Commit Graph

2084 Commits

Author SHA1 Message Date
Craig Topper 56b33391d3 [SelectionDAG] Move ISD:PARITY formation from DAGCombine to SimplifyDemandedBits.
Previously, we formed ISD::PARITY by looking for (and (ctpop X), 1)
but the AND might be separated from the ctpop. For example if the
parity result is multiplied by 2, we'll pull the AND through the
shift.

So to handle more cases, move to SimplifyDemandedBits where we
can handle more cases that result in only the LSB of the CTPOP
being used.
2020-09-13 21:04:13 -07:00
Simon Pilgrim d816499f95 [KnownBits] Move SelectionDAG::computeKnownBits ISD::ABS handling to KnownBits::abs
Move the ISD::ABS handling to a KnownBits::abs handler, to simplify future implementations in ValueTracking/GlobalISel.
2020-09-09 13:22:58 +01:00
Simon Wallis 79ea83e104 [SelectionDAG] memcpy expansion of const volatile struct ignores const zero
In getMemcpyLoadsAndStores(), a memcpy where the source is a zero constant is expanded to a MemOp::Set instead of a MemOp::Copy, even when the memcpy is volatile.
This is incorrect.

The fix is to add a check for volatile, and expand to MemOp::Copy in the volatile case.

Reviewed By: chill

Differential Revision: https://reviews.llvm.org/D87134
2020-09-07 13:22:09 +01:00
Jay Foad 5350e1b509 [KnownBits] Implement accurate unsigned and signed max and min
Use the new implementation in ValueTracking, SelectionDAG and
GlobalISel.

Differential Revision: https://reviews.llvm.org/D87034
2020-09-07 09:09:01 +01:00
David Sherwood 73a3d350a4 [SVE][CodeGen] Fix up warnings in sve-split-insert/extract tests
I have fixed up some more ElementCount/TypeSize related warnings in
the following tests:

  CodeGen/AArch64/sve-split-extract-elt.ll
  CodeGen/AArch64/sve-split-insert-elt.ll

In SelectionDAG::CreateStackTemporary we were relying upon the implicit
cast from TypeSize -> uint64_t when calling MachineFrameInfo::CreateStackObject.
I've fixed this by passing in the known minimum size instead, which I
believe is fine because the associated stack id indicates whether this
is a scalable object or not.

I've also fixed up a case in TargetLowering::SimplifyDemandedBits when
extracting a vector element from a scalable vector. The result is a scalar,
hence it wasn't caught at the start of the function. If the vector is
scalable we just bail out for now.

Differential Revision: https://reviews.llvm.org/D86431
2020-09-04 09:51:31 +01:00
Simon Pilgrim 1673a08044 SelectionDAG.h - remove unnecessary FunctionLoweringInfo.h include. NFCI.
Use forward declarations and move the include down to dependent files that actually use it.

This also exposes a number of implicit dependencies on KnownBits.h
2020-09-03 18:33:25 +01:00
Matt Arsenault 759482ddaa GlobalISel: Implement computeKnownBits for G_BSWAP and G_BITREVERSE 2020-09-01 12:49:57 -04:00
David Sherwood 9fbb113247 [SVE][CodeGen] Fix TypeSize/ElementCount related warnings in sve-split-load.ll
I have fixed up a number of warnings resulting from TypeSize -> uint64_t
casts and calling getVectorNumElements() on scalable vector types. I
think most of the changes are fairly trivial except for those in
DAGTypeLegalizer::SplitVecRes_MLOAD I've tried to ensure we create
the MachineMemoryOperands in a sensible way for scalable vectors.

I have added a CHECK line to the following test:

  CodeGen/AArch64/sve-split-load.ll

that ensures no new warnings are added.

Differential Revision: https://reviews.llvm.org/D86697
2020-09-01 07:47:59 +01:00
Paul Walker 73ac3c0ede [SVE] Lower scalable vector ISD::FNEG operations.
Also updates isConstOrConstSplatFP to allow the mul(A,-1) -> neg(A)
transformation when -1 is expressed as an ISD::SPLAT_VECTOR.

Differential Revision: https://reviews.llvm.org/D86415
2020-08-25 11:22:28 +01:00
David Sherwood 88bbd30736 [SVE][CodeGen] Fix issues with EXTRACT_SUBVECTOR when using scalable FP vectors
In this patch I have fixed two issues:

1. Our SVE tuple get/set intrinsics were using the wrong constant type
for the index passed to EXTRACT_SUBVECTOR. I have fixed this by using the
function SelectionDAG::getVectorIdxConstant to create the value. Also, I
have updated the documentation for EXTRACT_SUBVECTOR describing what type
the constant index should be and we now enforce this when creating the
node.
2. The AArch64 backend was missing the appropriate patterns for
extracting certain subvectors (nxv4f16 and nxv2f32) from legal SVE types.
I have added them as part of this patch.

The only way that I could find to test the new patterns was to use the
SVE tuple get intrinsics, although I realise it looks a bit unusual.
Tests added here:

  test/CodeGen/AArch64/sve-extract-subvector.ll

Differential Revision: https://reviews.llvm.org/D85516
2020-08-12 08:35:46 +01:00
Kerry McLaughlin 455ed56d48 [SVE][CodeGen] Legalisation of INSERT_VECTOR_ELT for scalable vectors
When the result type of insertelement needs to be split,
SplitVecRes_INSERT_VECTOR_ELT will try to store the vector to a
stack temporary, store the element at the location of the stack
temporary plus the index, and reload the Lo/Hi parts.

