Introduce a method to walk through use-def chains to decide whether
it's possible to remove a given instruction and its users. These
instructions are then stored in a set until the end of the transform
when they're erased. This is now used to perform checks on the
iteration count (LoopDec chain), element count (VCTP chain) and the
possibly redundant iteration count.
As well as being able to remove chains of instructions, we know also
check that the sub feeding the vctp is producing the expected value.
Differential Revision: https://reviews.llvm.org/D71837
Summary:
This patch fixes pr23772 [ARM] r226200 can emit illegal thumb2 instruction: "sub sp, r12, #80".
The violation was that SUB and ADD (reg, immediate) instructions can only write to SP if the source register is also SP. So the above instructions was unpredictable.
To enforce that the instruction t2(ADD|SUB)ri does not write to SP we now enforce the destination register to be rGPR (That exclude PC and SP).
Different than the ARM specification, that defines one instruction that can read from SP, and one that can't, here we inserted one that can't write to SP, and other that can only write to SP as to reuse most of the hard-coded size optimizations.
When performing this change, it uncovered that emitting Thumb2 Reg plus Immediate could not emit all variants of ADD SP, SP #imm instructions before so it was refactored to be able to. (see test/CodeGen/Thumb2/mve-stacksplot.mir where we use a subw sp, sp, Imm12 variant )
It also uncovered a disassembly issue of adr.w instructions, that were only written as SUBW instructions (see llvm/test/MC/Disassembler/ARM/thumb2.txt).
Reviewers: eli.friedman, dmgreen, carwil, olista01, efriedma, andreadb
Reviewed By: efriedma
Subscribers: gbedwell, john.brawn, efriedma, ostannard, kristof.beyls, hiraditya, dmgreen, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D70680
Summary:
This patch fixes pr23772 [ARM] r226200 can emit illegal thumb2 instruction: "sub sp, r12, #80".
The violation was that SUB and ADD (reg, immediate) instructions can only write to SP if the source register is also SP. So the above instructions was unpredictable.
To enforce that the instruction t2(ADD|SUB)ri does not write to SP we now enforce the destination register to be rGPR (That exclude PC and SP).
Different than the ARM specification, that defines one instruction that can read from SP, and one that can't, here we inserted one that can't write to SP, and other that can only write to SP as to reuse most of the hard-coded size optimizations.
When performing this change, it uncovered that emitting Thumb2 Reg plus Immediate could not emit all variants of ADD SP, SP #imm instructions before so it was refactored to be able to. (see test/CodeGen/Thumb2/mve-stacksplot.mir where we use a subw sp, sp, Imm12 variant )
It also uncovered a disassembly issue of adr.w instructions, that were only written as SUBW instructions (see llvm/test/MC/Disassembler/ARM/thumb2.txt).
Reviewers: eli.friedman, dmgreen, carwil, olista01, efriedma
Reviewed By: efriedma
Subscribers: john.brawn, efriedma, ostannard, kristof.beyls, hiraditya, dmgreen, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D70680
Summary:
Instead of generating two i32 instructions for each load or store of a volatile
i64 value (two LDRs or STRs), now emit LDRD/STRD.
These improvements cover architectures implementing ARMv5TE or Thumb-2.
Reviewers: dmgreen, efriedma, john.brawn, nickdesaulniers
Reviewed By: efriedma, nickdesaulniers
Subscribers: nickdesaulniers, vvereschaka, kristof.beyls, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D70072
1) Fix an issue with the incorrect value being used for the number of
elements being passed to [d|w]lstp. We were trying to check that
the value was available at LoopStart, but this doesn't consider
that the last instruction in the block could also define the
register. Two helpers have been added to RDA for this.
2) Insert some code to now try to move the element count def or the
insertion point so that we can perform more tail predication.
3) Related to (1), the same off-by-one could prevent us from
generating a low-overhead loop when a mov lr could have been
the last instruction in the block.
4) Fix up some instruction attributes so that not all the
low-overhead loop instructions are labelled as branches and
terminators - as this is not true for dls/dlstp.
Differential Revision: https://reviews.llvm.org/D71609
Summary:
Instead of generating two i32 instructions for each load or store of a volatile
i64 value (two LDRs or STRs), now emit LDRD/STRD.
These improvements cover architectures implementing ARMv5TE or Thumb-2.
Reviewers: dmgreen, efriedma, john.brawn
Reviewed By: efriedma
Subscribers: kristof.beyls, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D70072
This patch adds instruction selection patterns for the TT, TTT, TTA, and TTAT
instructions and tests for llvm.arm.cmse.tt, llvm.arm.cmse.ttt,
llvm.arm.cmse.tta, and llvm.arm.cmse.ttat intrinsics (added in a previous
patch).
Patch by Javed Absar.
Differential Revision: https://reviews.llvm.org/D70407
This adds some new qdadd patterns to go along with the other recently added
qadd's.
Differential Revision: https://reviews.llvm.org/D68999
llvm-svn: 375414
This lowers a sadd_sat to a qadd by treating it as legal. Also adds qsub at the
same time.
The qadd instruction sets the q flag, but we already have many cases where we
do not model this in llvm.
Differential Revision: https://reviews.llvm.org/D68976
llvm-svn: 375411
Lower the target independent signed saturating intrinsics to qadd8 and qadd16.
