-fno-strict-return is on, the code generator emits the ureachable and trap
IR only when the function returns either a record type with a non-trivial
destructor or another non-trivially copyable type.

The primary goal of this flag is to avoid treating falling off the end of a
non-void function as undefined behaviour. The burden of undefined behaviour
is placed on the caller instead: if the caller ignores the returned value then
the undefined behaviour is avoided. This kind of behaviour is useful in
several cases, e.g. when compiling C code in C++ mode.

rdar://13102603

Differential Revision: https://reviews.llvm.org/D27163

llvm-svn: 290960
2017-01-04 13:40:34 +00:00
Chandler Carruth fcd33149b4 Cleanup the handling of noinline function attributes, -fno-inline,
-fno-inline-functions, -O0, and optnone.

These were really, really tangled together:
- We used the noinline LLVM attribute for -fno-inline
  - But not for -fno-inline-functions (breaking LTO)
  - But we did use it for -finline-hint-functions (yay, LTO is happy!)
  - But we didn't for -O0 (LTO is sad yet again...)
- We had weird structuring of CodeGenOpts with both an inlining
  enumeration and a boolean. They interacted in weird ways and
  needlessly.
- A *lot* of set smashing went on with setting these, and then got worse
  when we considered optnone and other inlining-effecting attributes.
- A bunch of inline affecting attributes were managed in a completely
  different place from -fno-inline.
- Even with -fno-inline we failed to put the LLVM noinline attribute
  onto many generated function definitions because they didn't show up
  as AST-level functions.
- If you passed -O0 but -finline-functions we would run the normal
  inliner pass in LLVM despite it being in the O0 pipeline, which really
  doesn't make much sense.
- Lastly, we used things like '-fno-inline' to manipulate the pass
  pipeline which forced the pass pipeline to be much more
  parameterizable than it really needs to be. Instead we can *just* use
  the optimization level to select a pipeline and control the rest via
  attributes.

Sadly, this causes a bunch of churn in tests because we don't run the
optimizer in the tests and check the contents of attribute sets. It
would be awesome if attribute sets were a bit more FileCheck friendly,
but oh well.

I think this is a significant improvement and should remove the semantic
need to change what inliner pass we run in order to comply with the
requested inlining semantics by relying completely on attributes. It
also cleans up tho optnone and related handling a bit.

One unfortunate aspect of this is that for generating alwaysinline
routines like those in OpenMP we end up removing noinline and then
adding alwaysinline. I tried a bunch of other approaches, but because we
recompute function attributes from scratch and don't have a declaration
here I couldn't find anything substantially cleaner than this.

Differential Revision: https://reviews.llvm.org/D28053

llvm-svn: 290398
2016-12-23 01:24:49 +00:00
Chandler Carruth 93786da2cb Make '-disable-llvm-optzns' an alias for '-disable-llvm-passes'.
Much to my surprise, '-disable-llvm-optzns' which I thought was the
magical flag I wanted to get at the raw LLVM IR coming out of Clang
deosn't do that. It still runs some passes over the IR. I don't want
that, I really want the *raw* IR coming out of Clang and I strongly
suspect everyone else using it is in the same camp.

There is actually a flag that does what I want that I didn't know about
called '-disable-llvm-passes'. I suspect many others don't know about it
either. It both does what I want and is much simpler.

This removes the confusing version and makes that spelling of the flag
an alias for '-disable-llvm-passes'. I've also moved everything in Clang
to use the 'passes' spelling as it seems both more accurate (*all* LLVM
passes are disabled, not just optimizations) and much easier to remember
and spell correctly.

This is part of simplifying how Clang drives LLVM to make it cleaner to
wire up to the new pass manager.

Differential Revision: https://reviews.llvm.org/D28047

llvm-svn: 290392
2016-12-23 00:23:01 +00:00
Richard Smith 30e304e2a6 Remove custom handling of array copies in lambda by-value array capture and
copy constructors of classes with array members, instead using
ArrayInitLoopExpr to represent the initialization loop.

