Dse mssa opt 2 #3613
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Dse mssa opt 2 #3613
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(cherry-picked from 1a2a7cc)
That's https://reviews.llvm.org/D90328 follow-up. This change eliminates writes to variables where the value that is being written is already stored in the variable. This achieves the goal by looping through all memory definitions in the current state and getting defining access from each of them. When there is defining access where the write instruction is identical to the original instruction it will remove this redundant write. For example: void f() { x = 1; if foo() { x = 1; g(); } else { h(); } } void g(); void h(); The second x=1 will be eliminated since it is rewriting 1 to x. This pass will produce this: void f() { x = 1; if foo() { g(); } else { h(); } } void g(); void h(); Differential Revision: https://reviews.llvm.org/D111727 (cherry-picked from f87e0c6)
This patch adds support to remove stores that write the same value as earlier memesets. It uses isOverwrite to check that a memset completely overwrites a later store. The candidate store must store the same bytewise value as the byte stored by the memset. Reviewed By: nikic Differential Revision: https://reviews.llvm.org/D112321 (cherry-picked from 274a9b0)
Add OR_None code to indicate that there is no overwrite. This has no any effect for current uses but will be used in one of the next patches building support for PHI translation. Reviewed By: fhahn Differential Revision: https://reviews.llvm.org/D105098 (cherry-picked from 47e2644)
This patch extends the code that walks memory defs upwards to find
clobbering accesses to also try to optimize the clobbering defining
access.
We should be able to find set the optimized access of our starting def
(KillingDef), if the following holds:
1. It is the first call of getDomMemoryDef for KillingDef (so Current
== KillingDef->getDefiningAccess().
2. No potentially aliasing defs are skipped.
Then if a (partly) aliasing def is encountered, it can be used as
optimized access for KillingDef. No further optimizations can be
applied to KillingDef.
I'd appreciate a careful look, as the existing documentation is not too
clear on what is expected for optimized accesses.
The motivation for this patch is to use the optimized accesses to cover
more cases of redundant stores as follow-up to D111727.
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D112313
(cherry-picked from 25dad10)
Using the optimized access enables additional optimizations in cases
where the defining access is a non-aliasing store.
Alternatively we could also walk upwards and skip non-aliasing defs
here, but my experiments so far showed that this will noticeably
increase compile-time for little extra gain compared to just using the
optimized access.
Improvements of dse.NumRedundantStores on MultiSource/CINT2006/CPF2006
on X86 with -O3:
test-suite...-typeset/consumer-typeset.test 1.00 76.00 7500.0%
test-suite.../Benchmarks/Bullet/bullet.test 3.00 12.00 300.0%
test-suite...006/453.povray/453.povray.test 3.00 6.00 100.0%
test-suite...telecomm-gsm/telecomm-gsm.test 1.00 2.00 100.0%
test-suite...ediabench/gsm/toast/toast.test 1.00 2.00 100.0%
test-suite...marks/7zip/7zip-benchmark.test 1.00 2.00 100.0%
test-suite...ications/JM/lencod/lencod.test 7.00 10.00 42.9%
test-suite...6/464.h264ref/464.h264ref.test 6.00 8.00 33.3%
test-suite...ications/JM/ldecod/ldecod.test 6.00 7.00 16.7%
test-suite...006/447.dealII/447.dealII.test 33.00 33.00 0.0%
test-suite...6/471.omnetpp/471.omnetpp.test NaN 1.00 nan%
test-suite...006/450.soplex/450.soplex.test NaN 2.00 nan%
test-suite.../CINT2006/403.gcc/403.gcc.test NaN 7.00 nan%
test-suite...lications/ClamAV/clamscan.test NaN 1.00 nan%
test-suite...CI_Purple/SMG2000/smg2000.test NaN 3.00 nan%
Follow-up to D111727.
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D112315
(cherry-picked from c9ad356)
This allows for better optimization of 'stores-of-existing-values' and possibly helps passes further down the pipeline. Reviewed By: asbirlea Differential Revision: https://reviews.llvm.org/D113712 (cherry-picked from 7de4104)
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@swift-ci please test |
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