This custom lowers them from a sadd_sat, catching the node early before it is
promoted. It also adds a QADD8b and QADD16b node to mean the bottom "lane" of a
qadd8/qadd16, so that we can call demand bits on it to show that it does not
use the upper bits.
Also handles QSUB8 and QSUB16.
Differential Revision: https://reviews.llvm.org/D68974
llvm-svn: 375402
This is an attempt to fill in some of the missing instructions from the
Cortex-M4 schedule, and make it easier to do the same for other ARM cpus.
- Some instructions are marked as hasNoSchedulingInfo as they are pseudos or
otherwise do not require scheduling info
- A lot of features have been marked not supported
- Some WriteRes's have been added for cvt instructions.
- Some extra instruction latencies have been added, notably by relaxing the
regex for dsp instruction to catch more cases, and some fp instructions.
This goes a long way to get the CompleteModel working for this CPU. It does not
go far enough as to get all scheduling info for all output operands correct.
Differential Revision: https://reviews.llvm.org/D67957
llvm-svn: 373163
During legalisation we can end up with some pretty strange nodes, like shifts
of 0. We need to make sure we don't try to make long shifts of these, ending up
with invalid assembly instructions. A long shift with a zero immediate actually
encodes a shift by 32.
Differential Revision: https://reviews.llvm.org/D67664
llvm-svn: 372839
This reverts r372314, reapplying r372285 and the commits which depend
on it (r372286-r372293, and r372296-r372297)
This was missing one switch to getTargetConstant in an untested case.
llvm-svn: 372338
This broke the Chromium build, causing it to fail with e.g.
fatal error: error in backend: Cannot select: t362: v4i32 = X86ISD::VSHLI t392, Constant:i8<15>
See llvm-commits thread of r372285 for details.
This also reverts r372286, r372287, r372288, r372289, r372290, r372291,
r372292, r372293, r372296, and r372297, which seemed to depend on the
main commit.
> Encode them directly as an imm argument to G_INTRINSIC*.
>
> Since now intrinsics can now define what parameters are required to be
> immediates, avoid using registers for them. Intrinsics could
> potentially want a constant that isn't a legal register type. Also,
> since G_CONSTANT is subject to CSE and legalization, transforms could
> potentially obscure the value (and create extra work for the
> selector). The register bank of a G_CONSTANT is also meaningful, so
> this could throw off future folding and legalization logic for AMDGPU.
>
> This will be much more convenient to work with than needing to call
> getConstantVRegVal and checking if it may have failed for every
> constant intrinsic parameter. AMDGPU has quite a lot of intrinsics wth
> immarg operands, many of which need inspection during lowering. Having
> to find the value in a register is going to add a lot of boilerplate
> and waste compile time.
>
> SelectionDAG has always provided TargetConstant for constants which
> should not be legalized or materialized in a register. The distinction
> between Constant and TargetConstant was somewhat fuzzy, and there was
> no automatic way to force usage of TargetConstant for certain
> intrinsic parameters. They were both ultimately ConstantSDNode, and it
> was inconsistently used. It was quite easy to mis-select an
> instruction requiring an immediate. For SelectionDAG, start emitting
> TargetConstant for these arguments, and using timm to match them.
>
> Most of the work here is to cleanup target handling of constants. Some
> targets process intrinsics through intermediate custom nodes, which
> need to preserve TargetConstant usage to match the intrinsic
> expectation. Pattern inputs now need to distinguish whether a constant
> is merely compatible with an operand or whether it is mandatory.
>
> The GlobalISelEmitter needs to treat timm as a special case of a leaf
> node, simlar to MachineBasicBlock operands. This should also enable
> handling of patterns for some G_* instructions with immediates, like
> G_FENCE or G_EXTRACT.
>
> This does include a workaround for a crash in GlobalISelEmitter when
> ARM tries to uses "imm" in an output with a "timm" pattern source.
llvm-svn: 372314
Encode them directly as an imm argument to G_INTRINSIC*.
Since now intrinsics can now define what parameters are required to be
immediates, avoid using registers for them. Intrinsics could
potentially want a constant that isn't a legal register type. Also,
since G_CONSTANT is subject to CSE and legalization, transforms could
potentially obscure the value (and create extra work for the
selector). The register bank of a G_CONSTANT is also meaningful, so
this could throw off future folding and legalization logic for AMDGPU.
This will be much more convenient to work with than needing to call
getConstantVRegVal and checking if it may have failed for every
constant intrinsic parameter. AMDGPU has quite a lot of intrinsics wth
immarg operands, many of which need inspection during lowering. Having
to find the value in a register is going to add a lot of boilerplate
and waste compile time.
SelectionDAG has always provided TargetConstant for constants which
should not be legalized or materialized in a register. The distinction
between Constant and TargetConstant was somewhat fuzzy, and there was
no automatic way to force usage of TargetConstant for certain
intrinsic parameters. They were both ultimately ConstantSDNode, and it
was inconsistently used. It was quite easy to mis-select an
instruction requiring an immediate. For SelectionDAG, start emitting
TargetConstant for these arguments, and using timm to match them.
Most of the work here is to cleanup target handling of constants. Some
targets process intrinsics through intermediate custom nodes, which
need to preserve TargetConstant usage to match the intrinsic
expectation. Pattern inputs now need to distinguish whether a constant
is merely compatible with an operand or whether it is mandatory.
The GlobalISelEmitter needs to treat timm as a special case of a leaf
node, simlar to MachineBasicBlock operands. This should also enable
handling of patterns for some G_* instructions with immediates, like
G_FENCE or G_EXTRACT.
