Please refer to
https://lists.llvm.org/pipermail/llvm-dev/2021-September/152440.html
(and that whole thread.)
TLDR: the original patch had no prior RFC, yet it had some changes that
really need a proper RFC discussion. It won't be productive to discuss
such an RFC, once it's actually posted, while said patch is already
committed, because that introduces bias towards already-committed stuff,
and the tree is potentially in broken state meanwhile.
While the end result of discussion may lead back to the current design,
it may also not lead to the current design.
Therefore i take it upon myself
to revert the tree back to last known good state.
This reverts commit 4c4093e6e3.
This reverts commit 0a2b1ba33a.
This reverts commit d9873711cb.
This reverts commit 791006fb8c.
This reverts commit c22b64ef66.
This reverts commit 72ebcd3198.
This reverts commit 5fa6039a5f.
This reverts commit 9efda541bf.
This reverts commit 94d3ff09cf.
Basically the same as G_LROUND. Handles the llvm.llround family of intrinsics.
Also add a helper function to the MachineVerifier for checking if all of the
(virtual register) operands of an instruction are scalars. Seems like a useful
thing to have.
Differential Revision: https://reviews.llvm.org/D108429
For some reductions like G_VECREDUCE_OR on AArch64, we need to scalarize
completely if the source is <= 64b. This change adds support for that in
the legalizer. If the source has a pow-2 num elements, then we can do
a tree reduction using the scalar operation in the individual elements.
Otherwise, we just create a sequential chain of operations.
For AArch64, we only need to scalarize if the input is <64b. If it's great than
64b then we can first do a fewElements step to 64b, taking advantage of vector
instructions until we reach the point of scalarization.
I also had to relax the verifier checks for reductions because the intrinsics
support <1 x EltTy> types, which we lower to scalars for GlobalISel.
Differential Revision: https://reviews.llvm.org/D108276
Add a generic opcode equivalent to the `llvm.isnan` intrinsic +
MachineVerifier support for it.
We need an opcode here because we may want target-specific lowering later on.
Differential Revision: https://reviews.llvm.org/D108222
This will currently accept the old number of bytes syntax, and convert
it to a scalar. This should be removed in the near future (I think I
converted all of the tests already, but likely missed a few).
Not sure what the exact syntax and policy should be. We can continue
printing the number of bytes for non-generic instructions to avoid
test churn and only allow non-scalar types for generic instructions.
This will currently print the LLT in parentheses, but accept parsing
the existing integers and implicitly converting to scalar. The
parentheses are a bit ugly, but the parser logic seems unable to deal
without either parentheses or some keyword to indicate the start of a
type.
This was picking a concrete size for a physical register, and
enforcing exact match on the virtual register's type size. Some
targets add multiple types to a register class, and some are smaller
than the full bit width. For example x86 adds f32 to 128-bit xmm
registers, and AMDGPU adds i16/f16 to 32-bit registers.
It might be better to represent these cases as a copy of the full
register and an extraction of the subpart, but a lot of code assumes
you can directly copy. This will help fix the current usage of the DAG
calling convention infrastructure which is incompatible with how
GlobalISel is now using it.
The API is somewhat cumbersome here, but I just mirrored the existing
functions, except now with LLTs (and allow returning null on failure,
unlike the MVT version). I think the concept of selecting register
classes based on type is flawed to begin with, but I'm trying to keep
this compatible with the existing handling.
Darwin platforms for both AArch64 and X86 can provide optimized `bzero()`
routines. In this case, it may be preferable to use `bzero` in place of a
memset of 0.
This adds a G_BZERO generic opcode, similar to G_MEMSET et al. This opcode can
be generated by platforms which may want to use bzero.
To emit the G_BZERO, this adds a pre-legalize combine for AArch64. The
conditions for this are largely a port of the bzero case in
`AArch64SelectionDAGInfo::EmitTargetCodeForMemset`.
