64037 Commits

Author SHA1 Message Date
Kai Luo
5eaebd5d64 [PowerPC] Implement quadword atomic load/store
Add support to load/store i128 atomically.

Reviewed By: jsji

Differential Revision: https://reviews.llvm.org/D105612
2021-09-01 06:55:40 +00:00
Luke
a78dd726f4 [SLP][RISCV] Implement unsigned getMinVectorRegisterBitWidth() for RISCV
Reviewed By: craig.topper

Differential Revision: https://reviews.llvm.org/D108973
2021-09-01 14:25:15 +08:00
hsmahesha
98f4713122 [AMDGPU] Split entry basic block after alloca instructions.
While initializing the LDS pointers within entry basic block of kernel(s), make
sure that the entry basic block is split after alloca instructions.

Reviewed By: rampitec

Differential Revision: https://reviews.llvm.org/D108971
2021-09-01 10:18:44 +05:30
Wang, Pengfei
74043caef2 [X86] Enable half type support in inline assembly constraints
Reviewed By: LuoYuanke

Differential Revision: https://reviews.llvm.org/D105799
2021-09-01 09:29:31 +08:00
Nick Desaulniers
e9b3f25730 [RISCVISelLowering] avoid emitting libcalls to __mulodi4() and __multi3()
Similar to D108842, D108844, D108926, D108928, and D108936.

__has_builtin(builtin_mul_overflow) returns true for 32b RISCV targets,
but Clang is deferring to compiler RT when encountering long long types.

If the semantics of __has_builtin mean "the compiler resolves these,
always" then we shouldn't conditionally emit a libcall.

Link: https://bugs.llvm.org/show_bug.cgi?id=28629

Reviewed By: craig.topper

Differential Revision: https://reviews.llvm.org/D108939
2021-08-31 11:23:56 -07:00
Nick Desaulniers
d8b6ae072d [PPCISelLowering] avoid emitting libcalls to __mulodi4()
Similar to D108842, D108844, and D108926.

__has_builtin(builtin_mul_overflow) returns true for 32b PPC targets,
but Clang is deferring to compiler RT when encountering long long types.
This breaks ppc44x_defconfig + CONFIG_BLK_DEV_NBD=y builds of the Linux
kernel that are using builtin_mul_overflow with these types for these
targets.

If the semantics of __has_builtin mean "the compiler resolves these,
always" then we shouldn't conditionally emit a libcall.

This will still need to be worked around in the Linux kernel in order to
continue to support these builds of the Linux kernel for this
target with older releases of clang.

Link: https://bugs.llvm.org/show_bug.cgi?id=28629
Link: https://github.com/ClangBuiltLinux/linux/issues/1438

Reviewed By: nemanjai

Differential Revision: https://reviews.llvm.org/D108936
2021-08-31 11:09:58 -07:00
Joe Nash
c96839265a [AMDGPU] Enable ds_min/ds_max on more subtargets
Adds patterns for f64 ds_min/ds_max. Shrinks HasLDSFPAtomics
scope to enable f32.

Reviewed By: rampitec

Differential Revision: https://reviews.llvm.org/D108994

Change-Id: Id890b677841ee588b20d42b1bb3f4cdbf6e9ba1a
2021-08-31 13:22:31 -04:00
David Green
22c384129e [ARM] Add missing validForTailPredication for VMINNM/VMAXNM
Apparently this was missing, preventing the generation of tail
predication loops containing VMINNM, VMAXNM, VMINNMA and VMAXNMA.
2021-08-31 18:19:03 +01:00
Simon Pilgrim
9e2d14c285 [X86] Copy X86SchedSkylakeServer.td to X86SchedIceLake.td
Icelake, Rocketlake and Tigerlake targets currently use the SkylakeServer scheduler model, despite being a later microarchitecture, leading to both reported bugs (PR48110) and discrepancies when comparing llvm-mca reports to other profiling tools (OSACA, uops, uica, etc.). And tbh I'm getting sick of llvm-mca getting blamed for what are backend scheduler model issues :-(

This patch doesn't attempt to fix any of these discrepancies - there should be no changes in codegen - its a setup patch that copies the skx model, renames all the resources, adds the additional ports (but doesn't reference them yet) and updates the llvm-exegesis pfm counter mappings (based off https://sourceforge.net/p/perfmon2/libpfm4/ci/master/tree/lib/events/intel_icl_events.h).

