This was originally introduced in r278321 to work around correctness
problems in the ExecutionDepsFix pass; Probably also to keep the
performance benefits of breaking the false dependencies which of course
also affect undef operands.
ExecutionDepsFix has been improved here recently (see for example
r278321) so we should not need this exception any longer.
Differential Revision: https://reviews.llvm.org/D29525
llvm-svn: 294087
This re-applies commit r292189, reverted in r292191.
SelectionDAGBuilder recognizes libfuncs using some homegrown
parameter type-checking.
Use TLI instead, removing another heap of redundant code.
This isn't strictly NFC, as the SDAG code was too lax.
Concretely, this means changes are required to a few tests:
- calling a non-variadic function via a variadic prototype isn't OK;
it just happens to work on x86_64 (but not on, e.g., aarch64).
- mempcpy has a size_t parameter; the SDAG code accepts any integer
type, which meant using i32 on x86_64 worked.
- a handful of SystemZ tests check the SDAG support for lax prototype
checking: Ulrich agrees on removing them.
I don't think it's worth supporting any of these (IMO) invalid
testcases. Instead, fix them to be more meaningful.
llvm-svn: 294028
ISD::DELETED_NODE && "NodeToMatch was removed partway through
selection"' failed.
NodeToMatch can be modified during matching, but code does not handle
this situation.
Differential Revision: https://reviews.llvm.org/D29292
llvm-svn: 294003
Summary:
llc would hit a fatal error for errors in inline assembly. The
diagnostics message is now printed.
Reviewers: rengolin, MatzeB, javed.absar, anemet
Reviewed By: anemet
Subscribers: jyknight, nemanjai, llvm-commits
Differential Revision: https://reviews.llvm.org/D29408
llvm-svn: 293999
On one test this seems to have given more chance for DAG combine to do other INSERT_SUBVECTOR/EXTRACT_SUBVECTOR combines before the BLENDI was created. Looks like we can still improve more by teaching DAG combine to optimize INSERT_SUBVECTOR/EXTRACT_SUBVECTOR with BLENDI.
llvm-svn: 293944
Recommiting after fixing X86 inc/dec chain bug.
* Simplify Consecutive Merge Store Candidate Search
Now that address aliasing is much less conservative, push through
simplified store merging search and chain alias analysis which only
checks for parallel stores through the chain subgraph. This is cleaner
as the separation of non-interfering loads/stores from the
store-merging logic.
When merging stores search up the chain through a single load, and
finds all possible stores by looking down from through a load and a
TokenFactor to all stores visited.
This improves the quality of the output SelectionDAG and the output
Codegen (save perhaps for some ARM cases where we correctly constructs
wider loads, but then promotes them to float operations which appear
but requires more expensive constant generation).
Some minor peephole optimizations to deal with improved SubDAG shapes (listed below)
Additional Minor Changes:
1. Finishes removing unused AliasLoad code
2. Unifies the chain aggregation in the merged stores across code
paths
3. Re-add the Store node to the worklist after calling
SimplifyDemandedBits.
4. Increase GatherAllAliasesMaxDepth from 6 to 18. That number is
arbitrary, but seems sufficient to not cause regressions in
tests.
5. Remove Chain dependencies of Memory operations on CopyfromReg
nodes as these are captured by data dependence
6. Forward loads-store values through tokenfactors containing
{CopyToReg,CopyFromReg} Values.
7. Peephole to convert buildvector of extract_vector_elt to
extract_subvector if possible (see
CodeGen/AArch64/store-merge.ll)
8. Store merging for the ARM target is restricted to 32-bit as
some in some contexts invalid 64-bit operations are being
generated. This can be removed once appropriate checks are
added.
This finishes the change Matt Arsenault started in r246307 and
jyknight's original patch.
Many tests required some changes as memory operations are now
reorderable, improving load-store forwarding. One test in
particular is worth noting:
CodeGen/PowerPC/ppc64-align-long-double.ll - Improved load-store
forwarding converts a load-store pair into a parallel store and
a memory-realized bitcast of the same value. However, because we
lose the sharing of the explicit and implicit store values we
must create another local store. A similar transformation
happens before SelectionDAG as well.
Reviewers: arsenm, hfinkel, tstellarAMD, jyknight, nhaehnle
llvm-svn: 293893
This is a first attempt at using the MOVMSK instructions to replace all_of/any_of reduction patterns (i.e. an and/or + shuffle chain).
So far this only matches patterns where we are reducing an all/none bits source vector (i.e. a comparison result) but we should be able to expand on this in conjunction with improvements to 'bool vector' handling both in the x86 backend as well as the vectorizers etc.
Differential Revision: https://reviews.llvm.org/D28810
llvm-svn: 293880
Summary:
Currently the test implicit-null-checks.mir crashes if we run llc with
-enable-implicit-null-checks -start-before implicit-null-checks
options. Change fixes the RET instruction causing the crash.
Patch by Serguei Katkov!
