Commit Graph

109092 Commits

Author SHA1 Message Date
Rafael Espindola
45968c54e9 Fix a bit of confusion about .set and produce more readable assembly.
Every target we support has support for assembly that looks like

a = b - c
.long a

What is special about MachO is that the above combination suppresses the
production of a relocation.

With this change we avoid producing the intermediary labels when they don't
add any value.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220256 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-21 01:17:30 +00:00
Paul Robinson
f8c9d3d3c2 Do not attribute static allocas to the call site's DebugLoc.
When functions are inlined, instructions without debug information are
attributed to the call site's DebugLoc. After inlining, inlined static
allocas are moved to the caller's entry block, adjacent to the caller's
original static alloca instructions. By retaining the call site's
DebugLoc, these instructions could cause instructions that were
subsequently inserted at the entry block to pick up the same DebugLoc.

Patch by Wolfgang Pieb!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220255 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-21 01:00:55 +00:00
Rafael Espindola
f46dd92ba4 Make this test a bit more strict.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220253 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-21 00:47:49 +00:00
Chandler Carruth
14e55b16df Teach lit to filter the host LDFLAGS down from the build system and into
the CGO build environment. This lets things like -rpath propagate down
to the C++ code that is built along side the Go bindings when testing
them.

Patch by Peter Collingbourne, and verified that it works by me.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220252 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-21 00:36:28 +00:00
David Blaikie
82805eb232 PR21202: Memory leak in Windows RWMutexImpl when using SRWLOCK
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220251 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-21 00:34:39 +00:00
Rafael Espindola
33966cf988 Make AsmPrinter::EmitLabelOffsetDifference a static helper and simplify.
It had exactly one caller in a position where we know hasSetDirective is true.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220250 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-21 00:25:49 +00:00
Lang Hames
acaf8f5618 [MCJIT] Temporarily revert r220245 - it broke several bots.
(See e.g. http://bb.pgr.jp/builders/cmake-llvm-x86_64-linux/builds/17653)



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220249 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-21 00:24:02 +00:00
Philip Reames
9be9473394 Introduce enum values for previously defined metadata types. (NFC)
Our metadata scheme lazily assigns IDs to string metadata, but we have a mechanism to preassign them as well.  Using a preassigned ID is helpful since we get compile time type checking, and avoid some (minimal) string construction and comparison.  This change adds enum value for three existing metadata types:
+    MD_nontemporal = 9, // "nontemporal"
+    MD_mem_parallel_loop_access = 10, // "llvm.mem.parallel_loop_access"
+    MD_nonnull = 11 // "nonnull"

I went through an updated various uses as well.  I made no attempt to get all uses; I focused on the ones which were easily grepable and easily to translate.  For example, there were several items in LoopInfo.cpp I chose not to update.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220248 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-21 00:13:20 +00:00
Philip Reames
c0c4f1b78e Extend the verifier to validate range metadata on calls and invokes.
Range metadata applies to loads, call, and invokes.  We were validating that metadata applied to loads was correct according to the LangRef, but we were not validating metadata applied to calls or invokes.  This change extracts the checking functionality to a common location, reuses it for all valid locations, and adds a simple test to ensure a misused range on a call gets reported.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220246 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-20 23:52:07 +00:00
Lang Hames
32aaaeaa05 [MCJIT] Make MCJIT honor symbol visibility settings when populating the global
symbol table.

Patch by Anthony Pesch. Thanks Anthony!



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220245 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-20 23:39:54 +00:00
Quentin Colombet
a37862e2de [X86] Fix a bug in the lowering of the mask of VSELECT.
X86 code to lower VSELECT messed a bit with the bits set in the mask of VSELECT
when it knows it can be lowered into BLEND. Indeed, only the high bits need to be
set for those and it optimizes those accordingly.
However, when the mask is a compile time constant, the lowering will be handled
by the generic optimizer and those modifications will generate bad code in the
generic optimizer.

This patch fixes that by preventing the optimization if the VSELECT will be
handled by the generic optimizer.