This should make it trivial for anyone with hardware access to use llvm-exegesis reports to iteratively improve the model (my attempts to get hold of a cheap tiger lake box haven't been fruitful yet....).

I will copy the SkylakeServer llvm-mca resource tests as follow up commits - the diff should entirely be the resource renames.

Differential Revision: https://reviews.llvm.org/D108914
2021-08-31 11:57:20 +01:00
Simon Wallis
f417b660ee [Arm] Add assert in T2 Imm7s code emitter
Add assert to provoke failure in object file output, not just in disassembly output.

Reviewed By: yroux

Differential Revision: https://reviews.llvm.org/D107259
2021-08-31 08:16:48 +01:00
Alexander Pivovarov
eb946cc5b6 Fix typo in comments
Reviewed By: MaskRay, jsji

Differential Revision: https://reviews.llvm.org/D108857
2021-08-31 11:55:40 +05:30
Heejin Ahn
3419e85b15 [WebAssembly] Free setjmpTable before exiting calls in EmSjLj
This is an improvement over D107852. We don't need to enumerate specific
function names; we can just check for `noreturn` attribute. This also
requires us to make sure `__resumeExeption` and `emscripten_longjmp`
have `noreturn` attribute too; one of them is a JS function and the
other calls a JS function so Clang does not have a way to deduce they
don't return.

This is effectively NFC, because I'm not sure if there is an additional
case this case covers; if we add a custom function call that has
`noreturn` attribute, it will be processed within the SjLj handling and
turned into `__invoke` call. So this really applies to some special
functions like `emscripten_longjmp`.

Reviewed By: dschuff

Differential Revision: https://reviews.llvm.org/D108955
2021-08-30 21:46:25 -07:00
Heejin Ahn
b8fc71b7ae [WebAssembly] Share rethrowing BBs in LowerEmscriptenEHSjLj
There are three kinds of "rethrowing" BBs in this pass:
1. In Emscripten SjLj, after a possibly longjmping function call, we
   check if the thrown longjmp corresponds to one of setjmps within the
   current function. If not, we rethrow the longjmp by calling
   `emscripten_longjmp`.
2. In Emscripten EH, after a possibly throwing function call, we check
   if the thrown exception corresponds to the current `catch` clauses.
   If not, we rethrow the exception by calling `__resumeException`.
3. When both Emscripten EH and SjLj are used, when we check for an
   exception after a possibly throwing function call, it is possible
   that we get not an exception but a longjmp. In this case, we
   shouldn't swallow it; we should rethrow the longjmp by calling
   `emscripten_longjmp`.
4. When both Emscripten EH and SjLj are used, when we check for a
   longjmp after a possibly longjmping function call, it is possible
   that we get not a longjmp but an exception. In this case, we
   shouldn't swallot it; we should rethrow the exception by calling
   `__resumeException`.

Case 1 is in Emscripten SjLj, 2 is in Emscripten EH, and 3 and 4 are
relevant when both Emscripten EH and SjLj are used. 3 and 4 were first
implemented in D106525.

We create BBs for 1, 3, and 4 in this pass. We create those BBs for
every throwing/longjmping function call, along with other BBs that
contain condition checks. What this CL does is to create a single BB
within a function for each of 1, 3, and 4 cases. These BBs are exiting
BBs in the function and thus don't have successors, so easy to be shared
between calls.

The names of BBs created are:
Case 1: `call.em.longjmp`
Case 3: `rethrow.exn`
Case 4: `rethrow.longjmp`

For the case 2 we don't currently create BBs; we only replace the
existing `resume` instruction with `call @__resumeException`. And Clang
already creates only a single `resume` BB per function and reuses it,
so we don't need to optimize this case.

Not sure what are good benchmarks for EH/SjLj, but this decreases the
size of the object file for `grfmt_jpeg.bc` (presumably from opencv) we
got from one of our users by 8.9%. Even after running `wasm-opt -O4` on
them, there is still 4.8% improvement.

Reviewed By: dschuff

Differential Revision: https://reviews.llvm.org/D108945
2021-08-30 21:44:34 -07:00
Nikita Popov
c1b7540645 [TTI] Sink IVDescriptors.h include (NFC)
Forward declare RecurrenceDescriptor and include IVDescritor.h
only in implementation code that actually needs it.
2021-08-30 22:41:58 +02:00
Owen Anderson
db9de22f2b Teach the AArch64 backend patterns to generate the EOR3 instruction.
Adds patterns to match the EOR3 instruction.