Reviewers: sanjoy, reames
Reviewed By: sanjoy
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D29390
llvm-svn: 293789
Summary:
This change allows a re-order of two intructions if their uses
are overlapped.
Patch by Serguei Katkov!
Reviewers: reames, sanjoy
Reviewed By: sanjoy
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D29120
llvm-svn: 293775
When choosing the best successor for a block, ordinarily we would have preferred
a block that preserves the CFG unless there is a strong probability the other
direction. For small blocks that can be duplicated we now skip that requirement
as well, subject to some simple frequency calculations.
Differential Revision: https://reviews.llvm.org/D28583
llvm-svn: 293716
Also add the ability to recognise PINSR(Vex, 0, Idx).
Targets shuffle combines won't replace multiple insertions with a bit mask until a depth of 3 or more, so we avoid codesize bloat.
The unnecessary vpblendw in clearupper8xi16a will be fixed in an upcoming patch.
llvm-svn: 293627
Summary:
In revision rL278321, ExecutionDepsFix learned how to pick a better
register for undef register reads, e.g. for instructions such as
`vcvtsi2sdq`. While this revision improved performance on a good number
of our benchmarks, it unfortunately also caused significant regressions
(up to 3x) on others. This regression turned out to be caused by loops
such as:
PH -> A -> B (xmm<Undef> -> xmm<Def>) -> C -> D -> EXIT
^ |
+----------------------------------+
In the previous version of the clearance calculation, we would visit
the blocks in order, remembering for each whether there were any
incoming backedges from blocks that we hadn't processed yet and if
so queuing up the block to be re-processed. However, for loop structures
such as the above, this is clearly insufficient, since the block B
does not have any unknown backedges, so we do not see the false
dependency from the previous interation's Def of xmm registers in B.
To fix this, we need to consider all blocks that are part of the loop
and reprocess them one the correct clearance values are known. As
an optimization, we also want to avoid reprocessing any later blocks
that are not part of the loop.
In summary, the iteration order is as follows:
Before: PH A B C D A'
Corrected (Naive): PH A B C D A' B' C' D'
Corrected (w/ optimization): PH A B C A' B' C' D
To facilitate this optimization we introduce two new counters for each
basic block. The first counts how many of it's predecssors have
completed primary processing. The second counts how many of its
predecessors have completed all processing (we will call such a block
*done*. Now, the criteria to reprocess a block is as follows:
- All Predecessors have completed primary processing
- For x the number of predecessors that have completed primary
processing *at the time of primary processing of this block*,
the number of predecessors that are done has reached x.
The intuition behind this criterion is as follows:
We need to perform primary processing on all predecessors in order to
find out any direct defs in those predecessors. When predecessors are
done, we also know that we have information about indirect defs (e.g.
in block B though that were inherited through B->C->A->B). However,
we can't wait for all predecessors to be done, since that would
cause cyclic dependencies. However, it is guaranteed that all those
predecessors that are prior to us in reverse postorder will be done
before us. Since we iterate of the basic blocks in reverse postorder,
the number x above, is precisely the count of the number of predecessors
prior to us in reverse postorder.
Reviewers: myatsina
Differential Revision: https://reviews.llvm.org/D28759
llvm-svn: 293571
Previously this test case fired an assertion in getNode because we tried to create an insert_subvector with both input types the same size and the index pointing to half the vector width.
llvm-svn: 293446
Replaces an xor+movd/movq with an xorps which will be shorter in codesize, avoid an int-fpu transfer, allow modern cores to fast path the result during decode and helps other combines recognise an all-zero vector.
The only reason I can think of that we'd want to keep scalar_to_vector in this case is to help recognise the upper elts are undef but this doesn't seem to be a problem.
Differential Revision: https://reviews.llvm.org/D29097
llvm-svn: 293438
PACKUSWB converts Signed word to Unsigned byte, (the same about DW) and it can't be used for umin+truncate pattern.
AVX-512 VPMOVUS* instructions fit the pattern since they convert Unsigned to Unsigned.
See https://llvm.org/bugs/show_bug.cgi?id=31773
Differential Revision: https://reviews.llvm.org/D29196
llvm-svn: 293431
The matching code tries to canonicalize XOR to the left, but if there are two XORs and only one is a vnot, this canonicalization can prevent matching.
llvm-svn: 293402
In r292621, the recommit fixes a bug related with live interval update
after the partial redundent copy is moved.
This recommit solves an additional bug related to the lack of update of
subranges.
The original patch is to solve the performance problem described in
PR27827. Register coalescing sometimes cannot remove a copy because of
interference. But if we can find a reverse copy in one of the predecessor
block of the copy, the copy is partially redundent and we may remove the
copy partially by moving it to the predecessor block without the
reverse copy.
Differential Revision: https://reviews.llvm.org/D28585
Re-apply r292621
Revert "Revert rL292621. Caused some internal build bot failures in apple."
This reverts commit r292984.
