Issues addressed since original review:
- Avoid bug in regalloc greedy/machine verifier when forwarding to use
in an instruction that re-defines the same virtual register.
- Fixed bug when forwarding to use in EarlyClobber instruction slot.
- Fixed incorrect forwarding to register definitions that showed up in
explicit_uses() iterator (e.g. in INLINEASM).
- Moved removal of dead instructions found by
LiveIntervals::shrinkToUses() outside of loop iterating over
instructions to avoid instructions being deleted while pointed to by
iterator.
- Fixed ARMLoadStoreOptimizer bug exposed by this change in r311907.
- The pass no longer forwards COPYs to physical register uses, since
doing so can break code that implicitly relies on the physical
register number of the use.
- The pass no longer forwards COPYs to undef uses, since doing so
can break the machine verifier by creating LiveRanges that don't
end on a use (since the undef operand is not considered a use).
[MachineCopyPropagation] Extend pass to do COPY source forwarding
This change extends MachineCopyPropagation to do COPY source forwarding.
This change also extends the MachineCopyPropagation pass to be able to
be run during register allocation, after physical registers have been
assigned, but before the virtual registers have been re-written, which
allows it to remove virtual register COPY LiveIntervals that become dead
through the forwarding of all of their uses.
llvm-svn: 314729
Issues addressed since original review:
- Moved removal of dead instructions found by
LiveIntervals::shrinkToUses() outside of loop iterating over
instructions to avoid instructions being deleted while pointed to by
iterator.
- Fixed ARMLoadStoreOptimizer bug exposed by this change in r311907.
- The pass no longer forwards COPYs to physical register uses, since
doing so can break code that implicitly relies on the physical
register number of the use.
- The pass no longer forwards COPYs to undef uses, since doing so
can break the machine verifier by creating LiveRanges that don't
end on a use (since the undef operand is not considered a use).
[MachineCopyPropagation] Extend pass to do COPY source forwarding
This change extends MachineCopyPropagation to do COPY source forwarding.
This change also extends the MachineCopyPropagation pass to be able to
be run during register allocation, after physical registers have been
assigned, but before the virtual registers have been re-written, which
allows it to remove virtual register COPY LiveIntervals that become dead
through the forwarding of all of their uses.
llvm-svn: 312328
It caused PR34387: Assertion failed: (RegNo < NumRegs && "Attempting to access record for invalid register number!")
> Issues identified by buildbots addressed since original review:
> - Fixed ARMLoadStoreOptimizer bug exposed by this change in r311907.
> - The pass no longer forwards COPYs to physical register uses, since
> doing so can break code that implicitly relies on the physical
> register number of the use.
> - The pass no longer forwards COPYs to undef uses, since doing so
> can break the machine verifier by creating LiveRanges that don't
> end on a use (since the undef operand is not considered a use).
>
> [MachineCopyPropagation] Extend pass to do COPY source forwarding
>
> This change extends MachineCopyPropagation to do COPY source forwarding.
>
> This change also extends the MachineCopyPropagation pass to be able to
> be run during register allocation, after physical registers have been
> assigned, but before the virtual registers have been re-written, which
> allows it to remove virtual register COPY LiveIntervals that become dead
> through the forwarding of all of their uses.
llvm-svn: 312178
Issues identified by buildbots addressed since original review:
- Fixed ARMLoadStoreOptimizer bug exposed by this change in r311907.
- The pass no longer forwards COPYs to physical register uses, since
doing so can break code that implicitly relies on the physical
register number of the use.
- The pass no longer forwards COPYs to undef uses, since doing so
can break the machine verifier by creating LiveRanges that don't
end on a use (since the undef operand is not considered a use).
[MachineCopyPropagation] Extend pass to do COPY source forwarding
This change extends MachineCopyPropagation to do COPY source forwarding.