<rdar://problem/18675020>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220242 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-20 23:13:30 +00:00
Philip Reames
90f3f15da5 Introduce a 'nonnull' metadata on Load instructions.
The newly introduced 'nonnull' metadata is analogous to existing 'nonnull' attributes, but applies to load instructions rather than call arguments or returns.  Long term, it would be nice to combine these into a single construct.   The value of the load is allowed to vary between successive loads, but null is not a valid value to be loaded by any load marked nonnull.

Reviewed by: Hal Finkel
Differential Revision:  http://reviews.llvm.org/D5220




git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220240 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-20 22:40:55 +00:00
Simon Pilgrim
0d1978b813 [X86] Memory folding for commutative instructions (updated)
This patch improves support for commutative instructions in the x86 memory folding implementation by attempting to fold a commuted version of the instruction if the original folding fails - if that folding fails as well the instruction is 're-commuted' back to its original order before returning.

Updated version of r219584 (reverted in r219595) - the commutation attempt now explicitly ensures that neither of the commuted source operands are tied to the destination operand / register, which was the source of all the regressions that occurred with the original patch attempt.

Added additional regression test case provided by Joerg Sonnenberger.

Differential Revision: http://reviews.llvm.org/D5818



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220239 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-20 22:14:22 +00:00
Rafael Espindola
b9c7f60191 Explain why we don't always use --gc-sections.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220237 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-20 21:37:38 +00:00
Tim Northover
4e399f4500 ARM: rework Thumb1 frame index rewriting
The previous code had a few problems, motivating the choices here.

1. It could create instructions clobbering CPSR, but the incoming MachineInstr
   didn't reflect this. A potential source of corruption. This is why the patch
   has a new PseudoInst for before lowering.
2. Similarly, there was some code to handle the incoming instruction not being
   ARMCC::AL, but this would have caused massive problems if it was actually
   invoked when a complex offset needing more than one instruction was requested.
3. It wasn't designed to handle unaligned pointers (or offsets). These should
   probably be minimised anyway, but the code needs to deal with them properly
   regardless.
4. It had some rather dubious ad-hoc code to avoid calling
   emitThumbRegPlusImmediate, a function which should be designed to do precisely
   this job.

We seem to cover the common cases correctly now, and hopefully can enhance
emitThumbRegPlusImmediate to handle any extra optimisations we need to add in
future.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220236 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-20 21:28:41 +00:00
Alexey Samsonov
2d6aee13e5 Try to fix GCC error about invalid use of const_cast in const version of ErrorOr::get()
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220233 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-20 20:41:21 +00:00
Alexey Samsonov
e505b3d541 Constify getELFDynamicSymbolIterators standalone function. NFC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220232 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-20 20:33:20 +00:00
Alexey Samsonov
262b278dae Add const version of OwningBinary::getBinary
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220231 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-20 20:32:47 +00:00
Alexey Samsonov
9170808b2a Be more specific about return type of MachOUniversalBinary::getObjectForArch
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220230 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-20 20:30:57 +00:00
Alexey Samsonov
10051f0f62 Constify input argument of RelocVisitor and DWARFContext constructors. NFC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220228 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-20 20:28:51 +00:00
Dan Liew
559074a285 Teach Lit to catch OSError exceptions when creating a process during the
execution of a shell command. This can happen for example if the
``RUN:`` line calls a python script which can work correctly under
Linux/OSX but will not work under Windows. A more useful error message
is now shown rather than an unhelpful backtrace.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220227 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-20 20:14:28 +00:00
Robert Khasanov
10646db916 Moved out IIT_V64 from common values section.
Thanks Juergen Ributzka for notice.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220224 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-20 19:25:05 +00:00
Gerolf Hoflehner
1591cf0cef [AArch64] test case for compfail fixed by r219748
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220206 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-20 16:08:33 +00:00
Steven Wu
3ea39890d1 Fix Intrinsic::getType not working with vararg
VarArg Intrinsic functions are encoded with "void" type as the last
argument. Now Intrinsic::getType can correctly return all the intrinsic
function type.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220205 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-20 15:47:24 +00:00
Oliver Stannard
e7c9c44387 [Thumb2] RFE, SRS and "SUBS pc, lr" are undefined on v7M
These instructions are related to the v7[AR] exception model, and are
not defined on v7M.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220204 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-20 15:37:35 +00:00
Sid Manning
958df22c9f Remove unnecessary else.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220200 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-20 13:08:19 +00:00
NAKAMURA Takumi
7c771b0293 Revert r220174, "Always use -Wl,-gc-sections on our build."
It dropped required functions for plugins with gnu ld 2.20 and 2.21.

