Skip operation on the lower byte in int16 logical left shift when
shift amount is greater than 8.
Skip operation on the higher byte in int16 logical & arithmetic
right shift when shift amount is greater than 8.
Reviewed By: aykevl
Differential Revision: https://reviews.llvm.org/D115594
This reverts commit fd4808887e.
This patch causes gcc to issue a lot of warnings like:
warning: base class ‘class llvm::MCParsedAsmOperand’ should be
explicitly initialized in the copy constructor [-Wextra]
No intended behavior change.
EmitGCCInlineAsmStr() used to explicitly check for modifier 'l'
after handling block address and machine basic block operands.
This prevented passing a MachineOperand with 'l' modifier to
PrintAsmMemoryOperand(). Conceptually that seems kind of nice,
but in practice the overrides of PrintAsmMemoryOperand() in all (*)
AsmPrinter subclasses already reject modifiers they don't know about,
and none of them don't know about 'l'. So removing this doesn't have
a behavior difference, is less code, and it makes EmitGCCInlineAsmStr()
and EmitMSInlineAsmStr() more similar, to prepare for merging them later.
(Why not _add_ the branch to EmitMSInlineAsmStr() instead? Because that
always works with X86AsmPrinter I think, and
X86AsmPrinter::PrintAsmMemoryOperand() very decisively rejects the 'l'
modifier, so it's hard to motivate adding that branch.)
*: The one exception was AVRAsmPrinter, which had an llvm_unreachable instead
of returning true. So this commit changes that, so that the AVR target keeps
emitting an error instead of crashing when passing a mem operand with a :l
modifier to it. All the other targets already don't crash on this.
Differential Revision: https://reviews.llvm.org/D114216
- When an unconditional branch is expanded into an indirect branch, if
there is no scavenged register, an SGPR pair needs spilling to enable
the destination PC calculation. In addition, before jumping into the
destination, that clobbered SGPR pair need restoring.
- As SGPR cannot be spilled to or restored from memory directly, the
spilling/restoring of that SGPR pair reuses the regular SGPR spilling
support but without spilling it into memory. As that spilling and
restoring points are fully controlled, we only need to spill that SGPR
into the temporary VGPR, which needs spilling into its emergency slot.
- The target-specific hook is revised to take additional restore block,
where the restoring code is filled. After that, the relaxation will
place that restore block directly before the destination block and
insert an unconditional branch in any fall-through block into the
destination block.
Reviewed By: arsenm
Differential Revision: https://reviews.llvm.org/D106449
This moves the registry higher in the LLVM library dependency stack.
Every client of the target registry needs to link against MC anyway to
actually use the target, so we might as well move this out of Support.
This allows us to ensure that Support doesn't have includes from MC/*.
Differential Revision: https://reviews.llvm.org/D111454
On some architectures such as Arm and X86 the encoding for a nop may
change depending on the subtarget in operation at the time of
encoding. This change replaces the per module MCSubtargetInfo retained
by the targets AsmBackend in favour of passing through the local
MCSubtargetInfo in operation at the time.
On Arm using the architectural NOP instruction can have a performance
benefit on some implementations.
For Arm I've deleted the copy of the AsmBackend's MCSubtargetInfo to
limit the chances of this causing problems in the future. I've not
done this for other targets such as X86 as there is more frequent use
of the MCSubtargetInfo and it looks to be for stable properties that
we would not expect to vary per function.
This change required threading STI through MCNopsFragment and
MCBoundaryAlignFragment.
I've attempted to take into account the in tree experimental backends.
Differential Revision: https://reviews.llvm.org/D45962
The current inconsistency confuse contributors which coding guidlines to follow.
It would be better to have it consistent using clang-format tool.
Reviewed By: mhjacobson
Differential Revision: https://reviews.llvm.org/D109270
AttributeList::hasAttribute() is confusing, use clearer methods like
hasParamAttr()/hasRetAttr().
Add hasRetAttr() since it was missing from AttributeList.
Emit references to '__do_global_ctors' and '__do_global_dtors' to allow
constructor/destructor routines to run.
Reviewed by: MaskRay
Differential Revision: https://reviews.llvm.org/D107133
Most other registers are allocatable and therefore cannot be used.
This issue was flagged by the machine verifier, because reading other
registers is considered reading from an undefined register.
Differential Revision: https://reviews.llvm.org/D96969
This patch fixes some issues with the RORB pseudo instruction.
- A minor issue in which the instructions were said to use the SREG,
which is not true.
- An issue with the BLD instruction, which did not have an output operand.