This patch does the following to ensure this works for scalable vectors:
 - Sets the StackID with getStackIDForScalableVectors() in CreateStackTemporary
 - Adds an IsScalable flag to getMemBasePlusOffset() and scales the
    offset by VScale when this is true
 - Ensures the immediate is clamped correctly by clampDynamicVectorIndex
    so that we don't try to use an out of range index

Reviewed By: david-arm

Differential Revision: https://reviews.llvm.org/D84874
2020-08-11 12:57:28 +01:00
Kerry McLaughlin 85c7e89f3b [CodeGen] Refactor getMemBasePlusOffset & getObjectPtrOffset to accept a TypeSize
Changes the Offset arguments to both functions from int64_t to TypeSize
& updates all uses of the functions to create the offset using TypeSize::Fixed()

Reviewed By: efriedma

Differential Revision: https://reviews.llvm.org/D85220
2020-08-11 12:17:10 +01:00
Simon Pilgrim 66a163f328 [DAG] GetDemandedBits - remove custom AND handling.
As mentioned on D85463, we should be using SimplifyMultipleUseDemandedBits (which is the default fallback).

The minor regression in illegal-bitfield-loadstore.ll will be addressed properly by D77804.
2020-08-07 12:55:47 +01:00
Simon Pilgrim fcefb53222 Remove unreachable break. NFC 2020-08-07 12:37:49 +01:00
Paul Walker 0d33a8ef5b [SVE] Lower scalable vector mul operations.
This allows us to remove extra patterns from AArch64SVEInstrInfo.td
because we can reuse those required for fixed length vectors.

Differential Revision: https://reviews.llvm.org/D85328
2020-08-06 11:15:35 +01:00
Eli Friedman 4a47f1c4ce [SelectionDAG][SVE] Support scalable vectors in getConstantFP()
Differential Revision: https://reviews.llvm.org/D85249
2020-08-04 15:32:43 -07:00
Matt Arsenault 57bd64ff84 Support addrspacecast initializers with isNoopAddrSpaceCast
Moves isNoopAddrSpaceCast to the TargetMachine. It logically belongs
with the DataLayout.
2020-07-31 10:42:43 -04:00
Simon Pilgrim b4b6e77454 [DAG] isSplatValue - add support for TRUNCATE/SIGN_EXTEND/ZERO_EXTEND
These are just pass-throughs to the source operand - we can't assume that ANY_EXTEND(splat) will still be a splat though.
2020-07-28 19:56:11 +01:00
Paul Walker 6e198aae1d [SelectionDAG] Prevent warnings when extracting fixed length vector from scalable.
ComputeNumSignBits and computeKnownBits both trigger "Scalable flag
may be dropped" warnings when a fixed length vector is extracted
from a scalable vector.  This patch assumes nothing about the
demanded elements thus matching the behaviour when extracting a
scalable vector from a scalable vector.

Differential Revision: https://reviews.llvm.org/D83642
2020-07-14 11:12:56 +00:00
David Sherwood 229dfb4728 [CodeGen] Replace calls to getVectorNumElements() in SelectionDAG::SplitVector
This patch replaces some invalid calls to getVectorNumElements() with calls
to getVectorMinNumElements() instead, since the code paths changed in this
patch work for both fixed and scalable vector types.

Fixes warnings in this test:

  sve-sext-zext.ll

Differential Revision: https://reviews.llvm.org/D83203
2020-07-10 08:11:30 +01:00
Lucas Prates fc39a9ca0e [CodeGen] Matching promoted type for 16-bit integer bitcasts from fp16 operand
Summary:
When legalizing a biscast operation from an fp16 operand to an i16 on a
target that requires both input and output types to be promoted to
32-bits, an assertion can fail when building the new node due to a
mismatch between the the operation's result size and the type specified to
the node.

This patches fix the issue by making sure the bit width of the types
match for the FP_TO_FP16 node, covering the difference with an extra
ANYEXTEND operation.

Reviewers: ostannard, efriedma, pirama, jmolloy, plotfi

Reviewed By: efriedma

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D82552
2020-07-09 09:46:17 +01:00
Kerry McLaughlin 5e8084beba [SVE][CodeGen] Legalisation of unpredicated load instructions
Summary:
When splitting a load of a scalable type, the new address is
calculated in SplitVecRes_LOAD using a vscale and an add instruction.

This patch also adds a DAG combiner fold to visitADD for vscale:
 - Fold (add (vscale(C0)), (vscale(C1))) to (add (vscale(C0 + C1)))

Reviewers: sdesmalen, efriedma, david-arm

Reviewed By: david-arm

Subscribers: tschuett, hiraditya, rkruppe, psnobl, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D82792
2020-07-07 11:05:03 +01:00
Simon Pilgrim 56a8a5c9fe [DAG] matchBinOpReduction - match subvector reduction patterns beyond a matched shufflevector reduction
Currently matchBinOpReduction only handles shufflevector reduction patterns, but in many cases these only occur in the final stages of a reduction, once we're down to legal vector widths.

Before this its likely that we are performing reductions using subvector extractions to repeatedly split the source vector in half and perform the binop on the halves.

Assuming we've found a non-partial reduction, this patch continues looking for subvector reductions as far as it can beyond the last shufflevector.

Fixes PR37890
2020-07-04 15:28:15 +01:00
Guillaume Chatelet c1cd61e02a [Alignment][NFC] Migrate SelectionDAGTargetInfo::EmitTargetCodeForMemcpy to Align
This 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

Differential Revision: https://reviews.llvm.org/D82849
2020-06-30 13:12:31 +00:00
Guillaume Chatelet 306d7c6929 [Alignment][NFC] Migrate SelectionDAGTargetInfo::EmitTargetCodeForMemmove to Align
This 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

Differential Revision: https://reviews.llvm.org/D82850
2020-06-30 12:46:59 +00:00
Guillaume Chatelet 6a6af30d43 [Alignment][NFC] Migrate SelectionDAGTargetInfo::EmitTargetCodeForMemset to Align
This 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

Differential Revision: https://reviews.llvm.org/D82851
2020-06-30 12:46:26 +00:00
David Sherwood c02332a693 [CodeGen] Fix warning in getNode for EXTRACT_SUBVECTOR
Fix a warning in getNode() when extracting a subvector from a
concat vector. We can simply replace the call to getVectorNumElements
with getVectorMinNumElements as this follows the defined behaviour
for EXTRACT_SUBVECTOR.

