Summary:
Also, made a few minor tweaks to shave off a little more cumulative memory consumption:
* All rules share a single NewMIs instead of constructing their own. Only one
will end up using it.
* Use MIs.resize(1) instead of MIs.clear();MIs.push_back(I) and prevent
GIM_RecordInsn from changing MIs[0].
Depends on D33764
Reviewers: rovka, vitalybuka, ab, t.p.northover, qcolombet, aditya_nandakumar
Reviewed By: ab
Subscribers: kristof.beyls, igorb, llvm-commits
Differential Revision: https://reviews.llvm.org/D33766
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@307159 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This further improves the compile-time regressions that will be caused by a
re-commit of r303259.
Also added included preliminary work in preparation for the multi-insn emitter
since I needed to change the relevant part of the API for this patch anyway.
Depends on D33758
Reviewers: rovka, vitalybuka, ab, t.p.northover, qcolombet, aditya_nandakumar
Reviewed By: ab
Subscribers: kristof.beyls, igorb, llvm-commits
Differential Revision: https://reviews.llvm.org/D33764
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@307133 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Replace the matcher if-statements for each rule with a state-machine. This
significantly reduces compile time, memory allocations, and cumulative memory
allocation when compiling AArch64InstructionSelector.cpp.o after r303259 is
recommitted.
The following patches will expand on this further to fully fix the regressions.
Reviewers: rovka, ab, t.p.northover, qcolombet, aditya_nandakumar
Reviewed By: ab
Subscribers: vitalybuka, aemerson, javed.absar, igorb, llvm-commits, kristof.beyls
Differential Revision: https://reviews.llvm.org/D33758
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@307079 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
As part of this
* Emitted instructions now have named MachineInstr variables associated
with them. This isn't particularly important yet but it's a small step
towards multiple-insn emission.
* constrainSelectedInstRegOperands() is no longer hardcoded. It's now added
as the ConstrainOperandsToDefinitionAction() action. COPY_TO_REGCLASS uses
an alternate constraint mechanism ConstrainOperandToRegClassAction() which
supports arbitrary constraints such as that defined by COPY_TO_REGCLASS.
Reviewers: ab, qcolombet, t.p.northover, rovka, kristof.beyls, aditya_nandakumar
Reviewed By: ab
Subscribers: javed.absar, igorb, llvm-commits
Differential Revision: https://reviews.llvm.org/D33590
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@305791 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
It's rare but a small number of patterns use IntInit's at the root of the match.
On X86, one such rule is enabled by the OptForSize predicate and causes the
compiler to use the smaller:
%0 = MOV32r1
instead of the usual:
%0 = MOV32ri 1
This patch adds support for matching IntInit's at the root and uses this as a
test case for the optsize attribute that was implemented in r301750
Reviewers: qcolombet, ab, t.p.northover, rovka, kristof.beyls, aditya_nandakumar
Reviewed By: qcolombet
Subscribers: igorb, llvm-commits
Differential Revision: https://reviews.llvm.org/D32791
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@303678 91177308-0d34-0410-b5e6-96231b3b80d8
It's causing some buildbots to timeout whenever tablegen needs re-compilation,
particularly those with -fsanitize=memory but not only them. A compile time
regression was expected since it triples the amount of SelectionDAG rules we
are able to import but it's currently too high.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@303542 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
As of this patch, 1018 out of 3938 rules are currently imported.
Depends on D32275
Reviewers: qcolombet, kristof.beyls, rovka, t.p.northover, ab, aditya_nandakumar
Reviewed By: qcolombet
Subscribers: dberris, igorb, llvm-commits
Differential Revision: https://reviews.llvm.org/D32278
The previous commit failed on test-suite/Bitcode/simd_ops/AArch64_halide_runtime.bc
because isImmOperandEqual() assumed MO was a register operand and that's not
always true.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@303341 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
As of this patch, 1018 out of 3938 rules are currently imported.
Depends on D32275
Reviewers: qcolombet, kristof.beyls, rovka, t.p.northover, ab, aditya_nandakumar
Reviewed By: qcolombet
Subscribers: dberris, igorb, llvm-commits
Differential Revision: https://reviews.llvm.org/D32278
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@303259 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Without this, it's possible to encounter multiple defs for a register.
This is triggered by the current version of D32868 when applied to trunk.