- A major issue in which invalid instructions were generated. The fix
also reduce RORB from 4 to 3 instructions, so it's also a small
optimization.
These issues were flagged by the machine verifier.
Differential Revision: https://reviews.llvm.org/D96957
This patch makes sure shift instructions such as this one:
%result = shl i32 %n, %amount
are expanded just before the IR to SelectionDAG conversion to a loop so
that calls to non-existing library functions such as __ashlsi3 are
avoided. The generated code is currently pretty bad but there's a lot of
room for improvement: the shift itself can be done in just four
instructions.
Differential Revision: https://reviews.llvm.org/D96677
There were some serious issues with atomic operations. This patch should
fix the biggest issues.
For details on the issue take a look at this Compiler Explorer sample:
https://godbolt.org/z/n3ndhn
Code:
void atomicadd(_Atomic char *val) {
*val += 5;
}
Output:
atomicadd:
movw r26, r24
ldi r24, 5 ; 'operand' register
in r0, 63
cli
ld r24, X ; load value
add r24, r26 ; value += X
st X, r24 ; store value back
out 63, r0
ret ; return the wrong value (in r24)
There are various problems with this.
- The value to add (5) is stored in r24. However, the value to add to
is loaded in the same register: r24.
- The `add` instruction adds half of the pointer to the loaded value,
instead of (attempting to) add the operand with value 5.
- The output value of the cmpxchg instruction (which is not used in
this code sample) is the new value with 5 added, not the old value.
The LangRef specifies that it has to be the old value, before the
operation.
This patch fixes the first two and leaves the third problem to be fixed
at a later date. I believe atomics were mostly broken before this patch,
with this patch they should become usable as long as you ignore the
output of the atomic operation. In particular it fixes the following
things:
- It sets the earlyclobber flag for the input ('$operand' operand) so
that the register allocator puts it in a different register than the
output value.
- It fixes a number of issues with the pseudo op expansion pass, for
example now it adds the $operand field instead of the pointer. This
fixes most machine instruction verifier issues (other flagged issues
are unrelated to atomics).
Differential Revision: https://reviews.llvm.org/D97127
In most cases, using R31R30 is fine because the call (which always
precedes ADJCALLSTACKDOWN) will clobber R31R30 anyway. However, in some
rare cases the register allocator might insert an instruction between
the call and the ADJCALLSTACKDOWN instruction and expect the register
pair to be live afterwards. I think this happens as a result of
rematerialization. Therefore, to fix this, the instruction needs to have
Defs set to R31R30.
Setting the Defs field does have the effect of making the instruction
look dead, which it certainly is not. This is fixed by setting
hasSideEffects to true.
Differential Revision: https://reviews.llvm.org/D97745
Previously, AVRTargetLowering::LowerCall attempted to keep stack stores
in order with chains. Perhaps this worked in the past, but it does not
work now: it appears that the SelectionDAG legalization phase removes
these chains. Therefore, I've removed these chains entirely to match
X86 (which, similar to AVR, also prefers to use push instructions over
stack-relative stores to set up a call frame). With this change, all the
stack stores are in a somewhat reasonable order.
Differential Revision: https://reviews.llvm.org/D97853
The r1 register should be cleared in prologue of ISR as it is used
as constant zero.
Reviewed By: dylanmckay
Differential Revision: https://reviews.llvm.org/D99467
When you try to define a new DEBUG_TYPE in a header file, DEBUG_TYPE
definition defined around the #includes in files include it could
result in redefinition warnings even compile errors.
Reviewed By: tejohnson
Differential Revision: https://reviews.llvm.org/D102594
This patch is a large number of small changes that should hopefully not
affect the generated machine code but are still important to get right
so that the machine verifier won't complain about them.
The llvm/test/CodeGen/AVR/pseudo/*.mir changes are also necessary
because without the liveins the used registers are considered undefined
by the machine verifier and it will complain about them.
Differential Revision: https://reviews.llvm.org/D97172
Some instructions (especially mov+pop instructions) were setting the
wrong operands. For example, the pop instruction had the register set as
a source operand while it is a destination operand (the value is loaded
into the register).
I have found these issues using the machine verifier and using manual
code inspection.
Differential Revision: https://reviews.llvm.org/D97159
The previous expansion used SBCI, which is incorrect because the NEGW
pseudo instruction accepts a DREGS operand (2xGPR8) and SBCI only allows
LD8 registers. One solution could be to correct the NEGW pseudo
instruction, but another solution is to use a different instruction
(sbc) that does accept a GPR8 register and therefore allows more freedom
to the register allocator.