This does include a workaround for a crash in GlobalISelEmitter when
ARM tries to uses "imm" in an output with a "timm" pattern source.
llvm-svn: 372285
Arm 8.1-M adds a number of related CSEL instructions, including CSINC, CSNEG and CSINV. These choose between two values given the content in CPSR and a condition, performing an increment, negation or inverse of the false value.
This adds some selection for them, either from constant values or patterns. It does not include CSEL directly, which is currently not always making code better. It is still useful, but we will have to check more carefully where it should and shouldn't be used.
Code by Ranjeet Singh and Simon Tatham, with some modifications from me.
Differential revision: https://reviews.llvm.org/D66483
llvm-svn: 370739
Summary:
According to the Armv8.1-M manual CSEL, CSINC, CSINV and CSNEG are
"constrained unpredictable" when SP is used as the source register Rn.
The assembler should diagnose this case.
Reviewers: momchil.velikov, dmgreen, ostannard, simon_tatham, t.p.northover
Reviewed By: ostannard
Subscribers: javed.absar, kristof.beyls, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65505
llvm-svn: 367433
Both WhileLoopStart and LoopEnd may get turned into a cmp and br pair,
so add an implicit def to these pseudo instructions in case that WLS
and LE aren't generated.
Differential Revision: https://reviews.llvm.org/D65275
llvm-svn: 367089
This adds patterns for the simpler VAND, VORR and VEOR bitwise vector
instructions. It also adjusts the top16Zero PatLeaf to not match on vector
instructions, which can otherwise cause problems.
Code written by David Sherwood.
Differential Revision: https://reviews.llvm.org/D63867
llvm-svn: 365113
Backend changes to enable WLS/LE low-overhead loops for armv8.1-m:
1) Use TTI to communicate to the HardwareLoop pass that we should try
to generate intrinsics that guard the loop entry, as well as setting
the loop trip count.
2) Lower the BRCOND that uses said intrinsic to an Arm specific node:
ARMWLS.
3) ISelDAGToDAG the node to a new pseudo instruction:
t2WhileLoopStart.
4) Add support in ArmLowOverheadLoops to handle the new pseudo
instruction.
Differential Revision: https://reviews.llvm.org/D63816
llvm-svn: 364733
The BF and WLS/WLSTP instructions have various branch-offset fields
occupying different positions and lengths in the instruction encoding,
and all of them were decoded at disassembly time by the function
DecodeBFLabelOffset() which returned SoftFail if the offset was zero.
In fact, it's perfectly fine and not even a SoftFail for most of those
offset fields to be zero. The only one that can't be zero is the 4-bit
field labelled `boff` in the architecture spec, occupying bits {26-23}
of the BF instruction family. If that one is zero, the encoding
overlaps other instructions (WLS, DLS, LETP, VCTP), so it ought to be
a full Fail.
Fixed by adding an extra template parameter to DecodeBFLabelOffset
which controls whether a zero offset is accepted or rejected. Adjusted
existing tests (only in error messages for bad disassemblies); added
extra tests to demonstrate zero offsets being accepted in all the
right places, and a few demonstrating rejection of zero `boff`.
Reviewers: DavidSpickett, ostannard
Subscribers: javed.absar, kristof.beyls, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63864
llvm-svn: 364533
In the `CSEL Rd,Rm,Rn` instruction family (also including CSINC, CSINV
and CSNEG), the architecture lists it as CONSTRAINED UNPREDICTABLE
(i.e. SoftFail) to use SP in the Rd or Rm slot, but outright illegal
to use it in the Rn slot, not least because some encodings of that
form are used by MVE instructions such as UQRSHLL.
MC was treating all three slots the same, as SoftFail. So the only
reason UQRSHLL was disassembled correctly at all was because the MVE
decode table is separate from the Thumb2 one and takes priority; if
you turned off MVE, then encodings such as `[0x5f,0xea,0x0d,0x83]`
would disassemble as spurious CSELs.
Fixed by inventing another version of the `GPRwithZR` register class,
which disallows SP completely instead of just SoftFailing it.
Reviewers: DavidSpickett, ostannard
Subscribers: javed.absar, kristof.beyls, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63862
llvm-svn: 364531
This final batch includes the tail-predicated versions of the
low-overhead loop instructions (LETP); the VPSEL instruction to select
between two vector registers based on the predicate mask without
having to open a VPT block; and VPNOT which complements the predicate
mask in place.
Reviewers: dmgreen, samparker, SjoerdMeijer, t.p.northover
Subscribers: javed.absar, kristof.beyls, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D62681
llvm-svn: 364292
This adds the rest of the vector memory access instructions. It
includes contiguous loads/stores, with an ordinary addressing mode
such as [r0,#offset] (plus writeback variants); gather loads and
scatter stores with a scalar base address register and a vector of
offsets from it (written [r0,q1] or similar); and gather/scatters with
a vector of base addresses (written [q0,#offset], again with
writeback). Additionally, some of the loads can widen each loaded
value into a larger vector lane, and the corresponding stores narrow
them again.
To implement these, we also have to add the addressing modes they
need. Also, in AsmParser, the `isMem` query function now has
subqueries `isGPRMem` and `isMVEMem`, according to which kind of base
register is used by a given memory access operand.