This exposed a bug in the static analyzer where it was unable to differentiate
between zero-initialized and unknown array values, which has also been fixed
here.

llvm-svn: 289618
2016-12-14 00:03:17 +00:00
John McCall 811b291d8c Forward ns_consumed delegate arguments with a move.
StartFunction enters a release cleanup for ns_consumed arguments in
ARC, so we need to balance that somehow.  We could teach StartFunction
that it's emitting a delegating function, so that the cleanup is
unnecessary, but that would be invasive and somewhat fraught.  We could
balance the consumed argument with an extra retain, but clearing the
original variable should be easier to optimize and avoid some extra work
at -O0.  And there shouldn't be any difference as long as nothing else
uses the argument, which should always be true for the places we emit
delegate arguments.

Fixes PR 27887.

llvm-svn: 287291
2016-11-18 01:08:24 +00:00
Victor Leschuk a7ece03b32 DebugInfo: pass alignment value only if it was forced
Preparation to implement DW_AT_alignment support:
 - We pass non-zero align value to DIBuilder only when alignment was forced
 - Modify tests to match this change

Differential Revision: https://reviews.llvm.org/D24426

llvm-svn: 284679
2016-10-20 00:13:19 +00:00
Akira Hatanaka 642f799b0d [CodeGen][ObjC] Do not call objc_storeStrong when initializing a
constexpr variable.

When compiling a constexpr NSString initialized with an objective-c
string literal, CodeGen emits objc_storeStrong on an uninitialized
alloca, which causes a crash.

This patch folds the code in EmitScalarInit into EmitStoreThroughLValue
and fixes the crash by calling objc_retain on the string instead of
using objc_storeStrong.

rdar://problem/28562009

Differential Revision: https://reviews.llvm.org/D25547

llvm-svn: 284516
2016-10-18 19:05:41 +00:00
Richard Smith 762672a73a Re-commit r282556, reverted in r282564, with a fix to CallArgList::addFrom to
function correctly when targeting MS ABIs (this appears to have never mattered
prior to this change).

Update test case to always cover both 32-bit and 64-bit Windows ABIs, since
they behave somewhat differently from each other here.

Update test case to also cover operators , && and ||, which it appears are also
affected by P0145R3 (they're not explicitly called out by the design document,
but this is the emergent behavior of the existing wording).


Original commit message:

P0145R3 (C++17 evaluation order tweaks): evaluate the right-hand side of
assignment and compound-assignment operators before the left-hand side. (Even
if it's an overloaded operator.)

This completes the implementation of P0145R3 + P0400R0 for all targets except
Windows, where the evaluation order guarantees for <<, >>, and ->* are
unimplementable as the ABI requires the function arguments are evaluated from
right to left (because parameter destructors are run from left to right in the
callee).

llvm-svn: 282619
2016-09-28 19:09:10 +00:00
Richard Smith 4499145a5f Revert r282556. This change made several bots unhappy.
llvm-svn: 282564
2016-09-28 02:20:06 +00:00
Richard Smith 97a616d624 P0145R3 (C++17 evaluation order tweaks): evaluate the right-hand side of
assignment and compound-assignment operators before the left-hand side. (Even
if it's an overloaded operator.)

This completes the implementation of P0145R3 + P0400R0 for all targets except
Windows, where the evaluation order guarantees for <<, >>, and ->* are
unimplementable as the ABI requires the function arguments are evaluated from
right to left (because parameter destructors are run from left to right in the
callee).

llvm-svn: 282556
2016-09-27 23:44:22 +00:00
Saleem Abdulrasool 82f6added3 CodeGen: further merge cstring literal construction
Use the new CreateCStringLiteral in an additional site.  Now all the C string
literals are created in one function.  Furthermore, mark the additional literal
as an `unnamed_addr constant`.

llvm-svn: 281997
2016-09-20 18:38:54 +00:00
Saleem Abdulrasool 3f307518f8 CodeGen: mark ObjC cstring literals as unnamed_addr
These are all emitted into a section with a cstring_literal attribute.  The
attribute permits the linker to coalesce the string contents.  The address of
the strings are not important.

llvm-svn: 281855
2016-09-18 16:12:14 +00:00
Saleem Abdulrasool 0c54dc862e CodeGen: mark ObjC cstring literals as constant
These strings are constants, mark them as such.  This doesn't matter too much in
practice on MachO since the constants are placed into a special section and not
referred to directly.

llvm-svn: 281854
2016-09-18 16:12:04 +00:00
Akira Hatanaka d542ccfc97 [CodeGen][ObjC] Block captures should inherit the type of the captured
field in the enclosing lambda or block.