The output now matches avr-gcc for the following code:
int foo(int n) {
return -n;
}
I've found this issue using the machine instruction verifier: it was
complaining about the wrong register class in NEGWRd.mir.
Differential Revision: https://reviews.llvm.org/D97131
These aliases are sometimes used in assembly code and make the code more
readable. They are supported by avr-gcc too.
Differential Revision: https://reviews.llvm.org/D96492
References to functions are in program memory and need a `pm()` fixup. This should fix trait objects for Rust on AVR.
Differential Revision: https://reviews.llvm.org/D87631
Patch by Alex Mikhalev.
As mentioned in TODO comment, casting double to float causes NaNs to change bits.
To avoid the change, this patch adds support for single-floating-point immediate value on MachineCode.
Patch by Yuta Saito.
Differential Revision: https://reviews.llvm.org/D77384
It was discussed a few years ago and agreed that it makes sense to
remove this assertion as other targets do not perform similar register
size checking in inline assembly constraint logic, so the check just
adds a needless barrier on AVR.
This patch removes the assertion and removes 'XFAIL' from two Generic
CodeGen tests for AVR as a result.
This patch factors out the part of printInstruction that gets the
mnemonic string for a given MCInst. This is intended to be used
subsequently for the instruction-mix remarks to display the final
mnemonic (D90040).
Unfortunately making `getMnemonic` available to the AsmPrinter
seems to require making it virtual. Not sure if there's a way around
that with the current layering of the AsmPrinters.
Reviewed By: Paul-C-Anagnostopoulos
Differential Revision: https://reviews.llvm.org/D90039
No longer rely on an external tool to build the llvm component layout.
Instead, leverage the existing `add_llvm_componentlibrary` cmake function and
introduce `add_llvm_component_group` to accurately describe component behavior.
These function store extra properties in the created targets. These properties
are processed once all components are defined to resolve library dependencies
and produce the header expected by llvm-config.
Differential Revision: https://reviews.llvm.org/D90848
These expansions were rather inefficient and were done with more code
than necessary. This change optimizes them to use expansions more
similar to GCC. The code size is the same (when optimizing for code
size) but somehow LLVM reorders blocks in a non-optimal way. Still, this
should be an improvement with a reduction in code size of around 0.12%
(when building compiler-rt).
Differential Revision: https://reviews.llvm.org/D86418
We were checking if the ConstantSDNode was null but then immediately dereferencing it afterward - fold these both into a single check. Use the APInt::ult() helper as well.
Found by clang static analyzer.
This patch fixes a corruption of the stack pointer and several registers in any AVR interrupt with non-empty stack frame. Previously, the callee-saved registers were popped before restoring the stack pointer, causing the pointer math to use the wrong base value while also corrupting the caller's register. This change fixes the code to restore the stack pointer last before exiting the interrupt service routine.
https://bugs.llvm.org/show_bug.cgi?id=47253
Reviewed By: dylanmckay
Differential Revision: https://reviews.llvm.org/D87735
Patch by Andrew Dona-Couch.
The versions that take 'unsigned' will be removed in the future.
I tried to use getOriginalAlign instead of getAlign in some
places. getAlign factors in the minimum alignment implied by
the offset in the pointer info. Since we're also passing the
pointer info we can use the original alignment.
Reviewed By: arsenm
Differential Revision: https://reviews.llvm.org/D87592
This patch implements initial backend support for a -mtune CPU controlled by a "tune-cpu" function attribute. If the attribute is not present X86 will use the resolved CPU from target-cpu attribute or command line.
This patch adds MC layer support a tune CPU. Each CPU now has two sets of features stored in their GenSubtargetInfo.inc tables . These features lists are passed separately to the Processor and ProcessorModel classes in tablegen. The tune list defaults to an empty list to avoid changes to non-X86. This annoyingly increases the size of static tables on all target as we now store 24 more bytes per CPU. I haven't quantified the overall impact, but I can if we're concerned.
One new test is added to X86 to show a few tuning features with mismatched tune-cpu and target-cpu/target-feature attributes to demonstrate independent control. Another new test is added to demonstrate that the scheduler model follows the tune CPU.
I have not added a -mtune to llc/opt or MC layer command line yet. With no attributes we'll just use the -mcpu for both. MC layer tools will always follow the normal CPU for tuning.