The only difference in comparison to the SelectionDAG code is that, when
compiling for minsize, this will fire for all memsets of 0. The original code
notes that it's not beneficial to do this for small memsets; however, using
bzero here will save a mov from wzr. For minsize, I think that it's preferable
to prioritise omitting the mov.
This also fixes a bug in the libcall legalization code which would delete
instructions which could not be legalized. It also adds a check to make sure
that we actually get a libcall name.
Code size improvements (Darwin):
- CTMark -Os: -0.0% geomean (-0.1% on pairlocalalign)
- CTMark -Oz: -0.2% geomean (-0.5% on bullet)
Differential Revision: https://reviews.llvm.org/D99358
There is a bunch of similar bitfield extraction code throughout *ISelDAGToDAG.
E.g, ARMISelDAGToDAG, AArch64ISelDAGToDAG, and AMDGPUISelDAGToDAG all contain
code that matches a bitfield extract from an and + right shift.
Rather than duplicating code in the same way, this adds two opcodes:
- G_UBFX (unsigned bitfield extract)
- G_SBFX (signed bitfield extract)
They work like this
```
%x = G_UBFX %y, %lsb, %width
```
Where `lsb` and `width` are
- The least-significant bit of the extraction
- The width of the extraction
This will extract `width` bits from `%y`, starting at `lsb`. G_UBFX zero-extends
the result, while G_SBFX sign-extends the result.
This should allow us to use the combiner to match the bitfield extraction
patterns rather than duplicating pattern-matching code in each target.
Differential Revision: https://reviews.llvm.org/D98464
This adds a G_ASSERT_SEXT opcode, similar to G_ASSERT_ZEXT. This instruction
signifies that an operation was already sign extended from a smaller type.
This is useful for functions with sign-extended parameters.
E.g.
```
define void @foo(i16 signext %x) {
...
}
```
This adds verifier, regbankselect, and instruction selection support for
G_ASSERT_SEXT equivalent to G_ASSERT_ZEXT.
Differential Revision: https://reviews.llvm.org/D96890
There's no need to call verifyVectorElementMatch since we already know
that the source and destination types are identical.
Differential Revision: https://reviews.llvm.org/D96589
This adds a generic opcode which communicates that a type has already been
zero-extended from a narrower type.
This is intended to be similar to AssertZext in SelectionDAG.
For example,
```
%x_was_extended:_(s64) = G_ASSERT_ZEXT %x, 16
```
Signifies that the top 48 bits of %x are known to be 0.
This is useful in cases like this:
```
define i1 @zeroext_param(i8 zeroext %x) {
%cmp = icmp ult i8 %x, -20
ret i1 %cmp
}
```
In AArch64, `%x` must use a 32-bit register, which is then truncated to a 8-bit
value.
If we know that `%x` is already zero-ed out in the relevant high bits, we can
avoid the truncate.
Currently, in GISel, this looks like this:
```
_zeroext_param:
and w8, w0, #0xff ; We don't actually need this!
cmp w8, #236
cset w0, lo
ret
```
While SDAG does not produce the truncation, since it knows that it's
unnecessary:
```
_zeroext_param:
cmp w0, #236
cset w0, lo
ret
```
This patch
- Adds G_ASSERT_ZEXT
- Adds MIRBuilder support for it
- Adds MachineVerifier support for it
- Documents it
It also puts G_ASSERT_ZEXT into its own class of "hint instruction." (There
should be a G_ASSERT_SEXT in the future, maybe a G_ASSERT_ALIGN as well.)
This allows us to skip over hints in the legalizer etc. These can then later
be selected like COPY instructions or removed.
Differential Revision: https://reviews.llvm.org/D95564
It's probably better to split these into separate G_FADD/G_FMUL + G_VECREDUCE
operations in the translator rather than carrying the scalar around. The
majority of the time it'll get simplified away as the scalars are probably
identity values.