  Failing Tests (1):
      LLVM :: Feature/load_module.ll

  Hello: bin/opt: symbol lookup error: lib/LLVMHello.so: undefined symbol: _ZN4llvm11raw_ostream13write_escapedENS_9StringRefEb

  Failing Tests (1):
      Clang :: Frontend/plugins.c

  error: unable to load plugin 'lib/PrintFunctionNames.so': 'lib/PrintFunctionNames.so: undefined symbol: _ZN5clang15PluginASTAction6anchorEv'

I think we should inspect linker's version or behavior to introduce --gc-sections for --export-dynamic.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220198 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-20 12:12:21 +00:00
Oliver Stannard
19d010b851 [ARM] Do not select SMULW[BT] or SMLAW[BT]
The current instruction selection patterns for SMULW[BT] and SMLAW[BT]
are incorrect. These instructions multiply a 32-bit and a 16-bit value
(both signed) and return the top 32 bits of the 48-bit result. This
preserves the 16 bits of overflow, whereas the patterns they currently
match truncate the result to 16 bits then sign extend.

To select these instructions, we would need to match an ISD::SMUL_LOHI,
a sign extend, two shifts and an or. There is no way to match SMUL_LOHI
in an instruction pattern as it defines multiple values, so this would
have to be done in C++. I have raised
http://llvm.org/bugs/show_bug.cgi?id=21297 to cover allowing correct
selection of these instructions.

This fixes http://llvm.org/bugs/show_bug.cgi?id=19396



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220196 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-20 11:30:35 +00:00
Oliver Stannard
508c39393a [Thumb] Fix crash in Thumb1RegisterInfo::rewriteFrameIndex
This function can, for some offsets from the SP, split one instruction
into two. Since it re-uses the original instruction as the first
instruction of the result, we need ensure its result register is not
marked as dead before we use it in the second instruction.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220194 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-20 11:00:18 +00:00
Chandler Carruth
34b45cdb95 Switch the default DataLayout to be little endian, and make the variable
be BigEndian so the default can continue to be zero-initialized.

This is one of the prerequisites to making DataLayout a constant and
always available part of every module.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220193 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-20 10:41:29 +00:00
Chandler Carruth
d413989edb Remove some completely superfluous trailing comments and clang-format
this header to remove numerous formatting inconsistencies that impede
making simple changes here without large diffs.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220192 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-20 10:35:11 +00:00
Chandler Carruth
64cf50d348 Clean up the comments and doxygen for DataLayout.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220191 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-20 10:27:53 +00:00
Chandler Carruth
3ac929c473 Fix a miscompile introduced in r220178.
The original code had an implicit assumption that if the test for
allocas or globals was reached, the two pointers were not equal. With my
changes to make the pointer analysis more powerful here, I also had to
guard against circumstances where the results weren't useful. That in
turn violated the assumption and gave rise to a circumstance in which we
could have a store with both the queried pointer and stored pointer
rooted at *the same* alloca. Clearly, we cannot ignore such a store.
There are other things we might do in this code to better handle the
case of both pointers ending up at the same alloca or global, but it
seems best to at least make the test explicit in what it intends to
check.

I've added tests for both the alloca and global case here.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220190 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-20 10:03:01 +00:00
David Majnemer
7798534e77 IR: Replace DataLayout::RoundUpAlignment with RoundUpToAlignment
No functional change intended, just cleaning up some code.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220187 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-20 06:13:33 +00:00
Chandler Carruth
080dfb5bda Fix a somewhat subtle pair of issues with JumpThreading I introduced in
r220178. First, the creation routine doesn't insert prior to the
terminator of the basic block provided, but really at the end of the
basic block. Instead, get the terminator and insert before that. The
next issue was that we need to ensure multiple PHI node entries for
a single predecessor re-use the same cast instruction rather than
creating new ones.

