Some early revisions of the Cortex-A53 have an erratum (835769) whereby it is
possible for a 64-bit multiply-accumulate instruction in AArch64 state to
generate an incorrect result. The details are quite complex and hard to
determine statically, since branches in the code may exist in some
circumstances, but all cases end with a memory (load, store, or prefetch)
instruction followed immediately by the multiply-accumulate operation.
The safest work-around for this issue is to make the compiler avoid emitting
multiply-accumulate instructions immediately after memory instructions and the
simplest way to do this is to insert a NOP.
This patch implements such work-around in the backend, enabled via the option
-aarch64-fix-cortex-a53-835769.
The work-around code generation is not enabled by default.
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This patch removes the PBQPBuilder class and its subclasses and replaces them
with a composable constraints class: PBQPRAConstraint. This allows constraints
that are only required for optimisation (e.g. coalescing, soft pairing) to be
mixed and matched.
This patch also introduces support for target writers to supply custom
constraints for their targets by overriding a TargetSubtargetInfo method:
std::unique_ptr<PBQPRAConstraints> getCustomPBQPConstraints() const;
This patch should have no effect on allocations.
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The code already folds sign-/zero-extends, but only if they are arguments to
mul and shift instructions. This extends the code to also fold them when they
are direct inputs.
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Tiny enhancement to the address computation code to also fold sub instructions
if the rhs is constant and can be folded into the offset.
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This commit fixes an issue with sign-/zero-extending loads that was discovered
by Richard Barton.
We use now the correct load instructions for sign-extending loads to 64bit. Also
updated and added more unit tests.
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These will make it easier to test further changes to the
code generation and optimization pipelines as those are
moved to subtargets initialized with target feature and
target cpu.
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Do not eliminate the frame pointer if there is a stackmap or patchpoint in the
function. All stackmap references should be FP relative.
This fixes PR21107.
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argument of the llvm.dbg.declare/llvm.dbg.value intrinsics.
Previously, DIVariable was a variable-length field that has an optional
reference to a Metadata array consisting of a variable number of
complex address expressions. In the case of OpPiece expressions this is
wasting a lot of storage in IR, because when an aggregate type is, e.g.,
SROA'd into all of its n individual members, the IR will contain n copies
of the DIVariable, all alike, only differing in the complex address
reference at the end.
By making the complex address into an extra argument of the
dbg.value/dbg.declare intrinsics, all of the pieces can reference the
same variable and the complex address expressions can be uniqued across
the CU, too.
Down the road, this will allow us to move other flags, such as
"indirection" out of the DIVariable, too.
The new intrinsics look like this:
declare void @llvm.dbg.declare(metadata %storage, metadata %var, metadata %expr)
declare void @llvm.dbg.value(metadata %storage, i64 %offset, metadata %var, metadata %expr)
This patch adds a new LLVM-local tag to DIExpressions, so we can detect
and pretty-print DIExpression metadata nodes.
What this patch doesn't do:
This patch does not touch the "Indirect" field in DIVariable; but moving
that into the expression would be a natural next step.
http://reviews.llvm.org/D4919
rdar://problem/17994491
Thanks to dblaikie and dexonsmith for reviewing this patch!
Note: I accidentally committed a bogus older version of this patch previously.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218787 91177308-0d34-0410-b5e6-96231b3b80d8
argument of the llvm.dbg.declare/llvm.dbg.value intrinsics.
Previously, DIVariable was a variable-length field that has an optional
reference to a Metadata array consisting of a variable number of
complex address expressions. In the case of OpPiece expressions this is
wasting a lot of storage in IR, because when an aggregate type is, e.g.,
SROA'd into all of its n individual members, the IR will contain n copies
of the DIVariable, all alike, only differing in the complex address
reference at the end.
By making the complex address into an extra argument of the
dbg.value/dbg.declare intrinsics, all of the pieces can reference the
same variable and the complex address expressions can be uniqued across
the CU, too.
Down the road, this will allow us to move other flags, such as
"indirection" out of the DIVariable, too.
The new intrinsics look like this:
declare void @llvm.dbg.declare(metadata %storage, metadata %var, metadata %expr)
declare void @llvm.dbg.value(metadata %storage, i64 %offset, metadata %var, metadata %expr)
This patch adds a new LLVM-local tag to DIExpressions, so we can detect
and pretty-print DIExpression metadata nodes.
What this patch doesn't do:
This patch does not touch the "Indirect" field in DIVariable; but moving
that into the expression would be a natural next step.
http://reviews.llvm.org/D4919
rdar://problem/17994491
Thanks to dblaikie and dexonsmith for reviewing this patch!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218778 91177308-0d34-0410-b5e6-96231b3b80d8
The A64 instruction set includes a generic register syntax for accessing
implementation-defined system registers. The syntax for these registers is:
S<op0>_<op1>_<CRn>_<CRm>_<op2>
The encoding space permitted for implementation-defined system registers
is:
op0 op1 CRn CRm op2
11 xxx 1x11 xxxx xxx
The full encoding space can now be accessed:
op0 op1 CRn CRm op2
xx xxx xxxx xxxx xxx
This is useful to anyone needing to write assembly code supporting new
system registers before the assembler has learned the official names for
them.