Reviewers: qcolombet, ab, t.p.northover, rovka, kristof.beyls
Reviewed By: qcolombet
Subscribers: llvm-commits, igorb
Differential Revision: https://reviews.llvm.org/D32869
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@303253 91177308-0d34-0410-b5e6-96231b3b80d8
When looping through a destination pattern's operands to decide how many
default operands we need to introduce, we used to count the "expanded"
number of operands. So if one default operand would be rendered as 2
values, we'd count it as 2 operands, when in fact it needs to count as
only 1 operand regardless of how many values it expands to.
This turns out to be a problem only in some very specific cases, e.g.
when we have one operand with multiple default values followed by more
operands with default values (see the new test). In such a situation
we'd stop looping before looking at all the operands, and then error out
assuming that we don't have enough default operands to make up the
shortfall.
At the moment this only affects ARM.
The patch removes the loop counting default operands entirely and
assumes that we'll have to introduce values for any default operand that
we find (i.e. we're assuming it cannot be given as a child at all). It
also extracts the code for adding renderers for default operands into a
helper method.
Differential Revision: https://reviews.llvm.org/D33031
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@303240 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Predicate<> now has a field to indicate how often it must be recomputed.
Currently, there are two frequencies, per-module (RecomputePerFunction==0)
and per-function (RecomputePerFunction==1). Per-function predicates are
currently recomputed more frequently than necessary since the only predicate
in this category is cheap to test. Per-module predicates are now computed in
getSubtargetImpl() while per-function predicates are computed in selectImpl().
Tablegen now manages the PredicateBitset internally. It should only be
necessary to add the required includes.
Also fixed a problem revealed by the test case where
constrainSelectedInstRegOperands() would attempt to tie operands that
BuildMI had already tied.
Reviewers: ab, qcolombet, t.p.northover, rovka, aditya_nandakumar
Reviewed By: rovka
Subscribers: kristof.beyls, igorb, llvm-commits
Differential Revision: https://reviews.llvm.org/D32491
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@301750 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
It functions just like RegisterClass except that the class is obtained
from a field.
Depends on D31761.
Reviewers: ab, qcolombet, t.p.northover, rovka, kristof.beyls, aditya_nandakumar
Reviewed By: ab
Subscribers: dberris, llvm-commits, igorb
Differential Revision: https://reviews.llvm.org/D32229
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@301080 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Some targets need to be able to do more complex rendering than just adding an
operand or two to an instruction. For example, it may need to insert an
instruction to extract a subreg first, or it may need to perform an operation
on the operand.
In SelectionDAG, targets would create SDNode's to achieve the desired effect
during the complex pattern predicate. This worked because SelectionDAG had a
form of garbage collection that would take care of SDNode's that were created
but not used due to a later predicate rejecting a match. This doesn't translate
well to GlobalISel and the churn was wasteful.
The API changes in this patch enable GlobalISel to accomplish the same thing
without the waste. The API is now:
InstructionSelector::OptionalComplexRendererFn selectArithImmed(MachineOperand &Root) const;
where Root is the root of the match. The return value can be omitted to
indicate that the predicate failed to match, or a function with the signature
ComplexRendererFn can be returned. For example:
return OptionalComplexRendererFn(
[=](MachineInstrBuilder &MIB) { MIB.addImm(Immed).addImm(ShVal); });
adds two immediate operands to the rendered instruction. Immed and ShVal are
captured from the predicate function.
As an added bonus, this also reduces the amount of information we need to
provide to GIComplexOperandMatcher.
Depends on D31418
Reviewers: aditya_nandakumar, t.p.northover, qcolombet, rovka, ab, javed.absar
Reviewed By: ab
Subscribers: dberris, kristof.beyls, igorb, llvm-commits
Differential Revision: https://reviews.llvm.org/D31761
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@301079 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
The SelectionDAG importer now imports rules with Predicate's attached via
Requires, PredicateControl, etc. These predicates are implemented as
bitset's to allow multiple predicates to be tested together. However,
unlike the MC layer subtarget features, each target only pays for it's own
predicates (e.g. AArch64 doesn't have 192 feature bits just because X86
needs a lot).
Both AArch64 and X86 derive at least one predicate from the MachineFunction
or Function so they must re-initialize AvailableFeatures before each
function. They also declare locals in <Target>InstructionSelector so that
computeAvailableFeatures() can use the code from SelectionDAG without
modification.