All of the logic here was without tests previously. I've reduced and
added a test case from the test suite that crashed without both of these
fixes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220186 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-20 05:34:36 +00:00
Lang Hames
96fc0d298c [PBQP] Use DenseSet rather than std::set for PBQP's PoolCostAllocator
implementation.

This is good for a ~6% reduction in total compile time on the nightly test suite
when running with -regalloc=pbqp.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220183 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-20 04:26:23 +00:00
Chandler Carruth
35c4e071be Teach the load analysis driving core instcombine logic and other bits of
logic to look through pointer casts, making them trivially stronger in
the face of loads and stores with intervening pointer casts.

I've included a few test cases that demonstrate the kind of folding
instcombine can do without pointer casts and then variations which
obfuscate the logic through bitcasts. Without this patch, the variations
all fail to optimize fully.

This is more important now than it has been in the past as I've started
moving the load canonicialization to more closely follow the value type
requirements rather than the pointer type requirements and thus this
needs to be prepared for more pointer casts. When I made the same change
to stores several test cases regressed without logic along these lines
so I wanted to systematically improve matters first.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220178 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-20 00:24:14 +00:00
Chandler Carruth
fc1c1ec435 Add a datalayout string to this test so that it exercises the full gamut
of InstCombine rather than just the bits enabled when datalayout is
optional.

The primary fixes here are because now things are little endian.

In good news, silliness like this seems like it will be going away as
we've got pretty stong consensus on dropping optional datalayout
entirely.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220176 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-20 00:11:31 +00:00
Rafael Espindola
0ea9c06fe0 Always use -Wl,-gc-sections on our build.
Both bfd ld and gold correctly handle --export-dynamic, so gc-sections is safe even for binaries
that support plugins.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220174 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-19 23:24:46 +00:00
Bill Schmidt
551a3d7b56 [PowerPC] Clean up -mattr=+vsx tests to always specify -mcpu
We recently discovered an issue that reinforces what a good idea it is
to always specify -mcpu in our code generation tests, particularly for
-mattr=+vsx.  This patch ensures that all tests that specify
-mattr=+vsx also specify -mcpu=pwr7 or -mcpu=pwr8, as appropriate.

Some of the uses of -mattr=+vsx added recently don't make much sense
(when specified for -mtriple=powerpc-apple-darwin8 or -march=ppc32,
for example).  For cases like this I've just removed the extra VSX
test commands; there's enough coverage without them.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220173 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-19 21:29:21 +00:00
Bill Schmidt
1d142d4d47 [PowerPC] Temporarily disable VSX for PowerPC fast-isel tests
Patch by Bill Seurer; some comment formatting changes by me.

There are a few PowerPC test cases for FastISel support that currently
fail with VSX support enabled.  The temporary workaround under
discussion in http://reviews.llvm.org/D5362 helps, but the tests still
fail because they specify -fast-isel-abort, and the VSX workaround
punts back to SelectionDAG.  We have plans to fix FastISel permanently
for VSX, but until that's in place these tests are preventing us from
enabling VSX by default.  Therefore we are adding -mattr=-vsx to these
tests until the full support is ready.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220172 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-19 20:48:47 +00:00
Bill Schmidt
ff8acb69e5 [PowerPC] Re-enable VSX test line for fma.ll with -mcpu=pwr7
The VSX testing variant in test/CodeGen/PowerPC/fma.ll had to be
disabled because of unexpected behavior on many of the builders.  I
tracked this down to a situation that occurs when the VSX attribute is
enabled for a target that disables the MI early scheduling pass.  This
patch adds -mcpu=pwr7 to make this predictable.  The other issue will
be addressed separately.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220171 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-19 20:27:56 +00:00
Lang Hames
63b14baf79 [ADT] Add a 'find_as' operation to DenseSet.
This operation is analogous to its counterpart in DenseMap: It allows lookup
via cheap-to-construct keys (provided that getHashValue and isEqual are
implemented for the cheap key-type in the DenseMapInfo specialization).