This patch fixes a bug in code-gen where it uses the type of the
declared variable rather than the type of the capture of the enclosing
lambda or block for the block capture. For example, in the following
function, code-gen currently uses i32* for the block capture "a" because
"a" is passed to foo1 as a reference, but it should use i32 since the
enclosing lambda captures "a" by value.

void foo1(int &a) {
  auto lambda = [a]{
    auto block1 = ^{
      i = a;
    };
    block1();
  };
  lambda();
}

rdar://problem/18586386

Differential Revision: https://reviews.llvm.org/D21104

llvm-svn: 281682
2016-09-16 00:02:06 +00:00
Wei Mi 6582669aa9 Update clang unittests for rL281586.
The change in rL281586 is in llvm component and tests updated here are
in clang component, so I have to commit them consecutively.

llvm-svn: 281587
2016-09-15 06:31:30 +00:00
Akira Hatanaka fd0fb204a0 [CodeGen][ObjC] Fix infinite recursion in getObjCEncodingForTypeImpl.
Check that ExpandStructures is true before visiting the list of ivars.

rdar://problem/27135221

Differential revision: https://reviews.llvm.org/D22929

llvm-svn: 278956
2016-08-17 19:42:22 +00:00
David Majnemer d61d963490 Update clang tests for LLVM r277950
We infer inbounds on GEPs of allocas leading to minor perturbations in
tests.

llvm-svn: 277953
2016-08-07 08:28:58 +00:00
Saleem Abdulrasool 369f4d64a2 CodeGen: try harder to make the CFString structure RW
The previous change was insufficient to mark the content as read-write as the
structure itself was marked constant.  Adjust this and add tests to ensure that
the section is marked appropriately as being read-write.

llvm-svn: 277200
2016-07-29 19:15:51 +00:00
Nico Weber fb42078d7c Fix mangled name of method with ns_consumed parameters.
When a function/method use a parameter with "ns_consumed" attribute,
ensure that the mangled name is the same whether -fobjc-arc is used
or not.

Since "ns_consumed" attribute is generally used to inform ARC that
a function/method does sink the reference, it mean it is usually
implemented in a compilation unit compiled without -fobjc-arc but
used form a compilation unit compiled with it.

Originally found while trying to use "ns_consumed" attribute in an
Objective-C++ file in Chromium (http://crbug.com/599980) where it
caused a linker error.

Regression introduced by revision 262278 (previously the attribute
was incorrectly not part of the mangled name).

Patch from Sylvain Defresne <sdefresne@chromium.org>!
http://reviews.llvm.org/D20113

llvm-svn: 270702
2016-05-25 14:15:08 +00:00
Akira Hatanaka fdacb5c056 [ObjC][CodeGen] Remove an assert that is no longer correct.
clang asserts when compiling the following code because r231508 made
changes to promote constant temporary arrays and records to globals
with constant initializers:

std::vector<NSString*> strs = {@"a", @"b"};

This commit changes the code to return early if the object returned by
createReferenceTemporary is a global variable with an initializer.

rdar://problem/25504992
rdar://problem/25955179

Differential Revision: http://reviews.llvm.org/D20045

llvm-svn: 269385
2016-05-13 01:21:23 +00:00
Akira Hatanaka 1cce6e15c1 [CodeGenObjCXX] Fix handling of blocks in lambda.
This fixes a crash that occurs when a block captures a reference that is
captured by its enclosing lambda.

rdar://problem/18586651

Differential Revision: http://reviews.llvm.org/D19536

llvm-svn: 268532
2016-05-04 18:40:33 +00:00
Pete Cooper 5dc2c3fb94 Update test CHECK lines after r268509. NFC.
r268509 causes this test case to be fully unrolled, so checking for an icmp is
no longer valid.  Given that this test is for ARC anyway, checking for the icmp seems
unecessary.

llvm-svn: 268523
2016-05-04 17:37:27 +00:00
Akira Hatanaka 3ba6535096 [CodeGenObjCXX] Don't rematerialize default arguments of function
parameters in the body of a block.

This fixes a bug where clang would materialize the default argument
inside the body of a block instead of passing the value via the block
descriptor.

For example, in the code below, foo1 would always print 42 regardless
of the value of argument "a" passed to foo1.

void foo1(const int a = 42 ) {
  auto block = ^{
    printf("%d\n", a);
  };
  block();
}

rdar://problem/24449235

llvm-svn: 268314
2016-05-02 21:52:57 +00:00
Duncan P. N. Exon Smith 383f8413cf DebugInfo: Adapt to loss of DITypeRef in LLVM r267296
LLVM stopped using MDString-based type references, and DIBuilder no
longer fills 'retainedTypes:' with every DICompositeType that has an
'identifier:' field.   There are just minor changes to keep the same
behaviour in CFE.

