This is how it ignores the dead code:
1) When a dead branch target, say block B, is identified, all the
    blocks dominated by B is dead as well.

2) The PHIs of those blocks in dominance-frontier(B) is updated such
   that the operands corresponding to dead predecessors are replaced
   by "UndefVal".

   Using lattice's jargon, the "UndefVal" is the "Top" in essence.
   Phi node like this "phi(v1 bb1, undef xx)" will be optimized into
   "v1" if v1 is constant, or v1 is an instruction which dominate this
   PHI node.

3) When analyzing the availability of a load L, all dead mem-ops which
   L depends on disguise as a load which evaluate exactly same value as L.

4) The dead mem-ops will be materialized as "UndefVal" during code motion.

llvm-svn: 191017

Various Windows SDK headers use _MSC_VER values to figure out what
version of the VC++ headers they're using, in particular for SAL macros.

Patch by Paul Hampson!

llvm-svn: 191015

  As its name suggests, this function will return all basic blocks
dominated by a given block.

llvm-svn: 191014

Patch by Paul Hampson!

llvm-svn: 191010

Adds a flag to the MemorySanitizer pass that enables runtime rewriting of
indirect calls. This is part of MSanDR implementation and is needed to return
control to the DynamiRio-based helper tool on transition between instrumented
and non-instrumented modules. Disabled by default.

llvm-svn: 191006

DAGCombiner: Don't fold vector muls with constants that look like a splat of a power of 2 but differ in bit width.

PR17283.

llvm-svn: 191000

llvm-svn: 190998

llvm-svn: 190997

llvm-svn: 190996

When selecting the DAG (add (WrapperRIP ...), (FrameIndex ...)), X86 code had
spotted the FrameIndex possibility and was working out whether it could fold
the WrapperRIP into this.

The test for forming a %rip version is notionally whether we already have a
base or index register (%rip precludes both), but we were forgetting to account
for the register that would be inserted later to access the frame.

rdar://problem/15024520

llvm-svn: 190995

Working on a better solution to this.

This reverts commit 7d4e9934e7ca83094c5cf41346966c8350179ff2.

llvm-svn: 190990

This puts all the global PassManager debugging flags, like
-print-after-all and -time-passes, behind a managed static. This
eliminates their static initializers and, more importantly, exit-time
destructors.

The only behavioral change I anticipate is that tools need to
initialize the PassManager before parsing the command line in order to
export these options, which makes sense. Tools that already initialize
the standard passes (opt/llc) don't need to do anything new.

llvm-svn: 190974

llvm-svn: 190973

1) make sure that the first two instructions of the sequence cannot
separate from each other. The linker requires that they be sequential.
If they get separated, it can still work but it will not work in all
cases because the first of the instructions mostly involves the hi part
of the pc relative offset and that part changes slowly. You would have
to be at the right boundary for this to matter.
2) make sure that this sequence begins  on a longword boundary. 
There appears to be a bug in binutils which makes some of these calculations
get messed up if the instruction sequence does not begin on a longword
boundary. This is being investigated with the appropriate binutils folks.

llvm-svn: 190966

Use the DIVariable::isIndirect() flag set by the frontend instead of
guessing whether to set the machine location's indirection bit.
Paired commit with CFE.

llvm-svn: 190961

-march=x86 to SLM test.

llvm-svn: 190958

Atom Silvermont.

Patch by Sriram Murali.

llvm-svn: 190957

advertised - but it does have the caveat that calls to DynamicLibrary::AddSymbol will 
"reset" if you shutdown llvm and try to come back for seconds.  This is a subtle 
behavior change, but I'm assuming that nobody is affected by it.

llvm-svn: 190946

-Wunused-private-field with Clang.

llvm-svn: 190941

llvm-svn: 190940

[asan] call __asan_stack_malloc_N only if use-after-return detection is enabled with the run-time option

llvm-svn: 190939

A couple of tests, in llvm/test/Transforms/*/xcore, are XCore-specific. They should be excluded when XCore is not built.

llvm-svn: 190938

llvm-svn: 190937

XCore target: Add XCoreTargetTransformInfo
This is where getNumberOfRegisters() resides, which in turn returns the
number of vector registers (=0).

llvm-svn: 190936

llvm-svn: 190934

For some reason I never got around to adding these at the same time as
the signed versions.  No idea why.

I'm not sure whether this SystemZII::BranchC* stuff is useful, or whether
it should just be replaced with an "is normal" flag.  I'll leave that
for later though.

There are some boundary conditions that can be tweaked, such as preferring
unsigned comparisons for equality with [128, 256), and "<= 255" over "< 256",
but again I'll leave those for a separate patch.

llvm-svn: 190930

llvm-svn: 190929

Patch by Bradley Smith!

llvm-svn: 190928

I'll roll it back in when I have a chance to look at it in detail.

llvm-svn: 190923

advertised - but it does have the caveat that calls to DynamicLibrary::AddSymbol will 
"reset" if you shutdown llvm and try to come back for seconds.  This is a subtle 
behavior change, but I'm assuming that nobody is affected by it.

llvm-svn: 190921

Prevent extra calls to ToggleFeature for Feature64Bit and FeatureCMOV if they've already been enabled. The extra call ends up clearing the bit in FeatureBits since its a 'toggle'. Can't prove that anything was broken because of this since I don't think the FeatureBits for these are used.

llvm-svn: 190920

Fix X86 subtarget to not overwrite the autodetected features by calling InitMCProcessorInfo right after detecting them. Instead add a new function that only updates the scheduling model and call that.

llvm-svn: 190919

llvm-svn: 190917

llvm-svn: 190916

llvm-svn: 190905

If address space 0 was smaller than the address space
in a constant inttoptr/ptrtoint pair, the wrong mask size
would be used.

llvm-svn: 190899

Summary:
We indicate that the object files are safe by emitting a @feat.00
absolute address symbol.  The address is presumably interpreted as a
bitfield of features that the compiler would like to enable.  Bit 0 is
documented in the PE COFF spec to opt in to "registered SEH", which is
what /safeseh enables.

LLVM's object files are safe by default because LLVM doesn't know how to
produce SEH handlers.

Reviewers: Bigcheese

CC: llvm-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D1691

llvm-svn: 190898

llvm-svn: 190897

For now it happens the argument is always the same.

llvm-svn: 190896

llvm-svn: 190893