NNT: Make sure stderr for build commands goes to log file, as intended but misdirected.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91379 91177308-0d34-0410-b5e6-96231b3b80d8

Propagate zest through logical shift.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91378 91177308-0d34-0410-b5e6-96231b3b80d8

Formatting.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91377 91177308-0d34-0410-b5e6-96231b3b80d8

Revert these. They may have been causing 483_xalancbmk to fail:

$ svn merge -c -91161 https://llvm.org/svn/llvm-project/llvm/trunk
--- Reverse-merging r91161 into '.':
U    lib/CodeGen/BranchFolding.cpp
U    lib/CodeGen/MachineBasicBlock.cpp
$ svn merge -c -91113 https://llvm.org/svn/llvm-project/llvm/trunk
--- Reverse-merging r91113 into '.':
G    lib/CodeGen/MachineBasicBlock.cpp
$ svn merge -c -91101 https://llvm.org/svn/llvm-project/llvm/trunk
--- Reverse-merging r91101 into '.':
U    include/llvm/CodeGen/MachineBasicBlock.h
G    lib/CodeGen/MachineBasicBlock.cpp
$ svn merge -c -91092 https://llvm.org/svn/llvm-project/llvm/trunk
--- Reverse-merging r91092 into '.':
G    include/llvm/CodeGen/MachineBasicBlock.h
G    lib/CodeGen/MachineBasicBlock.cpp

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91376 91177308-0d34-0410-b5e6-96231b3b80d8

nand atomic requires opposite operand ordering

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91371 91177308-0d34-0410-b5e6-96231b3b80d8

Fix integer cast code to handle vector types.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91362 91177308-0d34-0410-b5e6-96231b3b80d8

Move Flag and isVoid after the vector types, since bit arithmetic with
those enum values is less common.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91361 91177308-0d34-0410-b5e6-96231b3b80d8

Fix these asserts to check the invariant that the code actually
depends on.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91360 91177308-0d34-0410-b5e6-96231b3b80d8

Update this comment.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91356 91177308-0d34-0410-b5e6-96231b3b80d8

Fix this to properly clear the FastISel debug location. Thanks to
Bill for spotting this!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91355 91177308-0d34-0410-b5e6-96231b3b80d8

Rearrange rules to add missing dependency and allow parallel makes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91352 91177308-0d34-0410-b5e6-96231b3b80d8

Add encoding bits "let Inst{11-4} = 0b00000000;" to BR_JTr to disambiguate
between BR_JTr and STREXD.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91339 91177308-0d34-0410-b5e6-96231b3b80d8

The CIE says that the LSDA point in the FDE section is an "sdata4". That's fine,
but we need it to actually be 4-bytes in the FDE.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91337 91177308-0d34-0410-b5e6-96231b3b80d8

v6 sync insn copy/paste error

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91333 91177308-0d34-0410-b5e6-96231b3b80d8

Add ARMv6 memory and sync barrier instructions

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91329 91177308-0d34-0410-b5e6-96231b3b80d8

Fixed encoding bits typo of ldrexd/strexd.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91327 91177308-0d34-0410-b5e6-96231b3b80d8

Thumb2 atomic operations

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91321 91177308-0d34-0410-b5e6-96231b3b80d8

Add svn:ignore entries for the Disassembler files.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91320 91177308-0d34-0410-b5e6-96231b3b80d8

Move several function bodies which are rarely inlined out of line.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91319 91177308-0d34-0410-b5e6-96231b3b80d8

fix an obvious bug found by clang++ and collapse a redundant if.

Here's the diagnostic from clang:

/Volumes/Data/dgregor/Projects/llvm/lib/Target/CppBackend/CPPBackend.cpp:989:23: warning: 'gv' is always NULL in this context
        printConstant(gv);
                      ^
1 diagnostic generated.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91318 91177308-0d34-0410-b5e6-96231b3b80d8

Micro-optimize these functions in the case where they are not inlined.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91316 91177308-0d34-0410-b5e6-96231b3b80d8

correct selection requirements for thumb2 vs. arm versions of the barrier intrinsics

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91313 91177308-0d34-0410-b5e6-96231b3b80d8

Add radar fixed in comment.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91312 91177308-0d34-0410-b5e6-96231b3b80d8

add Thumb2 atomic and memory barrier instruction definitions

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91310 91177308-0d34-0410-b5e6-96231b3b80d8

whitespace

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91307 91177308-0d34-0410-b5e6-96231b3b80d8

ARM memory barrier instructions are not predicable

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91305 91177308-0d34-0410-b5e6-96231b3b80d8

NNT: Use [e]grep -a when scanning logs, its possibly they will have non-text
characters in them, in which case the grep will just return 'Binary file
matches' and the whole thing falls over.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91302 91177308-0d34-0410-b5e6-96231b3b80d8

NNT: Always create the -sentdata.txt file.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91301 91177308-0d34-0410-b5e6-96231b3b80d8

Clear the Processed set when it is no longer used, and clear the
IVUses list in releaseMemory().