Leaving 'retainedTypes:' unfilled has a dramatic impact on the output
order of the IR though.  There are a huge number of testcase changes,
which were unfortunately not really scriptable.

llvm-svn: 267297
2016-04-23 21:08:27 +00:00
Adrian Prantl 2526fca8d8 [ObjC++] Fix crash when emitting debug info for a block member capturing this.
rdar://problem/23871824

llvm-svn: 266698
2016-04-18 23:48:16 +00:00
Richard Smith 351241c83e Replace Sema-level implementation of -fassume-sane-operator-new with a
CodeGen-level implementation. Instead of adding an attribute to clang's
FunctionDecl, add the IR attribute directly. This means a module built with
this flag is now compatible with code built without it and vice versa.

This change also results in the 'noalias' attribute no longer being added to
calls to operator new in the IR; it's now only added to the declaration. It
also fixes a bug where we failed to add the attribute to the 'nothrow' versions
(because we didn't implicitly declare them, there was no good time to inject a
fake attribute).

llvm-svn: 265728
2016-04-07 21:46:12 +00:00
Nirav Dave e585b5c52b Fix broken tests from no-jump-table commit
Summary: Fix failing tests from no-jump-table flag addition

Reviewers: jyknight

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D18801

llvm-svn: 265439
2016-04-05 18:59:37 +00:00
John McCall 07daf721fb Mangle extended qualifiers in the proper order and mangle the
ARC ownership-convention function type modifications.

According to the Itanium ABI, vendor extended qualifiers are
supposed to be mangled in reverse-alphabetical order before
any CVR qualifiers.  The ARC function type conventions are
plausibly order-significant (they are associated with the
function type), which permits us to ignore the need to correctly
inter-order them with any other vendor qualifiers on the parameter
and return types.

Implementing these rules correctly is technically an ABI break.
Apple is comfortable with the risk of incompatibility here for
the ARC features, and I believe that address-space qualification
is still uncommon enough to allow us to adopt the conforming
rule without serious risk.  Still, targets which make heavy
use of address space qualification may want to revert to the
non-conforming order.

llvm-svn: 262414
2016-03-01 22:18:03 +00:00
Akira Hatanaka 9d8ac61fec [CodeGen] Fix an assert in CodeGenFunction::EmitFunctionEpilog
The assert is triggered because isObjCRetainableType() is called on the
canonicalized return type that has been stripped of the typedefs and
attributes attached to it. To fix this assert, this commit gets the
original return type from CurCodeDecl or BlockInfo and uses it instead
of the canoicalized type.

rdar://problem/24470031

Differential Revision: http://reviews.llvm.org/D16914

llvm-svn: 261151
2016-02-17 21:09:50 +00:00
Vedant Kumar 2f5bb1150d Reapply "[CodeGen] Fix assignments of inline layouts into the byref structure"
When using blocks, a byref structure is created to represent the
closure. The "byref.layout" field of this structure is an i8*. However,
some 'inline' layouts are represented as i64's, not i8*'s.

Prior to r246985 we cast the i64 'inline' layout to an i8* before
assigning it into the byref structure. This patch brings the cast back
and adds a regression test.

The original version of this patch was too invasive. This version only adds the
cast to BuildByrefLayout.

Differential Revision: http://reviews.llvm.org/D15674

rdar://23713871

llvm-svn: 256190
2015-12-21 20:21:15 +00:00
Vedant Kumar 3ed0df070e Revert "[CodeGen] Fix assignments of inline layouts into the byref structure"
This reverts commit r256185. It breaks CodeGenObjC/fragile-arc.m.

llvm-svn: 256186
2015-12-21 19:43:25 +00:00
Vedant Kumar eb37ec87e4 [CodeGen] Fix assignments of inline layouts into the byref structure
When using blocks, a byref structure is created to represent the
closure. The "byref.layout" field of this structure is an i8*. However,
some 'inline' layouts are represented as i64's, not i8*'s.