Reviewed By: dmgreen

Differential Revision: https://reviews.llvm.org/D108793
2021-08-30 20:01:08 +00:00
David Green
efa340fbd2 [ARM] Workaround tailpredication min/max costmodel
The min/max intrinsics are not yet canonical, but when they are the tail
predications analysis will change from treating them like icmp to
treating them like intrinsics. Unfortunately, they can currently produce
better code by not being tail predicated thanks to the vectorizer picking
higher VF's and the backend folding to better instructions (especially
for saturate patterns). In the long run we will need to improve the
vectorizers cost modelling, recognizing the instruction directly, but in
the meantime this treats min/max as before to prevent performance
regressions.
2021-08-30 19:19:51 +01:00
Nikita Popov
0529e2e018 [InstrInfo] Use 64-bit immediates for analyzeCompare() (NFCI)
The backend generally uses 64-bit immediates (e.g. what
MachineOperand::getImm() returns), so use that for analyzeCompare()
and optimizeCompareInst() as well. This avoids truncation for
targets that support immediates larger 32-bit. In particular, we
can avoid the bugprone value normalization hack in the AArch64
target.

This is a followup to D108076.

Differential Revision: https://reviews.llvm.org/D108875
2021-08-30 19:46:04 +02:00
Kazu Hirata
c50faffb4e [llvm] Remove redundant calls to str() and c_str() (NFC)
Identified with readability-redundant-string-cstr.
2021-08-30 09:05:05 -07:00
Craig Topper
0560a4adb3 [RISCV] Enable CONCAT_VECTORS for fixed FP vectors.
Reviewed By: frasercrmck

Differential Revision: https://reviews.llvm.org/D108487
2021-08-30 08:47:45 -07:00
Simon Pilgrim
af2920ec6f [TTI][X86] getArithmeticInstrCost - move opcode canonicalization before all target-specific costs. NFCI.
The GLM/SLM special cases still get tested first but after the the MUL/DIV/REM pattern detection - this will be necessary for when we make the SLM vXi32 MUL canonicalization generic to improve PMULLW/PMULHW/PMADDDW cost support etc.
2021-08-30 12:24:59 +01:00
Wang, Pengfei
ab40dbfe03 [X86] AVX512FP16 instructions enabling 6/6
Enable FP16 complex FMA instructions.

Ref.: https://software.intel.com/content/www/us/en/develop/download/intel-avx512-fp16-architecture-specification.html

Reviewed By: LuoYuanke

Differential Revision: https://reviews.llvm.org/D105269
2021-08-30 13:08:45 +08:00
Qiu Chaofan
3bdd850d0c [PowerPC] Set branch/call instructions as no hasSideEffects
PowerPC can model these instructions, so we don't need this flag set.

Reviewed By: shchenz, jsji

Differential Revision: https://reviews.llvm.org/D71983
2021-08-30 12:23:35 +08:00
Vince Bridgers
55ba1de7c5 [X86] Remove X86LowerAMXType::getRowFromCol from X86LowerAMXType.cpp
Remove method X86LowerAMXType::getRowFromCol since it's not used, and
it's causing a warning.

Reviewed By: LuoYuanke

Differential Revision: https://reviews.llvm.org/D108862
2021-08-29 12:27:34 -05:00
Yonghong Song
4948927058 [BPF] support btf_tag attribute in .BTF section
A new kind BTF_KIND_TAG is added to .BTF to encode
btf_tag attributes. The format looks like
   CommonType.name : attribute string
   CommonType.type : attached to a struct/union/func/var.
   CommonType.info : encoding BTF_KIND_TAG
                     kflag == 1 to indicate the attribute is
                     for CommonType.type, or kflag == 0
                     for struct/union member or func argument.
   one uint32_t    : to encode which member/argument starting from 0.

If one particular type or member/argument has more than one attribute,
multiple BTF_KIND_TAG will be generated.

Differential Revision: https://reviews.llvm.org/D106622
2021-08-28 21:02:27 -07:00
Nikita Popov
16086d47c0 [WebAssembly] Fix FastISel of condition in different block (PR51651)
If the icmp is in a different block, then the register for the icmp
operand may not be initialized, as it nominally does not have
cross-block uses. Add a check that the icmp is in the same block
as the branch, which should be the common case.

This matches what X86 FastISel does:
5b6b090cf2/llvm/lib/Target/X86/X86FastISel.cpp (L1648)

The "not" transform that could have a similar issue is dropped
entirely, because it is currently dead: The incoming value is
a branch or select condition of type i1, but this code requires
an i32 to trigger.

