This should really, really fix PR13916. For real this time. The
underlying bug is... a bit more subtle than I had imagined.
The setup is a code pattern that leads to an @llvm.memcpy call with two
equal pointers to an alloca in the source and dest. Now, not any pattern
will do. The alloca needs to be formed just so, and both pointers should
be wrapped in different bitcasts etc. When this precise pattern hits,
a funny sequence of events transpires. First, we correctly detect the
potential for overlap, and correctly optimize the memcpy. The first
time. However, we do simplify the set of users of the alloca, and that
causes us to run the alloca back through the SROA pass in case there are
knock-on simplifications. At this point, a curious thing has happened.
If we happen to have an i8 alloca, we have direct i8 pointer values. So
we don't bother creating a cast, we rewrite the arguments to the memcpy
to dircetly refer to the alloca.
Now, in an unrelated area of the pass, we have clever logic which
ensures that when visiting each User of a particular pointer derived
from an alloca, we only visit that User once, and directly inspect all
of its operands which refer to that particular pointer value. However,
the mechanism used to detect memcpy's with the potential to overlap
relied upon getting visited once per *Use*, not once per *User*. This is
always true *unless* the same exact value is both source and dest. It
turns out that almost nothing actually produces that pattern though.
We can hand craft test cases that more directly test this behavior of
course, and those are included. Also, note that there is a significant
missed optimization here -- we prove in many cases that there is
a non-volatile memcpy call with identical source and dest addresses. We
shouldn't prevent splitting the alloca in that case, and in fact we
should just remove such memcpy calls eagerly. I'll address that in
a subsequent commit.
llvm-svn: 164669
scalar-to-vector conversion that we cannot handle. For instance, when an invalid
constraint is used in an inline asm statement.
<rdar://problem/12284092>
llvm-svn: 164662
- Instead of embedding 'lock' into each mnemonic of atomic
instructions except 'xchg', we teach X86 assembly printer to output 'lock'
prefix similar to or consistent with code emitter.
llvm-svn: 164659
typeid (and a couple other non-standard places where we can transform an
unevaluated expression into an evaluated expression) is special
because it introduces an an expression evaluation context,
which conflicts with the mechanism to compute the current
lambda mangling context. PR12123.
I would appreciate if someone would double-check that we get the mangling
correct with this patch.
llvm-svn: 164658
scalar-to-vector conversion that we cannot handle. For instance, when an invalid
constraint is used in an inline asm statement.
<rdar://problem/12284092>
llvm-svn: 164657
enough information so we can mangle them correctly in cases involving
dependent parameter types. (This specifically impacts cases involving
null pointers and cases involving parameters of reference type.)
Fix the mangler to use this information instead of trying to scavenge
it out of the parameter declaration.
<rdar://problem/12296776>.
llvm-svn: 164656
The Apple buildbots are set up to pass --target to configure for both
cross- and non-cross-compile builds, and the standard autoconf response
to this is to set the program prefix to '<target>-'. Until we can figure
out the proper way to handle this (don't pass --target? pass an explicit
--program-prefix=""? don't auto-populate program_prefix with target_alias?)
it's more important to keep the buildbots running.
This reverts r164633 / ba48ceb1a3802e20e781ef04ea2573ffae2ac414.
llvm-svn: 164651
only a missed optimization opportunity if the store is over-aligned, but a
miscompile if the store's new type has a higher natural alignment than the
memcpy did. Fixes PR13920!
llvm-svn: 164641
This makes the behavior clearer concerning literals with the maximum
number of digits. For a 32-bit example, 4,000,000,000 is a valid uint32_t,
but 5,000,000,000 is not, so we'd have to count 10-digit decimal numbers
as "unsafe" (meaning we have to check for overflow when parsing them,
just as we would for numbers with 11 digits or higher). This is the same,
only with 64 bits to play with.
No functionality change.
llvm-svn: 164639
reason we were getting two of the same alloca is because of a memmove/memcpy
which had the same alloca in both the src and dest. Now we detect that case
directly. This has the same testcase as before, but fixes a clang test
CodeGenObjC/exceptions.m which runs clang -O2.
llvm-svn: 164636
Chandler, it's not obvious that it's okay that this alloca gets into the list
twice to begin with. Please review and see whether this is the fix you really
want, but I wanted to get a fix checked in quickly.
llvm-svn: 164634
Provide interface in TargetLowering to set or get the minimum number of basic
blocks whereby jump tables are generated for switch statements rather than an
if sequence.
getMinimumJumpTableEntries() defaults to 4.
setMinimumJumpTableEntries() allows target configuration.
This patch changes the default for the Hexagon architecture to 5
as it improves performance on some benchmarks.
llvm-svn: 164628
There are very few tests here because SValBuilder is fairly aggressive
about not building SymExprs that we can't evaluate, which saves memory
and CPU but also makes it very much tied to the current constraint
manager. We should probably scale back here and let things decay to
UnknownVal later on.
bitwise-ops.c tests that for the SymExprs we do create, we persist our
assumptions about them. traversal-path-unification.c tests that we do
clean out constraints on arbitrary SymExprs once they have actually died.
llvm-svn: 164623
Previously, we'd just keep constraints around forever, which means we'd
never be able to merge paths that differed only in constraints on dead
symbols.
Because we now allow constraints on symbolic expressions, not just single
symbols, this requires changing SymExpr::symbol_iterator to include
intermediate symbol nodes in its traversal, not just the SymbolData leaf
nodes.
This depends on the previous commit to be correct. Originally applied in
r163444, reverted in r164275, now being re-applied.
llvm-svn: 164622
No tests, but this allows the optimization of removing dead constraints.
We can then add tests that we don't do this prematurely.
<rdar://problem/12333297>
Note: the added FIXME to investigate SymbolRegionValue liveness is
tracked by <rdar://problem/12368183>. This patch does not change the
existing behavior.
llvm-svn: 164621
top-level frameworks can actually be symlinked over to embedded
frameworks, and accessed via the top-level framework's headers. In
this case, we need to determine that the framework was *actually* an
embedded framework, so we can load the appropriate top-level module.
llvm-svn: 164620
of this is derived from the Mach-O writer. Reviewed by: Nick Kledzik.
* Adds loop to SectionChunk::write traverse references calling the
writer's fixup handler, applyFixup.
* Adds method, ELFWriter::buildAtomToAddressMap to that creates a
mapping from an atom to its runtime address.
* Adds method, ELFWriter::addressOfAtom to return the runtime address
of the atom.
llvm-svn: 164618
Michael Liao