'bsf' instructions here.
This one is actually debatable to my eyes. It's not clear that any chip
implementing 'tzcnt' would have a slow 'bsf' for any reason, and unless
EFLAGS or a zero input matters, 'tzcnt' is just a longer encoding.
Still, this restores the old behavior with 'tzcnt' enabled for now.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147246 91177308-0d34-0410-b5e6-96231b3b80d8
X86ISelLowering C++ code. Because this is lowered via an xor wrapped
around a bsr, we want the dagcombine which runs after isel lowering to
have a chance to clean things up. In particular, it is very common to
see code which looks like:
(sizeof(x)*8 - 1) ^ __builtin_clz(x)
Which is trying to compute the most significant bit of 'x'. That's
actually the value computed directly by the 'bsr' instruction, but if we
match it too late, we'll get completely redundant xor instructions.
The more naive code for the above (subtracting rather than using an xor)
still isn't handled correctly due to the dagcombine getting confused.
Also, while here fix an issue spotted by inspection: we should have been
expanding the zero-undef variants to the normal variants when there is
an 'lzcnt' instruction. Do so, and test for this. We don't want to
generate unnecessary 'bsr' instructions.
These two changes fix some regressions in encoding and decoding
benchmarks. However, there is still a *lot* to be improve on in this
type of code.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147244 91177308-0d34-0410-b5e6-96231b3b80d8
ARM targets with NEON units have access to aligned vector loads and
stores that are potentially faster than unaligned operations.
Add support for spilling the callee-saved NEON registers to an aligned
stack area using 16-byte aligned NEON loads and store.
This feature is off by default, controlled by an -align-neon-spills
command line option.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147211 91177308-0d34-0410-b5e6-96231b3b80d8
My change r146949 added register clobbers to the eh_sjlj_dispatchsetup pseudo
instruction, but on Thumb1 some of those registers cannot be used. This
caused massive failures on the testsuite when compiling for Thumb1. While
fixing that, I noticed that the eh_sjlj_setjmp instruction has a "nofp"
variant, and I realized that dispatchsetup needs the same thing, so I have
added that as well.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147204 91177308-0d34-0410-b5e6-96231b3b80d8
tblgen has been renamed to llvm-tblgen so this command has been failing,
and it's no longer needed because llvm-tblgen is already installed by default.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147187 91177308-0d34-0410-b5e6-96231b3b80d8
This was disabled years ago because of a bug in GCC 4.1, which is
on our "broken compilers" list for other reasons. Saving ~500k
on a clang binary (Release+Asserts) is well worth dropping support
for it.
We currently disable it for shared libraries (where it would bring
the biggest win) because clang is broken (PR11642).
IMPORTANT: If you're doing incremental builds you may get tons of
linker warnings. make clean will fix them.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147182 91177308-0d34-0410-b5e6-96231b3b80d8
time regressions. In general, it is beneficial to compile-time.
Original commit message:
Fix for bug #11429: Wrong behaviour for switches. Small improvement for code
size heuristics.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147175 91177308-0d34-0410-b5e6-96231b3b80d8
The value from the operands isn't right yet, but we weren't encoding it at
all previously. The parser needs to twiddle the values when building the
instruction.
Partial for: rdar://10558523
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147170 91177308-0d34-0410-b5e6-96231b3b80d8
probability wouldn't be considered "hot" in some weird loop structures
or other compounding probability patterns. This makes it much harder to
confuse, but isn't really a principled fix. I'd actually like it if we
could model a zero probability, as it would make this much easier to
reason about. Suggestions for how to do this better are welcome.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147142 91177308-0d34-0410-b5e6-96231b3b80d8
