The motivation for filling out these select-of-constants cases goes back to D24480,
where we discussed removing an IR fold from add(zext) --> select. And that goes back to:
https://reviews.llvm.org/rL75531https://reviews.llvm.org/rL159230
The idea is that we should always canonicalize patterns like this to a select-of-constants
in IR because that's the smallest IR and the best for value tracking. Note that we currently
do the opposite in some cases (like the cases in *this* patch). Ie, the proposed folds in
this patch already exist in InstCombine today:
https://github.com/llvm-mirror/llvm/blob/master/lib/Transforms/InstCombine/InstCombineSelect.cpp#L1151
As this patch shows, most targets generate better machine code for simple ext/add/not ops
rather than a select of constants. So the follow-up steps to make this less of a patchwork
of special-case folds and missing IR canonicalization:
1. Have DAGCombiner convert any select of constants into ext/add/not ops.
2 Have InstCombine canonicalize in the other direction (create more selects).
Differential Revision: https://reviews.llvm.org/D30180
llvm-svn: 296137
This time with the missing files.
Similar to PR/25526, fast-regalloc introduces spills at the end of basic
blocks. When this occurs in between an ll and sc, the store can cause the
atomic sequence to fail.
This patch fixes the issue by introducing more pseudos to represent atomic
operations and moving their lowering to after the expansion of postRA
pseudos.
This resolves PR/32020.
Thanks to James Cowgill for reporting the issue!
Reviewers: slthakur
Differential Revision: https://reviews.llvm.org/D30257
llvm-svn: 296134
Similar to PR/25526, fast-regalloc introduces spills at the end of basic
blocks. When this occurs in between an ll and sc, the store can cause the
atomic sequence to fail.
This patch fixes the issue by introducing more pseudos to represent atomic
operations and moving their lowering to after the expansion of postRA
pseudos.
This resolves PR/32020.
Thanks to James Cowgill for reporting the issue!
Reviewers: slthakur
Differential Revision: https://reviews.llvm.org/D30257
llvm-svn: 296132
Summary:
This isn't testable for AArch64 by itself so this patch also adds
support for constant immediates in the pattern and physical
register uses in the result.
The new IntOperandMatcher matches the constant in patterns such as
'(set $rd:GPR32, (G_XOR $rs:GPR32, -1))'. It's always safe to fold
immediates into an instruction so this is the first rule that will match
across multiple BB's.
The Renderer hierarchy is responsible for adding operands to the result
instruction. Renderers can copy operands (CopyRenderer) or add physical
registers (in particular %wzr and %xzr) to the result instruction
in any order (OperandMatchers now import the operand names from
SelectionDAG to allow renderers to access any operand). This allows us to
emit the result instruction for:
%1 = G_XOR %0, -1 --> %1 = ORNWrr %wzr, %0
%1 = G_XOR -1, %0 --> %1 = ORNWrr %wzr, %0
although the latter is untested since the matcher/importer has not been
taught about commutativity yet.
Added BuildMIAction which can build new instructions and mutate them where
possible. W.r.t the mutation aspect, MatchActions are now told the name of
an instruction they can recycle and BuildMIAction will emit mutation code
when the renderers are appropriate. They are appropriate when all operands
are rendered using CopyRenderer and the indices are the same as the matcher.
This currently assumes that all operands have at least one matcher.
Finally, this change also fixes a crash in
AArch64InstructionSelector::select() caused by an immediate operand
passing isImm() rather than isCImm(). This was uncovered by the other
changes and was detected by existing tests.
Depends on D29711
Reviewers: t.p.northover, ab, qcolombet, rovka, aditya_nandakumar, javed.absar
Reviewed By: rovka
Subscribers: aemerson, dberris, kristof.beyls, llvm-commits
Differential Revision: https://reviews.llvm.org/D29712
llvm-svn: 296131
Noticed while profiling PR32037, the target shuffle ops were being stored in SmallVector<*,8> types but the combiner could store as many as 16 ops at maximum depth (2 per depth).
llvm-svn: 296130
This one seems more obvious than D30270 that it can't make improvements because an extension always needs
all of the incoming bits. There's one specific transform in SimplifyDemandedInstructionBits of converting
a sext to a zext when the sign-bit is known zero, but that is handled explicitly in visitSext() with
ComputeSignBit().
Like D30270, there are no IR differences (other than instruction names) for the case in PR32037:
https://bugs.llvm.org//show_bug.cgi?id=32037
...and no regression test differences.
Zext/sext are a smaller part of the profile, but this still appears to shave off another 0.5% or so from
'opt -O2'.