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91296 91177308-0d34-0410-b5e6-96231b3b80d8

Fix a thinko; isNotAlreadyContainedIn had a built-in negative, so the
condition was inverted when the code was converted to contains().

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91295 91177308-0d34-0410-b5e6-96231b3b80d8

Remove unnecessary #includes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91293 91177308-0d34-0410-b5e6-96231b3b80d8

Make the IVUses member private.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91291 91177308-0d34-0410-b5e6-96231b3b80d8

Instead of having a ScalarEvolution pointer member in BasedUser, just pass
the ScalarEvolution pointer into the functions which need it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91289 91177308-0d34-0410-b5e6-96231b3b80d8

Don't bother cleaning up if there's nothing to clean up.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91288 91177308-0d34-0410-b5e6-96231b3b80d8

Delete an unused variable.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91287 91177308-0d34-0410-b5e6-96231b3b80d8

Drop Loop::isNotAlreadyContainedIn in favor of Loop::contains. The
former was just exposing a LoopInfoBase implementation detail.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91286 91177308-0d34-0410-b5e6-96231b3b80d8

add ldrexd/strexd instructions

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91284 91177308-0d34-0410-b5e6-96231b3b80d8

LSR itself doesn't need LoopInfo.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91283 91177308-0d34-0410-b5e6-96231b3b80d8

LSR itself doesn't need DominatorTree.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91282 91177308-0d34-0410-b5e6-96231b3b80d8

Remove the code in LSR that manually hoists expansions out of loops;
SCEVExpander does this automatically.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91281 91177308-0d34-0410-b5e6-96231b3b80d8

Minor code cleanups.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91280 91177308-0d34-0410-b5e6-96231b3b80d8

Use DW_AT_specification to point to DIE describing function declaration.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91278 91177308-0d34-0410-b5e6-96231b3b80d8

Remove empty file completely

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91277 91177308-0d34-0410-b5e6-96231b3b80d8

Add "generic" fallback.

gcc warned that the function may not have a return value, indeed
for non-intel and non-amd X86 CPUs it is right (VIA, etc.).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91276 91177308-0d34-0410-b5e6-96231b3b80d8

Added CalcSpillWeights to CMakeLists.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91275 91177308-0d34-0410-b5e6-96231b3b80d8

Whitespace changes, comment clarification. No functional changes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91274 91177308-0d34-0410-b5e6-96231b3b80d8

Moved spill weight calculation out of SimpleRegisterCoalescing and into its own pass: CalculateSpillWeights.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91273 91177308-0d34-0410-b5e6-96231b3b80d8

revert r91184, because it causes a crash on a .bc file I just
sent to Bob.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91268 91177308-0d34-0410-b5e6-96231b3b80d8

atomic binary operations up to 32-bits wide.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91260 91177308-0d34-0410-b5e6-96231b3b80d8

Add a test for the 'init' option property.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91259 91177308-0d34-0410-b5e6-96231b3b80d8

Reinstate r91208 to fix available_externally linkage for globals, with
nlewycky's fix to add -rdynamic so the JIT can look symbols up in Linux builds
of the JITTests binary.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91250 91177308-0d34-0410-b5e6-96231b3b80d8

Using _MSC_VER there was wrong, better just use the already existing ifdefs for
x86 CPU detection for the X86 getHostCPUName too, and create a simple
getHostCPUName that returns "generic" for all else.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91240 91177308-0d34-0410-b5e6-96231b3b80d8

Don't leave pointers uninitialized in the default constructor. GCC complains
about the potential use of these uninitialized members under certain conditions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91239 91177308-0d34-0410-b5e6-96231b3b80d8

Fix weird typo which leads to unallocated memory access for nodes with 4 results.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91233 91177308-0d34-0410-b5e6-96231b3b80d8

Do not allow uninitialize access during debug printing

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91232 91177308-0d34-0410-b5e6-96231b3b80d8

More info on this transformation.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91230 91177308-0d34-0410-b5e6-96231b3b80d8