Differential Revision: https://reviews.llvm.org/D89150
AArch64, X86 and Mips currently directly consumes these and custom
lowering to produce a libcall, but really these should follow the
normal legalization process through the libcall/lower action.
Updated the AArch64 tests the best I could with my vague, inferred
understanding of AArch64 register banks. As far as I can tell, there
is only one 32-bit/64-bit type which will use the gpr register bank,
so we have to use the fpr bank for the other operand.
With an undef operand, it's possible for getVRegDef to fail and return
null. This is an edge case very little code bothered to
consider. Proper gMIR should use G_IMPLICIT_DEF instead.
I initially tried to apply this restriction to all SSA MIR, so then
getVRegDef would never fail anywhere. However, ProcessImplicitDefs
does technically run while the function is in SSA. ProcessImplicitDefs
and DetectDeadLanes would need to either move, or a new pseudo-SSA
type of function property would need to be introduced.
Summary:
Teach MachineVerifier to check branches for MBB operands if they are not declared indirect.
Add `isBarrier`, `isIndirectBranch` to `G_BRINDIRECT` and `G_BRJT`.
Without these, `MachineInstr.isConditionalBranch()` was giving a
false-positive for those instructions.
Reviewers: aemerson, qcolombet, dsanders, arsenm
Reviewed By: dsanders
Subscribers: hiraditya, wdng, simoncook, s.egerton, arsenm, rovka, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D81587
There's two properties we want to verify:
1. That the successors returned by analyzeBranch are in the CFG
successor list, and
2. That there are no extraneous successors are in the CFG successor
list.
The previous implementation mostly accomplished this, but in a very
convoluted manner.
Differential Revision: https://reviews.llvm.org/D79793
Confusingly, these were unrelated and had different semantics. The
G_PTR_MASK instruction predates the llvm.ptrmask intrinsic, but has a
different format. G_PTR_MASK only allows clearing the low bits of a
pointer, and only a constant number of bits. The ptrmask intrinsic
allows an arbitrary mask. Replace G_PTR_MASK to match the intrinsic.
Only selects the cases that look like the old instruction. More work
is needed to select the general case. Also new legalization code is
still needed to deal with the case where the incoming mask size does
not match the pointer size, which has a specified behavior in the
langref.
This reverts commit 80a34ae311 with fixes.
Previously, since bots turning on EXPENSIVE_CHECKS are essentially turning on
MachineVerifierPass by default on X86 and the fact that
inline-asm-avx-v-constraint-32bit.ll and inline-asm-avx512vl-v-constraint-32bit.ll
are not expected to generate functioning machine code, this would go
down to `report_fatal_error` in MachineVerifierPass. Here passing
`-verify-machineinstrs=0` to make the intent explicit.
This reverts commit 80a34ae311 with fixes.
On bots llvm-clang-x86_64-expensive-checks-ubuntu and
llvm-clang-x86_64-expensive-checks-debian only,
llc returns 0 for these two tests unexpectedly. I tweaked the RUN line a little
bit in the hope that LIT is the culprit since this change is not in the
codepath these tests are testing.
llvm\test\CodeGen\X86\inline-asm-avx-v-constraint-32bit.ll
llvm\test\CodeGen\X86\inline-asm-avx512vl-v-constraint-32bit.ll
This reverts commit rGcd5b308b828e, rGcd5b308b828e, rG8cedf0e2994c.
There are issues to be investigated for polly bots and bots turning on
EXPENSIVE_CHECKS.
Summary:
This patch could be treated as a rebase of D33960. It also fixes PR35547.
A fix for `llvm/test/Other/close-stderr.ll` is proposed in D68164. Seems
the consensus is that the test is passing by chance and I'm not
sure how important it is for us. So it is removed like in D33960 for now.
The rest of the test fixes are just adding `--crash` flag to `not` tool.
