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
Create a WasmDumper subclass of ObjDumper to support Webassembly binary
files.
Patch by Sam Clegg
Differential Revision: https://reviews.llvm.org/D27355
llvm-svn: 293569
- Move DEBUG_TYPE below includes
- Change unknown address space constant to be consistent with other
passes
- Grammar fixes in debug output
llvm-svn: 293567
combineX86ShufflesRecursively can still only handle a maximum of 2 shuffle inputs but everything before it now supports any number of shuffle inputs.
This will be necessary for combining OR(SHUFFLE, SHUFFLE) patterns.
llvm-svn: 293560
Summary: SamplePGO needs to check if it is legal to promote a target before it actually promotes it.
Reviewers: davidxl
Reviewed By: davidxl
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D29306
llvm-svn: 293559
Since we have no call support and late linking we can produce code
only for used symbols. This saves compilation time, size of the final
executable, and size of any intermediate dumps.
Run Internalize pass early in the opt pipeline followed by global
DCE pass. To enable it RT can pass -amdgpu-internalize-symbols option.
Differential Revision: https://reviews.llvm.org/D29214
llvm-svn: 293549
To better match the old darwin otool(1) behavior, when llvm-obdump(1) is used
with the -macho option and the input file is not an object file simply print
the file name and this message:
foo: is not an object file
and continue on to process other input files. Also in this case don’t exit
non-zero. This should help in some OSS projects' with autoconf scripts
that are expecting the old darwin otool(1) behavior.
rdar://26828015
llvm-svn: 293547
For some reason the exception selector register must be a pointer (that's
assumed by SDag); on the other hand, it gets moved into an IR-level type which
might be entirely different (i32 on AArch64). IRTranslator needs to be aware of
this.
llvm-svn: 293546
For targets with different addressing modes in each address space,
if this is dropped querying isLegalAddressingMode later with this
will give a nonsense result, breaking the isLegalUse assertions.
This is a candidate for the 4.0 release branch.
llvm-svn: 293542
This is worse if the original constant is an inline immediate.
This should also be done for 64-bit adds, but requires fixing
operand folding bugs first.
llvm-svn: 293540
Tablegen emitted a warning when the fast isel emitter created dead
code by emitting a pattern that has no predicate before a pattern
that has one.
This should be an error but was originally only a warning because the X86
backend had a buggy definition that unintentionally caused this to be hit
(PR21575). That has been fixed a while ago (r222094), so it's safe to
upgrade the warning to an error.
llvm-svn: 293534
Previously, we would hit UB (or the ISD::DELETED_NODE assert) if we
happened to replace a node during UpdateChains, because it would be
left in the list we were iterating over. This nulls out the pointer
when that happens so that we can avoid the issue.
Fixes llvm.org/PR31710
llvm-svn: 293522
To simplify/clarify memory ownership, make leaks (as one was found/fixed
recently) harder to write, etc.
(also, while I was there - removed a duplicate lookup in a container)
llvm-svn: 293506