Fixes https://bugs.llvm.org/show_bug.cgi?id=51651.

Differential Revision: https://reviews.llvm.org/D108840
2021-08-28 10:28:24 +02:00
Nick Desaulniers
c8c176d999 [MipsISelLowering] avoid emitting libcalls to __mulodi4()
__has_builtin(__builtin_mul_overflow) returns true for 32b MIPS targets,
but Clang is deferring to compiler RT when encountering `long long`
types. This breaks sanitizer builds of the Linux kernel that are using
__builtin_mul_overflow with these types for these targets.

If the semantics of __has_builtin mean "the compiler resolves these,
always" then we shouldn't conditionally emit a libcall.

This will still need to be worked around in the Linux kernel in order to
continue to support malta_defconfig builds of the Linux kernel for this
target with older releases of clang.

Link: https://bugs.llvm.org/show_bug.cgi?id=28629
Link: https://github.com/ClangBuiltLinux/linux/issues/1438

Reviewed By: rengolin

Differential Revision: https://reviews.llvm.org/D108844
2021-08-27 15:15:36 -07:00
Nick Desaulniers
5c91b98c5d [ARMISelLowering] avoid emitting libcalls to __mulodi4()
__has_builtin(__builtin_mul_overflow) returns true for 32b ARM targets,
but Clang is deferring to compiler RT when encountering `long long`
types. This breaks sanitizer builds of the Linux kernel that are using
__builtin_mul_overflow with these types for these targets.

If the semantics of __has_builtin mean "the compiler resolves these,
always" then we shouldn't conditionally emit a libcall.

This will still need to be worked around in the Linux kernel in order to
continue to support allmodconfig builds of the Linux kernel for this
target with older releases of clang.

Link: https://bugs.llvm.org/show_bug.cgi?id=28629
Link: https://github.com/ClangBuiltLinux/linux/issues/1438

Reviewed By: rengolin

Differential Revision: https://reviews.llvm.org/D108842
2021-08-27 15:14:47 -07:00
Craig Topper
dbf0d8118c [RISCV] Use ~0ULL instead of ~0U when checking for invalid ErrorInfo.
ErrorInfo is a uint64_t and is initialized to all 1s.

Not sure how to test this. Noticed while working on .insn support.
2021-08-27 12:30:33 -07:00
Roman Lebedev
6734018041
[Codegen][X86] EltsFromConsecutiveLoads(): if only have AVX1, ensure that the "load" is actually foldable (PR51615)
This fixes another reproducer from https://bugs.llvm.org/show_bug.cgi?id=51615
And again, the fix lies not in the code added in D105390

In this case, we completely don't check that the "broadcast-from-mem" we create
can actually fold the load. In this case, it's operand was not a load at all:
```
Combining: t16: v8i32 = vector_shuffle<0,u,u,u,0,u,u,u> t14, undef:v8i32
Creating new node: t29: i32 = undef
RepeatLoad:
t8: i32 = truncate t7
  t7: i64 = extract_vector_elt t5, Constant:i64<0>
    t5: v2i64,ch = load<(load (s128) from %ir.arg)> t0, t2, undef:i64
      t2: i64,ch = CopyFromReg t0, Register:i64 %0
        t1: i64 = Register %0
      t4: i64 = undef
    t3: i64 = Constant<0>
Combining: t15: v8i32 = undef

```

Reviewed By: RKSimon

Differential Revision: https://reviews.llvm.org/D108821
2021-08-27 20:26:53 +03:00
Philipp Krones
54e8cae565 [MC][RISCV] Add RISCV MCObjectFileInfo
This makes sure, that the text section will have a 2-byte alignment, if
the +c extension is enabled.

Reviewed By: MaskRay, luismarques

Differential Revision: https://reviews.llvm.org/D102052
2021-08-27 18:23:29 +01:00
Craig Topper
0eeab8b282 [RISCV] Add -riscv-v-fixed-length-vector-elen-max to limit the ELEN used for fixed length vectorization.
This adds an ELEN limit for fixed length vectors. This will scalarize
any elements larger than this. It will also disable some fractional
LMULs. For example, if ELEN=32 then mf8 becomes illegal, i32/f32
vectors can't use any fractional LMULs, i16/f16 can only use mf2,
and i8 can use mf2 and mf4.