I've also had to add an extra check in `checkTargetMatchPredicate` in
the AsmParser, without which our last-minute check of `rGPR` register
operands against SP and PC was failing an assertion because Tablegen
had inserted an immediate 0 in place of one of a pair of tied register
operands. (This matches the way the corresponding check for `MCK_rGPR`
in `validateTargetOperandClass` is guarded.) Apparently the MVE load
instructions were the first to have ever triggered this assertion, but
I think only because they were the first to have a combination of the
usual Arm pre/post writeback system and the `rGPR` class in particular.
Reviewers: dmgreen, samparker, SjoerdMeijer, t.p.northover
Subscribers: javed.absar, kristof.beyls, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D62680
llvm-svn: 364291
Introduce three pseudo instructions to be used during DAG ISel to
represent v8.1-m low-overhead loops. One maps to set_loop_iterations
while loop_decrement_reg is lowered to two, so that we can separate
the decrement and branching operations. The pseudo instructions are
expanded pre-emission, where we can still decide whether we actually
want to generate a low-overhead loop, in a new pass:
ARMLowOverheadLoops. The pass currently bails, reverting to an sub,
icmp and br, in the cases where a call or stack spill/restore happens
between the decrement and branching instructions, or if the loop is
too large.
Differential Revision: https://reviews.llvm.org/D63476
llvm-svn: 364288
This adds the family of loads and stores with names like VLD20.8 and
VST42.32, which load and store parts of multiple q-registers in such a
way that executing both VLD20 and VLD21, or all four of VLD40..VLD43,
will distribute 2 or 4 vectors' worth of memory data across the lanes
of the same number of registers but in a transposed order.
In addition to the Tablegen descriptions of the instructions
themselves, this patch also adds encode and decode support for the
QQPR and QQQQPR register classes (representing the range of loaded or
stored vector registers), and tweaks to the parsing system for lists
of vector registers to make it return the right format in this case
(since, unlike NEON, MVE regards q-registers as primitive, and not
just an alias for two d-registers).
llvm-svn: 364172
During assembly, the mask operand to an IT instruction (storing the
sequence of T/E for 'Then' and 'Else') is parsed out of the mnemonic
into a representation that encodes 'Then' and 'Else' in the same way
regardless of the condition code. At some point during encoding it has
to be converted into the instruction encoding used in the
architecture, in which the mask encodes a sequence of replacement
low-order bits for the condition code, so that which bit value means
'then' and which 'else' depends on whether the original condition code
had its low bit set.
Previously, that transformation was done by processInstruction(), half
way through assembly. So an MCOperand storing an IT mask would
sometimes store it in one format, and sometimes in the other,
depending on where in the assembly pipeline you were. You can see this
in diagnostics from `llvm-mc -debug -triple=thumbv8a -show-inst`, for
example: if you give it an instruction such as `itete eq`, you'd see
an `<MCOperand Imm:5>` in a diagnostic become `<MCOperand Imm:11>` in
the final output.
Having the same data structure store values with time-dependent
semantics is confusing already, and it will get more confusing when we
introduce the MVE VPT instruction which reuses the Then/Else bitmask
idea in a different context. So I'm refactoring: now, all `ARMOperand`
and `MCOperand` representations of an IT mask work exactly the same
way, namely, 0 means 'Then' and 1 means 'Else', regardless of what
original predicate is being referred to. The architectural encoding of
IT that depends on the original condition is now constructed at the
point when we turn the `MCOperand` into the final instruction bit
pattern, and decoded similarly in the disassembler.
The previous condition-independent parse-time format used 0 for Else
and 1 for Then. I've taken the opportunity to flip the sense of it
while I'm changing all of this anyway, because it seems to me more
natural to use 0 for 'leave the starting condition unchanged' and 1
for 'invert it', as if those bits were an XOR mask.
Reviewers: ostannard
Subscribers: javed.absar, kristof.beyls, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63219
llvm-svn: 363244
This introduces a new decoding table for MVE instructions, and starts
by adding the family of scalar shift instructions that are part of the
MVE architecture extension: saturating shifts within a single GPR, and
long shifts across a pair of GPRs (both saturating and normal).
Some of these shift instructions have only 3-bit register fields in
the encoding, with the low bit fixed. So they can only address an odd
or even numbered GPR (depending on the operand), and therefore I add
two new register classes, GPREven and GPROdd.
Differential Revision: https://reviews.llvm.org/D62668
Change-Id: Iad95d5f83d26aef70c674027a184a6b1e0098d33
llvm-svn: 363051
This adds support for the new family of conditional selection /
increment / negation instructions; the low-overhead branch
instructions (e.g. BF, WLS, DLS); the CLRM instruction to zero a whole
list of registers at once; the new VMRS/VMSR and VLDR/VSTR
instructions to get data in and out of 8.1-M system registers,
particularly including the new VPR register used by MVE vector
predication.
To support this, we also add a register name 'zr' (used by the CSEL
family to force one of the inputs to the constant 0), and operand
types for lists of registers that are also allowed to include APSR or
VPR (used by CLRM). The VLDR/VSTR instructions also need a new
addressing mode.
The low-overhead branch instructions exist in their own separate
architecture extension, which we treat as enabled by default, but you
can say -mattr=-lob or equivalent to turn it off.