Prior to r246985 we cast the i64 'inline' layout to an i8* before
assigning it into the byref structure. This patch brings the cast back
and adds a regression test.

rdar://23713871

llvm-svn: 256185
2015-12-21 19:30:37 +00:00
Pete Cooper 3b39e88ae0 Revert "Change memcpy/memset/memmove to have dest and source alignments."
This reverts commit r253512.

This likely broke the bots in:
http://lab.llvm.org:8011/builders/clang-ppc64-elf-linux2/builds/20202
http://bb.pgr.jp/builders/clang-3stage-i686-linux/builds/3787

llvm-svn: 253542
2015-11-19 05:55:59 +00:00
John McCall 00b2bbb7bb Don't actually add the __unsafe_unretained qualifier in MRC;
driving a canonical difference between that and an unqualified
type is a really bad idea when both are valid.  Instead, remember
that it was there in a non-canonical way, then look for that in
the one place we really care about it: block captures.  The net
effect closely resembles the behavior of a decl attribute, except
still closely following ARC's standard qualifier parsing rules.

llvm-svn: 253534
2015-11-19 02:28:03 +00:00
Pete Cooper 7bfd5cb7be Change memcpy/memset/memmove to have dest and source alignments.
This is a follow on from a similar LLVM commit: r253511.

Note, this was reviewed (and more details are in) http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20151109/312083.html

These intrinsics currently have an explicit alignment argument which is
required to be a constant integer.  It represents the alignment of the
source and dest, and so must be the minimum of those.

This change allows source and dest to each have their own alignments
by using the alignment attribute on their arguments.  The alignment
argument itself is removed.

The only code change to clang is hidden in CGBuilder.h which now passes
both dest and source alignment to IRBuilder, instead of taking the minimum of
dest and source alignments.

Reviewed by Hal Finkel.

llvm-svn: 253512
2015-11-18 22:18:45 +00:00
John McCall 0204e342ca Correctly handle type mismatches in the __weak copy/move-initialization
peephole I added in r250916.

rdar://23559789

llvm-svn: 253255
2015-11-16 22:11:41 +00:00
Peter Collingbourne 0900fe0f1b CodeGen: Update for debug info API change.
Differential Revision: http://reviews.llvm.org/D14266

llvm-svn: 252220
2015-11-05 22:04:14 +00:00
Akira Hatanaka 44a59f8976 [CodeGen] Attach function attributes to Objective-C and OpenMP
functions.

This commit fixes a bug in CGOpenMPRuntime.cpp and CGObjC.cpp where
some of the function attributes are not attached to newly created
functions.

rdar://problem/20828324

Differential Revision: http://reviews.llvm.org/D13928

llvm-svn: 251476
2015-10-28 02:30:47 +00:00
John McCall 3fd13f0665 Fix and stylize the emission of GC/ARC ivar and GC block layout strings.
Specifically, handle under-aligned object references (by explicitly
ignoring them, because this just isn't representable in the format;
yes, this means that GC silently ignores such references), descend
into anonymous structs and unions, stop classifying fields of
pointer-to-strong/weak type as strong/weak in ARC mode, and emit
skips to cover the entirety of block layouts in GC mode.  As a
cleanup, extract this code into a helper class, avoid a number of
unnecessary copies and layout queries, generate skips implicitly
instead of explicitly tracking them, and clarify the bitmap-creation
logic.

llvm-svn: 250919
2015-10-21 18:06:47 +00:00
John McCall f8a9b66f65 In ARC, peephole the initialization of a __weak variable with
a value loaded from a __weak variable into a call to
objc_copyWeak or objc_moveWeak.

llvm-svn: 250916
2015-10-21 18:06:31 +00:00
Douglas Katzman 3459ce2e5e Stop messing with the 'g' group of options in CompilerInvocation.
With this change, most 'g' options are rejected by CompilerInvocation.
They remain only as Driver options. The new way to request debug info
from cc1 is with "-debug-info-kind={line-tables-only|limited|standalone}"
and "-dwarf-version={2|3|4}". In the absence of a command-line option
to specify Dwarf version, the Toolchain decides it, rather than placing
Toolchain-specific logic in CompilerInvocation.

Also fix a bug in the Windows compatibility argument parsing
in which the "rightmost argument wins" principle failed.