We may also need something for the scalable vectors, but that has
interactions with the intrinsics and we can't scalarize a scalable
vector.

Longer term this should come from one of the Zve* features
2021-08-27 10:17:35 -07:00
Jun Ma
15b2a8e7fa [AArch64][SVE] Optimize ptrue predicate pattern with known sve register width.
For vectors that are exactly equal to getMaxSVEVectorSizeInBits, just use
AArch64SVEPredPattern::all, which can enable the use of unpredicated ptrue when available.

TestPlan: check-llvm

Differential Revision: https://reviews.llvm.org/D108706
2021-08-27 20:03:48 +08:00
Jun Ma
8c47103491 [AArch64][SVE] Add API for conversion between SVE predicate pattern and element number. NFC
This patch solely moves convert operation between SVE predicate pattern
and element number into two small functions. It's pre-commit patch for optimize
pture with known sve register width.

Differential Revision: https://reviews.llvm.org/D108705
2021-08-27 20:03:48 +08:00
Jun Ma
3f919dfe0d [AArch64][SVE] Use getPTrue uniformly.NFC. 2021-08-27 20:03:48 +08:00
Serge Pavlov
cdbe569fb6 [X86] Implement llvm.isnan(x86_fp80) as unordered comparison
x86_fp80 format allows values that do not fit any of IEEE-754 category.
Previously they were recognized by intrinsic __builtin_isnan as NaNs.
Now this intrinsic is implemented using instruction FXAM, which
distinguish between NaNs and unsupported values. It can make some
programs behave differently.

As a solution, this fix changes lowering of the intrinsic. If floating
point exceptions are ignored, llvm.isnan is lowered into unordered
comparison, as __buildtin_isnan was implemented earlier. In strictfp
functions the intrinsic is lowered using FXAM, which does not raise
exceptions even for signaling NaN, as required by IEEE-754 and C
standards.

Differential Revision: https://reviews.llvm.org/D108037
2021-08-27 18:06:07 +07:00
Nathan Sidwell
199ac3a839 [NFC][X86] Sret return register cleanup
There are no paths into LowerFormalParms that have already specified
the sret register. We always materialize a virtual and then assign it
to the physical reg at the point of the return.

Differential Revision: https://reviews.llvm.org/D108762
2021-08-27 04:03:49 -07:00
Ricky Taylor
8d3f112f0c [M68k] Update pointer data layout
Fixes PR51626.

The M68k requires that all instruction, word and long word reads are
aligned to word boundaries. From the 68020 onwards, there is a
performance benefit from aligning long words to long word boundaries.

The M68k uses the same data layout for pointers and integers.

In line with this, this commit updates the pointer data layout to
match the layout already set for 32-bit integers: 32:16:32.

Differential Revision: https://reviews.llvm.org/D108792
2021-08-27 11:47:27 +01:00
Roman Lebedev
d4d459e747
[X86] AMD Zen 3: MULX w/ mem operand has the same throughput as with reg op
Exegesis is faulty and sometimes when measuring throughput^-1
produces snippets that have loop-carried dependencies,
which must be what caused me to incorrectly measure it originally.

After looking much more carefully, the inverse throughput should match
that of the MULX w/ reg op.

As per llvm-exegesis measurements.
2021-08-27 13:27:05 +03:00
Roman Lebedev
0f04936a2d
[X86] AMD Zen 3: MULX produces low part of the result in 3cy, +1cy for high part
As per llvm-exegesis measurements.
2021-08-27 13:27:05 +03:00
Matt Arsenault
04ce2de330 AMDGPU: Remove implicit argument attributes when introducing new calls
In a future patch, a new set of amdgpu-no-* attributes will be
introduced to indicate when a function does not need an implicitly
passed input. This pass introduces new instances of these intrinsic
calls, and should remove the attributes if they were present before.
2021-08-26 22:08:04 -04:00
Chen Zheng
324bd467a2 [PowerPC][ELF] make sure local variable space does not overlap with parameter save area
Reviewed By: jsji

Differential Revision: https://reviews.llvm.org/D105271
2021-08-27 01:58:41 +00:00
Matt Arsenault
088cc63640 AMDGPU: Invert AMDGPUAttributor
Switch to using BitIntegerState for each of the inputs, and invert
their meanings.