Differential Revision: https://reviews.llvm.org/D85165
This fixes warnings raised by Clang's new -Wsuggest-override, in preparation for enabling that warning in the LLVM build. This patch also removes the virtual keyword where redundant, but only in places where doing so improves consistency within a given file. It also removes a couple unnecessary virtual destructor declarations in derived classes where the destructor inherited from the base class is already virtual.
Differential Revision: https://reviews.llvm.org/D83709
Summary:
The previous version relied on the standard calling convention using
std::reverse() to try to force the AVR ABI. But this only works for
simple cases, it fails for example with aggregate types.
This patch rewrites the calling convention with custom C++ code, that
implements the ABI defined in https://gcc.gnu.org/wiki/avr-gcc.
To do that it adds a few 16-bit pseudo registers for unaligned argument
passing, such as R24R23. For example this function:
define void @fun({ i8, i16 } %a)
will pass %a.0 in R22 and %a.1 in R24R23.
There are no instructions that can use these pseudo registers, so a new
register class, DREGSMOVW, is defined to make them apart.
Also the ArgCC_AVR_BUILTIN_DIV is no longer necessary, as it is
identical to the C++ behavior (actually the clobber list is more strict
for __div* functions, but that is currently unimplemented).
Reviewers: dylanmckay
Subscribers: Gaelan, Sh4rK, indirect, jwagen, efriedma, dsprenkels, hiraditya, Jim, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D68524
Patch by Rodrigo Rivas Costa.
Add disassembly support for the movw, adiw, and sbiw instructions.
I had previously committed test cases for the adiw and sbiw
instructions, but had accidentally made them not runnable so they were
skipped all this time. Oops. This patch fixes that by adding support for
disassembling those instructions.
Differential Revision: https://reviews.llvm.org/D82093
Some instructions have a fixed Z register and don't have an explicit
register operand. This can be worked around by simply printing the
operand directly if the particular register class is detected.
The LPM and ELPM instructions also needed a custom decoder, which is
also included in this patch.
Differential Revision: https://reviews.llvm.org/D82088
These can often only use a limited range of registers, and apparently
need special decoding support.
Differential Revision: https://reviews.llvm.org/D81971
This is a set of instructions that take just a single register as an
operand, with no immediates. Because all instructions share the same
format, I haven't added exhaustive bit testing to all instructions but
just to the inc instruction.
Differential Revision: https://reviews.llvm.org/D81968
I'm not entirely sure why this was ever needed, but when I remove both
adjustments all tests still pass.
This fixes a bug where a long branch (using the `jmp` instead of the
`rjmp` instruction) was incorrectly adjusted by 2 because it jumps to an
absolute address instead of a PC-relative address. I could have added
AVR::fixup_call to the list of exceptions, but it seemed more sensible
to me to just remove this code.
Differential Revision: https://reviews.llvm.org/D78459
Code like the following:
define i32 @foo(i32 %a, i1 zeroext %b) addrspace(1) {
entry:
%conv = zext i1 %b to i32
%add = add nsw i32 %conv, %a
ret i32 %add
}
Would compile to the following (incorrect) code:
foo:
mov r18, r20
clr r19
add r22, r18
adc r23, r19
sbci r24, 0
sbci r25, 0
ret
Those sbci instructions are clearly wrong, they should have been adc
instructions.
This commit improves codegen to use adc instead:
foo:
mov r18, r20
clr r19
ldi r20, 0
ldi r21, 0
add r22, r18
adc r23, r19
adc r24, r20
adc r25, r21
ret
This code is not optimal (it could be just 5 instructions instead of the
current 9) but at least it doesn't miscompile.
Differential Revision: https://reviews.llvm.org/D78439
This needed two fixes:
* 32-bit instructions were read in the wrong order. The machine code
swaps the two 16-bit instruction words, which wasn't undone when
decoding instructions.
* Jump and call instructions don't encode the lowest address bit,
which is always zero. Therefore, the address needed to be shifted by
one to fix that.
Differential Revision: https://reviews.llvm.org/D81961
An instruction like this will need to allocate some stack space for the
last parameter:
%x = call addrspace(1) i16 @bar(i64 undef, i64 undef, i16 undef, i16 0)
This worked fine when passing an actual value (in this case 0). However,
when passing undef, no value was pushed to the stack and therefore no
push instructions were created. This caused an unbalanced stack leading
to interesting results.
This commit fixes that by replacing the push logic with a regular stack
adjustment and stack-relative load/stores. This is less efficient but at
least it correctly compiles the code.
I can think of a few improvements in the future:
* The stack should have been adjusted in the function prologue when
there are no allocas in the function.
