Florian Hahn
fbcf8a8cbb
[ConstraintElim] Add (UGE, var, 0) to unsigned system for new vars. ( #76262 )
...
The constraint system used for ConstraintElimination assumes all
varibles to be signed. This can cause missed optimization in the
unsigned system, due to missing the information that all variables are
unsigned (non-negative).
Variables can be marked as non-negative by adding Var >= 0 for all
variables. This is done for arguments on ConstraintInfo construction and
after adding new variables. This handles cases like the ones outlined in
https://discourse.llvm.org/t/why-does-llvm-not-perform-range-analysis-on-integer-values/74341
The original example shared above is now handled without this change,
but adding another variable means that instcombine won't be able to
simplify examples like https://godbolt.org/z/hTnra7zdY
Adding the extra variables comes with a slight compile-time increase
https://llvm-compile-time-tracker.com/compare.php?from=7568b36a2bc1a1e496ec29246966ffdfc3a8b87f&to=641a47f0acce7755e340447386013a2e086f03d9&stat=instructions:u
stage1-O3 stage1-ReleaseThinLTO stage1-ReleaseLTO-g stage1-O0-g
+0.04% +0.07% +0.05% +0.02%
stage2-O3 stage2-O0-g stage2-clang
+0.05% +0.05% +0.05%
https://github.com/llvm/llvm-project/pull/76262
2023-12-23 15:53:48 +01:00
Florian Hahn
e9a56ab316
[PhaseOrdering] Add test with removable chained conditions.
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Based on https://godbolt.org/z/hTnra7zdY , which is a slightly more
complicated version of the example from
https://discourse.llvm.org/t/why-does-llvm-not-perform-range-analysis-on-integer-values/74341
2023-12-22 19:44:20 +00:00
dewen
3b82336188
Revert "[PM] Execute IndVarSimplifyPass precede RessociatePass" ( #71617 )
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Reverts llvm/llvm-project#71054
2023-11-08 09:22:55 +08:00
dewen
e4d27d7f32
[PM] Execute IndVarSimplifyPass precede RessociatePass ( #71054 )
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ReassociatePass may clear nsw/nuw flags of some instructions, which may
have side effects on optimizations in IndVarSimplifyPass.
2023-11-08 09:21:17 +08:00
Arthur Eubanks
3e39cfe5b4
Revert "Revert "InstSimplify: Require instruction be parented""
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This reverts commit 0c03f48480f69b854f86d31235425b5cb71ac921.
Going to fix forward size regression instead due to more dependent patches needing to be reverted otherwise.
2023-06-16 13:53:31 -07:00
Arthur Eubanks
0c03f48480
Revert "InstSimplify: Require instruction be parented"
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This reverts commit 1536e299e63d7788f38117b0212ca50eb76d7a3b.
Causes large binary size regressions, see comments on https://reviews.llvm.org/rG1536e299e63d7788f38117b0212ca50eb76d7a3b .
2023-06-16 11:24:29 -07:00
Florian Hahn
6162f6e9ff
[ConstraintElim] Add additional monotonic phi tests.
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Add extra test coverage with cases that showed mis-compiles in earlier
versions of an upcoming patch. Also add tests for integer phis
2023-06-10 21:43:06 +01:00