Reviewers: dmgreen, samparker, SjoerdMeijer, t.p.northover
Reviewed By: samparker
Subscribers: miyuki, javed.absar, kristof.beyls, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D62667
llvm-svn: 363039
These caused a build failure because I managed not to notice they
depended on a later unpushed commit in my current stack. Sorry about
that.
llvm-svn: 362956
This should have been part of r362953, but I had a finger-trouble
incident and committed the old rather than new version of the patch.
Sorry.
llvm-svn: 362955
This adds support for the new family of conditional selection /
increment / negation instructions; the low-overhead branch
instructions (e.g. BF, WLS, DLS); the CLRM instruction to zero a whole
list of registers at once; the new VMRS/VMSR and VLDR/VSTR
instructions to get data in and out of 8.1-M system registers,
particularly including the new VPR register used by MVE vector
predication.
To support this, we also add a register name 'zr' (used by the CSEL
family to force one of the inputs to the constant 0), and operand
types for lists of registers that are also allowed to include APSR or
VPR (used by CLRM). The VLDR/VSTR instructions also need some new
addressing modes.
The low-overhead branch instructions exist in their own separate
architecture extension, which we treat as enabled by default, but you
can say -mattr=-lob or equivalent to turn it off.
Reviewers: dmgreen, samparker, SjoerdMeijer, t.p.northover
Reviewed By: samparker
Subscribers: miyuki, javed.absar, kristof.beyls, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D62667
llvm-svn: 362953
The family of 32-bit Thumb instruction encodings that include t2ORR,
t2AND and t2EOR are all listed in the ArmARM as having (0) in bit 15.
The Tablegen descriptions of those instructions listed them as ?. This
change tightens that up by making them into 0 + Unpredictable.
In the specific case of t2ORR, we tighten it up still further by
making the zero bit mandatory. This change comes from Arm v8.1-M, in
which encodings with that bit equal to 1 will now be used for
different instructions.
Reviewers: dmgreen, samparker, SjoerdMeijer, efriedma
Reviewed By: dmgreen, efriedma
Subscribers: efriedma, javed.absar, kristof.beyls, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D60705
llvm-svn: 362470
This patch adds a simple Cortex-M4 schedule, renaming the existing M3
schedule to M4 and filling in the latencies as-per the Cortex-M4 TRM:
https://developer.arm.com/docs/ddi0439/latest
Most of these are 1, with the important exception being loads taking 2
cycles. A few others are also higher, but I don't believe they make a
large difference. I've repurposed the M3 schedule as the latencies are
mostly the same between the two cores, with the M4 having more FP and
DSP instructions. We also turn on MISched and UseAA for the cores that
now use this.
It also adds some schedule Write's to various instruction to make things
simpler.
Differential Revision: https://reviews.llvm.org/D54142
llvm-svn: 360768
Using SP in this position is unpredictable in ARMv7. CMP and CMN are not
affected, and of course v8 relaxes this requirement, but that's handled
elsewhere.
llvm-svn: 360242
The v8m.base ISA contains movw, which can operate on an unsigned
16-bit value. Add the pattern that converts an add with a negative
value, that could fit into 16-bits when negated, into a sub with that
positive value.
Differential Revision: https://reviews.llvm.org/D57942
llvm-svn: 353692
to reflect the new license.
We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.
Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.
llvm-svn: 351636
Using a PatLeaf for sext_16_node allowed matching smulbb and smlabb
instructions once the operands had been sign extended. But we also
need to use sext_inreg operands along with sext_16_node to catch a
few more cases that enable use to remove the unnecessary sxth.
Differential Revision: https://reviews.llvm.org/D55992
llvm-svn: 350613
SB (Speculative Barrier) is only mandatory from 8.5
onwards but is optional from Armv8.0-A. This patch adds a command
line option to enable SB, as it was previously only possible to
enable by selecting -march=armv8.5-a.
This patch also renames FeatureSpecRestrict to FeatureSB.
Reviewed By: olista01, LukeCheeseman
Differential Revision: https://reviews.llvm.org/D55990
llvm-svn: 350299
These features (fairly) recently got split out into their own feature, so we
should make CodeGen use them when available. The main change here is that the
check used to be based on the triple, but now it's based on CPU features.
llvm-svn: 349355
This has two positive effects. First, using a custom node prevents
recombination leading to an infinite loop since the output DAG is notionally a
little more complex than the input one. Using a flag-setting instruction also
allows the subtraction to be folded with the related comparison more easily.
https://reviews.llvm.org/D53190
llvm-svn: 348122
Currently, variadic operands on an MCInst are assumed to be uses,
because they come after the defs. However, this is not always the case,
for example the Arm/Thumb LDM instructions write to a variable number of
registers.
This adds a property of instruction definitions which can be used to
mark variadic operands as defs. This only affects MCInst, because
MachineInstruction already tracks use/def per operand in each instance
of the instruction, so can already represent this.
This property can then be checked in MCInstrDesc, allowing us to remove
some special cases in ARMAsmParser::isITBlockTerminator.
Differential revision: https://reviews.llvm.org/D54853
llvm-svn: 348114
This adds two new barrier instructions which can be used to restrict
speculative execution of load instructions.
Patch by Pablo Barrio!
Differential revision: https://reviews.llvm.org/D52484
llvm-svn: 343300
This is a new barrier which limits speculative execution of the
instructions following it.
Patch by Pablo Barrio!