Remove some stuff that's already implemented.  Also, remove the note about
merging x >u 5 and x <s 20 because it's impossible to implement.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91228 91177308-0d34-0410-b5e6-96231b3b80d8

Update install-clang target for clang-cc removal.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91226 91177308-0d34-0410-b5e6-96231b3b80d8

Disable r91104 for x86. It causes partial register stall which pessimize code in 32-bit.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91223 91177308-0d34-0410-b5e6-96231b3b80d8

Implement variable-width shifts.
No testcase yet - it seems we're exposing generic codegen bugs.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91221 91177308-0d34-0410-b5e6-96231b3b80d8

Add comment about potential partial register stall.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91220 91177308-0d34-0410-b5e6-96231b3b80d8

Fix an obvious bug. No test case since LEA16r is not being used.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91219 91177308-0d34-0410-b5e6-96231b3b80d8

Enable CPU detection when using MS VS 2k8 too.
MSVS2k8 doesn't define __i386__, hence all the CPU detection code was disabled.
Enable it by looking for _MSC_VER.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91217 91177308-0d34-0410-b5e6-96231b3b80d8

Fix some CHECK lines which were ignored by accident.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91214 91177308-0d34-0410-b5e6-96231b3b80d8

Revert r91208.  Something on Linux prevents the JIT from looking up a symbol
defined in the test, and I don't have time tonight to figure it out.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91209 91177308-0d34-0410-b5e6-96231b3b80d8

Fix available_externally linkage for globals.  It's probably still not
supported by emitGlobals, but I don't have a test case for that.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91208 91177308-0d34-0410-b5e6-96231b3b80d8

Make it easier to use the llvm_unreachable and DEBUG macros without "using
namespace llvm" by qualifying their implementations with ::llvm::.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91206 91177308-0d34-0410-b5e6-96231b3b80d8

Framework for atomic binary operations. The emitter for the pseudo instructions
just issues an error for the moment. The front end won't yet generate these
intrinsics for ARM, so this is behind the scenes until complete.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91200 91177308-0d34-0410-b5e6-96231b3b80d8

Revise scalar replacement to be more flexible about handle bitcasts and GEPs.
While scanning through the uses of an alloca, keep track of the current offset
relative to the start of the alloca, and check memory references to see if
the offset & size correspond to a component within the alloca.  This has the
nice benefit of unifying much of the code from isSafeUseOfAllocation,
isSafeElementUse, and isSafeUseOfBitCastedAllocation.  The code to rewrite
the uses of a promoted alloca, after it is determined to be safe, is
reorganized in the same way.

Also, when rewriting GEP instructions, mark them as "in-bounds" since all the
indices are known to be safe.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91184 91177308-0d34-0410-b5e6-96231b3b80d8

Delete an unnecessary line. The VTSDNode on a SIGN_EXTEND_REG is never
a vector type.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91181 91177308-0d34-0410-b5e6-96231b3b80d8

Lower setcc branchless, if this is profitable.
Based on the patch by Brian Lucas!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91175 91177308-0d34-0410-b5e6-96231b3b80d8

Don't try to move a MBB into the fall-through position if it's a landing pad or
branches only to a landing pad. Without this check, the compiler would go into
an infinite loop because the branch to a landing pad is an "abnormal" edge which
wasn't being taken into account.

This is the meat of that fix:

  if (!PrevBB.canFallThrough() && !MBB->BranchesToLandingPad(MBB)) {

The other stuff is simplification of the "branches to a landing pad" code.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91161 91177308-0d34-0410-b5e6-96231b3b80d8

Construct CompileUnits lazily.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91159 91177308-0d34-0410-b5e6-96231b3b80d8

Implement vector widening, splitting, and scalarizing for SIGN_EXTEND_INREG.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91158 91177308-0d34-0410-b5e6-96231b3b80d8

memory barrier instructions by definition have side effects. This prevents the post-RA scheduler from moving them around.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91150 91177308-0d34-0410-b5e6-96231b3b80d8

Change this to the correct PR number.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91148 91177308-0d34-0410-b5e6-96231b3b80d8

Make getUniqueExitBlocks's precondition assert more precise, to
avoid spurious failures. This fixes PR5758.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91147 91177308-0d34-0410-b5e6-96231b3b80d8

Fix the result type of SELECT nodes lowered from Select instructions with
aggregate return values. This fixes PR5754.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91145 91177308-0d34-0410-b5e6-96231b3b80d8

Honour setHasCalls() set from isel.
This is used in some weird cases like general dynamic TLS model.
This fixes PR5723

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91144 91177308-0d34-0410-b5e6-96231b3b80d8

Store Register Exclusive should leave the source register Inst{3-0} unspecified.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91143 91177308-0d34-0410-b5e6-96231b3b80d8

Update properties.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91140 91177308-0d34-0410-b5e6-96231b3b80d8

Simplify this class by removing the result cache.