Differential Revision: https://reviews.llvm.org/D82746
2020-06-30 08:11:41 +01:00
Michael Liao b1360caa82 [SDAG] Add new AssertAlign ISD node.
Summary:
- AssertAlign node records the guaranteed alignment on its source node,
  where these alignments are retrieved from alignment attributes in LLVM
  IR. These tracked alignments could help DAG combining and lowering
  generating efficient code.
- In this patch, the basic support of AssertAlign node is added. So far,
  we only generate AssertAlign nodes on return values from intrinsic
  calls.
- Addressing selection in AMDGPU is revised accordingly to capture the
  new (base + offset) patterns.

Reviewers: arsenm, bogner

Subscribers: jvesely, wdng, nhaehnle, tpr, hiraditya, kerbowa, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D81711
2020-06-23 00:51:11 -04:00
David Sherwood 9e811b0d93 [CodeGen] Fix ComputeNumSignBits for scalable vectors
When trying to calculate the number of sign bits for scalable vectors
we should just bail out for now and pretend we know nothing.

Differential Revision: https://reviews.llvm.org/D81093
2020-06-19 07:58:42 +01:00
David Sherwood 65912a9768 [CodeGen] Fix warnings in foldCONCAT_VECTORS
Instead of asserting the number of elements is the same, we should be
comparing the element counts instead. In addition, when looking at
concats of extract_subvectors it's fine to use getVectorMinNumElements()
for scalable vectors.

I discovered these warnings when compiling the structured loads tests in
this file:

  test/CodeGen/AArch64/sve-intrinsics-loads.ll

Differential Revision: https://reviews.llvm.org/D81936
2020-06-18 09:29:37 +01:00
Aaron Smith 7e01675ea5 [SelectionDAG] Add MVT::bf16 to getConstantFP()
Summary:
This was probably overlooked in recent bfloat patches.
Needed to handle bf16 constants in SelectionDAG.

  ConstantFP:bf16<APFloat(0)>

Reviewers: stuij

Reviewed By: stuij

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D81779
2020-06-16 15:10:05 -07:00
David Sherwood bd97342a0c [CodeGen] Let computeKnownBits do something sensible for scalable vectors
Until we have a real need for computing known bits for scalable
vectors I have simply changed the code to bail out for now and
pretend we know nothing. I've also fixed up some simple callers of
computeKnownBits too.

Differential Revision: https://reviews.llvm.org/D80437
2020-06-11 08:17:11 +01:00
Guillaume Chatelet e26ed6bdae Fix unused variable warning 2020-06-09 08:56:05 +00:00
David Sherwood cc8872400c [CodeGen] Ensure callers of CreateStackTemporary use sensible alignments
In two instances of CreateStackTemporary we are sometimes promoting
alignments beyond the stack alignment. I have introduced a new function
called getReducedAlign that will return the alignment for the broken
down parts of illegal vector types. For example, on NEON a <32 x i8>
type is made up of two <16 x i8> types - in this case the sensible
alignment is 16 bytes, not 32.

In the legalization code wherever we create stack temporaries I have
started using the reduced alignments instead for illegal vector types.

I added a test to

  CodeGen/AArch64/build-one-lane.ll

that tries to insert an element into an illegal fixed vector type
that involves creating a temporary stack object.

Differential Revision: https://reviews.llvm.org/D80370
2020-06-09 08:10:17 +01:00
Matt Arsenault af867b7850 DAG: Change computeKnownBitsForFrameIndex to be usable by GISel
This wasn't getting much value from the DAG or depth arguments, since
it's only called on the frame index root nodes. FrameIndexes can also
only return a scalar value, so it also didn't need DemandedElts.
2020-06-04 10:50:26 -04:00
Simon Pilgrim c438b257f1 [DAG] GetDemandedBits - don't bother asserting for a non-null cast<> result. NFC.
cast<> will assert on failure anyhow.

This lets us fold the cast<> with the getAPIntValue() that uses it.
2020-06-03 12:43:07 +01:00
Matt Arsenault 836c7dcf12 DAG: Fix getNode dropping flags if there's a glue output
The AMDGPU non-strict fdiv lowering needs to introduce an FP mode
switch in some cases, and has custom nodes to provide chain/glue for
the intermediate FP operations. We need to propagate nofpexcept here,
but getNode was dropping the flags.

Adding nofpexcept in the AMDGPU custom lowering is left to a future
patch.

Also fix a second case where flags were dropped, but in this case it
seems it just didn't handle this number of operands.

Test will be included in future AMDGPU patch.
2020-06-01 13:48:02 -04:00
Simon Pilgrim 9d0bfcec83 [SelectionDAG] ComputeNumSignBits - use Valid Min/Max shift amount helpers directly. NFCI.
We are calling getValidShiftAmountConstant first followed by getValidMinimumShiftAmountConstant/getValidMaximumShiftAmountConstant if that failed. But both are used in the same way in ComputeNumSignBits and the Min/Max variants call getValidShiftAmountConstant internally anyhow.
2020-05-30 14:02:14 +01:00
Simon Pilgrim 81b50a7823 [SelectionDAG] Remove repeated getOperand() call. NFC. 2020-05-30 10:21:36 +01:00
Paul Walker 92f3d29af0 [SelectionDAG] Update getNode asserts for EXTRACT/INSERT_SUBVECTOR.
Summary:
The description of EXTACT_SUBVECTOR and INSERT_SUBVECTOR has been
changed to accommodate scalable vectors (see ISDOpcodes.h). This
patch updates the asserts used to verify these requirements when
using SelectionDAG's getNode interface.