Thanks to Chandler for the review.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220168 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-19 19:36:33 +00:00
Chandler Carruth
63276ccdbd Do a better and more complete job of preserving metadata when combining
loads.

This handles many more cases than just the AA metadata, some of them
suggested by Hal in his review of the AA metadata handling patch. I've
tried to test this behavior where tractable to do so.

I'll point out that I have specifically *not* included a test for
debuginfo because it was going to require 2 or 3 times as much work to
craft some input which would survive the "helpful" stripping of debug
info metadata that doesn't match the desired schema. This is another
good example of why the current state of write-ability for our debug
info metadata is unacceptable. I spent over 30 minutes trying to conjure
some test case that would survive, even copying from other debug info
tests, but it always failed to survive with no explanation of why or how
I might fix it. =[

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220165 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-19 10:46:46 +00:00
Chandler Carruth
4d2a706176 Move previously dead code to handle computing the known bits of an alias
up to where it actually works as intended. The problem is that
a GlobalAlias isa GlobalValue and so the prior block handled all of the
cases.

This allows us to constant fold based on the actual constant expression
in the global alias. As an example, see the last function in the newly
added test case which explicitly aligns an unaligned pointer using
constant expression math. Without this change, we fail to see that and
fold an alignment test to zero.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220164 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-19 09:06:56 +00:00
David Majnemer
0fd4e2e5a1 InstCombine: (sub (or A B) (xor A B)) --> (and A B)
The following implements the transformation:
(sub (or A B) (xor A B)) --> (and A B).

Patch by Ankur Garg!

Differential Revision: http://reviews.llvm.org/D5719

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220163 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-19 08:32:32 +00:00
David Majnemer
242aeb9d84 InstCombine: Optimize icmp eq/ne (shl Const2, A), Const1
The following implements the optimization for sequences of the form:
icmp eq/ne (shl Const2, A), Const1

Such sequences can be transformed to:
icmp eq/ne A, (TrailingZeros(Const1) - TrailingZeros(Const2))

This handles only the equality operators for now. Other operators need
to be handled.

Patch by Ankur Garg!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220162 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-19 08:23:08 +00:00
Chandler Carruth
908d4514f6 Fix a long-standing miscompile in the load analysis that was uncovered
by my refactoring of this code.

The method isSafeToLoadUnconditionally assumes that the load will
proceed with the preferred type alignment. Given that, it has to ensure
that the alloca or global is at least that aligned. It has always done
this historically when a datalayout is present, but has never checked it
when the datalayout is absent. When I refactored the code in r220156,
I exposed this path when datalayout was present and that turned the
latent bug into a patent bug.

This fixes the issue by just removing the special case which allows
folding things without datalayout. This isn't worth the complexity of
trying to tease apart when it is or isn't safe without actually knowing
the preferred alignment.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220161 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-19 08:17:50 +00:00
Chandler Carruth
f84407be32 Switch how the datalayout availability test is handled in this code to
make much more sense and in theory be more correct.

If you trace the code alllll the way back to when it was first
introduced, the comments make it slightly more clear what was going on
here. At that time, the only way Base != V was if DL (then TD) was
non-null. As a consequence, if DL *was* null, that meant we were loading
directly from the alloca or global found above the test. After
refactoring, this has become at least terribly subtle and potentially
incorrect. There are many forms of pointer manipulation that can be
traversed without DataLayout, and some of them would in fact change the
size of object being loaded vs. allocated.

Rather than this subtlety, I've hoisted the actual 'return true' bits
into the code which actually found an alloca or global and based them on
the loaded pointer being that alloca or global. This is both more clear
and safer. I've also added comments about exactly why this set of
predicates is used.

I've also corrected a misleading comment about globals -- if overridden
they may not just have a different size, they may be null and completely
unsafe to load from!

Hopefully this confuses the next reader a bit less. I don't have any
test cases or anything, the patch is motivated strictly to improve the
readability of the code.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220156 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-19 00:42:16 +00:00
Bob Wilson
efed41c621 Use triple predicate functions instead of checking values directly. NFC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220155 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-19 00:39:30 +00:00