Differential revision: https://reviews.llvm.org/D52477
llvm-svn: 343213
Because t2LDREX (& t2STREX) were marked as AddrModeNone, but did allow a
FrameIndex operand, rewriteT2FrameIndex asserted. This gives them a
proper addressing-mode and tells the rewriter about it so that encodable
offsets are exploited and others are rejected.
Should fix PR38828.
llvm-svn: 341642
Add intrinsic isel patterns for sxtb16, sxtab16, uxtb16 and uxtab16
so that they can perform a ror.
Differential Revision: https://reviews.llvm.org/D51034
llvm-svn: 340405
Support for negative immediates was implemented in
https://reviews.llvm.org/rL298380, however few instruction options were missing.
This change adds negative immediates support and respective tests
for the following:
ADD
ADDS
ADDS.W
AND.W
ANDS
BIC.W
BICS
BICS.W
SUB
SUBS
SUBS.W
Differential Revision: https://reviews.llvm.org/D48649
llvm-svn: 336286
Thumb has more 16-bit encoding space dedicated to ADD than ORR, allowing both a
3-address encoding and a wider range of immediates. So, particularly when
optimizing for code size (but it doesn't make things worse elsewhere) it's
beneficial to select an OR operation to an ADD if we know overflow won't occur.
This is made even better by LLVM's penchant for putting operations in canonical
form by converting the other way.
llvm-svn: 335119
This patch teaches the Arm back-end to generate the SMMULR, SMMLAR and SMMLSR
instructions from equivalent IR patterns.
Differential Revision: https://reviews.llvm.org/D41775
llvm-svn: 322361
Summary:
Implement lower of unsigned saturation on an interval [0, k] where k + 1 is a power of two using USAT instruction in a similar way to how [~k, k] is lowered using SSAT on ARM models that supports it.
Patch by Marten Svanfeldt
Reviewers: t.p.northover, pbarrio, eastig, SjoerdMeijer, javed.absar, fhahn
Reviewed By: fhahn
Subscribers: fhahn, aemerson, javed.absar, llvm-commits, kristof.beyls
Differential Revision: https://reviews.llvm.org/D41348
llvm-svn: 321164
Summary:
This fixes PR35221.
Use pseudo-instructions to let MachineCSE hoist global address computation.
Subscribers: aemerson, javed.absar, kristof.beyls, llvm-commits, hiraditya
Differential Revision: https://reviews.llvm.org/D39871
llvm-svn: 318081
This change allows the pc to be used as a destination register for the
pseudo instruction LDR pc,=expression . The pseudo instruction must not be
transformed into a MOV, but it can use the Thumb2 LDR (literal) instruction
to a constant pool entry. See (A7.7.43 from ARMv7M ARM ARM).
Differential Revision: https://reviews.llvm.org/D34751
llvm-svn: 307640
Doing this means that if an LEApcrel is used in two places we will rematerialize
instead of generating two MOVs. This is particularly useful for printfs using
the same format string, where we want to generate an address into a register
that's going to get corrupted by the call.
Differential Revision: https://reviews.llvm.org/D32858
llvm-svn: 303054
Recently support was added for substituting one intruction for another by
negating or inverting the immediate, but ORR and ORN were missed so this patch
adds them.
This one is slightly different to the others in that ORN only exists in thumb,
so we only do the substitution in thumb.
Differential Revision: https://reviews.llvm.org/D32534
llvm-svn: 302224
Added the integer data processing intrinsics from ACLE v2.1 Chapter 9
but I have missed out the saturation_occurred intrinsics for now. For
the instructions that read and write the GE bits, a chain is included
and the only instruction that reads these flags (sel) is only
selectable via the implemented intrinsic.
Differential Revision: https://reviews.llvm.org/D32281
llvm-svn: 302126
The hardware div feature refers only to Thumb, but because of its name
it is tempting to use it to check for hardware division in general,
which may cause problems in ARM mode. See https://reviews.llvm.org/D32005.
This patch adds "Thumb" to its name, to make its scope clear. One
notable place where I haven't made the change is in the feature flag
(used with -mattr), which is still hwdiv. Changing it would also require
changes in a lot of tests, including clang tests, and it doesn't seem
like it's worth the effort.
Differential Revision: https://reviews.llvm.org/D32160
llvm-svn: 300827
- we are now using immediate AsmOperands so that the range check functions are
tablegen'ed.
- Big bonus is that error messages become much more accurate, i.e. instead of a
useless "invalid operand" error message it will not say that the immediate
operand must in range [x,y], which is why regression tests needed updating.
More tablegen operand descriptions could probably benefit from using
immediateAsmOperand, but this is a first good step to get rid of most of the
nearly identical range check functions. I will address the remaining immediate
operands in next clean ups.
Differential Revision: https://reviews.llvm.org/D31333
llvm-svn: 299358
Summary:
To support negative immediates for certain arithmetic instructions, the
instruction is converted to the inverse instruction with a negated (or inverted)
immediate. For example, "ADD r0, r1, #FFFFFFFF" cannot be encoded as an ADD
instruction. However, "SUB r0, r1, #1" is equivalent.
These conversions are different from instruction aliases. An alias maps
several assembler instructions onto one encoding. A conversion, however, maps
an *invalid* instruction--e.g. with an immediate that cannot be represented in
the encoding--to a different (but equivalent) instruction.
Several instructions with negative immediates were being converted already, but
this was not systematically tested, nor did it cover all instructions.
