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
of ObjectiveC properties to mean annotation of
NS_RETURNS_INNER_POINTER on its synthesized getter.
This also facilitates more migration to properties when
methods are annotated with NS_RETURNS_INNER_POINTER.
// rdar://14990439
llvm-svn: 191009
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
Targets and hosts today are little-endian (arm, x86), so this change
should be a no-op as they will not encounter the byte swapping cases.
Byte swapping will happen when cross debugging of big endian-targets
(e.g. MIPS, PPC) on a little-endian host (x86). Register- or word-
sized data copies need to be swapped, but calls to ExtractBytes or
CopyByteOrderedData that would invoke the swapping case are presumably
in error.
llvm-svn: 191005
Intrinsics added shaintrin.h, which is included from x86intrin.h if __SHA__ is
enabled. SHA implies SSE2, which is needed for the __m128i type.
Also add the -msha/-mno-sha option.
llvm-svn: 190999
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
We don't really need to perform semantic analysis on the dependent expression
anyway, so just call the cast dependent.
<rdar://problem/15012610>
llvm-svn: 190981
Before this patch, Lex() would recurse whenever the current lexer changed (e.g.
upon entry into a macro). This patch turns the recursion into a loop: the
various lex routines now don't return a token when the current lexer changes,
and at the top level Preprocessor::Lex() now loops until it finds a token.
Normally, the recursion wouldn't end up being very deep, but the recursion depth
can explode in edge cases like a bunch of consecutive macros which expand to
nothing (like in the testcase test/Preprocessor/macro_expand_empty.c in this
patch).
<rdar://problem/14569770>
llvm-svn: 190980
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
This patch adds the following, more specific warning flags:
gnu-anonymous-struct
gnu-compound-literal-initializer
gnu-empty-struct
gnu-flexible-array-initializer
gnu-flexible-array-union-member
gnu-folding-constant
redeclared-class-member
gnu-redeclared-enum
gnu-union-cast
gnu-variable-sized-type-not-at-end
Patch by Peter Lewis.
llvm-svn: 190972
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
I put in the warnings because MSVC has them, but I don't think they're very
useful.
Clang does not warn about overriding flags in general, e.g. it's perfectly
fine to have -fomit-frame-pointer followed by -fno-omit-frame-pointer.
We should focus on warning where things get confusing, such as with the
/TP and /TC options. In "clang-cl /TC a.c /TP b.cc", the user might not
realize that the /TP flag will apply to both files, and we warn about that.
Differential Revision: http://llvm-reviews.chandlerc.com/D1718
llvm-svn: 190964
David Blaikie