Reviewers: rovka, qcolombet, aditya_nandakumar, t.p.northover, ab
Reviewed By: rovka
Subscribers: aemerson, rengolin, dberris, kristof.beyls, llvm-commits, igorb
Differential Revision: https://reviews.llvm.org/D31418
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@300993 91177308-0d34-0410-b5e6-96231b3b80d8
It's causing llvm-clang-x86_64-expensive-checks-win to fail to compile and I
haven't worked out why. Reverting to make it green while I figure it out.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@300978 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
The SelectionDAG importer now imports rules with Predicate's attached via
Requires, PredicateControl, etc. These predicates are implemented as
bitset's to allow multiple predicates to be tested together. However,
unlike the MC layer subtarget features, each target only pays for it's own
predicates (e.g. AArch64 doesn't have 192 feature bits just because X86
needs a lot).
Both AArch64 and X86 derive at least one predicate from the MachineFunction
or Function so they must re-initialize AvailableFeatures before each
function. They also declare locals in <Target>InstructionSelector so that
computeAvailableFeatures() can use the code from SelectionDAG without
modification.
Reviewers: rovka, qcolombet, aditya_nandakumar, t.p.northover, ab
Reviewed By: rovka
Subscribers: aemerson, rengolin, dberris, kristof.beyls, llvm-commits, igorb
Differential Revision: https://reviews.llvm.org/D31418
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@300964 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
As far as instruction selection is concerned, all three appear to be same thing.
Support for these operands is experimental since AArch64 doesn't make use
of them and the in-tree targets that do use them (AMDGPU for
OperandWithDefaultOps, AMDGPU/ARM/Hexagon/Lanai for PredicateOperand, and ARM
for OperandWithDefaultOps) are not using tablegen-erated GlobalISel yet.
Reviewers: rovka, aditya_nandakumar, t.p.northover, qcolombet, ab
Reviewed By: rovka
Subscribers: inglorion, aemerson, rengolin, mehdi_amini, dberris, kristof.beyls, igorb, tpr, llvm-commits
Differential Revision: https://reviews.llvm.org/D31135
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@300037 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Temporaries are now allocated to operands instead of predicates and this
allocation is used to correctly pair up the rendered operands with the
matched operands.
Previously, ComplexPatterns were allocated temporaries independently in the
Src Pattern and Dst Pattern, leading to mismatches. Additionally, the Dst
Pattern failed to account for the allocated index and therefore always used
temporary 0, 1, ... when it should have used base+0, base+1, ...
Thanks to Aditya Nandakumar for noticing the bug.
Depends on D30539
Reviewers: ab, t.p.northover, qcolombet, rovka, aditya_nandakumar
Reviewed By: rovka
Subscribers: igorb, dberris, kristof.beyls, llvm-commits
Differential Revision: https://reviews.llvm.org/D31054
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@299538 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Lift the restrictions that prevented the tree walking introduced in the
previous change and add support for patterns like:
(G_ADD (G_MUL (G_SEXT $src1), (G_SEXT $src2)), $src3) -> SMADDWrrr $dst, $src1, $src2, $src3
Also adds support for G_SEXT and G_ZEXT to support these cases.
One particular aspect of this that I should draw attention to is that I've
tried to be overly conservative in determining the safety of matches that
involve non-adjacent instructions and multiple basic blocks. This is intended
to be used as a cheap initial check and we may add a more expensive check in
the future. The current rules are:
* Reject if any instruction may load/store (we'd need to check for intervening
memory operations.
* Reject if any instruction has implicit operands.
* Reject if any instruction has unmodelled side-effects.
See isObviouslySafeToFold().
Reviewers: t.p.northover, javed.absar, qcolombet, aditya_nandakumar, ab, rovka
Reviewed By: ab
Subscribers: igorb, dberris, llvm-commits, kristof.beyls
Differential Revision: https://reviews.llvm.org/D30539
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@299430 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Prepare the way for nested instruction matching support by having actions
like CopyRenderer look up operands in the RuleMatcher rather than a
specific InstructionMatcher. This allows actions to reference any operand
from any matched instruction.