** The reason it fixes PR35547 is
`exit` does cleanup including calling class destructor whereas `abort`
does not do any cleanup. In multithreading environment such as ThinLTO or JIT,
threads may share states which mostly are ManagedStatic<>. If faulting thread
tearing down a class when another thread is using it, there are chances of
memory corruption. This is bad 1. It will stop error reporting like pretty
stack printer; 2. The memory corruption is distracting and nondeterministic in
terms of error message, and corruption type (depending one the timing, it
could be double free, heap free after use, etc.).
Reviewers: rnk, chandlerc, zturner, sepavloff, MaskRay, espindola
Reviewed By: rnk, MaskRay
Subscribers: wuzish, jholewinski, qcolombet, dschuff, jyknight, emaste, sdardis, nemanjai, jvesely, nhaehnle, sbc100, arichardson, jgravelle-google, aheejin, kbarton, fedor.sergeev, asb, rbar, johnrusso, simoncook, apazos, sabuasal, niosHD, jrtc27, zzheng, edward-jones, atanasyan, rogfer01, MartinMosbeck, brucehoult, the_o, PkmX, jocewei, jsji, lenary, s.egerton, pzheng, cfe-commits, MaskRay, filcab, davide, MatzeB, mehdi_amini, hiraditya, steven_wu, dexonsmith, rupprecht, seiya, llvm-commits
Tags: #llvm, #clang
Differential Revision: https://reviews.llvm.org/D67847
MachineVerifier::visitMachineFunctionAfter() is extended to check the
live-through case for live-in lists. This is only done for registers without
aliases and that are neither allocatable or reserved, such as the SystemZ::CC
register.
The MachineVerifier earlier only catched the case of a live-in use without an
entry in the live-in list (as "using an undefined physical register").
A comment in LivePhysRegs.h has been added stating a guarantee that
addLiveOuts() can be trusted for a full register both before and after
register allocation.
Review: Quentin Colombet
Differential Revision: https://reviews.llvm.org/D68267
While working with a patch for instruction selection, the splitting of a
large immediate ended up begin treated incorrectly by the backend. Where a
register operand should have been created, it instead became an immediate. To
my surprise the machine verifier failed to report this, which at the time
would have been helpful.
This patch improves the verifier so that it will report this type of error.
This patch XFAILs CodeGen/SPARC/fp128.ll, which has been reported at
https://bugs.llvm.org/show_bug.cgi?id=44091
Review: thegameg, arsenm, fhahn
https://reviews.llvm.org/D63973
Summary:
G_GEP is rather poorly named. It's a simple pointer+scalar addition and
doesn't support any of the complexities of getelementptr. I therefore
propose that we rename it. There's a G_PTR_MASK so let's follow that
convention and go with G_PTR_ADD
Reviewers: volkan, aditya_nandakumar, bogner, rovka, arsenm
Subscribers: sdardis, jvesely, wdng, nhaehnle, hiraditya, jrtc27, atanasyan, arphaman, Petar.Avramovic, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D69734
MachineVerifier::visitMachineFunctionAfter() is extended to check the
live-through case for live-in lists. This is only done for registers without
aliases and that are neither allocatable or reserved, such as the SystemZ::CC
register.
The MachineVerifier earlier only catched the case of a live-in use without
an entry in the live-in list (as "using an undefined physical register").
A comment in LivePhysRegs.h has been added stating a guarantee that
addLiveOuts() can be trusted for a full register both before and after
register allocation.
Review: Quentin Colombet
https://reviews.llvm.org/D68267
We need to propagate this information from the IR in order to be able to safely
do tail call optimizations on the intrinsics during legalization. Assuming
it's safe to do tail call opt without checking for the marker isn't safe because
the mem libcall may use allocas from the caller.
This adds an extra immediate operand to the end of the intrinsics and fixes the
legalizer to handle it.
Differential Revision: https://reviews.llvm.org/D68151
llvm-svn: 373140
This just adds the opcode and verifier, it will be used to replace existing
dynamic alloca handling in a subsequent patch.
Differential Revision: https://reviews.llvm.org/D66677
llvm-svn: 369833
Roman Lebedev