Differential Revision: http://reviews.llvm.org/D13221

llvm-svn: 249655
2015-10-08 04:24:12 +00:00
Sanjoy Das a0bc8590fe Change arc-cxx11-init-list.mm to work with upcoming SCEV changes.
Summary:
The store being checked for in arc-cxx11-init-list.mm is a store to an
unescaped alloca.  After an uncoming change to ScalarEvolution, LLVM is
able to elide the store, so adjust the test accordingly.

Reviewers: compnerd

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D13183

llvm-svn: 248632
2015-09-25 23:07:11 +00:00
John McCall f0f0b7a0eb Fix a nasty bug with the partial destruction of nested arrays;
it escaped notice because it's only used for heterogeneous
initialization.

rdar://21397946

llvm-svn: 247597
2015-09-14 18:57:08 +00:00
John McCall 9c52b28003 When comparing two block captures for layout, don't crash
if they have the same alignment and one was 'this'.

Fixes PR24780.

llvm-svn: 247482
2015-09-11 22:00:51 +00:00
Nico Weber b833fd982d Let selector-expr-lvalue.mm actually test something.
I accidentally introduced a bug locally, and noticed that none of the tests
caught it. No longer!

llvm-svn: 247477
2015-09-11 21:24:40 +00:00
Vedant Kumar 276d5d9fbc [test] Specify exception object type in two tests
Replace:
    'try { throw 0; } catch (...)'
with
    'try { throw 0; } catch (int e)'

in two test cases.

Differential Revision: http://reviews.llvm.org/D12743

llvm-svn: 247437
2015-09-11 17:39:34 +00:00
Vedant Kumar db609471ce [CodeGen] Teach SimplifyPersonality about the updated LandingPadInst
When uses of personality functions were moved from LandingPadInst to
Function, we forgot to update SimplifyPersonality(). This patch corrects
that.

Note: SimplifyPersonality() is an optimization which replaces
personality functions with the default C++ personality when possible.
Without this update, some ObjC++ projects fail to link against C++
libraries (seeing as the exception ABI had effectively changed).

rdar://problem/22155434

llvm-svn: 247421
2015-09-11 15:40:05 +00:00
John McCall 7f416cc426 Compute and preserve alignment more faithfully in IR-generation.
Introduce an Address type to bundle a pointer value with an
alignment.  Introduce APIs on CGBuilderTy to work with Address
values.  Change core APIs on CGF/CGM to traffic in Address where
appropriate.  Require alignments to be non-zero.  Update a ton
of code to compute and propagate alignment information.

As part of this, I've promoted CGBuiltin's EmitPointerWithAlignment
helper function to CGF and made use of it in a number of places in
the expression emitter.

The end result is that we should now be significantly more correct
when performing operations on objects that are locally known to
be under-aligned.  Since alignment is not reliably tracked in the
type system, there are inherent limits to this, but at least we
are no longer confused by standard operations like derived-to-base
conversions and array-to-pointer decay.  I've also fixed a large
number of bugs where we were applying the complete-object alignment
to a pointer instead of the non-virtual alignment, although most of
these were hidden by the very conservative approach we took with
member alignment.

Also, because IRGen now reliably asserts on zero alignments, we
should no longer be subject to an absurd but frustrating recurring
bug where an incomplete type would report a zero alignment and then
we'd naively do a alignmentAtOffset on it and emit code using an
alignment equal to the largest power-of-two factor of the offset.

We should also now be emitting much more aggressive alignment
attributes in the presence of over-alignment.  In particular,
field access now uses alignmentAtOffset instead of min.

Several times in this patch, I had to change the existing
code-generation pattern in order to more effectively use
the Address APIs.  For the most part, this seems to be a strict
improvement, like doing pointer arithmetic with GEPs instead of
ptrtoint.  That said, I've tried very hard to not change semantics,
but it is likely that I've failed in a few places, for which I
apologize.

ABIArgInfo now always carries the assumed alignment of indirect and
indirect byval arguments.  In order to cut down on what was already
a dauntingly large patch, I changed the code to never set align
attributes in the IR on non-byval indirect arguments.  That is,
we still generate code which assumes that indirect arguments have
the given alignment, but we don't express this information to the
backend except where it's semantically required (i.e. on byvals).
This is likely a minor regression for those targets that did provide
this information, but it'll be trivial to add it back in a later
patch.

I partially punted on applying this work to CGBuiltin.  Please
do not add more uses of the CreateDefaultAligned{Load,Store}
APIs; they will be going away eventually.

llvm-svn: 246985
2015-09-08 08:05:57 +00:00