This change removes the DefaultConstructible
and CopyAssignable constraints on the template
parameter T (the first one).

The second template parameter (R) is defaulted to be
identical to the first and controls the result type.
By specifying it to be (const T&) additionally the
CopyConstructible constraint on T can be removed.

This allows to use StringSwitch e.g. for llvm::Constant
instances.

Regarding the other review feedback regarding performance
because of taking pointers, this class should be completely
optimizable like before, since all methods are inline and
the pointer dereferencing and result value caching should be
possible behind the scenes by the "as-if" rule.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91123 91177308-0d34-0410-b5e6-96231b3b80d8

Revert part of r91101 which was causing an infinite loop in the self-hosting
build bots.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91113 91177308-0d34-0410-b5e6-96231b3b80d8

Add utility method for determining whether a function argument
has the 'nest' attribute.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91109 91177308-0d34-0410-b5e6-96231b3b80d8

Tests for 91103 and 91104.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91105 91177308-0d34-0410-b5e6-96231b3b80d8

Add support to 3-addressify 16-bit instructions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91104 91177308-0d34-0410-b5e6-96231b3b80d8

Coalesce insert_subreg undef, x first to avoid phase ordering issue.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91103 91177308-0d34-0410-b5e6-96231b3b80d8

Address comments on last patch:

- Loosen the restrictions when checking of it branches to a landing pad.
- Make the loop more efficient by checking the '.insert' return value.
- Do cheaper checks first.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91101 91177308-0d34-0410-b5e6-96231b3b80d8

A machine basic block may end in an unconditional branch, however it may have
more than one successor. Normally, these extra successors are dead. However,
some of them may branch to exception handling landing pads. If we remove those
successors, then the landing pads could go away if all predecessors to it are
removed. Before, it was checking if the direct successor was the landing
pad. But it could be the result of jumping through multiple basic blocks to get
to it. If we were to only check for the existence of an EH_LABEL in the basic
block and not remove successors if it's in there, then it could stop actually
dead basic blocks from being removed.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91092 91177308-0d34-0410-b5e6-96231b3b80d8

Rough first pass at compare_and_swap atomic builtins for ARM mode. Work in progress.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91090 91177308-0d34-0410-b5e6-96231b3b80d8

Add qualifiers for calls to member functions in dependent bases.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91087 91177308-0d34-0410-b5e6-96231b3b80d8

If VariableDIe is not created (may be because global was optimzed away) then do not try to use the variable die.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91077 91177308-0d34-0410-b5e6-96231b3b80d8

Add a test for the fix in revision 91009.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91062 91177308-0d34-0410-b5e6-96231b3b80d8

It's not safe to coalesce a move where src and dst registers have different subregister indices. e.g.:
%reg16404:1<def> = MOV8rr %reg16412:2<kill>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91061 91177308-0d34-0410-b5e6-96231b3b80d8

Remove a broken, unused header

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91058 91177308-0d34-0410-b5e6-96231b3b80d8

Refactor code that finds context for a given die.
Create global variable DIEs after creating subprogram DIEs. This allows function level static variable's to find their context at the time of DIE creation.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91055 91177308-0d34-0410-b5e6-96231b3b80d8

Add instruction encoding for DMB/DSB

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91053 91177308-0d34-0410-b5e6-96231b3b80d8

Refactor.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91051 91177308-0d34-0410-b5e6-96231b3b80d8

Also attempt trivial coalescing for live intervals that end in a copy.

The coalescer is supposed to clean these up, but when setting up parameters
for a function call, there may be copies to physregs. If the defining
instruction has been LICM'ed far away, the coalescer won't touch it.

The register allocation hint does not always work - when the register
allocator is backtracking, it clears the hints.

This patch is more conservative than r90502, and does not break
483.xalancbmk/i686. It still breaks the PowerPC bootstrap, so it is disabled
by default, and can be enabled with the -trivial-coalesce-ends option.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91049 91177308-0d34-0410-b5e6-96231b3b80d8

Comparing std::string with NULL is a bad idea, so just check whether its empty.

This code was crashing always with oprofile enabled, since it tried to create a StringRef
out of NULL, which run strlen on NULL.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91046 91177308-0d34-0410-b5e6-96231b3b80d8