This patch implements all possible substitutions for ARM, Thumb1 and
Thumb2 assembler and adds tests. It also adds a feature flag
(-mattr=+no-neg-immediates) to turn these substitutions off. This is
helpful for users who want their code to assemble to exactly what they
wrote.
Reviewers: t.p.northover, rovka, samparker, javed.absar, peter.smith, rengolin
Reviewed By: javed.absar
Subscribers: aadg, aemerson, llvm-commits
Differential Revision: https://reviews.llvm.org/D30571
llvm-svn: 298380
Enable the selection of the 64-bit signed multiply accumulate
instructions which operate on 16-bit operands. These are enabled for
ARMv5TE onwards for ARM and for V6T2 and other DSP enabled Thumb
architectures.
Differential Revision: https://reviews.llvm.org/D30044
llvm-svn: 297809
Create nodes for smulwb and smulwt and move their selection from
DAGToDAG to DAG combine. smlawb and smlawt can then be selected
using tablegen. Added some helper functions to detect shift patterns
as well as a wrapper around SimplifyDemandBits. Added a couple of
extra tests.
Differential Revision: https://reviews.llvm.org/D30708
llvm-svn: 297716
Currently we handle this correctly in arm, but in thumb we don't which leads to
an unpredictable instruction being emitted for LSL #0 in an IT block and SP not
being permitted in some cases when it should be.
For the thumb2 LSL we can handle this by making LSL #0 an alias of MOV in the
.td file, but for thumb1 we need to handle it in checkTargetMatchPredicate to
get the IT handling right. We also need to adjust the handling of
MOV rd, rn, LSL #0 to avoid generating the 16-bit encoding in an IT block. We
should also adjust it to allow SP in the same way that it is allowed in
MOV rd, rn, but I haven't done that here because it looks like it would take
quite a lot of work to get right.
Additionally correct the selection of the 16-bit shift instructions in
processInstruction, where it was checking if the two registers were equal when
it should have been checking if they were low. It appears that previously this
code was never executed and the 16-bit encoding was selected by default, but
the other changes I've done here have somehow made it start being used.
Differential Revision: https://reviews.llvm.org/D30294
llvm-svn: 296342
This patch adds missing sched classes for Thumb2 instructions.
This has been missing so far, and as a consequence, machine
scheduler models for individual sub-targets have tended to
be larger than they needed to be. These patches should help
write schedulers better and faster in the future
for ARM sub-targets.
Reviewer: Diana Picus
Differential Revision: https://reviews.llvm.org/D29953
llvm-svn: 295811
PC isn't allowed in the source operand of t2MOVr, so change the register class
to one without PC. SP handling is slightly trickier and changes depending on if
we're in ARMv8, so do that in checkTargetMatchPredicate.
Differential Revision: https://reviews.llvm.org/D30199
llvm-svn: 295732
Removed the HasT2ExtractPack feature and replaced its references
with HasDSP. This then allows the Thumb2 extend instructions to be
selected for ARMv8M +dsp. These instruction descriptions have also
been refactored and more target tests have been added for their isel.
Differential Revision: https://reviews.llvm.org/D29623
llvm-svn: 295452
This implements execute-only support for ARM code generation, which
prevents the compiler from generating data accesses to code sections.
The following changes are involved:
* Add the CodeGen option "-arm-execute-only" to the ARM code generator.
* Add the clang flag "-mexecute-only" as well as the GCC-compatible
alias "-mpure-code" to enable this option.
* When enabled, literal pools are replaced with MOVW/MOVT instructions,
with VMOV used in addition for floating-point literals. As the MOVT
instruction is required, execute-only support is only available in
Thumb mode for targets supporting ARMv8-M baseline or Thumb2.
* Jump tables are placed in data sections when in execute-only mode.
* The execute-only text section is assigned section ID 0, and is
marked as unreadable with the SHF_ARM_PURECODE flag with symbol 'y'.
This also overrides selection of ELF sections for globals.
llvm-svn: 289784
The version of this instruction with the .w suffix already correctly accepts
this, but the alias without the .w did not.
Differential Revision: https://reviews.llvm.org/D26499
llvm-svn: 286446
The changes made in r269352, r269353 and r269354 to support the
transformation of the ldr rd,=immediate to mov introduced a regression
from 3.8 (ldr.w rd, =immediate) not supported.
This change puts support back in for ldr.w by means of a t2InstAlias for
the .w form. The .w is ignored in ARM state and propagated to the ldr in
Thumb2.
llvm-svn: 281319
descriptions now tag add instructions, and the Hexagon backend is using this to
identify loop induction statements.
Patch by Sam Parker and Sjoerd Meijer.
Differential Revision: https://reviews.llvm.org/D23601
llvm-svn: 281304
Created a Thumb2 predicated pattern matcher that uses Thumb2 and
HasT2ExtractPack and used it to redefine the patterns for sxta{b|h}
and uxta{b|h}. Also used the similar patterns to fill in isel pattern
gaps for the corresponding instructions in the ARM backend.
The patch is mainly changes to tests since most of this functionality
appears not to have been tested.
Differential Revision: https://reviews.llvm.org/D23273
llvm-svn: 278207
Added (sra (shl x, 16), 16) to the sext_16_node PatLeaf for ARM to
simplify some pattern matching. This has allowed several patterns
for smul* and smla* to be removed as well as making it easier to add
the matching for the corresponding instructions for Thumb2 targets.