* Many (if not most) stack adjustments can be replaced by
pushing/popping the values directly. Exactly like the previous code
attempted but didn't do correctly.
* Small stack adjustments can be done more efficiently with a few
push/pop instructions (pushing/popping bogus values), both for code
size and for speed.
All in all, as long as there are no allocas in the function I think that
it is almost always more efficient to emit regular push/pop
instructions. This is however left for future optimizations.
Differential Revision: https://reviews.llvm.org/D78581
This patch fixes a bug in stack save/restore code. Because the frame
pointer was saved/restored manually (not by marking it as clobbered) the
StackSize variable was not updated accordingly. Most code still worked,
but code that tried to load a parameter passed on the stack did not.
This commit fixes this by marking the frame pointer as a
callee-clobbered register. This will let it be saved without any effort
in prolog/epilog code and will make sure the correct address is
calculated for loading parameters that are passed on the stack.
This approach is used by most other targets (such as X86, AArch64 and
RISC-V).
Differential Revision: https://reviews.llvm.org/D78579
The in, out, and sbi/cbi family of instructions seem to require a custom
decoder. I'm not exactly sure why and would prefer to convince TableGen
to provide the correct decoders for these, but I can't seem to convince
it to do so. They simply disassemble without any operands.
Differential Revision: https://reviews.llvm.org/D74049
D77207 changed the bounds checks resulting in tests for positive unsigned values - dropping the superfluous check to fix gcc+Werror "error: comparison of unsigned expression >= 0 is always true [-Werror=type-limits]" warning.
Summary:
On XMEGA, I/O address space is same as data address space - there is no 0x20 offset,
because CPU General Purpose Registers are not mapped in data address space.
From https://en.wikipedia.org/wiki/AVR_microcontrollers
> In the XMEGA variant, the working register file is not mapped into the data address space; as such, it is not possible to treat any of the XMEGA's working registers as though they were SRAM. Instead, the I/O registers are mapped into the data address space starting at the very beginning of the address space.
Reviewers: dylanmckay
Reviewed By: dylanmckay
Subscribers: hiraditya, Jim, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D77207
Patch by Vlastimil Labsky.
Summary:
Before this patch, `relaxInstruction` takes three arguments, the first
argument refers to the instruction before relaxation and the third
argument is the output instruction after relaxation. There are two quite
strange things:
1) The first argument's type is `const MCInst &`, the third
argument's type is `MCInst &`, but they may be aliased to the same
variable
2) The backends of ARM, AMDGPU, RISC-V, Hexagon assume that the third
argument is a fresh uninitialized `MCInst` even if `relaxInstruction`
may be called like `relaxInstruction(Relaxed, STI, Relaxed)` in a
loop.
In this patch, we drop the thrid argument, and let `relaxInstruction`
directly modify the given instruction. Also, this patch fixes the bug https://bugs.llvm.org/show_bug.cgi?id=45580, which is introduced by D77851, and
breaks the assumption of ARM, AMDGPU, RISC-V, Hexagon.
Reviewers: Razer6, MaskRay, jyknight, asb, luismarques, enderby, rtaylor, colinl, bcain
Reviewed By: Razer6, MaskRay, bcain
Subscribers: bcain, nickdesaulniers, nathanchance, wuzish, annita.zhang, arsenm, dschuff, jyknight, dylanmckay, sdardis, nemanjai, jvesely, nhaehnle, tpr, sbc100, jgravelle-google, kristof.beyls, hiraditya, aheejin, kbarton, fedor.sergeev, asb, rbar, johnrusso, simoncook, sabuasal, niosHD, jrtc27, MaskRay, zzheng, edward-jones, atanasyan, rogfer01, MartinMosbeck, brucehoult, the_o, PkmX, jocewei, Jim, lenary, s.egerton, pzheng, sameer.abuasal, apazos, luismarques, kerbowa, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D78364
Previously, the AVR backend would put functions in .progmem.data. This
is probably a regression from when functions still lived in address
space 0. With this change, only global constants are placed in
.progmem.data.
This is not complete: avr-gcc additionally respects -fdata-sections for
progmem global constants, which LLVM doesn't yet do. But fixing that is
a bit more complicated (and I believe other backends such as RISC-V
might also have similar issues).
Differential Revision: https://reviews.llvm.org/D78212
In the past, AVR functions were only lowered with interrupt-specific
machine code if the function was defined with the "avr-interrupt" or
"avr-signal" calling conventions.