Differential Revision: https://reviews.llvm.org/D30280
llvm-svn: 296129
The 'Kind' member used in RTTI for InstructionPredicateMatcher was not
initialized but went undetected since I always ended up with the correct value.
llvm-svn: 296126
Previously LLVM was assuming 32-bit signed immediates which results in and with
a bitmask that has bit 31 set to incorrectly include bits 63-32 in the result.
After applying this patch I can now compile all of the FreeBSD mips assembly
code with clang.
This issue also affects the nor, slt and sltu macros and I will fix those in a
separate review.
Patch By: Alexander Richardson
Commit message reformatted by sdardis.
Reviewers: atanasyan, theraven, sdardis
Differential Revision: https://reviews.llvm.org/D30298
llvm-svn: 296125
Summary:
This makes more important rules have priority over less important rules.
For example, '%a = G_ADD $b:s64, $c:s64' has priority over
'%a = G_ADD $b:s32, $c:s32'. Previously these rules were emitted in the
correct order by chance.
NFC in this patch but it is required to make the next patch work correctly.
Depends on D29710
Reviewers: t.p.northover, ab, qcolombet, aditya_nandakumar, rovka
Reviewed By: ab, rovka
Subscribers: javed.absar, dberris, llvm-commits, kristof.beyls
Differential Revision: https://reviews.llvm.org/D29711
llvm-svn: 296121
Make the MIPS disassembler consistent with the other targets in returning
a Size of zero when the input buffer cannot contain an instruction due
to it's size. Previously it reported the minimum instruction size when
it failed due to the buffer not being big enough for an instruction
causing llvm-objdump to crash when disassembling all sections.
Reviewers: slthakur
Differential Revision: https://reviews.llvm.org/D29984
llvm-svn: 296105
The current pattern for setting bits in range is typically:
Mask |= APInt::getBitsSet(MaskSizeInBits, LoPos, HiPos);
Which can be particularly slow for large APInts (MaskSizeInBits > 64) as they require the allocation memory for the temporary variable.
This is one of the key compile time issues identified in PR32037.
This patch adds the APInt::setBits() helper method which avoids the temporary memory allocation completely, this first implementation uses setBit() internally instead but already significantly reduces the regression in PR32037 (~10% drop). Additional optimization may be possible.
I investigated whether there is need for APInt::clearBits() and APInt::flipBits() equivalents but haven't seen these patterns to be particularly common, but reusing the code would be trivial.
Differential Revision: https://reviews.llvm.org/D30265
llvm-svn: 296102
The Fuchsia ABI defines slots from the thread pointer where the
stack-guard value for stack-protector, and the unsafe stack pointer
for safe-stack, are stored. This parallels the Android ABI support.
Patch by Roland McGrath
Differential Revision: https://reviews.llvm.org/D30237
llvm-svn: 296081
clang will generate IR like this for input using packed bitfields;
very simple semantically, but it's a bit tricky to actually
generate good code.
llvm-svn: 296080
LoopUnswitch/simplify-with-nonvalness.ll is the test case for this.
The LIC has 2 users and deleting the 1st user when it can be simplified
invalidated the iterator for the 2nd user.
llvm-svn: 296069
Splitting critical edges when one of the source edges is an indirectbr
is hard in general (because it requires changing the memory the indirectbr
reads). But if a block only has a single indirectbr predecessor (which is
the common case), we can simulate splitting that edge by splitting
the destination block, and retargeting the *direct* branches.
This is motivated by the use of computed gotos in python 2.7: PyEval_EvalFrame()
ends up using an indirect branch with ~100 successors, and passing a constant to
each of those. Since MachineSink can't break indirect critical edges on demand
(and doing this in MIR doesn't look feasible), this causes us to emit about ~100
defs of registers containing constants, which we in the predecessor block, where
only one of those constants is used in each successor. So, at each computed goto,
we needlessly spill about a 100 constants to stack. The end result is that a
clang-compiled python interpreter can be about ~2.5x slower on a simple python
reduction loop than a gcc-compiled interpreter.
Differential Revision: https://reviews.llvm.org/D29916
llvm-svn: 296060
This allows the ability to call IPDBSession::getGlobalScope with a NativeSession and
to then query it for some basic fields from the PDB's InfoStream.
Note that the symbols now have non-const references back to the Session so that
NativeRawSymbol can access the PDBFile through the Session.
Differential Revision: https://reviews.llvm.org/D30314
llvm-svn: 296049
We were stopping the translation of the parent block when the
translation of an instruction failed, but we were still trying to
translate the other blocks of the parent function.
Don't do that.
llvm-svn: 296047