This patch introduces the MVT function getVectorMinNumElements
that can be used against fixed-length and scalable vectors when
only the known minimum vector length is required.

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D80709
2020-05-29 11:02:18 +00:00
David Sherwood 4265f1d23c [CodeGen] Fix warnings in getZeroExtendInReg
We should be using getVectorElementCount() to assert that two types
have the same numbers of elements. I encountered the warnings while
compiling this test:

  CodeGen/AArch64/sve-intrinsics-ld1.ll

Differential Revision: https://reviews.llvm.org/D80616
2020-05-29 11:51:07 +01:00
David Sherwood b147b88c84 [CodeGen] Add support for extracting elements of scalable vectors
I have tried to ensure that SelectionDAG and DAGCombiner do
sensible things for scalable vectors, and added support for a
limited number of simple folds. Codegen support for the vector
extract patterns have also been added to the AArch64 backend.

New vector extract tests have been added here:

  CodeGen/AArch64/sve-extract-element.ll

and I have also added new folds using inserts and extracts here:

  CodeGen/AArch64/sve-insert-element.ll

Differential Revision: https://reviews.llvm.org/D80208
2020-05-29 07:49:43 +01:00
Serge Pavlov 4d20e31f73 [FPEnv] Intrinsic llvm.roundeven
This intrinsic implements IEEE-754 operation roundToIntegralTiesToEven,
and performs rounding to the nearest integer value, rounding halfway
cases to even. The intrinsic represents the missed case of IEEE-754
rounding operations and now llvm provides full support of the rounding
operations defined by the standard.

Differential Revision: https://reviews.llvm.org/D75670
2020-05-26 19:24:58 +07:00
Arthur Eubanks 8a88755610 Reland [X86] Codegen for preallocated
See https://reviews.llvm.org/D74651 for the preallocated IR constructs
and LangRef changes.

In X86TargetLowering::LowerCall(), if a call is preallocated, record
each argument's offset from the stack pointer and the total stack
adjustment. Associate the call Value with an integer index. Store the
info in X86MachineFunctionInfo with the integer index as the key.

This adds two new target independent ISDOpcodes and two new target
dependent Opcodes corresponding to @llvm.call.preallocated.{setup,arg}.

The setup ISelDAG node takes in a chain and outputs a chain and a
SrcValue of the preallocated call Value. It is lowered to a target
dependent node with the SrcValue replaced with the integer index key by
looking in X86MachineFunctionInfo. In
X86TargetLowering::EmitInstrWithCustomInserter() this is lowered to an
%esp adjustment, the exact amount determined by looking in
X86MachineFunctionInfo with the integer index key.

The arg ISelDAG node takes in a chain, a SrcValue of the preallocated
call Value, and the arg index int constant. It produces a chain and the
pointer fo the arg. It is lowered to a target dependent node with the
SrcValue replaced with the integer index key by looking in
X86MachineFunctionInfo. In
X86TargetLowering::EmitInstrWithCustomInserter() this is lowered to a
lea of the stack pointer plus an offset determined by looking in
X86MachineFunctionInfo with the integer index key.

Force any function containing a preallocated call to use the frame
pointer.

Does not yet handle a setup without a call, or a conditional call.
Does not yet handle musttail. That requires a LangRef change first.

Tried to look at all references to inalloca and see if they apply to
preallocated. I've made preallocated versions of tests testing inalloca
whenever possible and when they make sense (e.g. not alloca related,
inalloca edge cases).

Aside from the tests added here, I checked that this codegen produces
correct code for something like

```
struct A {
        A();
        A(A&&);
        ~A();
};

void bar() {
        foo(foo(foo(foo(foo(A(), 4), 5), 6), 7), 8);
}
```

by replacing the inalloca version of the .ll file with the appropriate
preallocated code. Running the executable produces the same results as
using the current inalloca implementation.

Reverted due to unexpectedly passing tests, added REQUIRES: asserts for reland.

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D77689
2020-05-20 11:25:44 -07:00
Arthur Eubanks b8cbff51d3 Revert "[X86] Codegen for preallocated"
This reverts commit 810567dc69.

Some tests are unexpectedly passing
2020-05-20 10:04:55 -07:00
Arthur Eubanks 810567dc69 [X86] Codegen for preallocated
See https://reviews.llvm.org/D74651 for the preallocated IR constructs
and LangRef changes.

In X86TargetLowering::LowerCall(), if a call is preallocated, record
each argument's offset from the stack pointer and the total stack
adjustment. Associate the call Value with an integer index. Store the
info in X86MachineFunctionInfo with the integer index as the key.

This adds two new target independent ISDOpcodes and two new target
dependent Opcodes corresponding to @llvm.call.preallocated.{setup,arg}.

The setup ISelDAG node takes in a chain and outputs a chain and a
SrcValue of the preallocated call Value. It is lowered to a target
dependent node with the SrcValue replaced with the integer index key by
looking in X86MachineFunctionInfo. In
X86TargetLowering::EmitInstrWithCustomInserter() this is lowered to an
%esp adjustment, the exact amount determined by looking in
X86MachineFunctionInfo with the integer index key.

The arg ISelDAG node takes in a chain, a SrcValue of the preallocated
call Value, and the arg index int constant. It produces a chain and the
pointer fo the arg. It is lowered to a target dependent node with the
SrcValue replaced with the integer index key by looking in
X86MachineFunctionInfo. In
X86TargetLowering::EmitInstrWithCustomInserter() this is lowered to a
lea of the stack pointer plus an offset determined by looking in
X86MachineFunctionInfo with the integer index key.

Force any function containing a preallocated call to use the frame
pointer.

Does not yet handle a setup without a call, or a conditional call.
Does not yet handle musttail. That requires a LangRef change first.

Tried to look at all references to inalloca and see if they apply to
preallocated. I've made preallocated versions of tests testing inalloca
whenever possible and when they make sense (e.g. not alloca related,
inalloca edge cases).