Also added two Pat classes that are predicated on Thumb2 with the
hasDSP flag and UseMulOps flags. Updated the smul codegen test with
the wider range of patterns plus the ThumbV6 and ThumbV6T2 targets.
Differential Revision: https://reviews.llvm.org/D22908
llvm-svn: 277450
Summary:
Commit 276701 requires that targets have the DSP extensions to use
certain saturating instructions. This requires some corrections.
For ARM ISA the instructions in question are available in all v6*
architectures.
For Thumb2, the instructions in question are available from v6T2.
SSAT and USAT are part of the base architecture while SSAT16 and
USAT16 require the DSP extensions.
Reviewers: rengolin
Subscribers: aemerson, rengolin, samparker, llvm-commits
Differential Revision: https://reviews.llvm.org/D23010
llvm-svn: 277439
This option, compatible with gas's -mimplicit-it, controls the
generation/checking of implicit IT blocks in ARM/Thumb assembly.
This option allows two behaviours that were not possible before:
- When in ARM mode, emit a warning when assembling a conditional
instruction that is not in an IT block. This is enabled with
-mimplicit-it=never and -mimplicit-it=thumb.
- When in Thumb mode, automatically generate IT instructions when an
instruction with a condition code appears outside of an IT block. This
is enabled with -mimplicit-it=thumb and -mimplicit-it=always.
The default option is -mimplicit-it=arm, which matches the existing
behaviour (allow conditional ARM instructions outside IT blocks without
warning, and error if a conditional Thumb instruction is outside an IT
block).
The general strategy for generating IT blocks in Thumb mode is to keep a
small list of instructions which should be in the IT block, and only
emit them when we encounter something in the input which means we cannot
continue the block. This could be caused by:
- A non-predicable instruction
- An instruction with a condition not compatible with the IT block
- The IT block already contains 4 instructions
- A branch-like instruction (including ALU instructions with the PC as
the destination), which cannot appear in the middle of an IT block
- A label (branching into an IT block is not legal)
- A change of section, architecture, ISA, etc
- The end of the assembly file.
Some of these, such as change of section and end of file, are parsed
outside of the ARM asm parser, so I've added a new virtual function to
AsmParser to ensure any previously-parsed instructions have been
emitted. The ARM implementation of this flushes the currently pending IT
block.
We now have to try instruction matching up to 3 times, because we cannot
know if the current IT block is valid before matching, and instruction
matching changes depending on the IT block state (due to the 16-bit ALU
instructions, which set the flags iff not in an IT block). In the common
case of not having an open implicit IT block and the instruction being
matched not needing one, we still only have to run the matcher once.
I've removed the ITState.FirstCond variable, because it does not store
any information that isn't already represented by CurPosition. I've also
updated the comment on CurPosition to accurately describe it's meaning
(which this patch doesn't change).
Differential Revision: https://reviews.llvm.org/D22760
llvm-svn: 276747
The saturation instructions appeared in v6T2, with DSP extensions, but they
were being accepted / generated on any, with the new introduction of the
saturation detection in the back-end. This commit restricts the usage to
DSP-enable only cores.
Fixes PR28607.
llvm-svn: 276701
Follow up to r276624. Changes bits 22-20 to be parameters to
instruction class.
Differential Revision: https://reviews.llvm.org/D22562
llvm-svn: 276626
Recommitting after r274347 was reverted. This patch introduces some
classes to refactor the 3 and 4 register Thumb2 multiplication
instruction descriptions, plus improved tests for some of those
instructions.
Differential Revision: https://reviews.llvm.org/D21929
llvm-svn: 275979
Immediate branch targets aren't commonly used, but if they are we should make
sure they can actually be encoded. This means they must be divisible by 2 when
targeting Thumb mode, and by 4 when targeting ARM mode.
Also do a little naming cleanup while I was changing everything around anyway.
llvm-svn: 275116
No functional changes. Just created wrapper classes around the 3
and 4 reg mult and mac instruction classes.
Differential Revision: http://reviews.llvm.org/D21549
llvm-svn: 274347
Summary:
SSAT saturates an integer, making sure that its value lies within
an interval [-k, k]. Since the constant is given to SSAT as the
number of bytes set to one, k + 1 must be a power of 2, otherwise
the optimization is not possible. Also, the select_cc must use <
and > respectively so that they define an interval.
Reviewers: mcrosier, jmolloy, rengolin
Subscribers: aemerson, rengolin, llvm-commits
Differential Revision: http://reviews.llvm.org/D21372
llvm-svn: 273581
TargetLowering and DAGToDAG are used to combine ADDC, ADDE and UMLAL
dags into UMAAL. Selection is split into the two phases because it
is easier to match the two patterns at those different times.
Differential Revision: http://http://reviews.llvm.org/D21461
llvm-svn: 273165
The MSR instructions can write to the CPSR, but we did not model this
fact, so we could emit them in the middle of IT blocks, changing the
condition flags for later instructions in the block.
The tests use two calls to llvm.write_register.i32 because it is valid
to use these instructions at the end of an IT block, which if conversion
does do in some cases. With two calls, the first clobbers the flags, so
a branch has to be used to make the second one conditional.
Differential Revision: http://reviews.llvm.org/D21139
llvm-svn: 272154
new instruction to ARM and AArch64 targets and several system registers.
Patch by: Roger Ferrer Ibanez and Oliver Stannard
Differential Revision: http://reviews.llvm.org/D20282
llvm-svn: 271670
Sam Parker