This patch modifies the backend so that if the function does not have a
special calling convention, but does have an "interrupt" attribute,
that function is interpreted as a function with interrupts.
This also extracts the "is this function an interrupt" logic from
several disparate places in the backend into one AVRMachineFunctionInfo
attribute.
Bug found by Wilhelm Meier.
Follow-up of D72172 and D72180
This patch passes `uint64_t Address` to print methods of PC-relative
operands so that subsequent target specific patches can change
`*InstPrinter::print{Operand,PCRelImm,...}` to customize the output.
Add MCInstPrinter::PrintBranchImmAsAddress which is set to true by
llvm-objdump.
```
// Current llvm-objdump -d output
aarch64: 20000: bl #0
ppc: 20000: bl .+4
x86: 20000: callq 0
// Ideal output
aarch64: 20000: bl 0x20000
ppc: 20000: bl 0x20004
x86: 20000: callq 0x20005
// GNU objdump -d. The lack of 0x is not ideal because the result cannot be re-assembled
aarch64: 20000: bl 20000
ppc: 20000: bl 0x20004
x86: 20000: callq 20005
```
In `lib/Target/X86/X86GenAsmWriter1.inc` (generated by `llvm-tblgen -gen-asm-writer`):
```
case 12:
// CALL64pcrel32, CALLpcrel16, CALLpcrel32, EH_SjLj_Setup, JCXZ, JECXZ, J...
- printPCRelImm(MI, 0, O);
+ printPCRelImm(MI, Address, 0, O);
return;
```
Some targets have 2 `printOperand` overloads, one without `Address` and
one with `Address`. They should annotate derived `Operand` properly with
`let OperandType = "OPERAND_PCREL"`.
Reviewed By: jhenderson
Differential Revision: https://reviews.llvm.org/D76574
Summary:
This is patch is part of a series to introduce an Alignment type.
See this thread for context: http://lists.llvm.org/pipermail/llvm-dev/2019-July/133851.html
See this patch for the introduction of the type: https://reviews.llvm.org/D64790
Reviewers: courbet
Subscribers: dylanmckay, sdardis, nemanjai, hiraditya, kbarton, asb, rbar, johnrusso, simoncook, sabuasal, niosHD, jrtc27, MaskRay, zzheng, edward-jones, atanasyan, rogfer01, MartinMosbeck, brucehoult, the_o, PkmX, jocewei, Jim, lenary, s.egerton, pzheng, sameer.abuasal, apazos, luismarques, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D76551
ISD::ROTL/ROTR rotation values are guaranteed to act as a modulo amount, so for power-of-2 bitwidths we only need the lowest bits.
Differential Revision: https://reviews.llvm.org/D76201
For context, the proposed RISC-V bit manipulation extension has a subset
of instructions which require one of two SubtargetFeatures to be
enabled, 'zbb' or 'zbp', and there is no defined feature which both of
these can imply to use as a constraint either (see comments in D65649).
AssemblerPredicates allow multiple SubtargetFeatures to be declared in
the "AssemblerCondString" field, separated by commas, and this means
that the two features must both be enabled. There is no equivalent to
say that _either_ feature X or feature Y must be enabled, short of
creating a dummy SubtargetFeature for this purpose and having features X
and Y imply the new feature.
To solve the case where X or Y is needed without adding a new feature,
and to better match a typical TableGen style, this replaces the existing
"AssemblerCondString" with a dag "AssemblerCondDag" which represents the
same information. Two operators are defined for use with
AssemblerCondDag, "all_of", which matches the current behaviour, and
"any_of", which adds the new proposed ORing features functionality.
This was originally proposed in the RFC at
http://lists.llvm.org/pipermail/llvm-dev/2020-February/139138.html
Changes to all current backends are mechanical to support the replaced
functionality, and are NFCI.
At this stage, it is illegal to combine features with ands and ors in a
single AssemblerCondDag. I suspect this case is sufficiently rare that
adding more complex changes to support it are unnecessary.
Differential Revision: https://reviews.llvm.org/D74338
The initialization order was not correct. These bugs were discovered by
valgrind. They appear to work fine in practice but this patch should
unblock switching the AVR backend on by default as now a standard AVR
llc invocation runs without memory errors.
The AVRISelLowering constructor would run before the subtarget boolean
fields were initialized to false. Now, the initialization order is
correct.
Found by the LLVM MemorySanitizer tests when switching AVR to a default
backend.
ELFArch must be initialized before the call to
initializeSubtargetDependencies().
The uninitialized read would occur deep within TableGen'd code.
Ben Shi