Aside from the tests added here, I checked that this codegen produces
correct code for something like

```
struct A {
        A();
        A(A&&);
        ~A();
};

void bar() {
        foo(foo(foo(foo(foo(A(), 4), 5), 6), 7), 8);
}
```

by replacing the inalloca version of the .ll file with the appropriate
preallocated code. Running the executable produces the same results as
using the current inalloca implementation.

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D77689
2020-05-20 09:20:38 -07:00
David Sherwood fb1c55b57d [CodeGen] Fix FoldConstantVectorArithmetic for scalable vectors
For now I have changed FoldConstantVectorArithmetic to return early
if we encounter a scalable vector, since the subsequent code assumes
you can perform lane-wise constant folds. However, in future work we
should be able to extend this to look at splats of a constant value
and fold those if possible. I have also added the same code to
FoldConstantArithmetic, since that deals with vectors too.

The warnings I fixed in this patch were being generated by this
existing test:

  CodeGen/AArch64/sve-int-arith.ll

Differential Revision: https://reviews.llvm.org/D79421
2020-05-15 14:58:44 +01:00
David Sherwood 8ce4a8f6df [CodeGen] Refactor CreateStackTemporary
I've created a new variant of CreateStackTemporary that takes
TypeSize and Align arguments, and made the older instances of
CreateStackTemporary call this new function. This refactoring is
in preparation for more patches in this area related to scalable
vectors and improving the alignment calculations.

Differential Revision: https://reviews.llvm.org/D79933
2020-05-15 07:29:13 +01:00
Simon Pilgrim 80715b7124 SelectionDAG.cpp - remove non-constant EXTRACT_SUBVECTOR/INSERT_SUBVECTOR handling. NFC.
Now that D79814 has landed, we can assume that subvector ops use constant, in-range indices.
2020-05-14 13:23:00 +01:00
Eric Christopher bfa200ebcf Remove an unused variable. 2020-05-13 15:13:02 -07:00
Eli Friedman ed428c429e [SelectionDAG] Require constant index for INSERT/EXTRACT_SUBVECTOR.
It sounds like an interesting idea in theory, but nothing is actually
taking advantage of it, and specifying/implementing the edge cases is
painful. So just forbid it.

Differential Revision: https://reviews.llvm.org/D79814
2020-05-13 13:08:59 -07:00
David Sherwood 42c7a6d52b [CodeGen] Fix incorrect uses of getVectorNumElements()
I have fixed up some places in SelectionDAG::getNode() where we
used to assert that the number of vector elements for two types
are the same. I have changed such cases to assert that the
element counts are the same instead. I've added new tests that
exercise the code paths for all the truncations. All the extend
operations are covered by this existing test:

  CodeGen/AArch64/sve-sext-zext.ll

For the ISD::SETCC case I fixed this code path is exercised by
these existing tests:

  CodeGen/AArch64/sve-fcmp.ll
  CodeGen/AArch64/sve-intrinsics-int-compares-with-imm.ll

Differential Revision: https://reviews.llvm.org/D79399
2020-05-12 07:50:37 +01:00
Craig Topper d1119980e5 [SelectionDAG] Use Align/MaybeAlign for ConstantPoolSDNode.
This patch stores the alignment for ConstantPoolSDNode as an
Align and updates the getConstantPool interface to take a MaybeAlign.

Removing getAlignment() will be done as a follow up.

Differential Revision: https://reviews.llvm.org/D79436
2020-05-08 16:04:11 -07:00
David Sherwood cd3a54c55a [CodeGen] Fix warnings due to SelectionDAG::getSplatSourceVector
Summary:
I have fixed several places in getSplatSourceVector and isSplatValue
to work correctly with scalable vectors. I added new support for
the ISD::SPLAT_VECTOR DAG node as one of the obvious cases we can
support with scalable vectors. In other places I have tried to do
the sensible thing, such as bail out for vector types we don't yet
support or don't intend to support.

It's not possible to add IR test cases to cover these changes, since
they are currently only ever exercised on certain targets, e.g.
only X86 targets use the result of getSplatSourceVector. I've
assumed that X86 tests already exist to test these code paths for
fixed vectors. However, I have added some AArch64 unit tests that
test the specific functions I have changed.

Differential revision: https://reviews.llvm.org/D79083
2020-05-05 08:45:41 +01:00
David Sherwood 058cd8c5be [CodeGen] Add support for inserting elements into scalable vectors
Summary:
This patch tries to ensure that we do something sensible when
generating code for the ISD::INSERT_VECTOR_ELT DAG node when operating
on scalable vectors. Previously we always returned 'undef' when
inserting an element into an out-of-bounds lane index, whereas now
we only do this for fixed length vectors. For scalable vectors it
is assumed that the backend will do the right thing in the same way
that we have to deal with variable lane indices.

In this patch I have permitted a few basic combinations for scalable
vector types where it makes sense, but in general avoided most cases
for now as they currently require the use of BUILD_VECTOR nodes.

This patch includes tests for all scalable vector types when inserting
into lane 0, but I've only included one or two vector types for other
cases such as variable lane inserts.

Differential Revision: https://reviews.llvm.org/D78992
2020-04-30 11:14:04 +01:00
David Sherwood 096b25a8d8 [CodeGen] Use SPLAT_VECTOR for zeroinitialiser with scalable types
Summary:
When generating code for the LLVM IR zeroinitialiser operation, if
the vector type is scalable we should be using SPLAT_VECTOR instead
of BUILD_VECTOR.

Differential Revision: https://reviews.llvm.org/D78636
2020-04-27 15:57:59 +01:00
aartbik 907871d9ad [llvm] [CodeGen] Fixed vector halving bug for masked load
Summary:
Given a VL=14 that is enveloped by a proper VL=16, splitting the
masked load using the enveloping halving VL=8/8 should yields
should eventually yield V=8/5. This fixes various assert failures
in getHalfNumVectorElementsVT() and IncrementMemoryAddress().