This change also extends the MachineCopyPropagation pass to be able to
be run during register allocation, after physical registers have been
assigned, but before the virtual registers have been re-written, which
allows it to remove virtual register COPY LiveIntervals that become dead
through the forwarding of all of their uses.
llvm-svn: 312154
Two issues identified by buildbots were addressed:
- The pass no longer forwards COPYs to physical register uses, since
doing so can break code that implicitly relies on the physical
register number of the use.
- The pass no longer forwards COPYs to undef uses, since doing so
can break the machine verifier by creating LiveRanges that don't
end on a use (since the undef operand is not considered a use).
[MachineCopyPropagation] Extend pass to do COPY source forwarding
This change extends MachineCopyPropagation to do COPY source forwarding.
This change also extends the MachineCopyPropagation pass to be able to
be run during register allocation, after physical registers have been
assigned, but before the virtual registers have been re-written, which
allows it to remove virtual register COPY LiveIntervals that become dead
through the forwarding of all of their uses.
Reviewers: qcolombet, javed.absar, MatzeB, jonpa
Subscribers: jyknight, nemanjai, llvm-commits, nhaehnle, mcrosier, mgorny
Differential Revision: https://reviews.llvm.org/D30751
llvm-svn: 311135
This reverts commit r311038.
Several buildbots are breaking, and at least one appears to be due to
the forwarding of physical regs enabled by this change. Reverting while
I investigate further.
llvm-svn: 311062
This change extends MachineCopyPropagation to do COPY source forwarding.
This change also extends the MachineCopyPropagation pass to be able to
be run during register allocation, after physical registers have been
assigned, but before the virtual registers have been re-written, which
allows it to remove virtual register COPY LiveIntervals that become dead
through the forwarding of all of their uses.
Reviewers: qcolombet, javed.absar, MatzeB, jonpa
Subscribers: jyknight, nemanjai, llvm-commits, nhaehnle, mcrosier, mgorny
Differential Revision: https://reviews.llvm.org/D30751
llvm-svn: 311038
These were taking priority over the aligned load instructions since there is no vmovda8/16. I don't think there is really a difference between aligned and unaligned on newer cpus so I don't think it matters which instructions we use.
But with this change we reduce the size of the isel table a little and we allow the aligned information to pass through to the evex->vec pass and produce the same output has avx/avx2 in some cases.
I also generally dislike patterns rooted in a bitcast which these were.
Differential Revision: https://reviews.llvm.org/D35977
llvm-svn: 309589
Summary: LiveRangeShrink pass moves instruction right after the definition with the same BB if the instruction and its operands all have more than one use. This pass is inexpensive and guarantees optimal live-range within BB.
Reviewers: davidxl, wmi, hfinkel, MatzeB, andreadb
Reviewed By: MatzeB, andreadb
Subscribers: hiraditya, jyknight, sanjoy, skatkov, gberry, jholewinski, qcolombet, javed.absar, krytarowski, atrick, spatel, RKSimon, andreadb, MatzeB, mehdi_amini, mgorny, efriedma, davide, dberlin, llvm-commits
Differential Revision: https://reviews.llvm.org/D32563
llvm-svn: 304371
This also reverts follow-ups r303292 and r303298.
It broke some Chromium tests under MSan, and apparently also internal
tests at Google.
llvm-svn: 303369
Summary: LiveRangeShrink pass moves instruction right after the definition with the same BB if the instruction and its operands all have more than one use. This pass is inexpensive and guarantees optimal live-range within BB.
Reviewers: davidxl, wmi, hfinkel, MatzeB, andreadb
Reviewed By: MatzeB, andreadb
Subscribers: hiraditya, jyknight, sanjoy, skatkov, gberry, jholewinski, qcolombet, javed.absar, krytarowski, atrick, spatel, RKSimon, andreadb, MatzeB, mehdi_amini, mgorny, efriedma, davide, dberlin, llvm-commits
Differential Revision: https://reviews.llvm.org/D32563
llvm-svn: 302938
As described on PR31712, we miss a variety of legalization combines because we lower these to X86ISD::VSEXT/VZEXT despite them having the same functionality. This patch makes 128-bit (SSE41) SIGN/ZERO_EXTEND_VECTOR_IN_REG ops legal, adds the necessary tablegen plumbing and uses a helper 'getExtendInVec' to decide when to use SIGN/ZERO_EXTEND_VECTOR_IN_REG or VSEXT/VZEXT.