This now diverges more from the old AMDGPUAnnotateKernelFeatures, but
this isn't used yet anyway.
2021-08-26 21:32:13 -04:00
Matt Arsenault
46d82e7357 AMDGPU: Restrict attributor transforms
We only really want this to add the custom attributes. Theoretically
the regular transforms were already run at this point. Touching
undefined behavior breaks a lot of tests when this is enabled by
default, many of which are expecting to test handling of undef
operations.
2021-08-26 21:08:51 -04:00
Matt Arsenault
cf32d61a05 AMDGPU: Remove hacky attribute deduction from AMDGPUAttributor
amdgpu-calls and amdgpu-stack-objects don't really belong as
attributes, and are currently a hacky way of passing an analysis into
the DAG. These don't really belong in the IR, and don't really fit in
with the other attributes. Remove these to facilitate inverting the
pass.

I don't exactly understand the indirect call test changes. These tests
are using calls which are trivially replacable with a direct call, so
I'm not sure what the point is.
2021-08-26 20:31:14 -04:00
Matt Arsenault
98d7aa435f AMDGPU: Stop inferring use of llvm.amdgcn.kernarg.segment.ptr
We no longer use this intrinsic outside of the backend and no longer
support using it outside of kernels.
2021-08-26 20:30:03 -04:00
Heejin Ahn
f5cff292e2 [WebAssembly] Fix PHI when relaying longjmps
When doing Emscritpen EH, if SjLj is also enabled and used and if the
thrown exception has a possiblity being a longjmp instead of an
exception, we shouldn't swallow it; we should rethrow, or relay it. It
was done in D106525 and the code is here:
8441a8eea8/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp (L858-L898)

Here is the pseudocode of that part: (copied from comments)
```
if (%__THREW__.val == 0 || %__THREW__.val == 1)
  goto %tail
else
  goto %longjmp.rethrow

longjmp.rethrow: ;; This is longjmp. Rethrow it
  %__threwValue.val = __threwValue
  emscripten_longjmp(%__THREW__.val, %__threwValue.val);

tail: ;; Nothing happened or an exception is thrown
  ... Continue exception handling ...
```

If the current BB (where the `invoke` is created) has successors that
has the current BB as its PHI incoming node, now that has to change to
`tail` in the pseudocode, because `tail` is the latest BB that is
connected with the next BB, but this was missing.

Reviewed By: tlively

Differential Revision: https://reviews.llvm.org/D108785
2021-08-26 17:25:26 -07:00
Matt Arsenault
ce51c5d4a9 AMDGPU: Fix crashing on kernel declarations when lowering LDS
This was trying to insert the used marker into a declaration.
2021-08-26 19:01:10 -04:00
Kirill Stoimenov
2e83a0efb9 [asan] Fixed a runtime crash.
Looks like the NoRegister has some effect on the final code that is generated. My guess is that some optimization kicks in at the end?

When I use -S to dump the assembly I get the correct version with 'shrq    $3, %r8':
        movq    %r9, %r8
        shrq    $3, %r8
        movsbl  2147450880(%r8), %r8d

But, when I disassemble the final binary I get RAX in stead of R8:
        mov    %r9,%r8
        shr    $0x3,%rax
        movsbl 0x7fff8000(%r8),%r8d

Reviewed By: vitalybuka

Differential Revision: https://reviews.llvm.org/D108745
2021-08-26 20:30:25 +00:00
Jessica Paquette
2363a20001 [AArch64][GlobalISel] Optimize G_BUILD_VECTOR of undef + 1 elt -> SUBREG_TO_REG
This pattern

```
%elt = ... something ...
%undef = G_IMPLICIT_DEF
%vec = G_BUILD_VECTOR %elt, %undef, %undef, ... %undef
```

Can be selected to a SUBREG_TO_REG, assuming `%elt` and `%vec` have the same
register bank. We don't care about any of the bits in `%vec` aside from those
in `%elt`, which just happens to be the 0th element.

This is preferable to emitting `mov` instructions for every index.

This gives minor code size improvements on the test suite at -Os.

Differential Revision: https://reviews.llvm.org/D108773
2021-08-26 11:45:11 -07:00
Craig Topper
1b9417454e [RISCV] Insert a sext_inreg when type legalizing i32 shl by constant on RV64.
Similar to what we do for add/sub/mul.

This can help remove some sext.w. There are some regressions on
some bswap tests, but I have an idea how to fix that for a follow up.

A new PACKW pattern is added to handle the new sext_inreg placement.

Differential Revision: https://reviews.llvm.org/D108663
2021-08-26 10:20:19 -07:00