Note, I suspect similar fixes will be needed for other masked
operations, but for now I send out a fix for masked load only.

Bugzilla issue 45563
https://bugs.llvm.org/show_bug.cgi?id=45563

Reviewers: craig.topper, mehdi_amini, nicolasvasilache

Reviewed By: craig.topper

Subscribers: hiraditya, dmgreen, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D78608
2020-04-23 15:12:44 -07:00
Jay Foad c63aed890e [KnownBits] Move AND, OR and XOR logic into KnownBits
Summary:
There are at least three clients for KnownBits calculations:
ValueTracking, SelectionDAG and GlobalISel. To reduce duplication the
common logic should be moved out of these clients and into KnownBits
itself.

This patch does this for AND, OR and XOR calculations by implementing
and using appropriate operator overloads KnownBits::operator& etc.

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D74060
2020-04-09 10:10:37 +01:00
Craig Topper c41685b16f [SelectionDAG] Make getZeroExtendInReg take a vector VT if the operand VT is a vector.
This removes a call to getScalarType from a bunch of call sites.
It also makes the behavior consistent with SIGN_EXTEND_INREG.

Differential Revision: https://reviews.llvm.org/D77631
2020-04-07 11:34:08 -07:00
Simon Pilgrim b02c7a8152 Fix "result of 32-bit shift implicitly converted to 64 bits" MSVC warning. NFCI.
The shift of 1 by an amount that is never more than 31 means that the warning is a false positive but is safe and fixes Werror builds.
2020-04-02 12:02:04 +01:00
Guillaume Chatelet 3a78f44daf [Alignment][NFC] Convert SelectionDAG::InferPtrAlignment to MaybeAlign
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: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D77212
2020-04-01 13:22:11 +00:00
Guillaume Chatelet c7468c1696 [Alignment][NFC] Use Align in SelectionDAG::getMemIntrinsicNode
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: jholewinski, nemanjai, hiraditya, kbarton, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D77149
2020-04-01 09:32:05 +00:00
Guillaume Chatelet 998118c3d3 [Alignment][NFC] Deprecate MachineMemOperand::getMachineMemOperand version that takes an untyped alignement.
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: hiraditya, jfb, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D77138
2020-03-31 16:05:31 +00:00
Craig Topper 2a07221cf3 [SelectionDAG] Add an assert that the input VT and output VT for ISD::FREEZE are the same.
Differential Revision: https://reviews.llvm.org/D77092
2020-03-30 23:21:58 -07:00
Guillaume Chatelet bdf77209b9 [Alignment][NFC] Use Align version of getMachineMemOperand
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: jyknight, sdardis, nemanjai, hiraditya, kbarton, fedor.sergeev, asb, rbar, johnrusso, simoncook, sabuasal, niosHD, jrtc27, MaskRay, zzheng, edward-jones, atanasyan, rogfer01, MartinMosbeck, brucehoult, the_o, jfb, PkmX, jocewei, Jim, lenary, s.egerton, pzheng, sameer.abuasal, apazos, luismarques, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D77059
2020-03-30 15:46:27 +00:00
Guillaume Chatelet 01ba2ad9ef [Alignment][NFC] Provide tightened up functions in SelectionDAG, MachineFunction and MachineMemOperand
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: hiraditya, jfb, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D77046
2020-03-30 13:03:27 +00:00
Juneyoung Lee 1bcc500b48 [DAGCombine] Add basic optimizations for FREEZE in SelDag
Summary: This patch is the first effort to adding basic optimizations for FREEZE in SelDag.

Reviewers: spatel, lebedev.ri

Reviewed By: spatel

Subscribers: xbolva00, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D76707
2020-03-27 12:20:39 +09:00
Jay Foad 7cdbf1ed4b Make use of APInt::countLeadingOnes. NFC. 2020-03-23 09:08:20 +00:00
Craig Topper 498b53890d [SelectionDAGBuilder][FPEnv] Take into account SelectionDAG continuous CSE when setting the nofpexcept flag for constrained intrinsics
SelectionDAG CSEs nodes based on their result type and operands, but not their flags. The flags are expected to be intersected when they are CSEd. In SelectionDAGBuilder, for FP nodes we manage both the fast math flags and the nofpexcept flag after the nodes have already been CSEd when they were created with getNode. The management of the fastmath flags before the constrained nodes prevents the nofpexcept management from working correctly.

This commit moves the FMF handling for constrained intrinsics into their visitor and disables the common FMF handling for these nodes.

Differential Revision: https://reviews.llvm.org/D75224
2020-03-18 13:37:17 -07:00
Thomas Lively 4e589e6c26 [WebAssembly] Fix SIMD shift unrolling to avoid assertion failure
Summary:
Using the default DAG.UnrollVectorOp on v16i8 and v8i16 vectors
results in i8 or i16 nodes being inserted into the SelectionDAG. Since
those are illegal types, this causes a legalization assertion failure
for some code patterns, as uncovered by PR45178. This change unrolls
shifts manually to avoid this issue by adding and using a new optional
EVT argument to DAG.ExtractVectorElements to control the type of the
extract_element nodes.

Reviewers: aheejin, dschuff

Subscribers: sbc100, jgravelle-google, hiraditya, sunfish, zzheng, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D76043
2020-03-12 12:20:14 -07:00
Andrzej Warzynski 46b9f14d71 [AArch64][SVE] Add intrinsics for non-temporal scatters/gathers
Summary:
This patch adds the following intrinsics for non-temporal gather loads
and scatter stores:
  * aarch64_sve_ldnt1_gather_index
  * aarch64_sve_stnt1_scatter_index
These intrinsics implement the "scalar + vector of indices" addressing
mode.