It works by checking the 'shape' of the match and capturing
each matched instruction to a local variable. If the shape is wrong
(not enough operands, leaf nodes where non-leafs are expected, etc.), then
the rule exits early without checking the predicates. Once we've captured
the instructions, we then test the predicates as before (except using the
local variables). If the match is successful, then we render the new
instruction as before using the local variables.
It's not noticable in this patch but by the time we support multiple
instruction matching, this patch will also cause a significant improvement
to readability of the emitted code since
MRI.getVRegDef(I->getOperand(0).getReg()) will simply be MI1 after
emitCxxCaptureStmts().
This isn't quite NFC because I've also fixed a bug that I'm surprised we
haven't encountered yet. It now checks there are at least the expected
number of operands before accessing them with getOperand().
Depends on D30531
Reviewers: t.p.northover, qcolombet, aditya_nandakumar, ab, rovka
Reviewed By: rovka
Subscribers: dberris, kristof.beyls, llvm-commits
Differential Revision: https://reviews.llvm.org/D30535
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@298257 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Adds a new kind of MachineOperand: MO_Placeholder.
This operand must not appear in the MIR and only exists as a way of
creating an 'uninitialized' operand until a matcher function overwrites it.
Depends on D30046, D29712
Reviewers: t.p.northover, ab, rovka, aditya_nandakumar, javed.absar, qcolombet
Reviewed By: qcolombet
Subscribers: dberris, kristof.beyls, llvm-commits
Differential Revision: https://reviews.llvm.org/D30089
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@297782 91177308-0d34-0410-b5e6-96231b3b80d8
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
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@296131 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Each OperandPredicateMatcher shouldn't need to know how to generate the expression
to reference a MachineOperand. The OperandMatcher should provide it.
In addition to separating responsibilities, this also lays some groundwork for
decoupling source patterns from destination patterns to allow invented operands
or operands provided by GlobalISel's equivalent to the ComplexPattern<> class.
Depends on D29709
Reviewers: t.p.northover, ab, rovka, qcolombet, aditya_nandakumar
Reviewed By: ab
Subscribers: dberris, kristof.beyls, llvm-commits, igorb
Differential Revision: https://reviews.llvm.org/D29710
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@295668 91177308-0d34-0410-b5e6-96231b3b80d8
This lets us split out PatternToMatch from the top-level RuleMatcher,
where it doesn't really belong. That, in turn, lets us eventually
generate RuleMatchers from non-SelectionDAG sources.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294076 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
AMDGPU has two register classes with the same set of registers, and this
was causing this tablegen backend would get stuck in infinite recursion.
Reviewers: dsanders
Reviewed By: dsanders
Subscribers: tpr, wdng, llvm-commits
Differential Revision: https://reviews.llvm.org/D29049
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@293483 91177308-0d34-0410-b5e6-96231b3b80d8
Tablegen's -gen-instr-info pass has a bug in its emitEnums() routine.
The function intends for values in a vector to be deduplicated, but it
accidentally skips over elements after performing a deletion.
I think there are smarter ways of doing this deduplication, but we can
do that in a follow-up commit if there's interest. See the thread:
[PATCH] TableGen InstrMapping Bug fix.
Patch by Tyler Kenney!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@288408 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This allows specifying instructions that are available only in specific assembler variant. If AsmVariantName is specified then instruction will be presented only in MatchTable for this variant. If not specified then assembler variants will be determined based on AsmString.
Also this allows splitting assembler match tables in same way as it is done in dissasembler.
Reviewers: ab, tstellarAMD, craig.topper, vpykhtin
Subscribers: wdng
Differential Revision: https://reviews.llvm.org/D24249
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@280952 91177308-0d34-0410-b5e6-96231b3b80d8
These tests don't actually care about the internal opcode number, but have to
be updated whenever we add a new one for GlobalISel. That's bad.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@274774 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
The `"patchable-function"` attribute can be used by an LLVM client to
influence LLVM's code generation in ways that makes the generated code
easily patchable at runtime (for instance, to redirect control).
Right now only one patchability scheme is supported,
`"prologue-short-redirect"`, but this can be expanded in the future.
Reviewers: joker.eph, rnk, echristo, dberris
Subscribers: joker.eph, echristo, mcrosier, llvm-commits
Differential Revision: http://reviews.llvm.org/D19046
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@266715 91177308-0d34-0410-b5e6-96231b3b80d8
This required changing several places to print VT enums as strings instead of raw ints since the proper method to use to print became ambiguous. This is probably an improvement anyway.