We're missing a couple of shuffle combines that will be added in a future patch for review.
Later patches can then support the AVX2 cases as a mixture of SIGN/ZERO_EXTEND and SIGN/ZERO_EXTEND_VECTOR_IN_REG, and then finally deal with the AVX512 cases.
Differential Revision: https://reviews.llvm.org/D30549
llvm-svn: 296985
VZEROUPPER should not be issued on Knights Landing (KNL), but on Skylake-avx512 it should be.
Differential Revision: https://reviews.llvm.org/D29874
llvm-svn: 296859
This is a tiny patch with a big pile of test changes.
This partially fixes PR27885:
https://llvm.org/bugs/show_bug.cgi?id=27885
My motivating case looks like this:
- vpshufd {{.*#+}} xmm1 = xmm1[0,1,0,2]
- vpshufd {{.*#+}} xmm0 = xmm0[0,2,2,3]
- vpblendw {{.*#+}} xmm0 = xmm0[0,1,2,3],xmm1[4,5,6,7]
+ vshufps {{.*#+}} xmm0 = xmm0[0,2],xmm1[0,2]
And this happens several times in the diffs. For chips with domain-crossing penalties,
the instruction count and size reduction should usually overcome any potential
domain-crossing penalty due to using an FP op in a sequence of int ops. For chips such
as recent Intel big cores and Atom, there is no domain-crossing penalty for shufps, so
using shufps is a pure win.
So the test case diffs all appear to be improvements except one test in
vector-shuffle-combining.ll where we miss an opportunity to use a shift to generate
zero elements and one test in combine-sra.ll where multiple uses prevent the expected
shuffle combining.
Differential Revision: https://reviews.llvm.org/D27692
llvm-svn: 289837
PMULDQ returns the 64-bit result of the signed multiplication of the lower 32-bits of vXi64 vector inputs, we can lower with this if the sign bits stretch that far.
Differential Revision: https://reviews.llvm.org/D27657
llvm-svn: 289426
Adds support for bitcasting a little endian 'small element' vector to 'large element' scalar/vector (e.g. v16i8 to v4i32 or v2i32 to i64), which is required for PR30845. We extract the knownbits for each 'small element' part and concatenate the results together.
We can add support for big endian and 'large element' scalar/vector to 'small element' vector bitcasting once we have test cases for them.
Differential Revision: https://reviews.llvm.org/D27129
llvm-svn: 289200
vXi64 multiplication is lowered into 3 calls of vpmuludq with the upper/lower 32-bit halves.
If any of these halves are zero then we can remove individual calls. Although there was isBuildVectorAllZeros code to do this I don't think it ever worked (maybe just for constant folded cases that don't seem to be tested for any longer).
This requires additional X86ISD support for computeKnownBitsForTargetNode, so far I've just added support for X86ISD::VZEXT (VPMOVZX* - helping the AVX2+ cases).
Partial fix for PR30845
Differential Revision: https://reviews.llvm.org/D26590
llvm-svn: 287223
We already have (V)PMOVZX* combining support, this is the beginning of handling (V)PMOVSX* similarly - other combines in combineVSZext can be generalized in future patches.
This unearthed an interesting bug in that we were generating illegal build vectors on 32-bit targets - it was proving difficult to create a test for it from PMOVZX, but it fired immediately with PMOVSX. I've created a more general form of the existing getConstVector to handle these cases - ideally this should be handled in non-target-specific code but I couldn't find an equivalent.