As opposed to regular and first-faulting gathers/scatters, there's no
instruction that would take indices and then scale them. Instead, the
indices for non-temporal gathers/scatters are scaled before the
intrinsics are lowered to `ldnt1` instructions.

The new ISD nodes, GLDNT1_INDEX and SSTNT1_INDEX, are only used as
placeholders so that we can easily identify the cases implemented in
this patch in performGatherLoadCombine and performScatterStoreCombined.
Once encountered, they are replaced with:
  * GLDNT1_INDEX -> SPLAT_VECTOR + SHL + GLDNT1
  * SSTNT1_INDEX -> SPLAT_VECTOR + SHL + SSTNT1

The patterns for lowering ISD::SHL for scalable vectors (required by
this patch) were missing, so these are added too.

Reviewed By: sdesmalen

Differential Revision: https://reviews.llvm.org/D75601
2020-03-12 13:55:56 +00:00
Sanjay Patel 29a2b20ab3 [SDAG] simplify FP binops to undef
As discussed in the commit thread for rGa253a2a and D73978, we can do more undef folding for FP ops.
The nnan and ninf fast-math-flags specify that if an operand is the disallowed value, the result is
poison, so we can produce an undef result.

But this doesn't work as expected (the undef operand cases remain) because of a Flags propagation
problem in SelectionDAGBuilder.

I've added DAGCombiner calls to enable these for the other cases because we've shown in other
patches that (because of the limited way that SDAG iterates), it is possible to miss simplifications
like this if they are done only at node creation time.

Several potential follow-ups to expand on this patch are possible.

Differential Revision: https://reviews.llvm.org/D75576
2020-03-04 10:42:16 -05:00
Simon Pilgrim 53b597cfa2 [SelectionDAG] Merge constant SDNode arithmetic into foldConstantArithmetic
This is the second patch as part of https://bugs.llvm.org/show_bug.cgi?id=36544

Merging in the ConstantSDNode variant of FoldConstantArithmetic. After this, I will begin merging in FoldConstantVectorArithmetic

I've ensured this patch can build & pass all lit tests in Windows and Linux environments.

Patch by @justice_adams (Justice Adams)

Differential Revision: https://reviews.llvm.org/D74881
2020-02-24 18:54:22 +00:00
Craig Topper 3a6bb32bd2 [SelectionDAG] Remove ISD::LIFETIME_START/LIFETIME_END from assert in getMemIntrinsicNode.
These appear to have their own SDNode type and shouldn't use
MemIntrinsicSDNode.
2020-02-23 22:32:36 -08:00
Sanjay Patel a253a2a793 [SDAG] fold fsub -0.0, undef to undef rather than NaN
A question about this behavior came up on llvm-dev:
http://lists.llvm.org/pipermail/llvm-dev/2020-February/139003.html
...and as part of backend improvements in D73978.

We decided not to implement a more general change that would have
folded any FP binop with nearly arbitrary constant + undef operand
to undef because that is not theoretically correct (even if it is
practically correct).

This is the SDAG-equivalent to the IR change in D74713.
2020-02-23 11:36:53 -05:00
Simon Pilgrim a1585aec6f [SelectionDAG] Expose the "getValidShiftAmount" helpers available. NFCI.
These are going to be useful in TargetLowering::SimplifyDemandedBits, so expose these helpers outside of SelectionDAG.cpp

Also add an getValidShiftAmountConstant early-out to getValidMinimumShiftAmountConstant/getValidMaximumShiftAmountConstant so we can use them for scalar cases as well.
2020-02-17 16:28:46 +00:00
Jay Foad 32aac25637 [KnownBits] Introduce anyext instead of passing a flag into zext
Summary:
This was a very odd API, where you had to pass a flag into a zext
function to say whether the extended bits really were zero or not. All
callers passed in a literal true or false.

I think it's much clearer to make the function name reflect the
operation being performed on the value we're tracking (rather than on
the KnownBits Zero and One fields), so zext means the value is being
zero extended and new function anyext means the value is being extended
with unknown bits.

NFC.

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D74482
2020-02-12 19:06:53 +00:00
Guillaume Chatelet 333f2ad8b8 [Alignment][NFC] Use Align for getMemcpy/Memmove/Memset
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: arsenm, dschuff, jyknight, sdardis, nemanjai, jvesely, nhaehnle, sbc100, jgravelle-google, hiraditya, aheejin, kbarton, fedor.sergeev, asb, rbar, johnrusso, simoncook, sabuasal, niosHD, jrtc27, MaskRay, zzheng, edward-jones, atanasyan, rogfer01, MartinMosbeck, brucehoult, the_o, PkmX, jocewei, jsji, Jim, lenary, s.egerton, pzheng, sameer.abuasal, apazos, luismarques, kerbowa, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D73885
2020-02-03 17:13:19 +01:00
Guillaume Chatelet fc19465965 [Alignment][NFC] Use Align for code creating MemOp
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: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D73874
2020-02-03 14:10:30 +01:00
Guillaume Chatelet 75d9994a51 Fix broken invariant
Summary:
A Copy with a source that is zeros is the same as a Set of zeros.
This fixes the invariant that SrcAlign should always be non-null.

Reviewers: courbet

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D73791
2020-02-03 11:01:05 +01:00
Guillaume Chatelet 3c89b75f23 [NFC] Introduce a type to model memory operation
Summary: This is a first step before changing the types to llvm::Align and introduce functions to ease client code.

Reviewers: courbet

Subscribers: arsenm, sdardis, nemanjai, jvesely, nhaehnle, hiraditya, kbarton, jrtc27, atanasyan, jsji, kerbowa, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D73785
2020-01-31 17:29:01 +01:00
Wang, Pengfei 17b8f96d65 [FPEnv] Divide macro INSTRUCTION into INSTRUCTION and DAG_INSTRUCTION,
and macro FUNCTION likewise. NFCI.