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Summary: The natual vector cast node (similar to bitcast) AArch64ISD::NVCAST
was introduced in r217159 and r217138. This patch adds a missing cast from
v2f32 to v1i64 which is causing some compilation failures. Also added test
cases to cover various modimm types and BUILD_VECTORs with i64 elements.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218751 91177308-0d34-0410-b5e6-96231b3b80d8
Note: This version fixed an issue with the TBZ/TBNZ instructions that were
generated in FastISel. The issue was that the 64bit version of TBZ (TBZX)
automagically sets the upper bit of the immediate field that is used to specify
the bit we want to test. To test for any of the lower 32bits we have to first
extract the subregister and use the 32bit version of the TBZ instruction (TBZW).
Original commit message:
Teach selectBranch to fold bit test and branch into a single instruction (TBZ or
TBNZ).
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The sign-/zero-extension of the loaded value can be performed by the memory
instruction for free. If the result of the load has only one use and the use is
a sign-/zero-extend, then we emit the proper load instruction. The extend is
only a register copy and will be optimized away later on.
Other instructions that consume the sign-/zero-extended value are also made
aware of this fact, so they don't fold the extend too.
This fixes rdar://problem/18495928.
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Factor out the code that determines the implicit scale factor of memory
operations for a given value type.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218652 91177308-0d34-0410-b5e6-96231b3b80d8
Primarily refines all of the instructions with accurate latency
and micro-op information. Refinements largely focus on the NEON
instructions.
Additionally, a few advanced features are modeled, including
forwarding for MAC instructions and hazards for floating point SQRT
and DIV.
Lastly, the issue-width is reduced to three so that the scheduler
will better accommodate the narrower decode and dispatch width.
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This patch improves the target-specific cost model to better handle signed
division by a power of two. The immediate result is that this enables the SLP
vectorizer to do a better job.
http://reviews.llvm.org/D5469
PR20714
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e.g., add w1, w2, w3, lsl #(2 - 1)
This sort of thing comes up in pre-processed assembly playing macro games.
Still validate that it's an assembly time constant. The early exit error check
was just a bit overzealous and disallowed a left paren.
rdar://18430542
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Fix a null pointer dereference when trying to swap the endianness of
fixups in the .eh_frame section in the AArch64 backend.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218311 91177308-0d34-0410-b5e6-96231b3b80d8
Shift-left immediate with sign-/zero-extensions also works for boolean values.
Update the assert and the test cases to reflect that fact.
This should fix a bug found by Chad.
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When looking through sign/zero-extensions the code would always assume there is
such an extension instruction and use the wrong operand for the address.
There was also a minor issue in the handling of 'AND' instructions. I
accidentially used a 'cast' instead of a 'dyn_cast'.
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When folding the intrinsic flag into the branch or select we also have to
consider the fact if the intrinsic got simplified, because it changes the
flag we have to check for.
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Small optimization in 'simplifyAddress'. When the offset cannot be encoded in
the load/store instruction, then we need to materialize the address manually.
The add instruction can encode a wider range of immediates than the load/store
instructions. This change tries to fold the offset into the add instruction
first before materializing the offset in a register.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218031 91177308-0d34-0410-b5e6-96231b3b80d8
The 'AND' instruction could be used to mask out the lower 32 bits of a register.
If this is done inside an address computation we might be able to fold the
instruction into the memory instruction itself.
and x1, x1, #0xffffffff ---> ldrb x0, [x0, w1, uxtw]
ldrb x0, [x0, x1]
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Emit an optimized instruction sequence for sdiv by power-of-2 depending on the
exact flag.
This fixes rdar://problem/18224511.
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Try to fold the multiply into the add/sub or logical operations (when
possible).
This is related to rdar://problem/18369687.
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Teach 'computeAddress' to also fold multiplies into the address computation
(when possible).
This fixes rdar://problem/18369443.
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This takes advanatage of the CBZ and CBNZ instruction to further optimize the
common null check pattern into a single instruction.
This is related to rdar://problem/18358882.
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This adds the last two missing floating-point condition codes (FCMP_UEQ and
FCMP_ONE) also to the branch selection. In these two cases an additonal branch
instruction is required.
This also adds unit tests to checks all the different condition codes.
This is related o rdar://problem/18358882.
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This required a new hook called hasLoadLinkedStoreConditional to know whether
to expand atomics to LL/SC (ARM, AArch64, in a future patch Power) or to
CmpXchg (X86).
Apart from that, the new code in AtomicExpandPass is mostly moved from
X86AtomicExpandPass. The main result of this patch is to get rid of that
pass, which had lots of code duplicated with AtomicExpandPass.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217928 91177308-0d34-0410-b5e6-96231b3b80d8
Allow handling of vectors during return lowering at least for little endian machines.
This was restricted in r208200 to fix it for big endian machines (according to
the comment), but it also disabled it for little endian too.
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