Original patch: Wei Mi <wmi@google.com>
Subrange fix: Mostly Matthias Braun <matze@braunis.de>
llvm-svn: 293353
This commit introduces a set of experimental intrinsics intended to prevent
optimizations that make assumptions about the rounding mode and floating point
exception behavior. These intrinsics will later be extended to specify
flush-to-zero behavior. More work is also required to model instruction
dependencies in machine code and to generate these instructions from clang
(when required by pragmas and/or command line options that are not currently
supported).
Differential Revision: https://reviews.llvm.org/D27028
llvm-svn: 293226
* Simplify Consecutive Merge Store Candidate Search
Now that address aliasing is much less conservative, push through
simplified store merging search and chain alias analysis which only
checks for parallel stores through the chain subgraph. This is cleaner
as the separation of non-interfering loads/stores from the
store-merging logic.
When merging stores search up the chain through a single load, and
finds all possible stores by looking down from through a load and a
TokenFactor to all stores visited.
This improves the quality of the output SelectionDAG and the output
Codegen (save perhaps for some ARM cases where we correctly constructs
wider loads, but then promotes them to float operations which appear
but requires more expensive constant generation).
Some minor peephole optimizations to deal with improved SubDAG shapes (listed below)
Additional Minor Changes:
1. Finishes removing unused AliasLoad code
2. Unifies the chain aggregation in the merged stores across code
paths
3. Re-add the Store node to the worklist after calling
SimplifyDemandedBits.
4. Increase GatherAllAliasesMaxDepth from 6 to 18. That number is
arbitrary, but seems sufficient to not cause regressions in
tests.
5. Remove Chain dependencies of Memory operations on CopyfromReg
nodes as these are captured by data dependence
6. Forward loads-store values through tokenfactors containing
{CopyToReg,CopyFromReg} Values.
7. Peephole to convert buildvector of extract_vector_elt to
extract_subvector if possible (see
CodeGen/AArch64/store-merge.ll)
8. Store merging for the ARM target is restricted to 32-bit as
some in some contexts invalid 64-bit operations are being
generated. This can be removed once appropriate checks are
added.
This finishes the change Matt Arsenault started in r246307 and
jyknight's original patch.
Many tests required some changes as memory operations are now
reorderable, improving load-store forwarding. One test in
particular is worth noting:
CodeGen/PowerPC/ppc64-align-long-double.ll - Improved load-store
forwarding converts a load-store pair into a parallel store and
a memory-realized bitcast of the same value. However, because we
lose the sharing of the explicit and implicit store values we
must create another local store. A similar transformation
happens before SelectionDAG as well.
Reviewers: arsenm, hfinkel, tstellarAMD, jyknight, nhaehnle
llvm-svn: 293184
The previous patch (https://reviews.llvm.org/rL289538) got reverted because of a bug. Chandler also requested some changes to the algorithm.
http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20161212/413479.html
This is an updated patch. The key difference is that collectBitProviders (renamed to calculateByteProvider) now collects the origin of one byte, not the whole value. It simplifies the implementation and allows to stop the traversal earlier if we know that the result won't be used.
From the original commit:
Match a pattern where a wide type scalar value is loaded by several narrow loads and combined by shifts and ors. Fold it into a single load or a load and a bswap if the targets supports it.
Assuming little endian target:
i8 *a = ...
i32 val = a[0] | (a[1] << 8) | (a[2] << 16) | (a[3] << 24)
=>
i32 val = *((i32)a)
i8 *a = ...
i32 val = (a[0] << 24) | (a[1] << 16) | (a[2] << 8) | a[3]
=>
i32 val = BSWAP(*((i32)a))
This optimization was discussed on llvm-dev some time ago in "Load combine pass" thread. We came to the conclusion that we want to do this transformation late in the pipeline because in presence of atomic loads load widening is irreversible transformation and it might hinder other optimizations.
Eventually we'd like to support folding patterns like this where the offset has a variable and a constant part:
i32 val = a[i] | (a[i + 1] << 8) | (a[i + 2] << 16) | (a[i + 3] << 24)
Matching the pattern above is easier at SelectionDAG level since address reassociation has already happened and the fact that the loads are adjacent is clear. Understanding that these loads are adjacent at IR level would have involved looking through geps/zexts/adds while looking at the addresses.
The general scheme is to match OR expressions by recursively calculating the origin of individual bytes which constitute the resulting OR value. If all the OR bytes come from memory verify that they are adjacent and match with little or big endian encoding of a wider value. If so and the load of the wider type (and bswap if needed) is allowed by the target generate a load and a bswap if needed.
Reviewed By: RKSimon, filcab, chandlerc
Differential Revision: https://reviews.llvm.org/D27861
llvm-svn: 293036
clang already emits this with -cl-no-signed-zeros, but codegen
doesn't do anything with it. Treat it like the other fast math
attributes, and change one place to use it.
llvm-svn: 293024
Matthias Braun