Some functions like fmuladd don't really have a node, we should divide
the declaration form those have node to avoid introducing fake nodes.

Differential Revision: https://reviews.llvm.org/D72871
2020-01-27 10:38:05 +08:00
Simon Pilgrim 3daa71ee00 [SelectionDAG] ComputeNumSignBits - add DemandedElts support for MIN/MAX ops 2020-01-25 20:21:14 +00:00
Simon Pilgrim 3f8916b2e8 [SelectionDAG] ComputeNumSignBits - add support for rotate non-uniform vector amounts 2020-01-25 19:15:05 +00:00
Simon Pilgrim e3c26a9d1b [SelectionDAG] ComputeNumSignBits - add support for rotate uniform vector amounts 2020-01-25 18:55:47 +00:00
@justice_adams (Justice Adams) daee63f974 [SelectionDag] Updated FoldConstantArithmetic method signature in preparation for merge with FoldConstantVectorArithmetic
Updated FoldConstantArithmetic method signature to match that of
FoldConstantVectorArithmetic in preparation for merging the two
functions together

https://bugs.llvm.org/show_bug.cgi?id=36544

This is the first step in combining the various
FoldConstantVectorArithmetic and FoldConstantVectorArithmetic
functions into one FoldConstantArithmetic function.

Differential Revision: https://reviews.llvm.org/D72870
2020-01-24 18:00:58 -05:00
Simon Pilgrim 0b45c2264a [SelectionDAG] rot(x, y) --> x iff ComputeNumSignBits(x) == BitWidth(x)
Rotating an 0/-1 value by any amount will always result in the same 0/-1 value
2020-01-24 10:35:57 +00:00
Simon Pilgrim e25eee4db7 [SelectionDAG] ComputeNumSignBits - add ISD::ADD demanded elts support 2020-01-23 17:48:07 +00:00
Simon Pilgrim 0fec8acdd8 [SelectionDAG] ComputeNumSignBits - add ISD::ADD vector support
Add missing handling for (ADD (AND X, 1), -1) uniform vectors
2020-01-23 16:42:12 +00:00
Simon Pilgrim fc5bbbf328 [SelectionDAG] ComputeNumSignBits - add ISD::SUB demanded elts support 2020-01-23 16:20:48 +00:00
Simon Pilgrim 48d4ba8fb2 [SelectionDAG] Compute Known + Sign Bits - merge INSERT_VECTOR_ELT known/unknown index paths
Match the approach in SimplifyDemandedBits where we calculate the demanded elts and then have a common path for the ComputeKnownBits/ComputeNumSignBits call.
2020-01-23 13:31:37 +00:00
Simon Pilgrim 03cae086f4 [SelectionDAG] ComputeKnownBits - merge EXTRACT_VECTOR_ELT known/unknown index paths
Match the approach in SimplifyDemandedBits/ComputeNumSignBits where we calculate the demanded elts and then have a common path for the ComputeKnownBits call.
2020-01-23 11:29:16 +00:00
Simon Pilgrim 98da49d979 [SelectionDAG] Compute Known + Sign Bits - merge INSERT_SUBVECTOR known/unknown index paths
Match the approach in SimplifyDemandedBits where we calculate the demanded elts and then have a common path for the ComputeKnownBits/ComputeNumSignBits call, additionally we only ever need original demanded elts of the base vector even if the index is unknown.
2020-01-23 11:29:15 +00:00
Sander de Smalen 4cf16efe49 [AArch64][SVE] Add patterns for unpredicated load/store to frame-indices.
This patch also fixes up a number of cases in DAGCombine and
SelectionDAGBuilder where the size of a scalable vector is used in a
fixed-width context (thus triggering an assertion failure).

Reviewers: efriedma, c-rhodes, rovka, cameron.mcinally

Reviewed By: efriedma

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D71215
2020-01-22 14:32:27 +00:00
Simon Pilgrim 80656fd7ae [SelectionDAG] getShiftAmountConstant - assert the type is an integer. 2020-01-22 13:52:44 +00:00
Sander de Smalen 67d4c9924c Add support for (expressing) vscale.
In LLVM IR, vscale can be represented with an intrinsic. For some targets,
this is equivalent to the constexpr:

  getelementptr <vscale x 1 x i8>, <vscale x 1 x i8>* null, i32 1

This can be used to propagate the value in CodeGenPrepare.

In ISel we add a node that can be legalized to one or more
instructions to materialize the runtime vector length.

This patch also adds SVE CodeGen support for VSCALE, which maps this
node to RDVL instructions (for scaled multiples of 16bytes) or CNT[HSD]
instructions (scaled multiples of 2, 4, or 8 bytes, respectively).

Reviewers: rengolin, cameron.mcinally, hfinkel, sebpop, SjoerdMeijer, efriedma, lattner

Reviewed by: efriedma

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D68203
2020-01-22 10:09:27 +00:00
Simon Pilgrim 47f99d2ca8 [SelectionDAG] GetDemandedBits - remove ANY_EXTEND handling
Rely on SimplifyMultipleUseDemandedBits fallback instead.
2020-01-21 14:39:00 +00:00
Simon Pilgrim 9c06c10fba [SelectionDAG] GetDemandedBits - fallback to SimplifyMultipleUseDemandedBits by default.
First step towards removing SelectionDAG::GetDemandedBits entirely since it so similar to SimplifyMultipleUseDemandedBits anyhow.
2020-01-20 16:51:52 +00:00
Michael Liao 6d0d86a64d [DAG] Add helper for creating constant vector index with correct type. NFC. 2020-01-18 01:23:36 -05:00
Simon Pilgrim 1dc2f25790 [SelectionDAG] ComputeKnownBits - assert we're computing the 0'th (difference) result for the SUB/SUBC cases
Matches what we already do for the ADD/ADDC/ADDE case.
2020-01-17 13:53:57 +00:00