This also appears to save ~8K from an x86 self host build of llc.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@266562 91177308-0d34-0410-b5e6-96231b3b80d8
Currently you can't specify node properties like commutativity on
a PatFrag. If you want to create a PatFrag on a commutative node
with a hasOneUse predicate, this enables you to specify that the
PatFrag is also commutable.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@260404 91177308-0d34-0410-b5e6-96231b3b80d8
The AMDGPU backend was the last user of the old StringMatcher
recognition code. Move it over to the new lookupLLVMIntrinsicName
funciton, which is now improved to handle all of the interesting edge
cases exposed by AMDGPU intrinsic names.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@258875 91177308-0d34-0410-b5e6-96231b3b80d8
The selection process being split into separate passes, we need generic opcodes
to translate the LLVM IR to target independent code.
This patch adds an opcode for addition: G_ADD.
Differential Revision: http://reviews.llvm.org/D15472
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@258333 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Add the necessary plumbing so that llvm_token_ty can be used as an
argument/return type in intrinsic definitions and correspondingly require
TokenTy in function types. TokenTy is an opaque type that has no target
lowering, but can be used in machine-independent intrinsics. It is
required for the upcoming llvm.eh.padparam intrinsic.
Reviewers: majnemer, rnk
Subscribers: stoklund, llvm-commits
Differential Revision: http://reviews.llvm.org/D12532
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@246651 91177308-0d34-0410-b5e6-96231b3b80d8
This is to fix an incorrect error when trying to initialize
DwarfNumbers with a !cast<int> of a bits initializer.
getValuesAsListOfInts("DwarfNumbers") would not see an IntInit
and instead the cast, so would give up.
It seems likely that this could be generalized to attempt
the convertInitializerTo for any type. I'm not really sure
why the existing code seems to special case the string cast cases
when convertInitializerTo seems like it should generally handle this
sort of thing.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@243722 91177308-0d34-0410-b5e6-96231b3b80d8
When FixedLenDecoder matches an input bitpattern of form [01]+ with an
instruction bitpattern of form [01?]+ (where 0/1 are static bits and ? are
mixed/variable bits) it passes the input bitpattern to a specific instruction
decoder method which then makes a final decision whether the bitpattern is a
valid instruction or not. This means the decoder must handle all possible
values of the variable bits which sometimes leads to opcode rewrites in the
decoder method when the instructions are not fully orthogonal.
The patch provides a way for the decoder method to say that when it returns
Fail it does not necessarily mean the bitpattern is invalid, but rather that
the bitpattern is definitely not an instruction that is recognized by the
decoder method. The decoder can then try to match the input bitpattern with
other possible instruction bitpatterns.
For example, this allows to solve a situation on AArch64 where the `MSR
(immediate)` instruction has form:
1101 0101 0000 0??? 0100 ???? ???1 1111
but not all values of the ? bits are allowed. The rejected values should be
handled by the `extended MSR (register)` instruction:
1101 0101 000? ???? ???? ???? ???? ????
The decoder will first try to decode an input bitpattern that matches both
bitpatterns as `MSR (immediate)` but currently this puts the decoder method of
`MSR (immediate)` into a situation when it must be able to decode all possible
values of the ? bits, i.e. it would need to rewrite the instruction to `MSR
(register)` when it is not `MSR (immediate)`.
The patch allows to specify that the decoder method cannot determine if the
instruction is valid for all variable values. The decoder method can simply
return Fail when it knows it is definitely not `MSR (immediate)`. The decoder
will then backtrack the decoding and find that it can match the input
bitpattern with the more generic `MSR (register)` bitpattern too.
Differential Revision: http://reviews.llvm.org/D7174
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242274 91177308-0d34-0410-b5e6-96231b3b80d8
Previously, subtarget features were a bitfield with the underlying type being uint64_t.
Since several targets (X86 and ARM, in particular) have hit or were very close to hitting this bound, switching the features to use a bitset.
No functional change.
The first several times this was committed (e.g. r229831, r233055), it caused several buildbot failures.
Apparently the reason for most failures was both clang and gcc's inability to deal with large numbers (> 10K) of bitset constructor calls in tablegen-generated initializers of instruction info tables.
This should now be fixed.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238192 91177308-0d34-0410-b5e6-96231b3b80d8