Differential Revision: https://reviews.llvm.org/D25874
llvm-svn: 285072
Previously we were extending to copying the whole ZMM register. The register allocator shouldn't use XMM16-31 or YMM16-31 in this configuration as the instructions to spill them aren't available.
llvm-svn: 280648
An identity COPY like this:
%AL = COPY %AL, %EAX<imp-def>
has no semantic effect, but encodes liveness information: Further users
of %EAX only depend on this instruction even though it does not define
the full register.
Replace the COPY with a KILL instruction in those cases to maintain this
liveness information. (This reverts a small part of r238588 but this
time adds a comment explaining why a KILL instruction is useful).
llvm-svn: 274952
Extend the existing lowering of vXi8 multiplies to support v64i8 on avx512bw targets.
I added the Lower512IntArith helper function to help with this - not sure how often this could be used in the future, but it seemed better than putting all that logic inside LowerMUL.
Differential Revision: http://reviews.llvm.org/D18937
llvm-svn: 265902
When we multiply two 64-bit vectors, we extract lower and upper part and use the PMULUDQ instruction.
When one of the operands is a constant, the upper part may be zero, we know this at compile time.
Example: %a = mul <4 x i64> %b, <4 x i64> < i64 5, i64 5, i64 5, i64 5>.
I'm checking the value of the upper part and prevent redundant "multiply", "shift" and "add" operations.
llvm-svn: 239802
Patch to allow int8 vectors to be multiplied on the SSE unit instead of being scalarized.
The patch sign extends the i8 lanes to i16, uses the SSE2 pmullw multiplication instruction, then packs the lower byte from each result.
Differential Revision: http://reviews.llvm.org/D9115
llvm-svn: 235837
to generically lower blends and is particularly nice because it is
available frome SSE2 onward. This removes a lot of the remaining domain
crossing blends in SSE2 code.
I'm hoping to replace some of the "interleaved" lowering hacks with
something closer to this which should be more principled. First, this
needs to learn how to detect and use other interleavings besides that of
the natural type provided. That will be a follow-up patch though.
llvm-svn: 229378
Update the entire regression test suite for the new shuffles. Remove
most of the old testing which was devoted to the old shuffle lowering
path and is no longer relevant really. Also remove a few other random
tests that only really exercised shuffles and only incidently or without
any interesting aspects to them.
Benchmarking that I have done shows a few small regressions with this on
LNT, zero measurable regressions on real, large applications, and for
several benchmarks where the loop vectorizer fires in the hot path it
shows 5% to 40% improvements for SSE2 and SSE3 code running on Sandy
Bridge machines. Running on AMD machines shows even more dramatic
improvements.
When using newer ISA vector extensions the gains are much more modest,
but the code is still better on the whole. There are a few regressions
being tracked (PR21137, PR21138, PR21139) but by and large this is
expected to be a win for x86 generated code performance.
It is also more correct than the code it replaces. I have fuzz tested
this extensively with ISA extensions up through AVX2 and found no
crashes or miscompiles (yet...). The old lowering had a few miscompiles
and crashers after a somewhat smaller amount of fuzz testing.
There is one significant area where the new code path lags behind and
that is in AVX-512 support. However, there was *extremely little*
support for that already and so this isn't a significant step backwards
and the new framework will probably make it easier to implement lowering
that uses the full power of AVX-512's table-based shuffle+blend (IMO).
Many thanks to Quentin, Andrea, Robert, and others for benchmarking
assistance. Thanks to Adam and others for help with AVX-512. Thanks to
Hal, Eric, and *many* others for answering my incessant questions about
how the backend actually works. =]
I will leave the old code path in the tree until the 3 PRs above are at
least resolved to folks' satisfaction. Then I will rip it (and 1000s of
lines of code) out. =] I don't expect this flag to stay around for very
long. It may not survive next week.
llvm-svn: 219046
Geoff Berry