This combine is essentially combining target-specific nodes back into target
independent nodes that it "knows" will be combined yet again by a target
independent DAG combine into a different set of target-independent nodes that
are legal (not custom though!) and thus "ok". This seems... deeply flawed. The
crux of the problem is that we don't combine un-legalized shuffles that are
introduced by legalizing other operations, and thus we don't see a very
profitable combine opportunity. So the backend just forces the input to that
combine to re-appear.
However, for this to work, the conditions detected to re-form the unlegalized
nodes must be *exactly* right. Previously, failing this would have caused poor
code (if you're lucky) or a crasher when we failed to select instructions.
After r215611 we would fall back into the legalizer. In some cases, this just
"fixed" the crasher by produces bad code. But in the test case added it caused
the legalizer and the dag combiner to iterate forever.
The fix is to make the alignment checking in the x86 side of things match the
alignment checking in the generic DAG combine exactly. This isn't really a
satisfying or principled fix, but it at least make the code work as intended.
It also highlights that it would be nice to detect the availability of under
aligned loads for a given type rather than bailing on this optimization. I've
left a FIXME to document this.
Original commit message for r215611 which covers the rest of the chang:
[SDAG] Fix a case where we would iteratively legalize a node during
combining by replacing it with something else but not re-process the
node afterward to remove it.
In a truly remarkable stroke of bad luck, this would (in the test case
attached) end up getting some other node combined into it without ever
getting re-processed. By adding it back on to the worklist, in addition
to deleting the dead nodes more quickly we also ensure that if it
*stops* being dead for any reason it makes it back through the
legalizer. Without this, the test case will end up failing during
instruction selection due to an and node with a type we don't have an
instruction pattern for.
It took many million runs of the shuffle fuzz tester to find this.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216537 91177308-0d34-0410-b5e6-96231b3b80d8
We supported transforming:
(gep i8* X, -(ptrtoint Y))
to:
(inttoptr (sub (ptrtoint X), (ptrtoint Y)))
However, this only fired if 'X' had type i8*. Generalize this to
support various types of different sizes. This results in much better
CodeGen, especially for pointers to packed structs.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216523 91177308-0d34-0410-b5e6-96231b3b80d8
When a shift with extension or an add with shift and extension cannot be folded
into the memory operation, then the address calculation has to be materialized
separately. While doing so the code forgot to consider a possible sign-/zero-
extension. This fix folds now also the sign-/zero-extension into the add or
shift instruction which is used to materialize the address.
This fixes rdar://problem/18141718.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216511 91177308-0d34-0410-b5e6-96231b3b80d8
By taking a reference we can do the ownership transfer in one place instead of
expecting every caller to do it.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216492 91177308-0d34-0410-b5e6-96231b3b80d8
The attached patch simplifies a few interfaces that don't need to take
ownership of a buffer.
For example, both parseAssembly and parseBitcodeFile will parse the
entire buffer before returning. There is no need to take ownership.
Using a MemoryBufferRef makes it obvious in the type signature that
there is no ownership transfer.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216488 91177308-0d34-0410-b5e6-96231b3b80d8
Long term the idea if for the engine to not own the buffers, but for now
this is consistent with the rest of the API.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216484 91177308-0d34-0410-b5e6-96231b3b80d8
The existing matcher has lots of AT&T assembly dialect assumptions baked
into it. In particular, the hack for resolving the size of a memory
operand by appending the four most common suffixes doesn't work at all.
The Intel assembly dialect mnemonic table has ambiguous entries, so we
need to try matching multiple times with different operand sizes, since
that's the only way to choose different instruction variants.
This makes us more compatible with gas's implementation of Intel
assembly syntax. MSVC assumes you want byte-sized operations for the
instructions that we reject as ambiguous.
Reviewed By: grosbach
Differential Revision: http://reviews.llvm.org/D4747
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216481 91177308-0d34-0410-b5e6-96231b3b80d8
The memory management in BugPoint is fairly convoluted, so this just unwraps
one layer by changing the return type of functions that always return
owned Modules.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216464 91177308-0d34-0410-b5e6-96231b3b80d8
We had two functions for finding the temp or cache directory. Each had a
different set of smarts about OS specific APIs.
With this patch system_temp_directory becomes the only way to do it.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216460 91177308-0d34-0410-b5e6-96231b3b80d8
It seems on Darwin the illegal round-trip ::iterator -> MachineInstr* -> ::iterator breaks execution horribly when the iterator is not a real MachineInstr, like ::end().
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216455 91177308-0d34-0410-b5e6-96231b3b80d8
(X >> Z) & (Y >> Z) -> (X&Y) >> Z for all shifts.
(X >> Z) | (Y >> Z) -> (X|Y) >> Z for all shifts.
(X >> Z) ^ (Y >> Z) -> (X^Y) >> Z for all shifts.
These patterns were previously handled separately in visitAnd()/visitOr()/visitXor().
Differential Revision: http://reviews.llvm.org/D4951
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216443 91177308-0d34-0410-b5e6-96231b3b80d8
consider:
long long *f(long long *b, long long *e) {
return b + (e - b);
}
we would lower this to something like:
define i64* @f(i64* %b, i64* %e) {
%1 = ptrtoint i64* %e to i64
%2 = ptrtoint i64* %b to i64
%3 = sub i64 %1, %2
%4 = ashr exact i64 %3, 3
%5 = getelementptr inbounds i64* %b, i64 %4
ret i64* %5
}
This should fold away to just 'e'.
N.B. This adds m_SpecificInt as a convenient way to match against a
particular 64-bit integer when using LLVM's match interface.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216439 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
There is no functionality change here except in the way we assemble and
dump musttail calls in variadic functions. There's really no need to
separate out the bits for musttail and "is forwarding varargs" on call
instructions. A musttail call by definition has to forward the ellipsis
or it would fail verification.
Reviewers: chandlerc, nlewycky
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D4892
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216423 91177308-0d34-0410-b5e6-96231b3b80d8
Adding, removing, or changing non-pack parameters can change the ABI
classification of pack parameters. Clang and other frontends encode the
classification in the IR of the call site, but the callee side
determines it dynamically based on the number of registers consumed so
far. Changing the prototype affects the number of registers consumed
would break such code.
Dead argument elimination performs a similar task and already has a
similar check to avoid this problem.
Patch by Thomas Jablin!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216421 91177308-0d34-0410-b5e6-96231b3b80d8
The expressions 'Reloc.Addend - Addend' and 'Reloc.Offset' should always be
equal in this context. The latter is prefered - we want to remove the
RelocationValueRef::Addend field in the future.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216418 91177308-0d34-0410-b5e6-96231b3b80d8
This patch fixes a subtle bug in the UNIX implementation of
llvm::sys::argumentsFitWithinSystemLimits() regarding the misuse of a static
variable. This bug causes our cached number that stores the system command line
maximum length to be halved after each call to the function. With a sufficient
number of calls to this function, it will eventually report any given command
line string to be over system limits.
Patch by Rafael Auler.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216415 91177308-0d34-0410-b5e6-96231b3b80d8
This patch refactors the argument serialization logic used in the Execute
function, used to launch new Windows processes. There is a critical step that
joins char** arguments into a single string, building the command line used to
launch the new process, and the readability of this code is improved if this
part is refactored in its own helper function.
Patch by Rafael Auler!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216411 91177308-0d34-0410-b5e6-96231b3b80d8
Take a StringRef instead of a "const char *".
Take a "std::error_code &" instead of a "std::string &" for error.
A create static method would be even better, but this patch is already a bit too
big.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216393 91177308-0d34-0410-b5e6-96231b3b80d8
