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git_commit commit eac23a5b971362cda3c646e018b9f26d0bc1ff3a
Author: Florian Hahn <flo@fhahn.com>
Date: Thu Jan 16 15:57:01 2025 +0000

[libc++] Add assumption for align of begin and end pointers of vector. (#108961)

Missing information about begin and end pointers of std::vector can lead
to missed optimizations in LLVM.

This patch adds alignment assumptions at the point where the begin and
end pointers are loaded. If the pointers would not have the same
alignment, end might never get hit when incrementing begin.

See https://github.com/llvm/llvm-project/issues/101372 for a discussion
of missed range check optimizations in hardened mode.

Once https://github.com/llvm/llvm-project/pull/108958 lands, the created
`llvm.assume` calls for the alignment should be folded into the `load`
instructions, resulting in no extra instructions after InstCombine.

Co-authored-by: Louis Dionne <ldionne.2@gmail.com>
Filter

ldionne-old-macbook-results test results

Run Order Start Time Duration
Current 524051 2025-12-16T16:40:01 0:00:00
Previous 523851 2025-12-16T16:40:01 0:00:00
Baseline 485288 2025-12-16T16:40:01 0:00:00


Tests Summary

Status Group # # (B)
Performance Regressions 1 0
Performance Improvements 3 0
Added Tests 1 18
Unchanged Tests 85 72
Total Tests 90

Performance Regressions - execution_time Δ Previous Current σ Δ (B) σ (B)
710_omnetpp_r 2.37% 8.540 8.743 - 0.00% -

Performance Improvements - execution_time Δ Previous Current σ Δ (B) σ (B)
706_stockfish_r -1.39% 22.209 21.901 - 0.00% -
767_nest_r -1.38% 14.264 14.067 - 0.00% -
736_ocio_r -1.13% 16.317 16.133 - 0.00% -

Added Tests - execution_time
735_gem5_r

Added Tests - execution_time
706_stockfish_r
707_ntest_r
709_cactus_r
710_omnetpp_r
721_gcc_r
723_llvm_r
727_cppcheck_r
729_abc_r
731_astcenc_r
734_vpr_r
735_gem5_r
736_ocio_r
737_gmsh_r
748_flightdm_r
750_sealcrypto_r
753_ns3_r
766_femflow_r
767_nest_r


Report Time: 0.07s
Name Current %
706_stockfish_r 21.901 -1.39%
707_ntest_r 17.988 -
709_cactus_r 19.698 -
710_omnetpp_r 8.743 2.37%
721_gcc_r 12.929 -
723_llvm_r 11.448 -
727_cppcheck_r 24.456 -
729_abc_r 18.688 -
731_astcenc_r 10.025 -
734_vpr_r 15.445 -
735_gem5_r 13.435 -
736_ocio_r 16.133 -1.13%
737_gmsh_r 13.078 -
748_flightdm_r 8.917 -
750_sealcrypto_r 18.367 -
753_ns3_r 10.412 -
766_femflow_r 12.784 -
767_nest_r 14.067 -1.38%
Geometric Mean 14.290 -